solved a number of problems highlighted by the syntax analyzer

builtin-base.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"math"
 	"strconv"
+	"strings"
 )
 
 const (
@@ -188,6 +189,30 @@ func fractFunc(ctx ExprContext, name string, args map[string]any) (result any, e
 // 	return
 // }
 
+func evalFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
+	if source, ok := args[ParamSource].(string); ok {
+		var expr Expr
+
+		parser := NewParser()
+		if ctx == nil {
+			ctx = NewSimpleStore()
+		}
+
+		r := strings.NewReader(source)
+		scanner := NewScanner(r, DefaultTranslations())
+
+		if expr, err = parser.Parse(scanner); err == nil {
+			CtrlEnable(ctx, control_export_all)
+			result, err = expr.Eval(ctx)
+		}
+	} else {
+		err = ErrWrongParamType(name, ParamSource, TypeString, args[ParamSource])
+	}
+	return
+}
+
+//// import
+
 func ImportBuiltinsFuncs(ctx ExprContext) {
 	anyParams := []ExprFuncParam{
 		NewFuncParam(ParamValue),
@@ -211,6 +236,10 @@ func ImportBuiltinsFuncs(ctx ExprContext) {
 		NewFuncParam(ParamValue),
 		NewFuncParamFlagDef(ParamDenominator, PfDefault, int64(1)),
 	})
+
+	ctx.RegisterFunc("eval", NewGolangFunctor(evalFunc), TypeAny, []ExprFuncParam{
+		NewFuncParam(ParamSource),
+	})
 }
 
 func init() {

common-errors.go

@@ -55,8 +55,25 @@ func ErrInvalidParameterValue(funcName, paramName string, paramValue any) error
 	return fmt.Errorf("%s(): invalid value %s (%v) for parameter %q", funcName, TypeName(paramValue), paramValue, paramName)
 }
 
+func undefArticle(s string) (article string) {
+	if len(s) > 0 && strings.Contains("aeiou", s[0:1]) {
+		article = "an"
+	} else {
+		article = "a"
+	}
+	return
+}
+
+func prependUndefArticle(s string) (result string) {
+	return undefArticle(s) + " " + s
+}
+
 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)
+	var artWantType, artGotType string
+	gotType := TypeName(paramValue)
+	artGotType = prependUndefArticle(gotType)
+	artWantType = prependUndefArticle(paramType)
+	return fmt.Errorf("%s(): the %q parameter must be %s, got %s (%v)", funcName, paramName, artWantType, artGotType, paramValue)
 }
 
 func ErrUnknownParam(funcName, paramName string) error {

context-helpers.go

@@ -29,7 +29,7 @@ func exportObjects(destCtx, sourceCtx ExprContext) {
 	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] == '@' }) {
+	for _, refName := range sourceCtx.EnumVars(func(name string) bool { return (exportAll || name[0] == '@') && !(name[0] == '_') }) {
 		// fmt.Printf("\tExporting %q\n", refName)
 		refValue, _ := sourceCtx.GetVar(refName)
 		exportVar(destCtx, refName, refValue)

fraction-type.go

@@ -126,34 +126,36 @@ func (f *FractionType) ToString(opt FmtOpt) string {
 	if opt&MultiLine == 0 {
 		sb.WriteString(fmt.Sprintf("%d:%d", f.num, f.den))
 	} else {
-		var s, num string
+		var sign, num string
 		if f.num < 0 && opt&TTY == 0 {
 			num = strconv.FormatInt(-f.num, 10)
-			s = "-"
+			sign = "-"
 		} else {
 			num = strconv.FormatInt(f.num, 10)
 		}
 		den := strconv.FormatInt(f.den, 10)
 		size := max(len(num), len(den))
 		if opt&TTY != 0 {
-			sb.WriteString(fmt.Sprintf("\x1b[4m%[1]*s\x1b[0m\n", -size, fmt.Sprintf("%[1]*s", (size+len(num))/2, s+num)))
+			sNum := fmt.Sprintf("\x1b[4m%[1]*s\x1b[0m\n", -size, fmt.Sprintf("%[1]*s", (size+len(num))/2, sign+num))
+			sb.WriteString(sNum)
 		} else {
-			if len(s) > 0 {
+			if len(sign) > 0 {
 				sb.WriteString("  ")
 			}
 			sb.WriteString(fmt.Sprintf("%[1]*s", -size, fmt.Sprintf("%[1]*s", (size+len(num))/2, num)))
 			sb.WriteByte('\n')
-			if len(s) > 0 {
+			if len(sign) > 0 {
-				sb.WriteString(s)
+				sb.WriteString(sign)
 				sb.WriteByte(' ')
 			}
 			sb.WriteString(strings.Repeat("-", size))
 			sb.WriteByte('\n')
-			if len(s) > 0 {
+			if len(sign) > 0 {
 				sb.WriteString("  ")
 			}
 		}
-		sb.WriteString(fmt.Sprintf("%[1]*s", -size, fmt.Sprintf("%[1]*s", (size+len(den))/2, den)))
+		sDen := fmt.Sprintf("%[1]*s", size, fmt.Sprintf("%[1]*s", (size+len(den))/2, den))
+		sb.WriteString(sDen)
 	}
 
 	return sb.String()

iterator.go

@@ -5,7 +5,7 @@
 package expr
 
 import (
-	"errors"
+	// "errors"
 	"fmt"
 )
 
@@ -43,6 +43,6 @@ func errNoOperation(name string) error {
 	return fmt.Errorf("no %s() function defined in the data-source", name)
 }
 
-func errInvalidDataSource() error {
+// func errInvalidDataSource() error {
-	return errors.New("invalid data-source")
+// 	return errors.New("invalid data-source")
-}
+// }

operator-context.go

@@ -20,7 +20,7 @@ func evalContextValue(ctx ExprContext, opTerm *term) (v any, err error) {
 	var childValue any
 
 	var sourceCtx ExprContext
-	if opTerm.children == nil || len(opTerm.children) == 0 {
+	if len(opTerm.children) == 0 {
 		sourceCtx = ctx
 	} else if opTerm.children[0].symbol() == SymVariable && opTerm.children[0].source() == "global" {
 		sourceCtx = globalCtx

scanner.go

@@ -460,7 +460,7 @@ func (scanner *scanner) parseNumber(firstCh byte) (tk *Token) {
 		tk = scanner.makeErrorToken(err)
 	} else {
 		var value any
-		err = scanner.sync(err) // TODO: Check this function
+		_ = scanner.sync(err) // TODO: Check this function
 		txt := sb.String()
 		if sym == SymFloat {
 			value, err = strconv.ParseFloat(txt, 64)

t_builtin-base_test.go

@@ -56,11 +56,12 @@ func TestFuncBase(t *testing.T) {
 		/*  42 */ {`dec(false)`, float64(0), nil},
 		/*  43 */ {`dec(1:2)`, float64(0.5), nil},
 		/*  44 */ {`dec([1])`, nil, `dec(): can't convert list to float`},
+		/*  45 */ {`eval("a=3"); a`, int64(3), nil},
 		// /*  45 */ {`string([1])`, nil, `string(): can't convert list to string`},
 	}
 
 	t.Setenv("EXPR_PATH", ".")
 
-	// runTestSuiteSpec(t, section, inputs, 30)
+	// runTestSuiteSpec(t, section, inputs, 45)
 	runTestSuite(t, section, inputs)
 }

t_builtin-string_test.go

@@ -15,7 +15,7 @@ func TestFuncString(t *testing.T) {
 		/*   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, `strJoin(): the "separator" parameter must be a string, got a integer (1)`},
+		/*   4 */ {`builtin "string"; ls= ["one", "two", "three"]; strJoin(1, ls)`, nil, `strJoin(): the "separator" parameter must be a string, got an integer (1)`},
 		/*   5 */ {`builtin "string"; ls= ["one", 2, "three"]; strJoin("-", ls)`, nil, `strJoin(): expected string, got integer (2)`},
 		/*   6 */ {`builtin "string"; "<"+strTrim("  bye bye  ")+">"`, "<bye bye>", nil},
 		/*   7 */ {`builtin "string"; strSub("0123456789", 1,2)`, "12", nil},

t_fractions_test.go

@@ -59,10 +59,9 @@ func TestFractionToStringMultiline(t *testing.T) {
 	}
 }
 
-// TODO Check this test: the output string ends with a space
+func TestToStringMultilineTty(t *testing.T) {
-func _TestToStringMultilineTty(t *testing.T) {
 	source := newFraction(-1, 2)
-	want := "\x1b[4m-1\x1b[0m\n2"
+	want := "\x1b[4m-1\x1b[0m\n 2"
 	got := source.ToString(MultiLine | TTY)
 	if got != want {
 		t.Errorf(`(1,2) -> result = %#v [%T], want = %#v [%T]`, got, got, want, want)

t_plugin_test.go

@@ -8,18 +8,18 @@ import (
 	"testing"
 )
 
-func _TestImportPlugin(t *testing.T) {
+// func TestImportPlugin(t *testing.T) {
-	t.Setenv("PLUGINS", "${HOME}/go/src/git.portale-stac.it/go")
+// 	t.Setenv("PLUGINS", "${HOME}/go/src/git.portale-stac.it/go")
-	t.Setenv("EXPR_PLUGIN_PATH","${PLUGINS}/expr-json-plugin:${PLUGINS}/expr-csv-plugin")
+// 	t.Setenv("EXPR_PLUGIN_PATH","${PLUGINS}/expr-json-plugin:${PLUGINS}/expr-csv-plugin")
 
-	gotCount, gotErr := importPluginFromSearchPath("json")
+// 	gotCount, gotErr := importPluginFromSearchPath("json")
-	if gotCount != 1 {
+// 	if gotCount != 1 {
-		t.Errorf("Import count: got=%d, want=1", gotCount)
+// 		t.Errorf("Import count: got=%d, want=1", gotCount)
-	}
+// 	}
-	if gotErr != nil {
+// 	if gotErr != nil {
-		t.Errorf("importPlugin() failed: %v", gotErr)
+// 		t.Errorf("importPlugin() failed: %v", gotErr)
-	}
+// 	}
-}
+// }
 
 func TestPluginExists(t *testing.T) {
 	name := "json"