data-cursor.go

@@ -5,14 +5,11 @@
 package expr
 
 import (
-	"errors"
 	"io"
 )
 
 const (
 	initName    = "init"
-	cleanName   = "clean"
-	resetName   = "reset"
 	nextName    = "next"
 	currentName = "current"
 )
@@ -23,8 +20,6 @@ type dataCursor struct {
 	index       int
 	resource    any
 	nextFunc    Functor
-	cleanFunc   Functor
-	resetFunc   Functor
 	currentFunc Functor
 }
 
@@ -40,30 +35,6 @@ func (dc *dataCursor) String() string {
 	return "$(...)"
 }
 
-func (dc *dataCursor) Reset() (err error) {
-	if dc.resetFunc != nil {
-		ctx := cloneContext(dc.ctx)
-		if _, err = dc.resetFunc.Invoke(ctx, resetName, []any{}); err == nil {
-			dc.index = -1
-		}
-		exportObjects(dc.ctx, ctx)
-	} else {
-		err = errors.New("no 'reset' function defined in the data-source")
-	}
-	return
-}
-
-func (dc *dataCursor) Clean() (err error) {
-	if dc.cleanFunc != nil {
-		ctx := cloneContext(dc.ctx)
-		_, err = dc.cleanFunc.Invoke(ctx, cleanName, []any{})
-		exportObjects(dc.ctx, ctx)
-	} else {
-		err = errors.New("no 'clean' function defined in the data-source")
-	}
-	return
-}
-
 func (dc *dataCursor) Current() (item any, err error) { // must return io.EOF at the last item
 	ctx := cloneContext(dc.ctx)
 	if item, err = dc.currentFunc.Invoke(ctx, currentName, []any{}); err == nil && item == nil {

func-builtins.go

@@ -55,5 +55,5 @@ func ImportBuiltinsFuncs(ctx ExprContext) {
 }
 
 func init() {
-	registerImport("base", ImportBuiltinsFuncs, "Base expression tools like isNil(), int(), etc.")
+	registerImport("builtins", ImportBuiltinsFuncs)
 }

func-import.go

@@ -142,5 +142,5 @@ func ImportImportFuncs(ctx ExprContext) {
 }
 
 func init() {
-	registerImport("import", ImportImportFuncs, "Functions import() and include()")
+	registerImport("import", ImportImportFuncs)
 }

func-math.go

@@ -115,5 +115,5 @@ func ImportMathFuncs(ctx ExprContext) {
 }
 
 func init() {
-	registerImport("math.arith", ImportMathFuncs, "Function add() and mul()")
+	registerImport("math.arith", ImportMathFuncs)
 }

func-os.go

@@ -164,5 +164,5 @@ func ImportOsFuncs(ctx ExprContext) {
 }
 
 func init() {
-	registerImport("os.file", ImportOsFuncs, "Operating system file functions")
+	registerImport("os", ImportOsFuncs)
 }

function-register.go

@@ -0,0 +1,47 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// function-register.go
+package expr
+
+import (
+	"path/filepath"
+)
+
+var functionRegister map[string]func(ExprContext)
+
+func registerImport(name string, importFunc func(ExprContext)) {
+	if functionRegister == nil {
+		functionRegister = make(map[string]func(ExprContext))
+	}
+	functionRegister[name] = importFunc
+}
+
+func ImportInContext(ctx ExprContext, name string) (exists bool) {
+	var importFunc func(ExprContext)
+	if importFunc, exists = functionRegister[name]; exists {
+		importFunc(ctx)
+	}
+	return
+}
+
+func ImportInContextByGlobPattern(ctx ExprContext, pattern string) (count int, err error) {
+	var matched bool
+	for name, importFunc := range functionRegister {
+		if matched, err = filepath.Match(pattern, name); err == nil {
+			if matched {
+				count++
+				importFunc(ctx)
+			}
+		} else {
+			break
+		}
+	}
+	return
+}
+
+func init() {
+	if functionRegister == nil {
+		functionRegister = make(map[string]func(ExprContext))
+	}
+}

helpers.go

@@ -6,8 +6,6 @@ package expr
 
 import (
 	"fmt"
-	"io"
-	"os"
 	"strings"
 )
 
@@ -61,24 +59,3 @@ func EvalStringV(source string, args []Arg) (result any, err error) {
 	}
 	return
 }
-
-func EvalStream(ctx ExprContext, r io.Reader) (result any, err error) {
-	var tree *ast
-	scanner := NewScanner(r, DefaultTranslations())
-	parser := NewParser(ctx)
-
-	if tree, err = parser.Parse(scanner); err == nil {
-		result, err = tree.Eval(ctx)
-	}
-	return
-}
-
-func EvalFile(ctx ExprContext, filePath string) (result any, err error) {
-	var fh *os.File
-	if fh, err = os.Open(filePath); err != nil {
-		return nil, err
-	}
-	defer fh.Close()
-	result, err = EvalStream(ctx, fh)
-	return
-}

module-register.go

@@ -1,74 +0,0 @@
-// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
-// All rights reserved.
-
-// module-register.go
-package expr
-
-import (
-	"fmt"
-	"path/filepath"
-)
-
-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 ImportInContext(ctx ExprContext, name string) (exists bool) {
-	var mod *module
-	if mod, exists = moduleRegister[name]; exists {
-		mod.importFunc(ctx)
-		mod.imported = true
-	}
-	return
-}
-
-func ImportInContextByGlobPattern(ctx ExprContext, pattern string) (count int, err error) {
-	var matched bool
-	for name, mod := range moduleRegister {
-		if matched, err = filepath.Match(pattern, name); err == nil {
-			if matched {
-				count++
-				mod.importFunc(ctx)
-				mod.imported = true
-			}
-		} else {
-			break
-		}
-	}
-	return
-}
-
-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-iterator.go

@@ -54,23 +54,14 @@ func getDataSourceDict(ctx ExprContext, self *term) (ds map[string]Functor, err
 
 	if dictAny, ok := value.(map[any]any); ok {
 		ds = make(map[string]Functor)
-		// required functions
+		for _, k := range []string{initName, currentName, nextName} {
-		for _, k := range []string{currentName, nextName} {
 			if item, exists := dictAny[k]; exists && item != nil {
 				if functor, ok := item.(*funcDefFunctor); ok {
 					ds[k] = functor
 				}
-			} else {
+			} else if k != initName {
 				err = fmt.Errorf("the data-source must provide a non-nil %q operator", k)
-				return
+				break
-			}
-		}
-		// Optional functions
-		for _, k := range []string{initName, resetName, cleanName} {
-			if item, exists := dictAny[k]; exists && item != nil {
-				if functor, ok := item.(*funcDefFunctor); ok {
-					ds[k] = functor
-				}
 			}
 		}
 	} else {
@@ -107,9 +98,6 @@ func evalIterator(ctx ExprContext, self *term) (v any, err error) {
 
 	dc.nextFunc, _ = ds[nextName]
 	dc.currentFunc, _ = ds[currentName]
-	dc.cleanFunc, _ = ds[cleanName]
-	dc.resetFunc, _ = ds[resetName]
-
 	v = dc
 
 	return

operator-builtin.go

@@ -1,7 +1,7 @@
 // Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
 // All rights reserved.
 
-// operator-builtin.go
+// operator-length.go
 package expr
 
 //-------- builtin term

operator-dot.go

@@ -17,67 +17,50 @@ func newDotTerm(tk *Token) (inst *term) {
 	}
 }
 
-func verifyIndex(ctx ExprContext, indexTerm *term, maxValue int) (index int, err error) {
-	var v int
-	var indexValue any
-	if indexValue, err = indexTerm.compute(ctx); err == nil {
-		if v, err = indexTerm.toInt(indexValue, "index expression value must be integer"); err == nil {
-			if v >= 0 && v < maxValue {
-				index = v
-			} else if index >= -maxValue {
-				index = maxValue + v
-			} else {
-				err = indexTerm.Errorf("index %d out of bounds", v)
-			}
-		}
-	}
-	return
-}
-
 func evalDot(ctx ExprContext, self *term) (v any, err error) {
 	var leftValue, rightValue any
 
-	if err = self.checkOperands(); err != nil {
+	if leftValue, rightValue, err = self.evalInfix(ctx); err != nil {
-		return
-	}
-	if leftValue, err = self.children[0].compute(ctx); err != nil {
 		return
 	}
 
 	indexTerm := self.children[1]
 
-	switch unboxedValue := leftValue.(type) {
+	if isList(leftValue) {
-	case []any:
 		var index int
-		if index, err = verifyIndex(ctx, indexTerm, len(unboxedValue)); err == nil {
+		if index, err = indexTerm.toInt(rightValue, "index expression value must be integer"); err != nil {
-			v = unboxedValue[index]
+			return
 		}
-	case string:
+
+		list, _ := leftValue.([]any)
+		if index >= 0 && index < len(list) {
+			v = list[index]
+		} else if index >= -len(list) {
+			v = list[len(list)+index]
+		} else {
+			err = indexTerm.Errorf("index %v out of bounds", index)
+		}
+	} else if isString(leftValue) {
 		var index int
-		if index, err = verifyIndex(ctx, indexTerm, len(unboxedValue)); err == nil {
+		if index, err = indexTerm.toInt(rightValue, "index expression value must be integer"); err != nil {
-			v = unboxedValue[index]
+			return
 		}
-	case map[any]any:
+
+		s, _ := leftValue.(string)
+		if index >= 0 && index < len(s) {
+			v = string(s[index])
+		} else if index >= -len(s) {
+			v = string(s[len(s)+index])
+		} else {
+			err = indexTerm.Errorf("index %v out of bounds", index)
+		}
+	} else if isDict(leftValue) {
 		var ok bool
-		var indexValue any
+		d, _ := leftValue.(map[any]any)
-		if indexValue, err = indexTerm.compute(ctx); err == nil {
+		if v, ok = d[rightValue]; !ok {
-			if v, ok = unboxedValue[indexValue]; !ok {
 			err = fmt.Errorf("key %v does not belong to the dictionary", rightValue)
 		}
-		}
-	case *dataCursor:
-		if indexTerm.symbol() == SymIdentifier {
-			opName := indexTerm.source()
-			if opName == resetName {
-				err = unboxedValue.Reset()
-			} else if opName == cleanName {
-				err = unboxedValue.Clean()
 	} else {
-				err = indexTerm.Errorf("iterators do not support command %q", opName)
-			}
-			v = err == nil
-		}
-	default:
 		err = self.errIncompatibleTypes(leftValue, rightValue)
 	}
 	return

operator-include.go

@@ -1,57 +0,0 @@
-// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
-// All rights reserved.
-
-// operator-include.go
-package expr
-
-//-------- include term
-
-func newIncludeTerm(tk *Token) (inst *term) {
-	return &term{
-		tk:       *tk,
-		children: make([]*term, 0, 1),
-		position: posPrefix,
-		priority: priSign,
-		evalFunc: evalInclude,
-	}
-}
-
-func evalInclude(ctx ExprContext, self *term) (v any, err error) {
-	var childValue any
-
-	if childValue, err = self.evalPrefix(ctx); err != nil {
-		return
-	}
-
-	count := 0
-	if isList(childValue) {
-		list, _ := childValue.([]any)
-		for i, filePathSpec := range list {
-			if filePath, ok := filePathSpec.(string); ok {
-				if v, err = EvalFile(ctx, filePath); err == nil {
-					count++
-				} else {
-					err = self.Errorf("can't load file %q", filePath)
-					break
-				}
-			} else {
-				err = self.Errorf("expected string at item nr %d, got %T", i+1, filePathSpec)
-				break
-			}
-		}
-	} else if isString(childValue) {
-		filePath, _ := childValue.(string)
-		v, err = EvalFile(ctx, filePath)
-	} else {
-		err = self.errIncompatibleType(childValue)
-	}
-	if err == nil {
-		v = count
-	}
-	return
-}
-
-// init
-func init() {
-	registerTermConstructor(SymKwInclude, newIncludeTerm)
-}

operator-length.go

@@ -25,12 +25,12 @@ func evalLength(ctx ExprContext, self *term) (v any, err error) {
 
 	if isList(rightValue) {
 		list, _ := rightValue.([]any)
-		v = int64(len(list))
+		v = len(list)
 	} else if isString(rightValue) {
 		s, _ := rightValue.(string)
-		v = int64(len(s))
+		v = len(s)
 	} else if it, ok := rightValue.(Iterator); ok {
-		v = int64(it.Index())
+		v = it.Index()
 	} else {
 		err = self.errIncompatibleType(rightValue)
 	}

symbol.go

@@ -33,7 +33,7 @@ const (
 	SymBackTick                          //  22: '`'
 	SymExclamation                       //  23: '!'
 	SymQuestion                          //  24: '?'
-	SymAmpersand                         //  25: '&'
+	SymAmpersand                         //  25: '&&'
 	SymDoubleAmpersand                   //  26: '&&'
 	SymPercent                           //  27: '%'
 	SymAt                                //  28: '@'
@@ -64,7 +64,7 @@ const (
 	SymCaret                             //  53: '^'
 	SymDollarRound                       //  54: '$('
 	SymOpenClosedRound                   //  55: '()'
-	SymDoubleDollar                      //  56: '$$'
+	SymDoubleDollar                      //  56: '$$
 	SymChangeSign
 	SymUnchangeSign
 	SymIdentifier
@@ -96,7 +96,6 @@ const (
 	SymKwBut
 	SymKwFunc
 	SymKwBuiltin
-	SymKwInclude
 	SymKwNil
 )
 
@@ -109,7 +108,6 @@ func init() {
 		"BUILTIN": SymKwBuiltin,
 		"BUT":     SymKwBut,
 		"FUNC":    SymKwFunc,
-		"INCLUDE": SymKwInclude,
 		"NOT":     SymKwNot,
 		"OR":      SymKwOr,
 		"NIL":     SymKwNil,

term.go

@@ -217,9 +217,9 @@ func (self *term) evalInfix(ctx ExprContext) (leftValue, rightValue any, err err
 	return
 }
 
-func (self *term) evalPrefix(ctx ExprContext) (childValue any, err error) {
+func (self *term) evalPrefix(ctx ExprContext) (rightValue any, err error) {
 	if err = self.checkOperands(); err == nil {
-		childValue, err = self.children[0].compute(ctx)
+		rightValue, err = self.children[0].compute(ctx)
 	}
 	return
 }