Iterator: added support for iterators over dictionaries

dict-iterator.go

@@ -0,0 +1,209 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// dict-iterator.go
+package expr
+
+import (
+	"fmt"
+	"io"
+	"slices"
+	"strings"
+)
+
+type dictIterMode int
+
+const (
+	dictIterModeKeys dictIterMode = iota
+	dictIterModeValues
+	dictIterModeItems
+)
+
+type DictIterator struct {
+	a        *DictType
+	count    int
+	index    int
+	keys     []any
+	iterMode dictIterMode
+}
+
+type sortType int
+
+const (
+	sortTypeNone sortType = iota
+	sortTypeAsc
+	sortTypeDesc
+	sortTypeDefault = sortTypeAsc
+)
+
+func (it *DictIterator) makeKeys(m map[any]any, sort sortType) {
+	it.keys = make([]any, 0, len(m))
+
+	if sort == sortTypeNone {
+		for keyAny := range m {
+			it.keys = append(it.keys, keyAny)
+		}
+	} else {
+		scalarMap := make(map[string]any, len(m))
+		scalerKeys := make([]string, 0, len(m))
+		for keyAny := range m {
+			keyStr := fmt.Sprint(keyAny)
+			scalarMap[keyStr] = keyAny
+			scalerKeys = append(scalerKeys, keyStr)
+		}
+
+		switch sort {
+		case sortTypeAsc:
+			slices.Sort(scalerKeys)
+		case sortTypeDesc:
+			slices.Sort(scalerKeys)
+			slices.Reverse(scalerKeys)
+		}
+		for _, keyStr := range scalerKeys {
+			it.keys = append(it.keys, scalarMap[keyStr])
+		}
+	}
+}
+
+func NewDictIterator(dict *DictType, args []any) (it *DictIterator, err error) {
+	var sortType = sortTypeNone
+	var s string
+	it = &DictIterator{a: dict, count: 0, index: -1, keys: nil, iterMode: dictIterModeKeys}
+	if len(args) > 0 {
+		if s, err = ToGoString(args[0], "sort type"); err == nil {
+			switch strings.ToLower(s) {
+			case "a", "asc":
+				sortType = sortTypeAsc
+			case "d", "desc":
+				sortType = sortTypeDesc
+			case "n", "none", "nosort", "no-sort":
+				sortType = sortTypeNone
+			case "", "default":
+				sortType = sortTypeDefault
+			default:
+				err = fmt.Errorf("invalid sort type %q", s)
+			}
+
+			if err == nil && len(args) > 1 {
+				if s, err = ToGoString(args[1], "iteration mode"); err == nil {
+					switch strings.ToLower(s) {
+					case "k", "key", "keys":
+						it.iterMode = dictIterModeKeys
+					case "v", "value", "values":
+						it.iterMode = dictIterModeValues
+					case "i", "item", "items":
+						it.iterMode = dictIterModeItems
+					case "", "default":
+						it.iterMode = dictIterModeKeys
+					default:
+						err = fmt.Errorf("invalid iteration mode %q", s)
+					}
+				}
+			}
+		}
+	}
+	it.makeKeys(*dict, sortType)
+	return
+}
+
+func NewMapIterator(m map[any]any) (it *DictIterator) {
+	it = &DictIterator{a: (*DictType)(&m), count: 0, index: -1, keys: nil}
+	it.makeKeys(m, sortTypeNone)
+	return
+}
+
+func (it *DictIterator) String() string {
+	var l = 0
+	if it.a != nil {
+		l = len(*it.a)
+	}
+	return fmt.Sprintf("$(#%d)", l)
+}
+
+func (it *DictIterator) TypeName() string {
+	return "DictIterator"
+}
+
+func (it *DictIterator) HasOperation(name string) bool {
+	// yes := name == NextName || name == ResetName || name == IndexName || name == CountName || name == CurrentName
+	yes := slices.Contains([]string{NextName, ResetName, IndexName, CountName, CurrentName, CleanName, KeyName, ValueName}, name)
+	return yes
+}
+
+func (it *DictIterator) CallOperation(name string, args map[string]any) (v any, err error) {
+	switch name {
+	case NextName:
+		v, err = it.Next()
+	case ResetName:
+		err = it.Reset()
+	case CleanName:
+		err = it.Clean()
+	case IndexName:
+		v = int64(it.Index())
+	case CurrentName:
+		v, err = it.Current()
+	case CountName:
+		v = it.count
+	case KeyName:
+		if it.index >= 0 && it.index < len(it.keys) {
+			v = it.keys[it.index]
+		} else {
+			err = io.EOF
+		}
+	case ValueName:
+		if it.index >= 0 && it.index < len(it.keys) {
+			a := *(it.a)
+			v = a[it.keys[it.index]]
+		} else {
+			err = io.EOF
+		}
+	default:
+		err = errNoOperation(name)
+	}
+	return
+}
+
+func (it *DictIterator) Current() (item any, err error) {
+	if it.index >= 0 && it.index < len(it.keys) {
+		switch it.iterMode {
+		case dictIterModeKeys:
+			item = it.keys[it.index]
+		case dictIterModeValues:
+			a := *(it.a)
+			item = a[it.keys[it.index]]
+		case dictIterModeItems:
+			a := *(it.a)
+			pair := []any{it.keys[it.index], a[it.keys[it.index]]}
+			item = newList(pair)
+		}
+	} else {
+		err = io.EOF
+	}
+	return
+}
+
+func (it *DictIterator) Next() (item any, err error) {
+	it.index++
+	if item, err = it.Current(); err != io.EOF {
+		it.count++
+	}
+	return
+}
+
+func (it *DictIterator) Index() int {
+	return it.index
+}
+
+func (it *DictIterator) Count() int {
+	return it.count
+}
+
+func (it *DictIterator) Reset() error {
+	it.index = -1
+	it.count = 0
+	return nil
+}
+
+func (it *DictIterator) Clean() error {
+	return nil
+}

iterator.go

@@ -21,6 +21,8 @@ const (
 	CountName   = "count"
 	FilterName  = "filter"
 	MapName     = "map"
+	KeyName     = "key"
+	ValueName   = "value"
 )
 
 type Iterator interface {
@@ -29,14 +31,14 @@ type Iterator interface {
 	Current() (item any, err error)
 	Index() int
 	Count() int
+	HasOperation(name string) bool
+	CallOperation(name string, args map[string]any) (value any, err error)
 }
 
 type ExtIterator interface {
 	Iterator
 	Reset() error
 	Clean() error
-	HasOperation(name string) bool
-	CallOperation(name string, args map[string]any) (value any, err error)
 }
 
 func errNoOperation(name string) error {

list-iterator.go

@@ -149,12 +149,12 @@ func (it *ListIterator) Count() int {
 	return it.count
 }
 
-func (it *ListIterator) Reset() (error) {
+func (it *ListIterator) Reset() error {
 	it.index = it.start - it.step
 	it.count = 0
 	return nil
 }
 
-func (it *ListIterator) Clean() (error) {
+func (it *ListIterator) Clean() error {
 	return nil
 }

operand-iterator.go

@@ -86,37 +86,49 @@ func evalIterator(ctx ExprContext, opTerm *term) (v any, err error) {
 		return
 	}
 
-	if ds, err = getDataSourceDict(opTerm, firstChildValue); err != nil {
+	if ds, err = getDataSourceDict(opTerm, firstChildValue); err != nil && ds == nil {
 		return
 	}
+	err = nil
 
 	if ds != nil {
-		var dc *dataCursor
+		if len(ds) > 0 {
-		dcCtx := ctx.Clone()
+			var dc *dataCursor
-		if initFunc, exists := ds[InitName]; exists && initFunc != nil {
+			dcCtx := ctx.Clone()
-			var args []any
+			if initFunc, exists := ds[InitName]; exists && initFunc != nil {
-			var resource any
+				var args []any
-			if len(opTerm.children) > 1 {
+				var resource any
-				if args, err = evalTermArray(ctx, opTerm.children[1:]); err != nil {
+				if len(opTerm.children) > 1 {
+					if args, err = evalTermArray(ctx, opTerm.children[1:]); err != nil {
+						return
+					}
+				} else {
+					args = []any{}
+				}
+
+				actualParams := bindActualParams(initFunc, args)
+
+				initCtx := ctx.Clone()
+				if resource, err = initFunc.InvokeNamed(initCtx, InitName, actualParams); err != nil {
 					return
 				}
+				exportObjects(dcCtx, initCtx)
+				dc = NewDataCursor(dcCtx, ds, resource)
 			} else {
-				args = []any{}
+				dc = NewDataCursor(dcCtx, ds, nil)
 			}
 
-			actualParams := bindActualParams(initFunc, args)
+			v = dc
-
-			initCtx := ctx.Clone()
-			if resource, err = initFunc.InvokeNamed(initCtx, InitName, actualParams); err != nil {
-				return
-			}
-			exportObjects(dcCtx, initCtx)
-			dc = NewDataCursor(dcCtx, ds, resource)
 		} else {
-			dc = NewDataCursor(dcCtx, ds, nil)
+			if dictIt, ok := firstChildValue.(*DictType); ok {
+				var args []any
+				if args, err = evalSibling(ctx, opTerm.children, nil); err == nil {
+					v, err = NewDictIterator(dictIt, args)
+				}
+			} else {
+				err = opTerm.children[0].Errorf("the data-source must be a dictionary")
+			}
 		}
-
-		v = dc
 	} else if list, ok := firstChildValue.(*ListType); ok {
 		var args []any
 		if args, err = evalSibling(ctx, opTerm.children, nil); err == nil {

operator-post-inc-dec.go

@@ -24,7 +24,27 @@ func evalPostInc(ctx ExprContext, opTerm *term) (v any, err error) {
 	}
 
 	if it, ok := childValue.(Iterator); ok {
+		var namePrefix string
 		v, err = it.Next()
+
+		if opTerm.children[0].symbol() == SymVariable {
+			namePrefix = opTerm.children[0].source()
+		}
+		ctx.UnsafeSetVar(namePrefix+"_index", it.Index())
+		if c, err1 := it.Current(); err1 == nil {
+			ctx.UnsafeSetVar(namePrefix+"_current", c)
+		}
+
+		if it.HasOperation(KeyName) {
+			if k, err1 := it.CallOperation(KeyName, nil); err1 == nil {
+				ctx.UnsafeSetVar(namePrefix+"_key", k)
+			}
+		}
+		if it.HasOperation(ValueName) {
+			if v1, err1 := it.CallOperation(ValueName, nil); err1 == nil {
+				ctx.UnsafeSetVar(namePrefix+"_value", v1)
+			}
+		}
 	} else if IsInteger(childValue) && opTerm.children[0].symbol() == SymVariable {
 		v = childValue
 		i, _ := childValue.(int64)

t_iterator_test.go

@@ -27,8 +27,10 @@ func TestIteratorParser(t *testing.T) {
 		/*  16 */ {`include "test-resources/filter.expr"; it=$(ds,10); it++`, int64(2), nil},
 		/*  17 */ {`it=$({"next":func(){5}}); it++`, int64(5), nil},
 		/*  18 */ {`it=$({"next":func(){5}}); it.clean`, nil, nil},
+		/*  19 */ {`it=$({1:"one",2:"two",3:"three"}); it++`, int64(1), nil},
+		/*  20 */ {`it=$({1:"one",2:"two",3:"three"}, "default", "value"); it++`, "one", nil},
 	}
 
-	//runTestSuiteSpec(t, section, inputs, 18)
+	runTestSuiteSpec(t, section, inputs, 20)
-	runTestSuite(t, section, inputs)
+	// runTestSuite(t, section, inputs)
 }

utils.go

@@ -218,6 +218,15 @@ func ToGoInt(value any, description string) (i int, err error) {
 	return
 }
 
+func ToGoString(value any, description string) (s string, err error) {
+	if s, ok := value.(string); ok {
+		return s, nil
+	} else {
+		err = fmt.Errorf("%s expected string, got %s (%v)", description, TypeName(value), value)
+	}
+	return
+}
+
 func ForAll[T, V any](ts []T, fn func(T) V) []V {
 	result := make([]V, len(ts))
 	for i, t := range ts {