1 files changed, 32 insertions, 11 deletions
diff --git a/main/command.go b/main/command.go
index 7d44309..5e77dd0 100644
--- a/main/command.go
+++ b/main/command.go
@@ -5,6 +5,10 @@ import (
 	"main/subex"
 )
 
+type Command interface {
+	exec(*ProgramState)
+}
+
 type PrintValueCommand struct {}
 func (cmd PrintValueCommand) exec(state *ProgramState) {
 	path := walk.PathFromWalkValues(state.path)
@@ -45,33 +49,50 @@ func (cmd DeleteAllCommand) exec(state *ProgramState) {
 	state.value = nil
 }
 
-type SubstituteCommand struct {
-	subex subex.SubexState
-	next Command
-}
-func (cmd SubstituteCommand) exec(state *ProgramState) {
+func runSubex(state subex.SubexState, in []walk.WalkValue) (out []walk.WalkValue, error bool) {
 	valueStream := make(chan walk.WalkValue)
 	go func(in []walk.WalkValue, out chan<- walk.WalkValue) {
 		for _, value := range in {
 			out <- value
 		}
 		close(out)
-	}(state.value, valueStream)
+	}(in, valueStream)
 	atomStream := walk.Atomise(valueStream)
-	atomsOut, error := subex.RunTransducer(cmd.subex, atomStream)
+	atomsOut, error := subex.RunTransducer(state, atomStream)
 	if error {
-		return
+		return nil, true
 	}
 	valuesOut, err := walk.MemoryCompound(atomsOut)
 	if err != nil {
+		return nil, true
+	}
+	return valuesOut, false
+}
+
+type SubstituteValueCommand struct {
+	subex subex.SubexState
+	next Command
+}
+func (cmd SubstituteValueCommand) exec(state *ProgramState) {
+	newValue, err := runSubex(cmd.subex, state.value)
+	if err {
 		return
 	}
-	state.value = valuesOut
+	state.value = newValue
 	cmd.next.exec(state)
 }
 
-type Command interface {
-	exec(*ProgramState)
+type SubstitutePathCommand struct {
+	subex subex.SubexState
+	next Command
+}
+func (cmd SubstitutePathCommand) exec(state *ProgramState) {
+	newPath, err := runSubex(cmd.subex, state.path)
+	if err {
+		return
+	}
+	state.path = newPath
+	cmd.next.exec(state)
 }
 
 type NoopCommand struct {}