Add map destructure

1 files changed, 25 insertions, 0 deletions

diff --git a/subex/subexstate.go b/subex/subexstate.go
index 45b5d00..26d7347 100644
--- a/subex/subexstate.go
+++ b/subex/subexstate.go
@@ -373,6 +373,31 @@ func (state SubexConstructArrayValuesState) epsilon(aux auxiliaryState) []SubexB
 	}}
 }
 
+type SubexConstructMapState struct {
+	next SubexState
+}
+func (state SubexConstructMapState) epsilon(aux auxiliaryState) []SubexBranch {
+	values, aux := aux.popOutput()
+	var m walk.MapValue
+	if len(values) % 2 != 0 {
+		panic("Tried to construct array with odd length input")
+	}
+	for i := 0; i < len(values); i += 2 {
+		key, isNum := values[i].(walk.StringValue)
+		if !isNum {
+			panic("Tried to construct array with non-numeric index")
+		}
+		m = append(m, walk.MapElement {
+			Key: string(key),
+			Value: values[i + 1],
+		})
+	}
+	return []SubexBranch {{
+		state: state.next,
+		aux: aux.topAppend([]walk.Value {m}),
+	}}
+}
+
 type SubexConstructStringState struct {
 	next SubexState
 }