Formatter option is now composed of two data: flags (lower 16 bits) and indentation size (higher 16 bits).

DictType and ListType formatter use both indent and flag options.
Simple-store now makes a DictType from its data and its ToString() function returns dict.ToString()

ast.go

@@ -10,7 +10,6 @@ import (
 
 type Expr interface {
 	Eval(ctx ExprContext) (result any, err error)
-	eval(ctx ExprContext, preset bool) (result any, err error)
 	String() string
 }
 
@@ -106,16 +105,10 @@ func (self *ast) Finish() {
 }
 
 func (self *ast) Eval(ctx ExprContext) (result any, err error) {
-	return self.eval(ctx, true)
-}
-
-func (self *ast) eval(ctx ExprContext, preset bool) (result any, err error) {
 	self.Finish()
 
 	if self.root != nil {
-		if preset {
+		// initDefaultVars(ctx)
-			initDefaultVars(ctx)
-		}
 		if self.forest != nil {
 			for _, root := range self.forest {
 				if result, err = root.compute(ctx); err == nil {

bind-expr-functions.go

@@ -0,0 +1,58 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// function.go
+package expr
+
+// ---- Linking with Expr functions
+type exprFunctor struct {
+	baseFunctor
+	params []ExprFuncParam
+	expr   Expr
+	defCtx ExprContext
+}
+
+// func newExprFunctor(e Expr, params []string, ctx ExprContext) *exprFunctor {
+// 	return &exprFunctor{expr: e, params: params, defCtx: ctx}
+// }
+
+func newExprFunctor(e Expr, params []ExprFuncParam, ctx ExprContext) *exprFunctor {
+	return &exprFunctor{expr: e, params: params, defCtx: ctx}
+}
+
+func (functor *exprFunctor) Invoke(ctx ExprContext, name string, args []any) (result any, err error) {
+	if functor.defCtx != nil {
+		ctx.Merge(functor.defCtx)
+	}
+
+	for i, p := range functor.params {
+		if i < len(args) {
+			arg := args[i]
+			if funcArg, ok := arg.(Functor); ok {
+				// ctx.RegisterFunc(p, functor, 0, -1)
+				paramSpecs := funcArg.GetParams()
+				ctx.RegisterFunc(p.Name(), funcArg, TypeAny, paramSpecs)
+			} else {
+				ctx.UnsafeSetVar(p.Name(), arg)
+			}
+		} else {
+			ctx.UnsafeSetVar(p.Name(), nil)
+		}
+	}
+	result, err = functor.expr.Eval(ctx)
+	return
+}
+
+func CallExprFunction(parentCtx ExprContext, funcName string, params ...any) (v any, err error) {
+	ctx := cloneContext(parentCtx)
+	ctx.SetParent(parentCtx)
+
+	if err == nil {
+		if err = checkFunctionCall(ctx, funcName, &params); err == nil {
+			if v, err = ctx.Call(funcName, params); err == nil {
+				exportObjects(parentCtx, ctx)
+			}
+		}
+	}
+	return
+}

bind-go-functions.go

@@ -0,0 +1,19 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// bind-go-function.go
+package expr
+
+// ---- Linking with Go functions
+type golangFunctor struct {
+	baseFunctor
+	f FuncTemplate
+}
+
+func NewGolangFunctor(f FuncTemplate) *golangFunctor {
+	return &golangFunctor{f: f}
+}
+
+func (functor *golangFunctor) Invoke(ctx ExprContext, name string, args []any) (result any, err error) {
+	return functor.f(ctx, name, args)
+}

builtin-base.go

@@ -1,7 +1,7 @@
 // Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
 // All rights reserved.
 
-// func-builtins.go
+// builtin-base.go
 package expr
 
 import (
@@ -67,7 +67,7 @@ func boolFunc(ctx ExprContext, name string, args []any) (result any, err error)
 	case string:
 		result = len(v) > 0
 	default:
-		err = errCantConvert(name, v, "bool")
+		err = ErrCantConvert(name, v, "bool")
 	}
 	return
 }
@@ -90,7 +90,7 @@ func intFunc(ctx ExprContext, name string, args []any) (result any, err error) {
 			result = int64(i)
 		}
 	default:
-		err = errCantConvert(name, v, "int")
+		err = ErrCantConvert(name, v, "int")
 	}
 	return
 }
@@ -115,7 +115,7 @@ func decFunc(ctx ExprContext, name string, args []any) (result any, err error) {
 	case *FractionType:
 		result = v.toFloat()
 	default:
-		err = errCantConvert(name, v, "float")
+		err = ErrCantConvert(name, v, "float")
 	}
 	return
 }
@@ -127,9 +127,9 @@ func fractFunc(ctx ExprContext, name string, args []any) (result any, err error)
 		if len(args) > 1 {
 			var ok bool
 			if den, ok = args[1].(int64); !ok {
-				err = errExpectedGot(name, "integer", args[1])
+				err = ErrExpectedGot(name, "integer", args[1])
 			} else if den == 0 {
-				err = errFuncDivisionByZero(name)
+				err = ErrFuncDivisionByZero(name)
 			}
 		}
 		if err == nil {
@@ -148,7 +148,7 @@ func fractFunc(ctx ExprContext, name string, args []any) (result any, err error)
 	case *FractionType:
 		result = v
 	default:
-		err = errCantConvert(name, v, "float")
+		err = ErrCantConvert(name, v, "float")
 	}
 	return
 }
@@ -159,28 +159,28 @@ func iteratorFunc(ctx ExprContext, name string, args []any) (result any, err err
 
 func ImportBuiltinsFuncs(ctx ExprContext) {
 	anyParams := []ExprFuncParam{
-		newFuncParam(paramValue),
+		NewFuncParam(ParamValue),
 	}
 
-	ctx.RegisterFunc("isNil", newGolangFunctor(isNilFunc), typeBoolean, anyParams)
+	ctx.RegisterFunc("isNil", NewGolangFunctor(isNilFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("isInt", newGolangFunctor(isIntFunc), typeBoolean, anyParams)
+	ctx.RegisterFunc("isInt", NewGolangFunctor(isIntFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("isFloat", newGolangFunctor(isFloatFunc), typeBoolean, anyParams)
+	ctx.RegisterFunc("isFloat", NewGolangFunctor(isFloatFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("isBool", newGolangFunctor(isBoolFunc), typeBoolean, anyParams)
+	ctx.RegisterFunc("isBool", NewGolangFunctor(isBoolFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("isString", newGolangFunctor(isStringFunc), typeBoolean, anyParams)
+	ctx.RegisterFunc("isString", NewGolangFunctor(isStringFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("isFract", newGolangFunctor(isFractionFunc), typeBoolean, anyParams)
+	ctx.RegisterFunc("isFract", NewGolangFunctor(isFractionFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("isRational", newGolangFunctor(isRationalFunc), typeBoolean, anyParams)
+	ctx.RegisterFunc("isRational", NewGolangFunctor(isRationalFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("isList", newGolangFunctor(isListFunc), typeBoolean, anyParams)
+	ctx.RegisterFunc("isList", NewGolangFunctor(isListFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("isDict", newGolangFunctor(isDictionaryFunc), typeBoolean, anyParams)
+	ctx.RegisterFunc("isDict", NewGolangFunctor(isDictionaryFunc), TypeBoolean, anyParams)
 
-	ctx.RegisterFunc("bool", newGolangFunctor(boolFunc), typeBoolean, anyParams)
+	ctx.RegisterFunc("bool", NewGolangFunctor(boolFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("int", newGolangFunctor(intFunc), typeInt, anyParams)
+	ctx.RegisterFunc("int", NewGolangFunctor(intFunc), TypeInt, anyParams)
-	ctx.RegisterFunc("dec", newGolangFunctor(decFunc), typeFloat, anyParams)
+	ctx.RegisterFunc("dec", NewGolangFunctor(decFunc), TypeFloat, anyParams)
-	ctx.RegisterFunc("fract", newGolangFunctor(fractFunc), typeFraction, []ExprFuncParam{
+	ctx.RegisterFunc("fract", NewGolangFunctor(fractFunc), TypeFraction, []ExprFuncParam{
-		newFuncParam(paramValue),
+		NewFuncParam(ParamValue),
-		newFuncParamFlagDef("denominator", pfOptional, 1),
+		NewFuncParamFlagDef("denominator", PfDefault, 1),
 	})
 }
 
 func init() {
-	registerImport("base", ImportBuiltinsFuncs, "Base expression tools like isNil(), int(), etc.")
+	RegisterBuiltinModule("base", ImportBuiltinsFuncs, "Base expression tools like isNil(), int(), etc.")
 }

builtin-fmt.go

@@ -1,7 +1,7 @@
 // Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
 // All rights reserved.
 
-// func-fmt.go
+// builtin-fmt.go
 package expr
 
 import "fmt"
@@ -23,14 +23,14 @@ func printLnFunc(ctx ExprContext, name string, args []any) (result any, err erro
 }
 
 func ImportFmtFuncs(ctx ExprContext) {
-	ctx.RegisterFunc("print", newGolangFunctor(printFunc), typeInt, []ExprFuncParam{
+	ctx.RegisterFunc("print", NewGolangFunctor(printFunc), TypeInt, []ExprFuncParam{
-		newFuncParamFlag(paramItem, pfRepeat),
+		NewFuncParamFlag(ParamItem, PfRepeat),
 	})
-	ctx.RegisterFunc("println", newGolangFunctor(printLnFunc), typeInt, []ExprFuncParam{
+	ctx.RegisterFunc("println", NewGolangFunctor(printLnFunc), TypeInt, []ExprFuncParam{
-		newFuncParamFlag(paramItem, pfRepeat),
+		NewFuncParamFlag(ParamItem, PfRepeat),
 	})
 }
 
 func init() {
-	registerImport("fmt", ImportFmtFuncs, "String and console formatting functions")
+	RegisterBuiltinModule("fmt", ImportFmtFuncs, "String and console formatting functions")
 }

builtin-import.go

@@ -0,0 +1,75 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// builtin-import.go
+package expr
+
+import (
+	"io"
+	"os"
+)
+
+func importFunc(ctx ExprContext, name string, args []any) (result any, err error) {
+	return importGeneral(ctx, name, args)
+}
+
+func importAllFunc(ctx ExprContext, name string, args []any) (result any, err error) {
+	CtrlEnable(ctx, control_export_all)
+	return importGeneral(ctx, name, args)
+}
+
+func importGeneral(ctx ExprContext, name string, args []any) (result any, err error) {
+	dirList := buildSearchDirList("sources", ENV_EXPR_SOURCE_PATH)
+	result, err = doImport(ctx, name, dirList, NewArrayIterator(args))
+	return
+}
+
+func doImport(ctx ExprContext, name string, dirList []string, it Iterator) (result any, err error) {
+	var v any
+	var sourceFilepath string
+
+	for v, err = it.Next(); err == nil; v, err = it.Next() {
+		if err = checkStringParamExpected(name, v, it.Index()); err != nil {
+			break
+		}
+		if sourceFilepath, err = makeFilepath(v.(string), dirList); err != nil {
+			break
+		}
+		var file *os.File
+		if file, err = os.Open(sourceFilepath); err == nil {
+			defer file.Close()
+			var expr *ast
+			scanner := NewScanner(file, DefaultTranslations())
+			parser := NewParser()
+			if expr, err = parser.parseGeneral(scanner, true, true); err == nil {
+				result, err = expr.Eval(ctx)
+			}
+			if err != nil {
+				break
+			}
+		} else {
+			break
+		}
+	}
+	if err != nil {
+		if err == io.EOF {
+			err = nil
+		} else {
+			result = nil
+		}
+	}
+	return
+}
+
+func ImportImportFuncs(ctx ExprContext) {
+	ctx.RegisterFunc("import", NewGolangFunctor(importFunc), TypeAny, []ExprFuncParam{
+		NewFuncParamFlag(ParamFilepath, PfRepeat),
+	})
+	ctx.RegisterFunc("importAll", NewGolangFunctor(importAllFunc), TypeAny, []ExprFuncParam{
+		NewFuncParamFlag(ParamFilepath, PfRepeat),
+	})
+}
+
+func init() {
+	RegisterBuiltinModule("import", ImportImportFuncs, "Functions import() and include()")
+}

builtin-math-arith.go

@@ -1,7 +1,7 @@
 // Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
 // All rights reserved.
 
-// funcs-math.go
+// builtin-math-arith.go
 package expr
 
 import (
@@ -167,15 +167,15 @@ func mulFunc(ctx ExprContext, name string, args []any) (result any, err error) {
 }
 
 func ImportMathFuncs(ctx ExprContext) {
-	ctx.RegisterFunc("add", &golangFunctor{f: addFunc}, typeNumber, []ExprFuncParam{
+	ctx.RegisterFunc("add", &golangFunctor{f: addFunc}, TypeNumber, []ExprFuncParam{
-		newFuncParamFlagDef(paramValue, pfOptional|pfRepeat, int64(0)),
+		NewFuncParamFlagDef(ParamValue, PfDefault|PfRepeat, int64(0)),
 	})
 
-	ctx.RegisterFunc("mul", &golangFunctor{f: mulFunc}, typeNumber, []ExprFuncParam{
+	ctx.RegisterFunc("mul", &golangFunctor{f: mulFunc}, TypeNumber, []ExprFuncParam{
-		newFuncParamFlagDef(paramValue, pfOptional|pfRepeat, int64(1)),
+		NewFuncParamFlagDef(ParamValue, PfDefault|PfRepeat, int64(1)),
 	})
 }
 
 func init() {
-	registerImport("math.arith", ImportMathFuncs, "Functions add() and mul()")
+	RegisterBuiltinModule("math.arith", ImportMathFuncs, "Functions add() and mul()")
 }

builtin-os-file.go

@@ -1,7 +1,7 @@
 // Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
 // All rights reserved.
 
-// func-os.go
+// builtin-os-file.go
 package expr
 
 import (
@@ -92,7 +92,7 @@ func appendFileFunc(ctx ExprContext, name string, args []any) (result any, err e
 			result = &osWriter{fh: fh, writer: bufio.NewWriter(fh)}
 		}
 	} else {
-		err = errMissingFilePath("openFile")
+		err = errMissingFilePath("appendFile")
 	}
 	return
 }
@@ -187,28 +187,28 @@ func readFileFunc(ctx ExprContext, name string, args []any) (result any, err err
 }
 
 func ImportOsFuncs(ctx ExprContext) {
-	ctx.RegisterFunc("openFile", newGolangFunctor(openFileFunc), typeHandle, []ExprFuncParam{
+	ctx.RegisterFunc("fileOpen", NewGolangFunctor(openFileFunc), TypeHandle, []ExprFuncParam{
-		newFuncParam(paramFilepath),
+		NewFuncParam(ParamFilepath),
 	})
-	ctx.RegisterFunc("appendFile", newGolangFunctor(appendFileFunc), typeHandle, []ExprFuncParam{
+	ctx.RegisterFunc("fileAppend", NewGolangFunctor(appendFileFunc), TypeHandle, []ExprFuncParam{
-		newFuncParam(paramFilepath),
+		NewFuncParam(ParamFilepath),
 	})
-	ctx.RegisterFunc("createFile", newGolangFunctor(createFileFunc), typeHandle, []ExprFuncParam{
+	ctx.RegisterFunc("fileCreate", NewGolangFunctor(createFileFunc), TypeHandle, []ExprFuncParam{
-		newFuncParam(paramFilepath),
+		NewFuncParam(ParamFilepath),
 	})
-	ctx.RegisterFunc("writeFile", newGolangFunctor(writeFileFunc), typeInt, []ExprFuncParam{
+	ctx.RegisterFunc("fileWrite", NewGolangFunctor(writeFileFunc), TypeInt, []ExprFuncParam{
-		newFuncParam(typeHandle),
+		NewFuncParam(TypeHandle),
-		newFuncParamFlagDef(typeItem, pfOptional|pfRepeat, ""),
+		NewFuncParamFlagDef(TypeItem, PfDefault|PfRepeat, ""),
 	})
-	ctx.RegisterFunc("readFile", newGolangFunctor(readFileFunc), typeString, []ExprFuncParam{
+	ctx.RegisterFunc("fileRead", NewGolangFunctor(readFileFunc), TypeString, []ExprFuncParam{
-		newFuncParam(typeHandle),
+		NewFuncParam(TypeHandle),
-		newFuncParamFlagDef("limitCh", pfOptional, "\n"),
+		NewFuncParamFlagDef("limitCh", PfDefault, "\n"),
 	})
-	ctx.RegisterFunc("closeFile", newGolangFunctor(closeFileFunc), typeBoolean, []ExprFuncParam{
+	ctx.RegisterFunc("fileClose", NewGolangFunctor(closeFileFunc), TypeBoolean, []ExprFuncParam{
-		newFuncParam(typeHandle),
+		NewFuncParam(TypeHandle),
 	})
 }
 
 func init() {
-	registerImport("os.file", ImportOsFuncs, "Operating system file functions")
+	RegisterBuiltinModule("os.file", ImportOsFuncs, "Operating system file functions")
 }

builtin-string.go

@@ -1,7 +1,7 @@
 // Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
 // All rights reserved.
 
-// func-string.go
+// builtin-string.go
 package expr
 
 import (
@@ -21,7 +21,7 @@ func doJoinStr(funcName string, sep string, it Iterator) (result any, err error)
 		if s, ok := v.(string); ok {
 			sb.WriteString(s)
 		} else {
-			err = errExpectedGot(funcName, typeString, v)
+			err = ErrExpectedGot(funcName, TypeString, v)
 			return
 		}
 	}
@@ -45,13 +45,13 @@ func joinStrFunc(ctx ExprContext, name string, args []any) (result any, err erro
 			} else if it, ok := args[1].(Iterator); ok {
 				result, err = doJoinStr(name, sep, it)
 			} else {
-				err = errInvalidParameterValue(name, paramParts, args[1])
+				err = ErrInvalidParameterValue(name, ParamParts, args[1])
 			}
 		} else {
 			result, err = doJoinStr(name, sep, NewArrayIterator(args[1:]))
 		}
 	} else {
-		err = errWrongParamType(name, paramSeparator, typeString, args[0])
+		err = ErrWrongParamType(name, ParamSeparator, TypeString, args[0])
 	}
 	return
 }
@@ -63,14 +63,14 @@ func subStrFunc(ctx ExprContext, name string, args []any) (result any, err error
 	var ok bool
 
 	if source, ok = args[0].(string); !ok {
-		return nil, errWrongParamType(name, paramSource, typeString, args[0])
+		return nil, ErrWrongParamType(name, ParamSource, TypeString, args[0])
 	}
 
-	if start, err = toInt(args[1], name+"()"); err != nil {
+	if start, err = ToInt(args[1], name+"()"); err != nil {
 		return
 	}
 
-	if count, err = toInt(args[2], name+"()"); err != nil {
+	if count, err = ToInt(args[2], name+"()"); err != nil {
 		return
 	}
 
@@ -91,7 +91,7 @@ func trimStrFunc(ctx ExprContext, name string, args []any) (result any, err erro
 	var ok bool
 
 	if source, ok = args[0].(string); !ok {
-		return nil, errWrongParamType(name, paramSource, typeString, args[0])
+		return nil, ErrWrongParamType(name, ParamSource, TypeString, args[0])
 	}
 	result = strings.TrimSpace(source)
 	return
@@ -104,7 +104,7 @@ func startsWithStrFunc(ctx ExprContext, name string, args []any) (result any, er
 	result = false
 
 	if source, ok = args[0].(string); !ok {
-		return result, errWrongParamType(name, paramSource, typeString, args[0])
+		return result, ErrWrongParamType(name, ParamSource, TypeString, args[0])
 	}
 	for i, targetSpec := range args[1:] {
 		if target, ok := targetSpec.(string); ok {
@@ -127,7 +127,7 @@ func endsWithStrFunc(ctx ExprContext, name string, args []any) (result any, err
 	result = false
 
 	if source, ok = args[0].(string); !ok {
-		return result, errWrongParamType(name, paramSource, typeString, args[0])
+		return result, ErrWrongParamType(name, ParamSource, TypeString, args[0])
 	}
 	for i, targetSpec := range args[1:] {
 		if target, ok := targetSpec.(string); ok {
@@ -150,7 +150,7 @@ func splitStrFunc(ctx ExprContext, name string, args []any) (result any, err err
 	var ok bool
 
 	if source, ok = args[0].(string); !ok {
-		return result, errWrongParamType(name, paramSource, typeString, args[0])
+		return result, ErrWrongParamType(name, ParamSource, TypeString, args[0])
 	}
 
 	if sep, ok = args[1].(string); !ok {
@@ -182,42 +182,42 @@ func splitStrFunc(ctx ExprContext, name string, args []any) (result any, err err
 
 // Import above functions in the context
 func ImportStringFuncs(ctx ExprContext) {
-	ctx.RegisterFunc("joinStr", newGolangFunctor(joinStrFunc), typeString, []ExprFuncParam{
+	ctx.RegisterFunc("strJoin", NewGolangFunctor(joinStrFunc), TypeString, []ExprFuncParam{
-		newFuncParam(paramSeparator),
+		NewFuncParam(ParamSeparator),
-		newFuncParamFlag(paramItem, pfRepeat),
+		NewFuncParamFlag(ParamItem, PfRepeat),
 	})
 
-	ctx.RegisterFunc("subStr", newGolangFunctor(subStrFunc), typeString, []ExprFuncParam{
+	ctx.RegisterFunc("strSub", NewGolangFunctor(subStrFunc), TypeString, []ExprFuncParam{
-		newFuncParam(paramSource),
+		NewFuncParam(ParamSource),
-		newFuncParamFlagDef(paramStart, pfOptional, int64(0)),
+		NewFuncParamFlagDef(ParamStart, PfDefault, int64(0)),
-		newFuncParamFlagDef(paramCount, pfOptional, int64(-1)),
+		NewFuncParamFlagDef(ParamCount, PfDefault, int64(-1)),
 	})
 
-	ctx.RegisterFunc("splitStr", newGolangFunctor(splitStrFunc), "list of "+typeString, []ExprFuncParam{
+	ctx.RegisterFunc("strSplit", NewGolangFunctor(splitStrFunc), "list of "+TypeString, []ExprFuncParam{
-		newFuncParam(paramSource),
+		NewFuncParam(ParamSource),
-		newFuncParamFlagDef(paramSeparator, pfOptional, ""),
+		NewFuncParamFlagDef(ParamSeparator, PfDefault, ""),
-		newFuncParamFlagDef(paramCount, pfOptional, int64(-1)),
+		NewFuncParamFlagDef(ParamCount, PfDefault, int64(-1)),
 	})
 
-	ctx.RegisterFunc("trimStr", newGolangFunctor(trimStrFunc), typeString, []ExprFuncParam{
+	ctx.RegisterFunc("strTrim", NewGolangFunctor(trimStrFunc), TypeString, []ExprFuncParam{
-		newFuncParam(paramSource),
+		NewFuncParam(ParamSource),
 	})
 
-	ctx.RegisterFunc("startsWithStr", newGolangFunctor(startsWithStrFunc), typeBoolean, []ExprFuncParam{
+	ctx.RegisterFunc("strStartsWith", NewGolangFunctor(startsWithStrFunc), TypeBoolean, []ExprFuncParam{
-		newFuncParam(paramSource),
+		NewFuncParam(ParamSource),
-		newFuncParam(paramPrefix),
+		NewFuncParam(ParamPrefix),
-		newFuncParamFlag("other "+paramPrefix, pfRepeat),
+		NewFuncParamFlag("other "+ParamPrefix, PfRepeat),
 	})
 
-	ctx.RegisterFunc("endsWithStr", newGolangFunctor(endsWithStrFunc), typeBoolean, []ExprFuncParam{
+	ctx.RegisterFunc("strEndsWith", NewGolangFunctor(endsWithStrFunc), TypeBoolean, []ExprFuncParam{
-		newFuncParam(paramSource),
+		NewFuncParam(ParamSource),
-		newFuncParam(paramSuffix),
+		NewFuncParam(ParamSuffix),
-		newFuncParamFlag("other "+paramSuffix, pfRepeat),
+		NewFuncParamFlag("other "+ParamSuffix, PfRepeat),
 	})
 }
 
 // Register the import function in the import-register.
 // That will allow to import all function of this module by the "builtin" operator."
 func init() {
-	registerImport("string", ImportStringFuncs, "string utilities")
+	RegisterBuiltinModule("string", ImportStringFuncs, "string utilities")
 }

builtins-register.go

@@ -0,0 +1,48 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// builtins-register.go
+package expr
+
+import (
+	"fmt"
+)
+
+type builtinModule struct {
+	importFunc  func(ExprContext)
+	description string
+	imported    bool
+}
+
+func newBuiltinModule(importFunc func(ExprContext), description string) *builtinModule {
+	return &builtinModule{importFunc, description, false}
+}
+
+var builtinModuleRegister map[string]*builtinModule
+
+func RegisterBuiltinModule(name string, importFunc func(ExprContext), description string) {
+	if builtinModuleRegister == nil {
+		builtinModuleRegister = make(map[string]*builtinModule)
+	}
+	if _, exists := builtinModuleRegister[name]; exists {
+		panic(fmt.Errorf("module %q already registered", name))
+	}
+	builtinModuleRegister[name] = newBuiltinModule(importFunc, description)
+}
+
+func IterateBuiltinModules(op func(name, description string, imported bool) bool) {
+	if op != nil {
+		for name, mod := range builtinModuleRegister {
+			if !op(name, mod.description, mod.imported) {
+				break
+			}
+		}
+	}
+}
+
+// ----
+func init() {
+	if builtinModuleRegister == nil {
+		builtinModuleRegister = make(map[string]*builtinModule)
+	}
+}

common-errors.go

@@ -8,7 +8,7 @@ import (
 	"fmt"
 )
 
-func errTooFewParams(funcName string, minArgs, maxArgs, argCount int) (err error) {
+func ErrTooFewParams(funcName string, minArgs, maxArgs, argCount int) (err error) {
 	if maxArgs < 0 {
 		err = fmt.Errorf("%s(): too few params -- expected %d or more, got %d", funcName, minArgs, argCount)
 	} else {
@@ -17,39 +17,39 @@ func errTooFewParams(funcName string, minArgs, maxArgs, argCount int) (err error
 	return
 }
 
-func errTooMuchParams(funcName string, maxArgs, argCount int) (err error) {
+func ErrTooMuchParams(funcName string, maxArgs, argCount int) (err error) {
 	err = fmt.Errorf("%s(): too much params -- expected %d, got %d", funcName, maxArgs, argCount)
 	return
 }
 
 // --- General errors
 
-func errCantConvert(funcName string, value any, kind string) error {
+func ErrCantConvert(funcName string, value any, kind string) error {
-	return fmt.Errorf("%s(): can't convert %s to %s", funcName, typeName(value), kind)
+	return fmt.Errorf("%s(): can't convert %s to %s", funcName, TypeName(value), kind)
 }
 
-func errExpectedGot(funcName string, kind string, value any) error {
+func ErrExpectedGot(funcName string, kind string, value any) error {
-	return fmt.Errorf("%s() expected %s, got %s (%v)", funcName, kind, typeName(value), value)
+	return fmt.Errorf("%s(): expected %s, got %s (%v)", funcName, kind, TypeName(value), value)
 }
 
-func errFuncDivisionByZero(funcName string) error {
+func ErrFuncDivisionByZero(funcName string) error {
 	return fmt.Errorf("%s(): division by zero", funcName)
 }
 
-func errDivisionByZero() error {
+func ErrDivisionByZero() error {
 	return fmt.Errorf("division by zero")
 }
 
 // --- Parameter errors
 
-func errMissingRequiredParameter(funcName, paramName string) error {
+func ErrMissingRequiredParameter(funcName, paramName string) error {
-	return fmt.Errorf("%s() missing required parameter %q", funcName, paramName)
+	return fmt.Errorf("%s(): missing required parameter %q", funcName, paramName)
 }
 
-func errInvalidParameterValue(funcName, paramName string, paramValue any) error {
+func ErrInvalidParameterValue(funcName, paramName string, paramValue any) error {
-	return fmt.Errorf("%s() invalid value %s (%v) for parameter %q", funcName, typeName(paramValue), paramValue, paramName)
+	return fmt.Errorf("%s(): invalid value %s (%v) for parameter %q", funcName, TypeName(paramValue), paramValue, paramName)
 }
 
-func errWrongParamType(funcName, paramName, paramType string, paramValue any) error {
+func ErrWrongParamType(funcName, paramName, paramType string, paramValue any) error {
-	return fmt.Errorf("%s() the %q parameter must be a %s, got a %s (%v)", funcName, paramName, paramType, typeName(paramValue), paramValue)
+	return fmt.Errorf("%s(): the %q parameter must be a %s, got a %s (%v)", funcName, paramName, paramType, TypeName(paramValue), paramValue)
 }

common-params.go

@@ -5,17 +5,17 @@
 package expr
 
 const (
-	paramCount     = "count"
+	ParamCount     = "count"
-	paramItem      = "item"
+	ParamItem      = "item"
-	paramParts     = "parts"
+	ParamParts     = "parts"
-	paramSeparator = "separator"
+	ParamSeparator = "separator"
-	paramSource    = "source"
+	ParamSource    = "source"
-	paramSuffix    = "suffix"
+	ParamSuffix    = "suffix"
-	paramPrefix    = "prefix"
+	ParamPrefix    = "prefix"
-	paramStart     = "start"
+	ParamStart     = "start"
-	paramEnd       = "end"
+	ParamEnd       = "end"
-	paramValue     = "value"
+	ParamValue     = "value"
-	paramEllipsis  = "..."
+	ParamEllipsis  = "..."
-	paramFilepath  = "filepath"
+	ParamFilepath  = "filepath"
-	paramDirpath   = "dirpath"
+	ParamDirpath   = "dirpath"
 )

common-type-names.go

@@ -5,14 +5,16 @@
 package expr
 
 const (
-	typeAny      = "any"
+	TypeAny      = "any"
-	typeBoolean  = "boolean"
+	TypeBoolean  = "boolean"
-	typeFloat    = "float"
+	TypeFloat    = "float"
-	typeFraction = "fraction"
+	TypeFraction = "fraction"
-	typeHandle   = "handle"
+	TypeHandle   = "handle"
-	typeInt      = "integer"
+	TypeInt      = "integer"
-	typeItem     = "item"
+	TypeItem     = "item"
-	typeNumber   = "number"
+	TypeNumber   = "number"
-	typePair     = "pair"
+	TypePair     = "pair"
-	typeString   = "string"
+	TypeString   = "string"
+	TypeListOf = "list-of-"
+	TypeListOfStrings = "list-of-strings"
 )

context-helpers.go

@@ -22,13 +22,11 @@ func exportFunc(ctx ExprContext, name string, info ExprFunc) {
 	if name[0] == '@' {
 		name = name[1:]
 	}
-	// ctx.RegisterFunc(name, info.Functor(), info.MinArgs(), info.MaxArgs())
-	// ctx.RegisterFuncInfo(name, info)
 	ctx.RegisterFunc(name, info.Functor(), info.ReturnType(), info.Params())
 }
 
 func exportObjects(destCtx, sourceCtx ExprContext) {
-	exportAll := isEnabled(sourceCtx, control_export_all)
+	exportAll := CtrlIsEnabled(sourceCtx, control_export_all)
 	// fmt.Printf("Exporting from sourceCtx [%p] to destCtx [%p] -- exportAll=%t\n", sourceCtx, destCtx, exportAll)
 	// Export variables
 	for _, refName := range sourceCtx.EnumVars(func(name string) bool { return exportAll || name[0] == '@' }) {

context.go

@@ -16,6 +16,7 @@ type Functor interface {
 type ExprFuncParam interface {
 	Name() string
 	Type() string
+	IsDefault() bool
 	IsOptional() bool
 	IsRepeat() bool
 	DefaultValue() any
@@ -36,6 +37,8 @@ type ExprFunc interface {
 type ExprContext interface {
 	Clone() ExprContext
 	Merge(ctx ExprContext)
+	SetParent(ctx ExprContext)
+	GetParent() (ctx ExprContext)
 	GetVar(varName string) (value any, exists bool)
 	SetVar(varName string, value any)
 	UnsafeSetVar(varName string, value any)

control.go

@@ -4,13 +4,13 @@
 // control.go
 package expr
 
-import "strings"
-
 // Preset control variables
 const (
-	ControlLastResult   = "last"
+	ControlPreset        = "_preset"
-	ControlBoolShortcut = "_bool_shortcut"
+	ControlLastResult    = "last"
-	ControlImportPath   = "_import_path"
+	ControlBoolShortcut  = "_bool_shortcut"
+	ControlSearchPath    = "_search_path"
+	ControlParentContext = "_parent_context"
 )
 
 // Other control variables
@@ -20,43 +20,14 @@ const (
 
 // Initial values
 const (
-	init_import_path = "~/.local/lib/go-pkg/expr:/usr/local/lib/go-pkg/expr:/usr/lib/go-pkg/expr"
+	init_search_path = "~/.local/lib/go-pkg/expr:/usr/local/lib/go-pkg/expr:/usr/lib/go-pkg/expr"
 )
 
 func initDefaultVars(ctx ExprContext) {
+	if _, exists := ctx.GetVar(ControlPreset); exists {
+		return
+	}
+	ctx.SetVar(ControlPreset, true)
 	ctx.SetVar(ControlBoolShortcut, true)
-	ctx.SetVar(ControlImportPath, init_import_path)
+	ctx.SetVar(ControlSearchPath, init_search_path)
-}
-
-func enable(ctx ExprContext, name string) {
-	if strings.HasPrefix(name, "_") {
-		ctx.SetVar(name, true)
-	} else {
-		ctx.SetVar("_"+name, true)
-	}
-}
-
-func disable(ctx ExprContext, name string) {
-	if strings.HasPrefix(name, "_") {
-		ctx.SetVar(name, false)
-	} else {
-		ctx.SetVar("_"+name, false)
-	}
-}
-
-func isEnabled(ctx ExprContext, name string) (status bool) {
-	if v, exists := ctx.GetVar(name); exists {
-		if b, ok := v.(bool); ok {
-			status = b
-		}
-	}
-	return
-}
-
-func getControlString(ctx ExprContext, name string) (s string, exists bool) {
-	var v any
-	if v, exists = ctx.GetVar(name); exists {
-		s, exists = v.(string)
-	}
-	return
 }

dict-type.go

@@ -12,6 +12,12 @@ import (
 
 type DictType map[any]any
 
+func MakeDict() (dict *DictType) {
+	d := make(DictType)
+	dict = &d
+	return
+}
+
 func newDict(dictAny map[any]*term) (dict *DictType) {
 	var d DictType
 	if dictAny != nil {
@@ -26,42 +32,52 @@ func newDict(dictAny map[any]*term) (dict *DictType) {
 	return
 }
 
-func (dict *DictType) toMultiLine(sb *strings.Builder, indent int) {
+func (dict *DictType) toMultiLine(sb *strings.Builder, opt FmtOpt) {
-	sb.WriteString(strings.Repeat("\t", indent))
+	indent := GetFormatIndent(opt)
-	sb.WriteString("{\n")
+	flags := GetFormatFlags(opt)
+	//sb.WriteString(strings.Repeat("  ", indent))
+	sb.WriteByte('{')
 
-	first := true
+	if len(*dict) > 0 {
-	for name, value := range *dict {
+		innerOpt := MakeFormatOptions(flags, indent+1)
-		if first {
+		nest := strings.Repeat("  ", indent+1)
-			first = false
+		sb.WriteByte('\n')
-		} else {
-			sb.WriteByte(',')
-			sb.WriteByte('\n')
-		}
 
-		sb.WriteString(strings.Repeat("\t", indent+1))
+		first := true
-		if key, ok := name.(string); ok {
+		for name, value := range *dict {
-			sb.WriteString(string('"') + key + string('"'))
+			if first {
-		} else {
+				first = false
-			sb.WriteString(fmt.Sprintf("%v", name))
+			} else {
-		}
+				sb.WriteByte(',')
-		sb.WriteString(": ")
+				sb.WriteByte('\n')
-		if f, ok := value.(Formatter); ok {
+			}
-			sb.WriteString(f.ToString(MultiLine))
+
-		} else if _, ok = value.(Functor); ok {
+			sb.WriteString(nest)
-			sb.WriteString("func(){}")
+			if key, ok := name.(string); ok {
-		} else {
+				sb.WriteString(string('"') + key + string('"'))
-			sb.WriteString(fmt.Sprintf("%v", value))
+			} else {
+				sb.WriteString(fmt.Sprintf("%v", name))
+			}
+			sb.WriteString(": ")
+			if f, ok := value.(Formatter); ok {
+				sb.WriteString(f.ToString(innerOpt))
+			} else if _, ok = value.(Functor); ok {
+				sb.WriteString("func(){}")
+			} else {
+				sb.WriteString(fmt.Sprintf("%v", value))
+			}
 		}
+		sb.WriteByte('\n')
+		sb.WriteString(strings.Repeat("  ", indent))
 	}
-	sb.WriteString(strings.Repeat("\t", indent))
+	sb.WriteString("}")
-	sb.WriteString("\n}")
 }
 
 func (dict *DictType) ToString(opt FmtOpt) string {
 	var sb strings.Builder
-	if opt&MultiLine != 0 {
+	flags := GetFormatFlags(opt)
-		dict.toMultiLine(&sb, 0)
+	if flags&MultiLine != 0 {
+		dict.toMultiLine(&sb, opt)
 	} else {
 		sb.WriteByte('{')
 		first := true
@@ -124,7 +140,12 @@ func (dict *DictType) merge(second *DictType) {
 }
 
 func (dict *DictType) setItem(key any, value any) (err error) {
-	(*dict)[key]=value
+	(*dict)[key] = value
 	return
 }
 
+////////////////
+
+type DictFormat interface {
+	ToDict() *DictType
+}

formatter.go

@@ -6,7 +6,7 @@ package expr
 
 import "fmt"
 
-type FmtOpt uint16
+type FmtOpt uint32 // lower 16 bits hold a bit-mask, higher 16 bits hold an indentation number
 
 const (
 	TTY FmtOpt = 1 << iota
@@ -30,6 +30,18 @@ func TruncateString(s string) (trunc string) {
 	return
 }
 
+func MakeFormatOptions(flags FmtOpt, indent int) FmtOpt {
+	return FmtOpt(indent<<16) | flags
+}
+
+func GetFormatFlags(opt FmtOpt) FmtOpt {
+	return opt & 0xFFFF
+}
+
+func GetFormatIndent(opt FmtOpt) int {
+	return int(opt >> 16)
+}
+
 type Formatter interface {
 	ToString(options FmtOpt) string
 }
@@ -51,7 +63,7 @@ type Typer interface {
 	TypeName() string
 }
 
-func typeName(v any) (name string) {
+func TypeName(v any) (name string) {
 	if v == nil {
 		name = "nil"
 	} else if typer, ok := v.(Typer); ok {

fraction-type.go

@@ -70,7 +70,7 @@ func makeGeneratingFraction(s string) (f *FractionType, err error) {
 			}
 			for _, c := range dec[0:lsd] {
 				if c < '0' || c > '9' {
-					return nil, errExpectedGot("fract", "digit", c)
+					return nil, ErrExpectedGot("fract", "digit", c)
 				}
 				num = num*10 + int64(c-'0')
 				den = den * 10
@@ -81,7 +81,7 @@ func makeGeneratingFraction(s string) (f *FractionType, err error) {
 			mul := int64(1)
 			for _, c := range subParts[0] {
 				if c < '0' || c > '9' {
-					return nil, errExpectedGot("fract", "digit", c)
+					return nil, ErrExpectedGot("fract", "digit", c)
 				}
 				num = num*10 + int64(c-'0')
 				sub = sub*10 + int64(c-'0')
@@ -94,7 +94,7 @@ func makeGeneratingFraction(s string) (f *FractionType, err error) {
 				p := subParts[1][0 : len(subParts[1])-1]
 				for _, c := range p {
 					if c < '0' || c > '9' {
-						return nil, errExpectedGot("fract", "digit", c)
+						return nil, ErrExpectedGot("fract", "digit", c)
 					}
 					num = num*10 + int64(c-'0')
 					den = den*10 + 9
@@ -212,7 +212,7 @@ func anyToFract(v any) (f *FractionType, err error) {
 		}
 	}
 	if f == nil {
-		err = errExpectedGot("fract", typeFraction, v)
+		err = ErrExpectedGot("fract", TypeFraction, v)
 	}
 	return
 }

func-import.go

@@ -1,150 +0,0 @@
-// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
-// All rights reserved.
-
-// func-import.go
-package expr
-
-import (
-	"errors"
-	"fmt"
-	"io"
-	"os"
-	"path"
-	"path/filepath"
-	"strings"
-)
-
-const ENV_EXPR_PATH = "EXPR_PATH"
-
-func importFunc(ctx ExprContext, name string, args []any) (result any, err error) {
-	return importGeneral(ctx, name, args)
-}
-
-func importAllFunc(ctx ExprContext, name string, args []any) (result any, err error) {
-	enable(ctx, control_export_all)
-	return importGeneral(ctx, name, args)
-}
-
-func importGeneral(ctx ExprContext, name string, args []any) (result any, err error) {
-	var dirList []string
-
-	dirList = addEnvImportDirs(dirList)
-	dirList = addPresetImportDirs(ctx, dirList)
-	result, err = doImport(ctx, name, dirList, NewArrayIterator(args))
-	return
-}
-
-func checkStringParamExpected(funcName string, paramValue any, paramPos int) (err error) {
-	if !(IsString(paramValue) /*|| isList(paramValue)*/) {
-		err = fmt.Errorf("%s(): param nr %d has wrong type %T, string expected", funcName, paramPos+1, paramValue)
-	}
-	return
-}
-
-func addEnvImportDirs(dirList []string) []string {
-	if dirSpec, exists := os.LookupEnv(ENV_EXPR_PATH); exists {
-		dirs := strings.Split(dirSpec, ":")
-		if dirList == nil {
-			dirList = dirs
-		} else {
-			dirList = append(dirList, dirs...)
-		}
-	}
-	return dirList
-}
-
-func addPresetImportDirs(ctx ExprContext, dirList []string) []string {
-	if dirSpec, exists := getControlString(ctx, ControlImportPath); exists {
-		dirs := strings.Split(dirSpec, ":")
-		if dirList == nil {
-			dirList = dirs
-		} else {
-			dirList = append(dirList, dirs...)
-		}
-	}
-	return dirList
-}
-
-func isFile(filePath string) bool {
-	info, err := os.Stat(filePath)
-	return (err == nil || errors.Is(err, os.ErrExist)) && info.Mode().IsRegular()
-}
-
-func searchAmongPath(filename string, dirList []string) (filePath string) {
-	for _, dir := range dirList {
-		if fullPath := path.Join(dir, filename); isFile(fullPath) {
-			filePath = fullPath
-			break
-		}
-	}
-	return
-}
-
-func isPathRelative(filePath string) bool {
-	unixPath := filepath.ToSlash(filePath)
-	return strings.HasPrefix(unixPath, "./") || strings.HasPrefix(unixPath, "../")
-}
-
-func makeFilepath(filename string, dirList []string) (filePath string, err error) {
-	if path.IsAbs(filename) || isPathRelative(filename) {
-		if isFile(filename) {
-			filePath = filename
-		}
-	} else {
-		filePath = searchAmongPath(filename, dirList)
-	}
-	if len(filePath) == 0 {
-		err = fmt.Errorf("source file %q not found", filename)
-	}
-	return
-}
-
-func doImport(ctx ExprContext, name string, dirList []string, it Iterator) (result any, err error) {
-	var v any
-	var sourceFilepath string
-
-	for v, err = it.Next(); err == nil; v, err = it.Next() {
-		if err = checkStringParamExpected(name, v, it.Index()); err != nil {
-			break
-		}
-		if sourceFilepath, err = makeFilepath(v.(string), dirList); err != nil {
-			break
-		}
-		var file *os.File
-		if file, err = os.Open(sourceFilepath); err == nil {
-			defer file.Close()
-			var expr *ast
-			scanner := NewScanner(file, DefaultTranslations())
-			parser := NewParser(ctx)
-			if expr, err = parser.parseGeneral(scanner, true, true); err == nil {
-				result, err = expr.eval(ctx, false)
-			}
-			if err != nil {
-				break
-			}
-		} else {
-			break
-		}
-	}
-	if err != nil {
-		if err == io.EOF {
-			err = nil
-		} else {
-			result = nil
-		}
-	}
-	return
-}
-
-func ImportImportFuncs(ctx ExprContext) {
-	ctx.RegisterFunc("import", newGolangFunctor(importFunc), typeAny, []ExprFuncParam{
-		newFuncParamFlag(paramFilepath, pfRepeat),
-	})
-	ctx.RegisterFunc("importAll", newGolangFunctor(importAllFunc), typeAny, []ExprFuncParam{
-		newFuncParamFlag(paramFilepath, pfRepeat),
-	})
-}
-
-func init() {
-	registerImport("import", ImportImportFuncs, "Functions import() and include()")
-}

function.go

@@ -21,7 +21,7 @@ func (functor *baseFunctor) ToString(opt FmtOpt) (s string) {
 	if functor.info != nil {
 		s = functor.info.ToString(opt)
 	} else {
-		s = "func() {<body>}"
+		s = "func() {}"
 	}
 	return s
 }
@@ -42,65 +42,13 @@ func (functor *baseFunctor) GetFunc() ExprFunc {
 	return functor.info
 }
 
-// ---- Linking with Go functions
-type golangFunctor struct {
-	baseFunctor
-	f FuncTemplate
-}
-
-func newGolangFunctor(f FuncTemplate) *golangFunctor {
-	return &golangFunctor{f: f}
-}
-
-func (functor *golangFunctor) Invoke(ctx ExprContext, name string, args []any) (result any, err error) {
-	return functor.f(ctx, name, args)
-}
-
-// ---- Linking with Expr functions
-type exprFunctor struct {
-	baseFunctor
-	params []ExprFuncParam
-	expr   Expr
-	defCtx ExprContext
-}
-
-// func newExprFunctor(e Expr, params []string, ctx ExprContext) *exprFunctor {
-// 	return &exprFunctor{expr: e, params: params, defCtx: ctx}
-// }
-
-func newExprFunctor(e Expr, params []ExprFuncParam, ctx ExprContext) *exprFunctor {
-	return &exprFunctor{expr: e, params: params, defCtx: ctx}
-}
-
-func (functor *exprFunctor) Invoke(ctx ExprContext, name string, args []any) (result any, err error) {
-	if functor.defCtx != nil {
-		ctx.Merge(functor.defCtx)
-	}
-
-	for i, p := range functor.params {
-		if i < len(args) {
-			arg := args[i]
-			if funcArg, ok := arg.(Functor); ok {
-				// ctx.RegisterFunc(p, functor, 0, -1)
-				paramSpecs := funcArg.GetParams()
-				ctx.RegisterFunc(p.Name(), funcArg, typeAny, paramSpecs)
-			} else {
-				ctx.UnsafeSetVar(p.Name(), arg)
-			}
-		} else {
-			ctx.UnsafeSetVar(p.Name(), nil)
-		}
-	}
-	result, err = functor.expr.eval(ctx, false)
-	return
-}
-
 // ---- Function Parameters
 type paramFlags uint16
 
 const (
-	pfOptional paramFlags = 1 << iota
+	PfDefault paramFlags = 1 << iota
-	pfRepeat
+	PfOptional
+	PfRepeat
 )
 
 type funcParamInfo struct {
@@ -109,15 +57,15 @@ type funcParamInfo struct {
 	defaultValue any
 }
 
-func newFuncParam(name string) ExprFuncParam {
+func NewFuncParam(name string) ExprFuncParam {
 	return &funcParamInfo{name: name}
 }
 
-func newFuncParamFlag(name string, flags paramFlags) ExprFuncParam {
+func NewFuncParamFlag(name string, flags paramFlags) ExprFuncParam {
 	return &funcParamInfo{name: name, flags: flags}
 }
 
-func newFuncParamFlagDef(name string, flags paramFlags, defValue any) *funcParamInfo {
+func NewFuncParamFlagDef(name string, flags paramFlags, defValue any) *funcParamInfo {
 	return &funcParamInfo{name: name, flags: flags, defaultValue: defValue}
 }
 
@@ -126,15 +74,19 @@ func (param *funcParamInfo) Name() string {
 }
 
 func (param *funcParamInfo) Type() string {
-	return "any"
+	return TypeAny
+}
+
+func (param *funcParamInfo) IsDefault() bool {
+	return (param.flags & PfDefault) != 0
 }
 
 func (param *funcParamInfo) IsOptional() bool {
-	return (param.flags & pfOptional) != 0
+	return (param.flags & PfOptional) != 0
 }
 
 func (param *funcParamInfo) IsRepeat() bool {
-	return (param.flags & pfRepeat) != 0
+	return (param.flags & PfRepeat) != 0
 }
 
 func (param *funcParamInfo) DefaultValue() any {
@@ -159,7 +111,7 @@ func newFuncInfo(name string, functor Functor, returnType string, params []ExprF
 			if maxArgs == -1 {
 				return nil, fmt.Errorf("no more params can be specified after the ellipsis symbol: %q", p.Name())
 			}
-			if p.IsOptional() {
+			if p.IsDefault() || p.IsOptional() {
 				maxArgs++
 			} else if maxArgs == minArgs {
 				minArgs++
@@ -207,7 +159,7 @@ func (info *funcInfo) ToString(opt FmtOpt) string {
 			}
 			sb.WriteString(p.Name())
 
-			if p.IsOptional() {
+			if p.IsDefault() {
 				sb.WriteByte('=')
 				if s, ok := p.DefaultValue().(string); ok {
 					sb.WriteByte('"')
@@ -226,9 +178,9 @@ func (info *funcInfo) ToString(opt FmtOpt) string {
 	if len(info.returnType) > 0 {
 		sb.WriteString(info.returnType)
 	} else {
-		sb.WriteString(typeAny)
+		sb.WriteString(TypeAny)
 	}
-	sb.WriteString(" {<body>}")
+	sb.WriteString(" {}")
 	return sb.String()
 }
 

global-context.go

@@ -4,13 +4,16 @@
 // global-context.go
 package expr
 
-import "path/filepath"
+import (
+	"path/filepath"
+	"strings"
+)
 
 var globalCtx *SimpleStore
 
 func ImportInContext(name string) (exists bool) {
-	var mod *module
+	var mod *builtinModule
-	if mod, exists = moduleRegister[name]; exists {
+	if mod, exists = builtinModuleRegister[name]; exists {
 		mod.importFunc(globalCtx)
 		mod.imported = true
 	}
@@ -19,7 +22,7 @@ func ImportInContext(name string) (exists bool) {
 
 func ImportInContextByGlobPattern(pattern string) (count int, err error) {
 	var matched bool
-	for name, mod := range moduleRegister {
+	for name, mod := range builtinModuleRegister {
 		if matched, err = filepath.Match(pattern, name); err == nil {
 			if matched {
 				count++
@@ -63,7 +66,78 @@ func GetFuncInfo(ctx ExprContext, name string) (item ExprFunc, exists bool, owne
 	return
 }
 
+func GlobalCtrlSet(name string, newValue any) (currentValue any) {
+	if !strings.HasPrefix(name, "_") {
+		name = "_" + name
+	}
+	currentValue, _ = globalCtx.GetVar(name)
+
+	globalCtx.SetVar(name, newValue)
+	return currentValue
+}
+
+func GlobalCtrlGet(name string) (currentValue any) {
+	if !strings.HasPrefix(name, "_") {
+		name = "_" + name
+	}
+	currentValue, _ = globalCtx.GetVar(name)
+	return currentValue
+}
+
+func CtrlEnable(ctx ExprContext, name string) (currentStatus bool) {
+	if !strings.HasPrefix(name, "_") {
+		name = "_" + name
+	}
+	if v, exists := ctx.GetVar(name); exists && IsBool(v) {
+		currentStatus, _ = v.(bool)
+	}
+
+	ctx.SetVar(name, true)
+	return currentStatus
+}
+
+func CtrlDisable(ctx ExprContext, name string) (currentStatus bool) {
+	if !strings.HasPrefix(name, "_") {
+		name = "_" + name
+	}
+	if v, exists := ctx.GetVar(name); exists && IsBool(v) {
+		currentStatus, _ = v.(bool)
+	}
+
+	ctx.SetVar(name, false)
+	return currentStatus
+}
+
+func CtrlIsEnabled(ctx ExprContext, name string) (status bool) {
+	var v any
+	var exists bool
+
+	if !strings.HasPrefix(name, "_") {
+		name = "_" + name
+	}
+
+	if v, exists = ctx.GetVar(name); !exists {
+		v, exists = globalCtx.GetVar(name)
+	}
+
+	if exists {
+		if b, ok := v.(bool); ok {
+			status = b
+		}
+	}
+	return
+}
+
+func getControlString(name string) (s string, exists bool) {
+	var v any
+	if v, exists = globalCtx.GetVar(name); exists {
+		s, exists = v.(string)
+	}
+	return
+}
+
 func init() {
 	globalCtx = NewSimpleStore()
+	initDefaultVars(globalCtx)
 	ImportBuiltinsFuncs(globalCtx)
 }

helpers.go

@@ -16,10 +16,10 @@ func EvalString(ctx ExprContext, source string) (result any, err error) {
 
 	r := strings.NewReader(source)
 	scanner := NewScanner(r, DefaultTranslations())
-	parser := NewParser(ctx)
+	parser := NewParser()
 
 	if tree, err = parser.Parse(scanner); err == nil {
-		result, err = tree.eval(ctx, true)
+		result, err = tree.Eval(ctx)
 	}
 	return
 }
@@ -38,10 +38,10 @@ func EvalStringV(source string, args []Arg) (result any, err error) {
 	for _, arg := range args {
 		if isFunc(arg.Value) {
 			if f, ok := arg.Value.(FuncTemplate); ok {
-				functor := newGolangFunctor(f)
+				functor := NewGolangFunctor(f)
 				// ctx.RegisterFunc(arg.Name, functor, 0, -1)
-				ctx.RegisterFunc(arg.Name, functor, typeAny, []ExprFuncParam{
+				ctx.RegisterFunc(arg.Name, functor, TypeAny, []ExprFuncParam{
-					newFuncParamFlagDef(paramValue, pfOptional|pfRepeat, 0),
+					NewFuncParamFlagDef(ParamValue, PfDefault|PfRepeat, 0),
 				})
 			} else {
 				err = fmt.Errorf("invalid function specification: %q", arg.Name)
@@ -68,7 +68,7 @@ func EvalStringV(source string, args []Arg) (result any, err error) {
 func EvalStream(ctx ExprContext, r io.Reader) (result any, err error) {
 	var tree *ast
 	scanner := NewScanner(r, DefaultTranslations())
-	parser := NewParser(ctx)
+	parser := NewParser()
 
 	if tree, err = parser.Parse(scanner); err == nil {
 		result, err = tree.Eval(ctx)

import-utils.go

@@ -0,0 +1,104 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// import-utils.go
+package expr
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path"
+	"path/filepath"
+	"strings"
+)
+
+const (
+	ENV_EXPR_SOURCE_PATH = "EXPR_PATH"
+	ENV_EXPR_PLUGIN_PATH = "EXPR_PLUGIN_PATH"
+)
+
+func checkStringParamExpected(funcName string, paramValue any, paramPos int) (err error) {
+	if !(IsString(paramValue) /*|| isList(paramValue)*/) {
+		err = fmt.Errorf("%s(): param nr %d has wrong type %s, string expected", funcName, paramPos+1, TypeName(paramValue))
+	}
+	return
+}
+
+func addSourceEnvImportDirs(varName string, dirList []string) []string {
+	return addEnvImportDirs(ENV_EXPR_SOURCE_PATH, dirList)
+}
+
+func addPluginEnvImportDirs(varName string, dirList []string) []string {
+	return addEnvImportDirs(ENV_EXPR_PLUGIN_PATH, dirList)
+}
+
+func addEnvImportDirs(envVarName string, dirList []string) []string {
+	if dirSpec, exists := os.LookupEnv(envVarName); exists {
+		dirs := strings.Split(dirSpec, ":")
+		if dirList == nil {
+			dirList = dirs
+		} else {
+			dirList = append(dirList, dirs...)
+		}
+	}
+	return dirList
+}
+
+func addSearchDirs(endingPath string, dirList []string) []string {
+	if dirSpec, exists := getControlString(ControlSearchPath); exists {
+		dirs := strings.Split(dirSpec, ":")
+		if dirList == nil {
+			dirList = dirs
+		} else {
+			if len(endingPath) > 0 {
+				for _, d := range dirs {
+					dirList = append(dirList, path.Join(d, endingPath))
+				}
+			} else {
+				dirList = append(dirList, dirs...)
+			}
+		}
+	}
+	return dirList
+}
+
+func buildSearchDirList(endingPath, envVarName string) (dirList []string) {
+	dirList = addEnvImportDirs(envVarName, dirList)
+	dirList = addSearchDirs(endingPath, dirList)
+	return
+}
+
+func isFile(filePath string) bool {
+	info, err := os.Stat(filePath)
+	return (err == nil || errors.Is(err, os.ErrExist)) && info.Mode().IsRegular()
+}
+
+func searchAmongPath(filename string, dirList []string) (filePath string) {
+	for _, dir := range dirList {
+		if fullPath := path.Join(dir, filename); isFile(fullPath) {
+			filePath = fullPath
+			break
+		}
+	}
+	return
+}
+
+func isPathRelative(filePath string) bool {
+	unixPath := filepath.ToSlash(filePath)
+	return strings.HasPrefix(unixPath, "./") || strings.HasPrefix(unixPath, "../")
+}
+
+func makeFilepath(filename string, dirList []string) (filePath string, err error) {
+	if path.IsAbs(filename) || isPathRelative(filename) {
+		if isFile(filename) {
+			filePath = filename
+		}
+	} else {
+		filePath = searchAmongPath(filename, dirList)
+	}
+	if len(filePath) == 0 {
+		err = fmt.Errorf("file %q not found", filename)
+	}
+	return
+}

iter-list.go

@@ -26,21 +26,21 @@ func NewListIterator(list *ListType, args []any) (it *ListIterator) {
 	}
 	it = &ListIterator{a: list, count: 0, index: -1, start: 0, stop: listLen - 1, step: 1}
 	if argc >= 1 {
-		if i, err := toInt(args[0], "start index"); err == nil {
+		if i, err := ToInt(args[0], "start index"); err == nil {
 			if i < 0 {
 				i = listLen + i
 			}
 			it.start = i
 		}
 		if argc >= 2 {
-			if i, err := toInt(args[1], "stop index"); err == nil {
+			if i, err := ToInt(args[1], "stop index"); err == nil {
 				if i < 0 {
 					i = listLen + i
 				}
 				it.stop = i
 			}
 			if argc >= 3 {
-				if i, err := toInt(args[2], "step"); err == nil {
+				if i, err := ToInt(args[2], "step"); err == nil {
 					if i < 0 {
 						i = -i
 					}

list-type.go

@@ -20,6 +20,10 @@ func newListA(listAny ...any) (list *ListType) {
 }
 
 func newList(listAny []any) (list *ListType) {
+	return NewList(listAny)
+}
+
+func NewList(listAny []any) (list *ListType) {
 	if listAny != nil {
 		ls := make(ListType, len(listAny))
 		for i, item := range listAny {
@@ -30,17 +34,42 @@ func newList(listAny []any) (list *ListType) {
 	return
 }
 
+func MakeList(length, capacity int) (list *ListType) {
+	if capacity < length {
+		capacity = length
+	}
+	ls := make(ListType, length, capacity)
+	list = &ls
+	return
+}
+
+func ListFromStrings(stringList []string) (list *ListType) {
+	list = MakeList(len(stringList), 0)
+	for i, s := range stringList {
+		(*list)[i] = s
+	}
+	return
+}
+
 func (ls *ListType) ToString(opt FmtOpt) (s string) {
+        indent := GetFormatIndent(opt)
+        flags := GetFormatFlags(opt)
+
 	var sb strings.Builder
 	sb.WriteByte('[')
 	if len(*ls) > 0 {
-		if opt&MultiLine != 0 {
+                innerOpt := MakeFormatOptions(flags, indent+1)
-			sb.WriteString("\n  ")
+                nest := strings.Repeat("  ", indent+1)
+
+		if flags&MultiLine != 0 {
+			sb.WriteByte('\n')
+			sb.WriteString(nest)
 		}
 		for i, item := range []any(*ls) {
 			if i > 0 {
-				if opt&MultiLine != 0 {
+				if flags&MultiLine != 0 {
-					sb.WriteString(",\n  ")
+					sb.WriteString(",\n")
+					sb.WriteString(nest)
 				} else {
 					sb.WriteString(", ")
 				}
@@ -49,17 +78,20 @@ func (ls *ListType) ToString(opt FmtOpt) (s string) {
 				sb.WriteByte('"')
 				sb.WriteString(s)
 				sb.WriteByte('"')
+			} else if formatter, ok := item.(Formatter); ok {
+				sb.WriteString(formatter.ToString(innerOpt))
 			} else {
 				sb.WriteString(fmt.Sprintf("%v", item))
 			}
 		}
-		if opt&MultiLine != 0 {
+		if flags&MultiLine != 0 {
 			sb.WriteByte('\n')
+			sb.WriteString(strings.Repeat("  ", indent))
 		}
 	}
 	sb.WriteByte(']')
 	s = sb.String()
-	if opt&Truncate != 0 && len(s) > TruncateSize {
+	if flags&Truncate != 0 && len(s) > TruncateSize {
 		s = TruncateString(s)
 	}
 	return

module-register.go

@@ -1,48 +0,0 @@
-// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
-// All rights reserved.
-
-// module-register.go
-package expr
-
-import (
-	"fmt"
-)
-
-type module struct {
-	importFunc  func(ExprContext)
-	description string
-	imported    bool
-}
-
-func newModule(importFunc func(ExprContext), description string) *module {
-	return &module{importFunc, description, false}
-}
-
-var moduleRegister map[string]*module
-
-func registerImport(name string, importFunc func(ExprContext), description string) {
-	if moduleRegister == nil {
-		moduleRegister = make(map[string]*module)
-	}
-	if _, exists := moduleRegister[name]; exists {
-		panic(fmt.Errorf("module %q already registered", name))
-	}
-	moduleRegister[name] = newModule(importFunc, description)
-}
-
-func IterateModules(op func(name, description string, imported bool) bool) {
-	if op != nil {
-		for name, mod := range moduleRegister {
-			if !op(name, mod.description, mod.imported) {
-				break
-			}
-		}
-	}
-}
-
-// ----
-func init() {
-	if moduleRegister == nil {
-		moduleRegister = make(map[string]*module)
-	}
-}

operand-func.go

@@ -26,18 +26,18 @@ func checkFunctionCall(ctx ExprContext, name string, varParams *[]any) (err erro
 	if info, exists, owner := GetFuncInfo(ctx, name); exists {
 		passedCount := len(*varParams)
 		if info.MinArgs() > passedCount {
-			err = errTooFewParams(name, info.MinArgs(), info.MaxArgs(), passedCount)
+			err = ErrTooFewParams(name, info.MinArgs(), info.MaxArgs(), passedCount)
 		}
 		for i, p := range info.Params() {
 			if i >= passedCount {
-				if !p.IsOptional() {
+				if !p.IsDefault() {
 					break
 				}
 				*varParams = append(*varParams, p.DefaultValue())
 			}
 		}
 		if err == nil && info.MaxArgs() >= 0 && info.MaxArgs() < len(*varParams) {
-			err = errTooMuchParams(name, info.MaxArgs(), len(*varParams))
+			err = ErrTooMuchParams(name, info.MaxArgs(), len(*varParams))
 		}
 		if err == nil && owner != ctx {
 			ctx.RegisterFuncInfo(info)
@@ -50,6 +50,7 @@ func checkFunctionCall(ctx ExprContext, name string, varParams *[]any) (err erro
 
 func evalFuncCall(parentCtx ExprContext, self *term) (v any, err error) {
 	ctx := cloneContext(parentCtx)
+	ctx.SetParent(parentCtx)
 	name, _ := self.tk.Value.(string)
 	params := make([]any, len(self.children), len(self.children)+5)
 	for i, tree := range self.children {
@@ -91,12 +92,12 @@ func evalFuncDef(ctx ExprContext, self *term) (v any, err error) {
 			var defValue any
 			flags := paramFlags(0)
 			if len(param.children) > 0 {
-				flags |= pfOptional
+				flags |= PfDefault
 				if defValue, err = param.children[0].compute(ctx); err != nil {
 					return
 				}
 			}
-			info := newFuncParamFlagDef(param.source(), flags, defValue)
+			info := NewFuncParamFlagDef(param.source(), flags, defValue)
 			paramList = append(paramList, info)
 		}
 		v = newExprFunctor(expr, paramList, ctx)

operator-assign.go

@@ -28,7 +28,7 @@ func assignCollectionItem(ctx ExprContext, collectionTerm, keyListTerm *term, va
 	if keyListValue, err = keyListTerm.compute(ctx); err != nil {
 		return
 	} else if keyList, ok = keyListValue.(*ListType); !ok || len(*keyList) != 1 {
-		err = keyListTerm.Errorf("index/key specification expected, got %v [%s]", keyListValue, typeName(keyListValue))
+		err = keyListTerm.Errorf("index/key specification expected, got %v [%s]", keyListValue, TypeName(keyListValue))
 		return
 	}
 	if keyValue = (*keyList)[0]; keyValue == nil {
@@ -41,7 +41,7 @@ func assignCollectionItem(ctx ExprContext, collectionTerm, keyListTerm *term, va
 		if index, ok := keyValue.(int64); ok {
 			err = collection.setItem(index, value)
 		} else {
-			err = keyListTerm.Errorf("integer expected, got %v [%s]", keyValue, typeName(keyValue))
+			err = keyListTerm.Errorf("integer expected, got %v [%s]", keyValue, TypeName(keyValue))
 		}
 	case *DictType:
 		err = collection.setItem(keyValue, value)
@@ -81,7 +81,7 @@ func evalAssign(ctx ExprContext, self *term) (v any, err error) {
 			} else if funcDef, ok := functor.(*exprFunctor); ok {
 				paramSpecs := ForAll(funcDef.params, func(p ExprFuncParam) ExprFuncParam { return p })
 
-				ctx.RegisterFunc(leftTerm.source(), functor, typeAny, paramSpecs)
+				ctx.RegisterFunc(leftTerm.source(), functor, TypeAny, paramSpecs)
 			} else {
 				err = self.Errorf("unknown function %s()", rightChild.source())
 			}

operator-bool.go

@@ -25,7 +25,7 @@ func evalNot(ctx ExprContext, self *term) (v any, err error) {
 		return
 	}
 
-	if b, ok := toBool(rightValue); ok {
+	if b, ok := ToBool(rightValue); ok {
 		v = !b
 	} else {
 		err = self.errIncompatibleType(rightValue)
@@ -48,7 +48,7 @@ func newAndTerm(tk *Token) (inst *term) {
 }
 
 func evalAnd(ctx ExprContext, self *term) (v any, err error) {
-	if isEnabled(ctx, ControlBoolShortcut) {
+	if CtrlIsEnabled(ctx, ControlBoolShortcut) {
 		v, err = evalAndWithShortcut(ctx, self)
 	} else {
 		v, err = evalAndWithoutShortcut(ctx, self)
@@ -65,8 +65,8 @@ func evalAndWithoutShortcut(ctx ExprContext, self *term) (v any, err error) {
 		return
 	}
 
-	leftBool, lok = toBool(leftValue)
+	leftBool, lok = ToBool(leftValue)
-	rightBool, rok = toBool(rightValue)
+	rightBool, rok = ToBool(rightValue)
 
 	if lok && rok {
 		v = leftBool && rightBool
@@ -87,13 +87,13 @@ func evalAndWithShortcut(ctx ExprContext, self *term) (v any, err error) {
 		return
 	}
 
-	if leftBool, lok := toBool(leftValue); !lok {
+	if leftBool, lok := ToBool(leftValue); !lok {
 		err = fmt.Errorf("got %T as left operand type of 'and' operator, it must be bool", leftBool)
 		return
 	} else if !leftBool {
 		v = false
 	} else if rightValue, err = self.children[1].compute(ctx); err == nil {
-		if rightBool, rok := toBool(rightValue); rok {
+		if rightBool, rok := ToBool(rightValue); rok {
 			v = rightBool
 		} else {
 			err = self.errIncompatibleTypes(leftValue, rightValue)
@@ -117,7 +117,7 @@ func newOrTerm(tk *Token) (inst *term) {
 }
 
 func evalOr(ctx ExprContext, self *term) (v any, err error) {
-	if isEnabled(ctx, ControlBoolShortcut) {
+	if CtrlIsEnabled(ctx, ControlBoolShortcut) {
 		v, err = evalOrWithShortcut(ctx, self)
 	} else {
 		v, err = evalOrWithoutShortcut(ctx, self)
@@ -134,8 +134,8 @@ func evalOrWithoutShortcut(ctx ExprContext, self *term) (v any, err error) {
 		return
 	}
 
-	leftBool, lok = toBool(leftValue)
+	leftBool, lok = ToBool(leftValue)
-	rightBool, rok = toBool(rightValue)
+	rightBool, rok = ToBool(rightValue)
 
 	if lok && rok {
 		v = leftBool || rightBool
@@ -156,13 +156,13 @@ func evalOrWithShortcut(ctx ExprContext, self *term) (v any, err error) {
 		return
 	}
 
-	if leftBool, lok := toBool(leftValue); !lok {
+	if leftBool, lok := ToBool(leftValue); !lok {
 		err = fmt.Errorf("got %T as left operand type of 'or' operator, it must be bool", leftBool)
 		return
 	} else if leftBool {
 		v = true
 	} else if rightValue, err = self.children[1].compute(ctx); err == nil {
-		if rightBool, rok := toBool(rightValue); rok {
+		if rightBool, rok := ToBool(rightValue); rok {
 			v = rightBool
 		} else {
 			err = self.errIncompatibleTypes(leftValue, rightValue)

operator-builtin.go

@@ -37,11 +37,11 @@ func evalBuiltin(ctx ExprContext, self *term) (v any, err error) {
 				if ImportInContext(module) {
 					count++
 				} else {
-					err = self.Errorf("unknown module %q", module)
+					err = self.Errorf("unknown builtin module %q", module)
 					break
 				}
 			} else {
-				err = self.Errorf("expected string at item nr %d, got %T", it.Index()+1, moduleSpec)
+				err = self.Errorf("expected string at item nr %d, got %s", it.Index()+1, TypeName(moduleSpec))
 				break
 			}
 		}

operator-coalesce.go

@@ -67,8 +67,8 @@ func evalAssignCoalesce(ctx ExprContext, self *term) (v any, err error) {
 	} else if rightValue, err = self.children[1].compute(ctx); err == nil {
 		if functor, ok := rightValue.(Functor); ok {
 			//ctx.RegisterFunc(leftTerm.source(), functor, 0, -1)
-			ctx.RegisterFunc(leftTerm.source(), functor, typeAny, []ExprFuncParam{
+			ctx.RegisterFunc(leftTerm.source(), functor, TypeAny, []ExprFuncParam{
-				newFuncParamFlag(paramValue, pfOptional|pfRepeat),
+				NewFuncParamFlag(ParamValue, PfDefault|PfRepeat),
 			})
 		} else {
 			v = rightValue

operator-context.go

@@ -31,10 +31,13 @@ func evalContextValue(ctx ExprContext, self *term) (v any, err error) {
 	}
 
 	if sourceCtx != nil {
-		if formatter, ok := sourceCtx.(Formatter); ok {
+		if formatter, ok := sourceCtx.(DictFormat); ok {
+			v = formatter.ToDict()
+		} else if formatter, ok := sourceCtx.(Formatter); ok {
 			v = formatter.ToString(0)
 		} else {
-			keys := sourceCtx.EnumVars(func(name string) bool { return name[0] != '_' })
+			// keys := sourceCtx.EnumVars(func(name string) bool { return name[0] != '_' })
+			keys := sourceCtx.EnumVars(nil)
 			d := make(map[string]any)
 			for _, key := range keys {
 				d[key], _ = sourceCtx.GetVar(key)

operator-ctrl.go

@@ -17,7 +17,7 @@ func newExportAllTerm(tk *Token) (inst *term) {
 }
 
 func evalExportAll(ctx ExprContext, self *term) (v any, err error) {
-	enable(ctx, control_export_all)
+	CtrlEnable(ctx, control_export_all)
 	return
 }
 

operator-index.go

@@ -23,7 +23,7 @@ func verifyKey(indexTerm *term, indexList *ListType) (index any, err error) {
 func verifyIndex(indexTerm *term, indexList *ListType, maxValue int) (index int, err error) {
 	var v int
 
-	if v, err = toInt((*indexList)[0], "index expression"); err == nil {
+	if v, err = ToInt((*indexList)[0], "index expression"); err == nil {
 		if v < 0 && v >= -maxValue {
 			v = maxValue + v
 		}

operator-length.go

@@ -36,7 +36,7 @@ func evalLength(ctx ExprContext, self *term) (v any, err error) {
 	} else if it, ok := childValue.(Iterator); ok {
 		if extIt, ok := childValue.(ExtIterator); ok && extIt.HasOperation(countName) {
 			count, _ := extIt.CallOperation(countName, nil)
-			v, _ = toInt(count, "")
+			v, _ = ToInt(count, "")
 		} else {
 			v = int64(it.Index() + 1)
 		}

operator-plugin.go

@@ -0,0 +1,58 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// operator-plugin.go
+package expr
+
+import (
+	"io"
+)
+
+//-------- plugin term
+
+func newPluginTerm(tk *Token) (inst *term) {
+	return &term{
+		tk:       *tk,
+		children: make([]*term, 0, 1),
+		position: posPrefix,
+		priority: priSign,
+		evalFunc: evalPlugin,
+	}
+}
+
+func evalPlugin(ctx ExprContext, self *term) (v any, err error) {
+	var childValue any
+	var moduleSpec any
+
+	if childValue, err = self.evalPrefix(ctx); err != nil {
+		return
+	}
+
+	dirList := buildSearchDirList("plugin", ENV_EXPR_PLUGIN_PATH)
+	count := 0
+	it := NewAnyIterator(childValue)
+	for moduleSpec, err = it.Next(); err == nil; moduleSpec, err = it.Next() {
+		if module, ok := moduleSpec.(string); ok {
+			if err = importPlugin(dirList, module); err != nil {
+				break
+			}
+			count++
+		} else {
+			err = self.Errorf("expected string as item nr %d, got %s", it.Index()+1, TypeName(moduleSpec))
+			break
+		}
+	}
+	if err == io.EOF {
+		err = nil
+	}
+
+	if err == nil {
+		v = int64(count)
+	}
+	return
+}
+
+// init
+func init() {
+	registerTermConstructor(SymKwPlugin, newPluginTerm)
+}

operator-range.go

@@ -12,7 +12,7 @@ type intPair struct {
 }
 
 func (p *intPair) TypeName() string {
-	return typePair
+	return TypePair
 }
 
 func (p *intPair) ToString(opt FmtOpt) string {

operator-rel.go

@@ -70,7 +70,7 @@ func newNotEqualTerm(tk *Token) (inst *term) {
 
 func evalNotEqual(ctx ExprContext, self *term) (v any, err error) {
 	if v, err = evalEqual(ctx, self); err == nil {
-		b, _ := toBool(v)
+		b, _ := ToBool(v)
 		v = !b
 	}
 	return

operator-selector.go

@@ -19,17 +19,17 @@ func newSelectorTerm(tk *Token) (inst *term) {
 func trySelectorCase(ctx ExprContext, exprValue, caseSel any, caseIndex int) (match bool, selectedValue any, err error) {
 	caseData, _ := caseSel.(*selectorCase)
 	if caseData.filterList == nil {
-		selectedValue, err = caseData.caseExpr.eval(ctx, false)
+		selectedValue, err = caseData.caseExpr.Eval(ctx)
 		match = true
 	} else if filterList, ok := caseData.filterList.value().([]*term); ok {
 		if len(filterList) == 0 && exprValue == int64(caseIndex) {
-			selectedValue, err = caseData.caseExpr.eval(ctx, false)
+			selectedValue, err = caseData.caseExpr.Eval(ctx)
 			match = true
 		} else {
 			var caseValue any
 			for _, caseTerm := range filterList {
 				if caseValue, err = caseTerm.compute(ctx); err != nil || caseValue == exprValue {
-					selectedValue, err = caseData.caseExpr.eval(ctx, false)
+					selectedValue, err = caseData.caseExpr.Eval(ctx)
 					match = true
 					break
 				}

parser.go

@@ -11,13 +11,10 @@ import (
 //-------- parser
 
 type parser struct {
-	ctx ExprContext
 }
 
-func NewParser(ctx ExprContext) (p *parser) {
+func NewParser() (p *parser) {
-	p = &parser{
+	p = &parser{}
-		ctx: ctx,
-	}
 	return p
 }
 

plugins.go

@@ -0,0 +1,94 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// plugin.go
+package expr
+
+import (
+	"fmt"
+	"plugin"
+)
+
+var pluginRegister map[string]*plugin.Plugin
+
+func registerPlugin(name string, p *plugin.Plugin) (err error) {
+	if pluginExists(name) {
+		err = fmt.Errorf("plugin %q already loaded", name)
+	} else {
+		pluginRegister[name] = p
+	}
+	return
+}
+
+func pluginExists(name string) (exists bool) {
+	_, exists = pluginRegister[name]
+	return
+}
+
+func importPlugin( /*ctx ExprContext,*/ dirList []string, name string) (err error) {
+	var filePath string
+	var p *plugin.Plugin
+	var sym plugin.Symbol
+	var moduleName string
+	var importFunc func(ExprContext)
+	var ok bool
+
+	decoratedName := fmt.Sprintf("expr-%s-plugin.so", name)
+
+	if filePath, err = makeFilepath(decoratedName, dirList); err != nil {
+		return
+	}
+
+	if p, err = plugin.Open(filePath); err != nil {
+		return
+	}
+
+	if sym, err = p.Lookup("MODULE_NAME"); err != nil {
+		return
+	}
+
+	if moduleName = *sym.(*string); moduleName == "" {
+		err = fmt.Errorf("plugin %q does not provide a valid module name", decoratedName)
+		return
+	}
+
+	if sym, err = p.Lookup("DEPENDENCIES"); err != nil {
+		return
+	}
+	if deps := *sym.(*[]string); len(deps) > 0 {
+		// var count int
+		if err = loadModules(dirList, deps); err != nil {
+			return
+		}
+	}
+
+	if sym, err = p.Lookup("ImportFuncs"); err != nil {
+		return
+	}
+
+	if importFunc, ok = sym.(func(ExprContext)); !ok {
+		err = fmt.Errorf("plugin %q does not provide a valid import function", decoratedName)
+		return
+	}
+
+	registerPlugin(moduleName, p)
+	importFunc(globalCtx)
+
+	return
+}
+
+func loadModules(dirList []string, moduleNames []string) (err error) {
+	for _, name := range moduleNames {
+		if err1 := importPlugin(dirList, name); err1 != nil {
+			if !ImportInContext(name) {
+				err = err1
+				break
+			}
+		}
+	}
+	return
+}
+
+func init() {
+	pluginRegister = make(map[string]*plugin.Plugin)
+}

scanner.go

@@ -178,13 +178,18 @@ func (self *scanner) fetchNextToken() (tk *Token) {
 				tk = self.makeToken(SymDot, ch)
 			}
 		case '\'':
-			tk = self.makeToken(SymQuote, ch)
+			if escape {
+				tk = self.makeToken(SymQuote, ch)
+				escape = false
+			} else {
+				tk = self.fetchString(ch)
+			}
 		case '"':
 			if escape {
 				tk = self.makeToken(SymDoubleQuote, ch)
 				escape = false
 			} else {
-				tk = self.fetchString()
+				tk = self.fetchString(ch)
 			}
 		case '`':
 			tk = self.makeToken(SymBackTick, ch)
@@ -533,7 +538,7 @@ func (self *scanner) fetchUntil(sym Symbol, allowEos bool, endings ...byte) (tk
 	return
 }
 
-func (self *scanner) fetchString() (tk *Token) {
+func (self *scanner) fetchString(termCh byte) (tk *Token) {
 	var err error
 	var ch, prev byte
 	var sb strings.Builder
@@ -554,7 +559,7 @@ func (self *scanner) fetchString() (tk *Token) {
 				sb.WriteByte(ch)
 			}
 			prev = 0
-		} else if ch == '"' {
+		} else if ch == termCh {
 			break
 		} else {
 			prev = ch

simple-store.go

@@ -7,10 +7,11 @@ package expr
 import (
 	"fmt"
 	"slices"
-	"strings"
+//	"strings"
 )
 
 type SimpleStore struct {
+	parent    ExprContext
 	varStore  map[string]any
 	funcStore map[string]ExprFunc
 }
@@ -26,6 +27,14 @@ func NewSimpleStore() *SimpleStore {
 func filterRefName(name string) bool  { return name[0] != '@' }
 func filterPrivName(name string) bool { return name[0] != '_' }
 
+func (ctx *SimpleStore) SetParent(parentCtx ExprContext) {
+	ctx.parent = parentCtx
+}
+
+func (ctx *SimpleStore) GetParent() ExprContext {
+	return ctx.parent
+}
+
 func (ctx *SimpleStore) Clone() ExprContext {
 	return &SimpleStore{
 		varStore:  CloneFilteredMap(ctx.varStore, filterRefName),
@@ -41,11 +50,11 @@ func (ctx *SimpleStore) Merge(src ExprContext) {
 		ctx.funcStore[name], _ = src.GetFuncInfo(name)
 	}
 }
-
+/*
 func varsCtxToBuilder(sb *strings.Builder, ctx ExprContext, indent int) {
 	sb.WriteString("vars: {\n")
 	first := true
-	for _, name := range ctx.EnumVars(filterPrivName) {
+	for _, name := range ctx.EnumVars(nil) {
 		if first {
 			first = false
 		} else {
@@ -68,7 +77,7 @@ func varsCtxToBuilder(sb *strings.Builder, ctx ExprContext, indent int) {
 		}
 	}
 	sb.WriteString(strings.Repeat("\t", indent))
-	sb.WriteString("\n}\n")
+	sb.WriteString("\n}")
 }
 
 func varsCtxToString(ctx ExprContext, indent int) string {
@@ -97,15 +106,59 @@ func funcsCtxToBuilder(sb *strings.Builder, ctx ExprContext, indent int) {
 			sb.WriteString(fmt.Sprintf("%v", value))
 		}
 	}
-	sb.WriteString("\n}\n")
+	sb.WriteString("\n}")
 }
 
 func (ctx *SimpleStore) ToString(opt FmtOpt) string {
 	var sb strings.Builder
 	varsCtxToBuilder(&sb, ctx, 0)
+	sb.WriteByte('\n')
 	funcsCtxToBuilder(&sb, ctx, 0)
 	return sb.String()
 }
+*/
+
+func (ctx *SimpleStore) ToString(opt FmtOpt) string {
+	dict := ctx.ToDict()
+	return dict.ToString(opt)
+}
+
+func (ctx *SimpleStore) varsToDict(dict *DictType) *DictType {
+	names := ctx.EnumVars(nil)
+	slices.Sort(names)
+	for _, name := range ctx.EnumVars(nil) {
+		value, _ := ctx.GetVar(name)
+		if f, ok := value.(Formatter); ok {
+			(*dict)[name] = f.ToString(0)
+		} else if _, ok = value.(Functor); ok {
+			(*dict)[name] = "func(){}"
+		} else {
+			(*dict)[name] = fmt.Sprintf("%v", value)
+		}
+	}
+	return dict
+}
+
+func (ctx *SimpleStore) funcsToDict(dict *DictType) *DictType {
+	names := ctx.EnumFuncs(func(name string) bool { return true })
+	slices.Sort(names)
+	for _, name := range names {
+		value, _ := ctx.GetFuncInfo(name)
+		if formatter, ok := value.(Formatter); ok {
+			(*dict)[name] = formatter.ToString(0)
+		} else {
+			(*dict)[name] = fmt.Sprintf("%v", value)
+		}
+	}
+	return dict
+}
+
+func (ctx *SimpleStore) ToDict() (dict *DictType) {
+	dict = MakeDict()
+	(*dict)["variables"] = ctx.varsToDict(MakeDict())
+	(*dict)["functions"] = ctx.funcsToDict(MakeDict())
+	return
+}
 
 func (ctx *SimpleStore) GetVar(varName string) (v any, exists bool) {
 	v, exists = ctx.varStore[varName]

symbol.go

@@ -101,6 +101,7 @@ const (
 	SymKwBut
 	SymKwFunc
 	SymKwBuiltin
+	SymKwPlugin
 	SymKwIn
 	SymKwInclude
 	SymKwNil
@@ -113,6 +114,7 @@ func init() {
 	keywords = map[string]Symbol{
 		"AND":     SymKwAnd,
 		"BUILTIN": SymKwBuiltin,
+		"PLUGIN":  SymKwPlugin,
 		"BUT":     SymKwBut,
 		"FUNC":    SymKwFunc,
 		"IN":      SymKwIn,

t_builtin-base_test.go

@@ -1,7 +1,7 @@
 // Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
 // All rights reserved.
 
-// t_func-base_test.go
+// t_builtin-base_test.go
 package expr
 
 import (
@@ -10,7 +10,7 @@ import (
 )
 
 func TestFuncBase(t *testing.T) {
-	section := "Func-Base"
+	section := "Builtin-Base"
 
 	inputs := []inputType{
 		/*   1 */ {`isNil(nil)`, true, nil},

t_builtin-import_test.go

@@ -0,0 +1,24 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// t_builtin-import_test.go
+package expr
+
+import (
+	"testing"
+)
+
+func TestFuncImport(t *testing.T) {
+	section := "Builtin-Import"
+	inputs := []inputType{
+		/*   1 */ {`builtin "import"; import("./test-resources/test-funcs.expr"); (double(3+a) + 1) * two()`, int64(34), nil},
+		/*   2 */ {`builtin "import"; import("test-funcs.expr"); (double(3+a) + 1) * two()`, int64(34), nil},
+		/*   3 */ {`builtin "import"; importAll("./test-resources/test-funcs.expr"); six()`, int64(6), nil},
+		/*   4 */ {`builtin "import"; import("./test-resources/sample-export-all.expr"); six()`, int64(6), nil},
+	}
+
+	t.Setenv("EXPR_PATH", "test-resources")
+
+	// parserTestSpec(t, section, inputs, 69)
+	parserTest(t, section, inputs)
+}

t_builtin-math-arith_test.go

@@ -1,7 +1,7 @@
 // Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
 // All rights reserved.
 
-// t_func-math-arith_test.go
+// t_builtin-math-arith_test.go
 package expr
 
 import (
@@ -10,7 +10,7 @@ import (
 )
 
 func TestFuncMathArith(t *testing.T) {
-	section := "Func-Math-Arith"
+	section := "Builtin-Math-Arith"
 	inputs := []inputType{
 		/*   1 */ {`builtin "math.arith"; add(1,2)`, int64(3), nil},
 		/*   2 */ {`builtin "math.arith"; add(1,2,3)`, int64(6), nil},

t_builtin-os-file_test.go

@@ -0,0 +1,29 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// t_builtin-os-file_test.go
+package expr
+
+import (
+	"errors"
+	"testing"
+)
+
+func TestFuncOs(t *testing.T) {
+	section := "Builtin-OS-File"
+	inputs := []inputType{
+		/*   1 */ {`builtin "os.file"`, int64(1), nil},
+		/*   2 */ {`builtin "os.file"; handle=fileOpen("/etc/hosts"); fileClose(handle)`, true, nil},
+		/*   3 */ {`builtin "os.file"; handle=fileOpen("/etc/hostsX")`, nil, errors.New(`open /etc/hostsX: no such file or directory`)},
+		/*   4 */ {`builtin "os.file"; handle=fileCreate("/tmp/dummy"); fileClose(handle)`, true, nil},
+		/*   5 */ {`builtin "os.file"; handle=fileAppend("/tmp/dummy"); fileWrite(handle, "bye-bye"); fileClose(handle)`, true, nil},
+		/*   6 */ {`builtin "os.file"; handle=fileOpen("/tmp/dummy"); word=fileRead(handle, "-"); fileClose(handle);word`, "bye", nil},
+		/*   7 */ {`builtin "os.file"; word=fileRead(nil, "-")`, nil, errors.New(`readFileFunc(): invalid file handle`)},
+		/*   7 */ {`builtin "os.file"; fileWrite(nil, "bye")`, nil, errors.New(`writeFileFunc(): invalid file handle`)},
+	}
+
+	// t.Setenv("EXPR_PATH", ".")
+
+	// parserTestSpec(t, section, inputs, 69)
+	parserTest(t, section, inputs)
+}

t_builtin-string_test.go

@@ -0,0 +1,69 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// t_builtin-string_test.go
+package expr
+
+import (
+	"errors"
+	"testing"
+)
+
+func TestFuncString(t *testing.T) {
+	section := "Builtin-String"
+
+	inputs := []inputType{
+		/*   1 */ {`builtin "string"; strJoin("-", "one", "two", "three")`, "one-two-three", nil},
+		/*   2 */ {`builtin "string"; strJoin("-", ["one", "two", "three"])`, "one-two-three", nil},
+		/*   3 */ {`builtin "string"; ls= ["one", "two", "three"]; strJoin("-", ls)`, "one-two-three", nil},
+		/*   4 */ {`builtin "string"; ls= ["one", "two", "three"]; strJoin(1, ls)`, nil, errors.New(`strJoin(): the "separator" parameter must be a string, got a integer (1)`)},
+		/*   5 */ {`builtin "string"; ls= ["one", 2, "three"]; strJoin("-", ls)`, nil, errors.New(`strJoin(): expected string, got integer (2)`)},
+		/*   6 */ {`builtin "string"; "<"+strTrim("  bye bye  ")+">"`, "<bye bye>", nil},
+		/*   7 */ {`builtin "string"; strSub("0123456789", 1,2)`, "12", nil},
+		/*   8 */ {`builtin "string"; strSub("0123456789", -3,2)`, "78", nil},
+		/*   9 */ {`builtin "string"; strSub("0123456789", -3)`, "789", nil},
+		/*  10 */ {`builtin "string"; strSub("0123456789")`, "0123456789", nil},
+		/*  11 */ {`builtin "string"; strStartsWith("0123456789", "xyz", "012")`, true, nil},
+		/*  12 */ {`builtin "string"; strStartsWith("0123456789", "xyz", "0125")`, false, nil},
+		/*  13 */ {`builtin "string"; strStartsWith("0123456789")`, nil, errors.New(`strStartsWith(): too few params -- expected 2 or more, got 1`)},
+		/*  14 */ {`builtin "string"; strEndsWith("0123456789", "xyz", "789")`, true, nil},
+		/*  15 */ {`builtin "string"; strEndsWith("0123456789", "xyz", "0125")`, false, nil},
+		/*  16 */ {`builtin "string"; strEndsWith("0123456789")`, nil, errors.New(`strEndsWith(): too few params -- expected 2 or more, got 1`)},
+		/*  17 */ {`builtin "string"; strSplit("one-two-three", "-")`, newListA("one", "two", "three"), nil},
+		/*  18 */ {`builtin "string"; strJoin("-", [1, "two", "three"])`, nil, errors.New(`strJoin(): expected string, got integer (1)`)},
+		/*  19 */ {`builtin "string"; strJoin()`, nil, errors.New(`strJoin(): too few params -- expected 1 or more, got 0`)},
+
+		/*  69 */ /*{`builtin "string"; $$global`, `vars: {
+		}
+		funcs: {
+		    	add(any=0 ...) -> number,
+		    	dec(any) -> decimal,
+		    	endsWithStr(source, suffix) -> boolean,
+		    	fract(any, denominator=1) -> fraction,
+		    	import( ...) -> any,
+		    	importAll( ...) -> any,
+		    	int(any) -> integer,
+		    	isBool(any) -> boolean,
+		    	isDec(any) -> boolean,
+		    	isDict(any) -> boolean,
+		    	isFloat(any) -> boolean,
+		    	isFract(any) -> boolean,
+		    	isInt(any) -> boolean,
+		    	isList(any) -> boolean,
+		    	isNil(any) -> boolean,
+		    	isString(any) -> boolean,
+		    	joinStr(separator, item="" ...) -> string,
+		    	mul(any=1 ...) -> number,
+		    	splitStr(source, separator="", count=-1) -> list of string,
+		    	startsWithStr(source, prefix) -> boolean,
+		    	subStr(source, start=0, count=-1) -> string,
+		    	trimStr(source) -> string
+		}
+		`, nil},*/
+	}
+
+	//t.Setenv("EXPR_PATH", ".")
+
+	// parserTestSpec(t, section, inputs, 19)
+	parserTest(t, section, inputs)
+}

t_dict_test.go

@@ -49,7 +49,7 @@ func TestDictParser(t *testing.T) {
 		ctx.SetVar("var1", int64(123))
 		ctx.SetVar("var2", "abc")
 		ImportMathFuncs(ctx)
-		parser := NewParser(ctx)
+		parser := NewParser()
 
 		logTest(t, i+1, "Dict", input.source, input.wantResult, input.wantErr)
 
@@ -110,7 +110,7 @@ func TestDictToStringMultiLine(t *testing.T) {
 	var good bool
 	section := "dict-ToString-ML"
 	want := `{
-	"first": 1
+  "first": 1
 }`
 	args := map[any]*term{
 		"first": newLiteralTerm(NewValueToken(0, 0, SymInteger, "1", 1)),

t_expr_test.go

@@ -14,7 +14,7 @@ func TestExpr(t *testing.T) {
 	inputs := []inputType{
 		/*   1 */ {`0?{}`, nil, nil},
 		/*   2 */ {`fact=func(n){(n)?{1}::{n*fact(n-1)}}; fact(5)`, int64(120), nil},
-		/*   3 */ {`builtin "os.file"; f=openFile("test-file.txt"); line=readFile(f); closeFile(f); line`, "uno", nil},
+		/*   3 */ {`builtin "os.file"; f=fileOpen("test-file.txt"); line=fileRead(f); fileClose(f); line`, "uno", nil},
 		/*   4 */ {`mynot=func(v){int(v)?{true}::{false}}; mynot(0)`, true, nil},
 		/*   5 */ {`1 ? {1} : [1+0] {3*(1+1)}`, int64(6), nil},
 		/*   6 */ {`

t_func-import_test.go

@@ -1,24 +0,0 @@
-// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
-// All rights reserved.
-
-// t_func-import_test.go
-package expr
-
-import (
-	"testing"
-)
-
-func TestFuncImport(t *testing.T) {
-	section := "Func-Import"
-	inputs := []inputType{
-		/*   1 */ {`builtin "import"; import("./test-funcs.expr"); (double(3+a) + 1) * two()`, int64(34), nil},
-		/*   2 */ {`builtin "import"; import("test-funcs.expr"); (double(3+a) + 1) * two()`, int64(34), nil},
-		/*   3 */ {`builtin "import"; importAll("./test-funcs.expr"); six()`, int64(6), nil},
-		/*   4 */ {`builtin "import"; import("./sample-export-all.expr"); six()`, int64(6), nil},
-	}
-
-	t.Setenv("EXPR_PATH", ".")
-
-	// parserTestSpec(t, section, inputs, 69)
-	parserTest(t, section, inputs)
-}

t_func-os_test.go

@@ -1,29 +0,0 @@
-// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
-// All rights reserved.
-
-// t_func-os_test.go
-package expr
-
-import (
-	"errors"
-	"testing"
-)
-
-func TestFuncOs(t *testing.T) {
-	section := "Func-OS"
-	inputs := []inputType{
-		/*   1 */ {`builtin "os.file"`, int64(1), nil},
-		/*   2 */ {`builtin "os.file"; handle=openFile("/etc/hosts"); closeFile(handle)`, true, nil},
-		/*   3 */ {`builtin "os.file"; handle=openFile("/etc/hostsX")`, nil, errors.New(`open /etc/hostsX: no such file or directory`)},
-		/*   4 */ {`builtin "os.file"; handle=createFile("/tmp/dummy"); closeFile(handle)`, true, nil},
-		/*   5 */ {`builtin "os.file"; handle=appendFile("/tmp/dummy"); writeFile(handle, "bye-bye"); closeFile(handle)`, true, nil},
-		/*   6 */ {`builtin "os.file"; handle=openFile("/tmp/dummy"); word=readFile(handle, "-"); closeFile(handle);word`, "bye", nil},
-		/*   7 */ {`builtin "os.file"; word=readFile(nil, "-")`, nil, errors.New(`readFileFunc(): invalid file handle`)},
-		/*   7 */ {`builtin "os.file"; writeFile(nil, "bye")`, nil, errors.New(`writeFileFunc(): invalid file handle`)},
-	}
-
-	// t.Setenv("EXPR_PATH", ".")
-
-	// parserTestSpec(t, section, inputs, 69)
-	parserTest(t, section, inputs)
-}

t_func-string_test.go

@@ -1,69 +0,0 @@
-// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
-// All rights reserved.
-
-// t_func-string_test.go
-package expr
-
-import (
-	"errors"
-	"testing"
-)
-
-func TestFuncString(t *testing.T) {
-	section := "Func-String"
-
-	inputs := []inputType{
-		/*   1 */ {`builtin "string"; joinStr("-", "one", "two", "three")`, "one-two-three", nil},
-		/*   2 */ {`builtin "string"; joinStr("-", ["one", "two", "three"])`, "one-two-three", nil},
-		/*   3 */ {`builtin "string"; ls= ["one", "two", "three"]; joinStr("-", ls)`, "one-two-three", nil},
-		/*   4 */ {`builtin "string"; ls= ["one", "two", "three"]; joinStr(1, ls)`, nil, errors.New(`joinStr() the "separator" parameter must be a string, got a integer (1)`)},
-		/*   5 */ {`builtin "string"; ls= ["one", 2, "three"]; joinStr("-", ls)`, nil, errors.New(`joinStr() expected string, got integer (2)`)},
-		/*   6 */ {`builtin "string"; "<"+trimStr("  bye bye  ")+">"`, "<bye bye>", nil},
-		/*   7 */ {`builtin "string"; subStr("0123456789", 1,2)`, "12", nil},
-		/*   8 */ {`builtin "string"; subStr("0123456789", -3,2)`, "78", nil},
-		/*   9 */ {`builtin "string"; subStr("0123456789", -3)`, "789", nil},
-		/*  10 */ {`builtin "string"; subStr("0123456789")`, "0123456789", nil},
-		/*  11 */ {`builtin "string"; startsWithStr("0123456789", "xyz", "012")`, true, nil},
-		/*  12 */ {`builtin "string"; startsWithStr("0123456789", "xyz", "0125")`, false, nil},
-		/*  13 */ {`builtin "string"; startsWithStr("0123456789")`, nil, errors.New(`startsWithStr(): too few params -- expected 2 or more, got 1`)},
-		/*  14 */ {`builtin "string"; endsWithStr("0123456789", "xyz", "789")`, true, nil},
-		/*  15 */ {`builtin "string"; endsWithStr("0123456789", "xyz", "0125")`, false, nil},
-		/*  16 */ {`builtin "string"; endsWithStr("0123456789")`, nil, errors.New(`endsWithStr(): too few params -- expected 2 or more, got 1`)},
-		/*  17 */ {`builtin "string"; splitStr("one-two-three", "-")`, newListA("one", "two", "three"), nil},
-		/*  18 */ {`builtin "string"; joinStr("-", [1, "two", "three"])`, nil, errors.New(`joinStr() expected string, got integer (1)`)},
-		/*  19 */ {`builtin "string"; joinStr()`, nil, errors.New(`joinStr(): too few params -- expected 1 or more, got 0`)},
-
-		/*  69 */ /*{`builtin "string"; $$global`, `vars: {
-		}
-		funcs: {
-		    	add(any=0 ...) -> number,
-		    	dec(any) -> decimal,
-		    	endsWithStr(source, suffix) -> boolean,
-		    	fract(any, denominator=1) -> fraction,
-		    	import( ...) -> any,
-		    	importAll( ...) -> any,
-		    	int(any) -> integer,
-		    	isBool(any) -> boolean,
-		    	isDec(any) -> boolean,
-		    	isDict(any) -> boolean,
-		    	isFloat(any) -> boolean,
-		    	isFract(any) -> boolean,
-		    	isInt(any) -> boolean,
-		    	isList(any) -> boolean,
-		    	isNil(any) -> boolean,
-		    	isString(any) -> boolean,
-		    	joinStr(separator, item="" ...) -> string,
-		    	mul(any=1 ...) -> number,
-		    	splitStr(source, separator="", count=-1) -> list of string,
-		    	startsWithStr(source, prefix) -> boolean,
-		    	subStr(source, start=0, count=-1) -> string,
-		    	trimStr(source) -> string
-		}
-		`, nil},*/
-	}
-
-	//t.Setenv("EXPR_PATH", ".")
-
-	// parserTestSpec(t, section, inputs, 19)
-	parserTest(t, section, inputs)
-}

t_funcs_test.go

@@ -43,8 +43,8 @@ func dummy(ctx ExprContext, name string, args []any) (result any, err error) {
 }
 
 func TestFunctionToStringSimple(t *testing.T) {
-	source := newGolangFunctor(dummy)
+	source := NewGolangFunctor(dummy)
-	want := "func() {<body>}"
+	want := "func() {}"
 	got := source.ToString(0)
 	if got != want {
 		t.Errorf(`(func() -> result = %v [%T], want = %v [%T]`, got, got, want, want)
@@ -52,7 +52,7 @@ func TestFunctionToStringSimple(t *testing.T) {
 }
 
 func TestFunctionGetFunc(t *testing.T) {
-	source := newGolangFunctor(dummy)
+	source := NewGolangFunctor(dummy)
 	want := ExprFunc(nil)
 	got := source.GetFunc()
 	if got != want {

t_iter-list_test.go

@@ -0,0 +1,162 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// t_iter-list_test.go
+package expr
+
+import (
+	"io"
+	"testing"
+)
+
+func TestNewListIterator(t *testing.T) {
+	list := newListA("a", "b", "c", "d")
+	it := NewListIterator(list, []any{1, 3, 1})
+	if item, err := it.Next(); err != nil {
+		t.Errorf("error: %v", err)
+	} else if item != "b" {
+		t.Errorf("expcted %q, got %q", "b", item)
+	} else {
+		t.Logf("Next: %v", item)
+	}
+}
+
+func TestNewListIterator2(t *testing.T) {
+	list := newListA("a", "b", "c", "d")
+	it := NewListIterator(list, []any{3, 1, -1})
+	if item, err := it.Next(); err != nil {
+		t.Errorf("error: %v", err)
+	} else if item != "d" {
+		t.Errorf("expcted %q, got %q", "d", item)
+	} else {
+		t.Logf("Next: %v", item)
+	}
+}
+
+func TestNewListIterator3(t *testing.T) {
+	list := newListA("a", "b", "c", "d")
+	it := NewListIterator(list, []any{1, -1, 1})
+	if item, err := it.Next(); err != nil {
+		t.Errorf("error: %v", err)
+	} else if item != "b" {
+		t.Errorf("expcted %q, got %q", "b", item)
+	} else {
+		t.Logf("Next: %v", item)
+	}
+}
+
+func TestNewIterList2(t *testing.T) {
+	list := []any{"a", "b", "c", "d"}
+	it := NewArrayIterator(list)
+	if item, err := it.Next(); err != nil {
+		t.Errorf("error: %v", err)
+	} else if item != "a" {
+		t.Errorf("expcted %q, got %q", "a", item)
+	} else {
+		t.Logf("Next: %v", item)
+	}
+}
+
+func TestNewIterList3(t *testing.T) {
+	list := []any{"a", "b", "c", "d"}
+	it := NewAnyIterator(list)
+	if item, err := it.Next(); err != nil {
+		t.Errorf("error: %v", err)
+	} else if item != "a" {
+		t.Errorf("expcted %q, got %q", "a", item)
+	} else {
+		t.Logf("Next: %v", item)
+	}
+}
+
+func TestNewIterList4(t *testing.T) {
+	list := any(nil)
+	it := NewAnyIterator(list)
+	if _, err := it.Next(); err != io.EOF {
+		t.Errorf("error: %v", err)
+	}
+}
+
+func TestNewIterList5(t *testing.T) {
+	list := "123"
+	it := NewAnyIterator(list)
+	if item, err := it.Next(); err != nil {
+		t.Errorf("error: %v", err)
+	} else if item != "123" {
+		t.Errorf("expcted %q, got %q", "123", item)
+	} else {
+		t.Logf("Next: %v", item)
+	}
+}
+
+func TestNewIterList6(t *testing.T) {
+	list := newListA("a", "b", "c", "d")
+	it1 := NewAnyIterator(list)
+	it := NewAnyIterator(it1)
+	if item, err := it.Next(); err != nil {
+		t.Errorf("error: %v", err)
+	} else if item != "a" {
+		t.Errorf("expcted %q, got %q", "a", item)
+	} else {
+		t.Logf("Next: %v", item)
+	}
+}
+func TestNewString(t *testing.T) {
+	list := "123"
+	it := NewAnyIterator(list)
+	if s := it.String(); s != "$(#1)" {
+		t.Errorf("expected $(#1), got %s", s)
+	}
+}
+
+func TestHasOperation(t *testing.T) {
+
+	list := newListA("a", "b", "c", "d")
+	it := NewListIterator(list, []any{1, 3, 1})
+	hasOp := it.HasOperation("reset")
+	if !hasOp {
+		t.Errorf("HasOperation(reset) must be true, got false")
+	}
+}
+
+func TestCallOperationReset(t *testing.T) {
+
+	list := newListA("a", "b", "c", "d")
+	it := NewListIterator(list, []any{1, 3, 1})
+	if v, err := it.CallOperation("reset", nil); err != nil {
+		t.Errorf("Error on CallOperation(reset): %v", err)
+	} else {
+		t.Logf("Reset result: %v", v)
+	}
+}
+
+func TestCallOperationIndex(t *testing.T) {
+
+	list := newListA("a", "b", "c", "d")
+	it := NewListIterator(list, []any{1, 3, 1})
+	if v, err := it.CallOperation("index", nil); err != nil {
+		t.Errorf("Error on CallOperation(index): %v", err)
+	} else {
+		t.Logf("Index result: %v", v)
+	}
+}
+
+func TestCallOperationCount(t *testing.T) {
+
+	list := newListA("a", "b", "c", "d")
+	it := NewListIterator(list, []any{1, 3, 1})
+	if v, err := it.CallOperation("count", nil); err != nil {
+		t.Errorf("Error on CallOperation(count): %v", err)
+	} else {
+		t.Logf("Count result: %v", v)
+	}
+}
+
+func TestCallOperationUnknown(t *testing.T) {
+
+	list := newListA("a", "b", "c", "d")
+	it := NewListIterator(list, []any{1, 3, 1})
+	if v, err := it.CallOperation("unknown", nil); err == nil {
+		t.Errorf("Expected error on CallOperation(unknown), got %v", v)
+	}
+}

t_iterator_test.go

@@ -8,15 +8,15 @@ import "testing"
 
 func TestIteratorParser(t *testing.T) {
 	inputs := []inputType{
-		/*   1 */ {`include "iterator.expr"; it=$(ds,3); ()it`, int64(0), nil},
+		/*   1 */ {`include "test-resources/iterator.expr"; it=$(ds,3); ()it`, int64(0), nil},
-		/*   2 */ {`include "iterator.expr"; it=$(ds,3); it++; it++`, int64(1), nil},
+		/*   2 */ {`include "test-resources/iterator.expr"; it=$(ds,3); it++; it++`, int64(1), nil},
-		/*   3 */ {`include "iterator.expr"; it=$(ds,3); it++; it++; #it`, int64(2), nil},
+		/*   3 */ {`include "test-resources/iterator.expr"; it=$(ds,3); it++; it++; #it`, int64(2), nil},
-		/*   4 */ {`include "iterator.expr"; it=$(ds,3); it++; it++; it.reset; ()it`, int64(0), nil},
+		/*   4 */ {`include "test-resources/iterator.expr"; it=$(ds,3); it++; it++; it.reset; ()it`, int64(0), nil},
-		/*   5 */ {`builtin "math.arith"; include "iterator.expr"; it=$(ds,3); add(it)`, int64(6), nil},
+		/*   5 */ {`builtin "math.arith"; include "test-resources/iterator.expr"; it=$(ds,3); add(it)`, int64(6), nil},
-		/*   6 */ {`builtin "math.arith"; include "iterator.expr"; it=$(ds,3); mul(it)`, int64(0), nil},
+		/*   6 */ {`builtin "math.arith"; include "test-resources/iterator.expr"; it=$(ds,3); mul(it)`, int64(0), nil},
-		/*   7 */ {`builtin "math.arith"; include "file-reader.expr"; it=$(ds,"int.list"); mul(it)`, int64(12000), nil},
+		/*   7 */ {`builtin "math.arith"; include "test-resources/file-reader.expr"; it=$(ds,"int.list"); mul(it)`, int64(12000), nil},
-		/*   8 */ {`include "file-reader.expr"; it=$(ds,"int.list"); it++; it.index`, int64(0), nil},
+		/*   8 */ {`include "test-resources/file-reader.expr"; it=$(ds,"int.list"); it++; it.index`, int64(0), nil},
-		/*  10 */ {`include "file-reader.expr"; it=$(ds,"int.list"); it.clean`, true, nil},
+		/*  10 */ {`include "test-resources/file-reader.expr"; it=$(ds,"int.list"); it.clean`, true, nil},
 		/*  11 */ {`it=$(1,2,3); it++`, int64(1), nil},
 	}
 	// inputs1 := []inputType{

t_list_test.go

@@ -6,19 +6,12 @@ package expr
 
 import (
 	"errors"
-	"strings"
 	"testing"
 )
 
 func TestListParser(t *testing.T) {
 	section := "List"
 
-	/*	type inputType struct {
-			source     string
-			wantResult any
-			wantErr    error
-		}
-	*/
 	inputs := []inputType{
 		/*   1 */ {`[]`, newListA(), nil},
 		/*   2 */ {`[1,2,3]`, newListA(int64(1), int64(2), int64(3)), nil},
@@ -64,74 +57,4 @@ func TestListParser(t *testing.T) {
 
 	// parserTestSpec(t, section, inputs, 17)
 	parserTest(t, section, inputs)
-	return
-	succeeded := 0
-	failed := 0
-
-	// inputs1 := []inputType{
-	// 	/*  7 */ {`add([1,4,3,2])`, int64(10), nil},
-	// }
-
-	for i, input := range inputs {
-		var expr *ast
-		var gotResult any
-		var gotErr error
-
-		ctx := NewSimpleStore()
-		ImportMathFuncs(ctx)
-		parser := NewParser(ctx)
-
-		logTest(t, i+1, "List", input.source, input.wantResult, input.wantErr)
-
-		r := strings.NewReader(input.source)
-		scanner := NewScanner(r, DefaultTranslations())
-
-		good := true
-		if expr, gotErr = parser.Parse(scanner); gotErr == nil {
-			gotResult, gotErr = expr.Eval(ctx)
-		}
-
-		if (gotResult == nil && input.wantResult != nil) || (gotResult != nil && input.wantResult == nil) {
-			t.Errorf("%d: %q -> result = %v [%T], want %v [%T]", i+1, input.source, gotResult, gotResult, input.wantResult, input.wantResult)
-			good = false
-		}
-
-		if gotList, okGot := gotResult.([]any); okGot {
-			if wantList, okWant := input.wantResult.([]any); okWant {
-				if (gotList == nil && wantList != nil) || (gotList != nil && wantList == nil) {
-					t.Errorf("%d: %q -> result = %v [%T], want %v [%T]", i+1, input.source, gotResult, gotResult, input.wantResult, input.wantResult)
-					good = false
-				} else {
-					equal := len(gotList) == len(wantList)
-					if equal {
-						for i, gotItem := range gotList {
-							wantItem := wantList[i]
-							equal = gotItem == wantItem
-							if !equal {
-								break
-							}
-						}
-					}
-					if !equal {
-						t.Errorf("%d: %q -> result = %v [%T], want %v [%T]", i+1, input.source, gotResult, gotResult, input.wantResult, input.wantResult)
-						good = false
-					}
-				}
-			}
-		}
-
-		if gotErr != input.wantErr {
-			if input.wantErr == nil || gotErr == nil || (gotErr.Error() != input.wantErr.Error()) {
-				t.Errorf("%d: %q  -> err = <%v>, want <%v>", i+1, input.source, gotErr, input.wantErr)
-				good = false
-			}
-		}
-
-		if good {
-			succeeded++
-		} else {
-			failed++
-		}
-	}
-	t.Logf("%s -- test count: %d, succeeded: %d, failed: %d", section, len(inputs), succeeded, failed)
 }

t_module-register_test.go

@@ -12,7 +12,7 @@ func TestIterateModules(t *testing.T) {
 	section := "Module-Register"
 
 	mods := make([]string, 0, 100)
-	IterateModules(func(name, description string, imported bool) bool {
+	IterateBuiltinModules(func(name, description string, imported bool) bool {
 		mods = append(mods, name)
 		return true
 	})

t_parser_test.go

@@ -188,7 +188,7 @@ func doTest(t *testing.T, section string, input *inputType, count int) (good boo
 	var gotErr error
 
 	ctx := NewSimpleStore()
-	parser := NewParser(ctx)
+	parser := NewParser()
 
 	logTest(t, count, section, input.source, input.wantResult, input.wantErr)
 
@@ -203,7 +203,7 @@ func doTest(t *testing.T, section string, input *inputType, count int) (good boo
 	eq := reflect.DeepEqual(gotResult, input.wantResult)
 
 	if !eq /*gotResult != input.wantResult*/ {
-		t.Errorf("%d: %q -> result = %v [%s], want = %v [%s]", count, input.source, gotResult, typeName(gotResult), input.wantResult, typeName(input.wantResult))
+		t.Errorf("%d: %q -> result = %v [%s], want = %v [%s]", count, input.source, gotResult, TypeName(gotResult), input.wantResult, TypeName(input.wantResult))
 		good = false
 	}
 

t_scanner_test.go

@@ -45,7 +45,7 @@ func TestScanner(t *testing.T) {
 		/* 22 */ {"@", SymAt, nil, nil},
 		/* 23 */ {`#`, SymHash, nil, nil},
 		/* 24 */ {`%`, SymPercent, nil, nil},
-		/* 25 */ {`'`, SymQuote, nil, nil},
+		/* 25 */ {`\'`, SymQuote, nil, nil},
 		/* 26 */ {`\"`, SymDoubleQuote, nil, nil},
 		/* 27 */ {`_`, SymUndescore, nil, nil},
 		/* 28 */ {`<>`, SymLessGreater, nil, nil},

t_utils_test.go

@@ -63,7 +63,7 @@ func TestIsString(t *testing.T) {
 	}
 
 	count++
-	b, ok := toBool(true)
+	b, ok := ToBool(true)
 	if !(ok && b) {
 		t.Errorf("%d: toBool(true) b=%v, ok=%v -> result = false, want true", count, b, ok)
 		failed++
@@ -72,7 +72,7 @@ func TestIsString(t *testing.T) {
 	}
 
 	count++
-	b, ok = toBool("abc")
+	b, ok = ToBool("abc")
 	if !(ok && b) {
 		t.Errorf("%d: toBool(\"abc\") b=%v, ok=%v -> result = false, want true", count, b, ok)
 		failed++
@@ -81,7 +81,7 @@ func TestIsString(t *testing.T) {
 	}
 
 	count++
-	b, ok = toBool([]int{})
+	b, ok = ToBool([]int{})
 	if ok {
 		t.Errorf("%d: toBool([]) b=%v, ok=%v -> result = true, want false", count, b, ok)
 		failed++
@@ -97,7 +97,7 @@ func TestToIntOk(t *testing.T) {
 	wantValue := int(64)
 	wantErr := error(nil)
 
-	gotValue, gotErr := toInt(source, "test")
+	gotValue, gotErr := ToInt(source, "test")
 
 	if gotErr != nil || gotValue != wantValue {
 		t.Errorf("toInt(%v, \"test\") gotValue=%v, gotErr=%v -> wantValue=%v, wantErr=%v",
@@ -110,7 +110,7 @@ func TestToIntErr(t *testing.T) {
 	wantValue := 0
 	wantErr := errors.New(`test expected integer, got uint64 (64)`)
 
-	gotValue, gotErr := toInt(source, "test")
+	gotValue, gotErr := ToInt(source, "test")
 
 	if gotErr.Error() != wantErr.Error() || gotValue != wantValue {
 		t.Errorf("toInt(%v, \"test\") gotValue=%v, gotErr=%v -> wantValue=%v, wantErr=%v",

term.go

@@ -156,15 +156,15 @@ func (self *term) toInt(computedValue any, valueDescription string) (i int, err
 	if index64, ok := computedValue.(int64); ok {
 		i = int(index64)
 	} else {
-		err = self.Errorf("%s, got %s (%v)", valueDescription, typeName(computedValue), computedValue)
+		err = self.Errorf("%s, got %s (%v)", valueDescription, TypeName(computedValue), computedValue)
 	}
 	return
 }
 
 func (self *term) errIncompatibleTypes(leftValue, rightValue any) error {
-	leftType := typeName(leftValue)
+	leftType := TypeName(leftValue)
 	leftText := getFormatted(leftValue, Truncate)
-	rightType := typeName(rightValue)
+	rightType := TypeName(rightValue)
 	rightText := getFormatted(rightValue, Truncate)
 	return self.tk.Errorf(
 		"left operand '%s' [%s] and right operand '%s' [%s] are not compatible with operator %q",
@@ -176,7 +176,7 @@ func (self *term) errIncompatibleTypes(leftValue, rightValue any) error {
 func (self *term) errIncompatibleType(value any) error {
 	return self.tk.Errorf(
 		"prefix/postfix operator %q do not support operand '%v' [%s]",
-		self.source(), value, typeName(value))
+		self.source(), value, TypeName(value))
 }
 
 func (self *term) Errorf(template string, args ...any) (err error) {

test-resources/file-reader.expr

@@ -1,13 +1,13 @@
 builtin ["os.file", "base"];
 
 readInt=func(fh){
-	line=readFile(fh);
+	line=fileRead(fh);
 	line ? [nil] {nil} :: {int(line)}
 };
 
 ds={
 	"init":func(filename){
-		fh=openFile(filename);
+		fh=fileOpen(filename);
 		fh ? [nil] {nil} :: { @current=readInt(fh); @prev=@current };
 		fh
 	},
@@ -20,7 +20,7 @@ ds={
 			:: {@prev=current; @current=readInt(fh) but current}
 	},
 	"clean":func(fh){
-		closeFile(fh)
+		fileClose(fh)
 	}
 }
 

utils.go

@@ -86,7 +86,7 @@ func numAsFloat(v any) (f float64) {
 	return
 }
 
-func toBool(v any) (b bool, ok bool) {
+func ToBool(v any) (b bool, ok bool) {
 	ok = true
 	switch x := v.(type) {
 	case string:
@@ -201,13 +201,13 @@ func CloneFilteredMap[K comparable, V any](source map[K]V, filter func(key K) (a
 	return CopyFilteredMap(dest, source, filter)
 }
 
-func toInt(value any, description string) (i int, err error) {
+func ToInt(value any, description string) (i int, err error) {
 	if valueInt64, ok := value.(int64); ok {
 		i = int(valueInt64)
 	} else if valueInt, ok := value.(int); ok {
 		i = valueInt
 	} else {
-		err = fmt.Errorf("%s expected integer, got %s (%v)", description, typeName(value), value)
+		err = fmt.Errorf("%s expected integer, got %s (%v)", description, TypeName(value), value)
 	}
 	return
 }