support of multi-indices

Makefile

@@ -11,7 +11,7 @@ linux:
 	GOOS=linux GOARCH=amd64 go build -o spiff++/spiff++ .
 
 test:
-	go test $(VERBOSE) ./...
+	go test $(VERBOSE) --count=1 ./...
 
 spiff_linux_amd64.zip:
 	GOOS=linux GOARCH=amd64 go build -o spiff++/spiff++ .

README.md

@@ -622,6 +622,9 @@ resolves `foo` again to the value `42`.
 
 **Note**: The index operator is usable on the root element (`.[index]`), also.
 
+It is possible, to specify multiple comma separated indicies to successive lists
+(`foo[0][1]` is equivalent to `foo[0,1]). In such case the indices may not be again lists.
+
 ## `(( list.[1..3] ))`
 
 The slice expression can be used to extract a dedicated sub list from a list

dynaml/dynamic_expression.go

@@ -48,6 +48,11 @@ func (e DynamicExpr) Evaluate(binding Binding, locally bool) (interface{}, Evalu
 
 	debug.Debug("dynamic reference: %+v\n", dyn)
 
+	if a, ok := dyn.([]yaml.Node); ok {
+		if len(a) == 1 {
+			dyn = a[0].Value()
+		}
+	}
 	var qual []string
 	switch v := dyn.(type) {
 	case int64:
@@ -59,6 +64,9 @@ func (e DynamicExpr) Evaluate(binding Binding, locally bool) (interface{}, Evalu
 	case string:
 		qual = []string{v}
 	case []yaml.Node:
+		if len(v) == 0 {
+			return info.Error("at least one index or field name required for reference qualifier")
+		}
 		qual = make([]string, len(v))
 		for i, e := range v {
 			switch v := e.Value().(type) {
@@ -88,5 +96,5 @@ func (e DynamicExpr) Evaluate(binding Binding, locally bool) (interface{}, Evalu
 }
 
 func (e DynamicExpr) String() string {
-	return fmt.Sprintf("%s.[%s]", e.Root, e.Index)
+	return fmt.Sprintf("%s.%s", e.Root, e.Index)
 }

dynaml/dynamic_expression_test.go

@@ -26,7 +26,7 @@ var _ = Describe("dynamic references", func() {
 		})
 	})
 
-	Context("when a dynamic array refernce is found", func() {
+	Context("when a dynamic array reference is found", func() {
 		It("evaluates to the indexed array entry", func() {
 			ref := ReferenceExpr{Path: []string{"foo"}}
 			idx := IntegerExpr{1}
@@ -39,5 +39,31 @@ var _ = Describe("dynamic references", func() {
 
 			Expect(expr).To(EvaluateAs(42, binding))
 		})
+
+		It("evaluates to the indexed array entry", func() {
+			ref := ReferenceExpr{Path: []string{"foo"}}
+			idx := ListExpr{[]Expression{IntegerExpr{1}}}
+			expr := DynamicExpr{ref, idx}
+			binding := FakeBinding{
+				FoundReferences: map[string]yaml.Node{
+					"foo": NewNode([]yaml.Node{NewNode(1, nil), NewNode(42, nil)}, nil),
+				},
+			}
+
+			Expect(expr).To(EvaluateAs(42, binding))
+		})
+
+		It("evaluates to the multi-indexed array entry", func() {
+			ref := ReferenceExpr{Path: []string{"foo"}}
+			idx := ListExpr{[]Expression{IntegerExpr{0}, IntegerExpr{1}}}
+			expr := DynamicExpr{ref, idx}
+			binding := FakeBinding{
+				FoundReferences: map[string]yaml.Node{
+					"foo": NewNode([]yaml.Node{NewNode([]yaml.Node{NewNode(1, nil), NewNode(42, nil)}, nil)}, nil),
+				},
+			}
+
+			Expect(expr).To(EvaluateAs(42, binding))
+		})
 	})
 })

dynaml/dynaml.peg

@@ -50,8 +50,9 @@ Level0 <- IP / String / Number / Boolean / Undefined / Nil / Symbol / Not /
 Chained <- ( MapMapping / Sync / Catch / Mapping / MapSelection / Selection / Sum / List / Map / Range / Grouped / Reference / TopIndex ) ChainedQualifiedExpression*
 ChainedQualifiedExpression <- ChainedCall / Currying / ChainedRef / ChainedDynRef / Projection
 ChainedRef <-  PathComponent FollowUpRef
-ChainedDynRef <- '.'? '[' Expression ']'
-TopIndex <- '.' '[' Expression ']'
+ChainedDynRef <- '.'? Indices
+TopIndex <- '.' Indices
+Indices <- StartList ExpressionList ']'
 Slice <- Range
 Currying <- '*' ChainedCall
 ChainedCall <- StartArguments  NameArgumentList? ')'