Implement for.

eval/boilerplate.go

@@ -77,14 +77,14 @@ func assignmentBegins(ns []*parse.Assignment) []int {
 	return begins
 }
 
-func (cp *compiler) indexingVars(ns []*parse.Indexing, msg string) []VariableOp {
+func (cp *compiler) singleVariables(ns []*parse.Indexing, msg string) []VariableOp {
 	ops := make([]VariableOp, len(ns))
 	for i, n := range ns {
-		ops[i] = cp.indexingVar(n, msg)
+		ops[i] = cp.singleVariable(n, msg)
 	}
 	return ops
 }
-func indexingVarBegins(ns []*parse.Indexing) []int {
+func singleVariableBegins(ns []*parse.Indexing) []int {
 	begins := make([]int, len(ns))
 	for i, n := range ns {
 		begins[i] = n.Begin()

eval/compile.go

@@ -277,8 +277,17 @@ func (cp *compiler) control(n *parse.Control) Op {
 			}
 		}
 	case parse.ForControl:
-		cp.errorf(n.Begin(), "not yet implemented")
-		panic("unreachable")
+		iteratorOp := cp.singleVariable(n.Iterator, "must be a single variable")
+		valuesOp := cp.array(n.Array)
+		bodyOp := cp.chunk(n.Body)
+		return func(ec *EvalCtx) {
+			iterator := iteratorOp(ec)
+			values := valuesOp(ec)
+			for _, v := range values {
+				doSet(ec, []Variable{iterator}, []Value{v})
+				bodyOp(ec)
+			}
+		}
 	case parse.BeginControl:
 		return cp.chunk(n.Body)
 	default:
@@ -298,21 +307,7 @@ func (cp *compiler) literal(n *parse.Primary, msg string) string {
 }
 
 func (cp *compiler) assignment(n *parse.Assignment) Op {
-	var variableOps []VariableOp
-	if n.Dst.Head.Type == parse.Braced {
-		compounds := n.Dst.Head.Braced
-		indexings := make([]*parse.Indexing, len(compounds))
-		for i, cn := range compounds {
-			if len(cn.Indexings) != 1 {
-				cp.errorf(cn.Begin(), "must be a variable spec")
-			}
-			indexings[i] = cn.Indexings[0]
-		}
-		variableOps = cp.indexingVars(indexings, "must be a variable spc")
-	} else {
-		variableOps = []VariableOp{cp.indexingVar(n.Dst, "must be a variable spec or a braced list of those")}
-	}
-
+	variableOps := cp.multiVariable(n.Dst)
 	valuesOp := cp.compound(n.Src)
 
 	return func(ec *EvalCtx) {
@@ -324,8 +319,27 @@ func (cp *compiler) assignment(n *parse.Assignment) Op {
 	}
 }
 
-func (cp *compiler) indexingVar(n *parse.Indexing, msg string) VariableOp {
-	// XXX will we be using indexingVar for purposes other than setting?
+func (cp *compiler) multiVariable(n *parse.Indexing) []VariableOp {
+	var variableOps []VariableOp
+	if n.Head.Type == parse.Braced {
+		// XXX ignore n.Indicies.
+		compounds := n.Head.Braced
+		indexings := make([]*parse.Indexing, len(compounds))
+		for i, cn := range compounds {
+			if len(cn.Indexings) != 1 {
+				cp.errorf(cn.Begin(), "must be a variable spec")
+			}
+			indexings[i] = cn.Indexings[0]
+		}
+		variableOps = cp.singleVariables(indexings, "must be a variable spc")
+	} else {
+		variableOps = []VariableOp{cp.singleVariable(n, "must be a variable spec or a braced list of those")}
+	}
+	return variableOps
+}
+
+func (cp *compiler) singleVariable(n *parse.Indexing, msg string) VariableOp {
+	// XXX will we be using this for purposes other than setting?
 	varname := cp.literal(n.Head, msg)
 	p := n.Begin()
 

parse/boilerplate.go

@@ -92,7 +92,7 @@ func (n *Control) setCondition(ch *Chunk) {
 	addChild(n, ch)
 }
 
-func (n *Control) setIterator(ch *Primary) {
+func (n *Control) setIterator(ch *Indexing) {
 	n.Iterator = ch
 	addChild(n, ch)
 }

parse/parse.go

@@ -287,7 +287,7 @@ type Control struct {
 	node
 	Kind       ControlKind
 	Condition  *Chunk    // Valid for WhileControl.
-	Iterator   *Primary // Valid for ForControl.
+	Iterator   *Indexing // Valid for ForControl.
 	Array      *Array    // Valid for ForControl.
 	Body       *Chunk    // Valid for all except IfControl.
 	Conditions []*Chunk  // Valid for IfControl.
@@ -374,7 +374,7 @@ func (ctrl *Control) parse(ps *parser, leader string) {
 	case "for":
 		ctrl.Kind = ForControl
 		parseSpaces(ctrl, ps)
-		ctrl.setIterator(parsePrimary(ps))
+		ctrl.setIterator(parseIndexing(ps))
 		parseSpaces(ctrl, ps)
 		if ps.findPossibleLeader() == "in" {
 			ps.advance(len("in"))