Add merge command

5 files changed, 144 insertions, 3 deletions

diff --git a/main/command.go b/main/command.go
index 3f22821..6d75974 100644
--- a/main/command.go
+++ b/main/command.go
@@ -44,13 +44,47 @@ func (cmd AppendNextCommand) exec(state *ProgramState) {
 	if err != nil {
 		panic("Missing next value")
 	}
+
+	state.prevStart = nextItem.PrevStart
+	state.start = nextItem.Start
+	state.end = nextItem.End
+	state.nextEnd = nextItem.NextEnd
+
 	state.value = append(state.value, nextItem.Value)
+
 	state.pc++
 }
 func (cmd AppendNextCommand) String() string {
 	return "N"
 }
 
+type MergeCommand struct {}
+func (cmd MergeCommand) exec(state *ProgramState) {
+	nextItem, err := state.in.Read()
+	if err != nil {
+		panic("Missing next value")
+	}
+
+	state.prevStart = nextItem.PrevStart
+	state.start = nextItem.Start
+	state.end = nextItem.End
+	state.nextEnd = nextItem.NextEnd
+
+	if len(state.value) == 0 {
+		state.value = []walk.Value {nextItem.Value}
+	} else {
+		state.value = append(
+			state.value[:len(state.value) - 1],
+			walk.Merge(state.value[len(state.value) - 1], nextItem.Value)...
+		)
+	}
+
+	state.pc++
+}
+func (cmd MergeCommand) String() string {
+	return "m"
+}
+
 type DeleteValueCommand struct {}
 func (cmd DeleteValueCommand) exec(state *ProgramState) {
 	state.value = nil
diff --git a/main/main_test.go b/main/main_test.go
index 7aa90aa..74f179b 100644
--- a/main/main_test.go
+++ b/main/main_test.go
@@ -64,6 +64,11 @@ func TestMain(t *testing.T) {
 			input: miscInput,
 			expected: `["Charlie Johnson","Tom Johnson","Charlie Chaplin","John Johnson"]`,
 		},
+		{
+			program: "s/#(\"people\" @(. #(\"first_name\" .)#)@)#/{ ms/#(\"people\" @(. (#(\"first_name\" \".{-0}$a\" \"last_name\" \".{-0}$b\")#$_) `#(\"name\" \"$a $b\")#`)@)#/ }",
+			input: miscInput,
+			expected: `{"something":{"nested":"Here is my test value"},"array":["Hello","world","these","are","values"],"people":[{"name":"Charlie Johnson","age":22},{"name":"Tom Johnson","age":18},{"name":"Charlie Chaplin","age":122},{"name":"John Johnson","age":48}]}`,
+		},
 	}
 
 	for i, test := range tests {
diff --git a/main/parse.go b/main/parse.go
index 3e0e80b..3c24e6c 100644
--- a/main/parse.go
+++ b/main/parse.go
@@ -69,6 +69,8 @@ func (p *parser) parseBasicCommand(commands []Command, commandChar rune) []Comma
 			return append(commands, NextCommand{})
 		case 'N':
 			return append(commands, AppendNextCommand{})
+		case 'm':
+			return append(commands, MergeCommand{})
 		case 's':
 			ast := p.parseSubex()
 			subex := subex.CompileTransducer(ast)
diff --git a/subex/parse.go b/subex/parse.go
index 619c1c3..d825f75 100644
--- a/subex/parse.go
+++ b/subex/parse.go
@@ -183,7 +183,7 @@ func parseRepeatRange(l RuneReader) (output []ConvexRange) {
 	return output
 }
 
-func parseValueReplacement(l RuneReader) (output SubexAST) {
+func parseValueReplacement(l RuneReader, end rune) (output SubexAST) {
 	output = SubexASTEmpty{}
 	// TODO escaping
 	// TODO add arrays, maps and strings
@@ -193,7 +193,7 @@ func parseValueReplacement(l RuneReader) (output SubexAST) {
 		case eof:
 			panic("Missing closing `")
 		case ' ':
-		case '`':
+		case end:
 			break loop
 		case '$':
 			slot := l.Next()
@@ -207,6 +207,21 @@ func parseValueReplacement(l RuneReader) (output SubexAST) {
 				},
 			}
 		// TODO: destructures
+		case '#':
+			if !accept(l, "(") {
+				panic("Missing ( after #")
+			}
+			output = SubexASTConcat {
+				First: output,
+				Second: SubexASTDestructure {
+					Destructure: NoneStructure,
+					Structure: MapStructure,
+					Content: parseValueReplacement(l, ')'),
+				},
+			}
+			if !accept(l, "#") {
+				panic("Missing # after )")
+			}
 		case '"':
 			output = SubexASTConcat {
 				First: output,
@@ -501,7 +516,7 @@ func parseSubex(l RuneReader, minPower int, inType Type) (lhs SubexAST, outType
 			lhs = SubexASTCopyNumber{}
 		case '`':
 			outType = inType
-			lhs = parseValueReplacement(l)
+			lhs = parseValueReplacement(l, '`')
 		case ' ':
 			if inType == RuneType {
 				outType = RuneType
diff --git a/walk/walk.go b/walk/walk.go
index 3fba62f..e66feff 100644
--- a/walk/walk.go
+++ b/walk/walk.go
@@ -148,3 +148,88 @@ func (item WalkItem) Debug() string {
 	builder.WriteString(item.Value.Debug())
 	return builder.String()
 }
+
+func Merge(first Value, second Value) []Value {
+	switch first := first.(type) {
+	case NullValue:
+		return []Value {first, second}
+	case BoolValue:
+		return []Value {first, second}
+	case NumberValue:
+		return []Value {first, second}
+	case StringValue:
+		return []Value {first, second}
+	case ArrayValue:
+		secondArr, isArr := second.(ArrayValue)
+		if !isArr {
+			return []Value {first, second}
+		}
+
+		if len(first) == 0 {
+			return []Value {second}
+		}
+
+		if len(secondArr) == 0 {
+			return []Value {first}
+		}
+
+		var res ArrayValue
+		for _, el := range first[:len(first) - 1] {
+			res = append(res, el)
+		}
+		midFirst := first[len(first) - 1]
+		midSecond := secondArr[0]
+		if midFirst.Index == midSecond.Index {
+			for _, el := range Merge(midFirst.Value, midSecond.Value) {
+				res = append(res, ArrayElement {
+					Index: midFirst.Index,
+					Value: el,
+				})
+			}
+		} else {
+			res = append(res, midFirst, midSecond)
+		}
+		for _, el := range secondArr[1:] {
+			res = append(res, el)
+		}
+
+		return []Value {res}
+	case MapValue:
+		secondMap, isMap := second.(MapValue)
+		if !isMap {
+			return []Value {first, second}
+		}
+
+		if len(first) == 0 {
+			return []Value {second}
+		}
+
+		if len(secondMap) == 0 {
+			return []Value {first}
+		}
+
+		var res MapValue
+		for _, el := range first[:len(first) - 1] {
+			res = append(res, el)
+		}
+		midFirst := first[len(first) - 1]
+		midSecond := secondMap[0]
+		if midFirst.Key == midSecond.Key {
+			for _, el := range Merge(midFirst.Value, midSecond.Value) {
+				res = append(res, MapElement {
+					Key: midFirst.Key,
+					Value: el,
+				})
+			}
+		} else {
+			res = append(res, midFirst, midSecond)
+		}
+		for _, el := range secondMap[1:] {
+			res = append(res, el)
+		}
+
+		return []Value {res}
+	default:
+		panic("first is invalid value type")
+	}
+}