Add breakable interface

analyzer/expression-multiplex.go

@@ -48,6 +48,8 @@ func (this *Tree) analyzeExpression (
 		return this.analyzeMatch(into, mode, expression)
 	case *entity.Loop:
 		return this.analyzeLoop(into, mode, expression)
+	case *entity.For:
+		return this.analyzeFor(into, mode, expression)
 	case *entity.Break:
 		return this.analyzeBreak(into, mode, expression)
 	case *entity.Return:

analyzer/expression.go

@@ -808,6 +808,17 @@ func (this *Tree) analyzeLoop (
 	return loop, nil
 }
 
+func (this *Tree) analyzeFor (
+	into entity.Type,
+	mode strictness,
+	loop *entity.For,
+) (
+	entity.Expression,
+	error,
+) {
+	// TODO
+}
+
 func (this *Tree) analyzeBreak (
 	into entity.Type,
 	mode strictness,

analyzer/scope.go

@@ -16,7 +16,7 @@ func (this *scopeContextManager) popScopeContext () {
 	*this = (*this)[:len(*this) - 1]
 }
 
-func (this *scopeContextManager) pushLoop (loop *entity.Loop) {
+func (this *scopeContextManager) pushLoop (loop entity.Breakable) {
 	this.assertPopulated()
 	(*this)[len(*this) - 1].pushLoop(loop)
 }
@@ -26,7 +26,7 @@ func (this *scopeContextManager) popLoop () {
 	(*this)[len(*this) - 1].popLoop()
 }
 
-func (this *scopeContextManager) topLoop () (*entity.Loop, bool) {
+func (this *scopeContextManager) topLoop () (entity.Breakable, bool) {
 	this.assertPopulated()
 	return (*this)[len(*this) - 1].topLoop()
 }
@@ -71,11 +71,11 @@ func (this *scopeContextManager) assertPopulated () {
 // entities.
 type scopeContext struct {
 	scopes      []entity.Scoped
-	loops       []*entity.Loop
+	loops       []entity.Breakable
 	declaration entity.TopLevel
 }
 
-func (this *scopeContext) pushLoop (loop *entity.Loop) {
+func (this *scopeContext) pushLoop (loop entity.Breakable) {
 	this.loops = append(this.loops, loop)
 }
 
@@ -84,7 +84,7 @@ func (this *scopeContext) popLoop () {
 	this.loops = this.loops[:len(this.loops) - 1]
 }
 
-func (this *scopeContext) topLoop () (*entity.Loop, bool) {
+func (this *scopeContext) topLoop () (entity.Breakable, bool) {
 	if len(this.loops) < 1 { return nil, false }
 	return this.loops[len(this.loops) - 1], true
 }

entity/expression.go

@@ -439,7 +439,14 @@ func (this *Match) String () string {
 	return out
 }
 
+// Breakable is any expression that can be halted using a break.
+type Breakable interface {
+	Expression
+	breakable()
+}
+
 var _ Expression = &Loop { }
+var _ Breakable  = &Loop { }
 // Loop is a control flow expression that repeats an expression until a break
 // statement is called from within it. The break statement must be given a value
 // if the value of the loop is used. Otherwise, it need not even have a break
@@ -456,6 +463,7 @@ type Loop struct {
 	Ty Type
 }
 func (*Loop) expression(){}
+func (*Loop) breakable(){}
 func (this *Loop) Position () errors.Position { return this.Pos }
 func (this *Loop) Type () Type { return this.Ty }
 func (this *Loop) HasExplicitType () bool {
@@ -468,6 +476,7 @@ func (this *Loop) String () string {
 }
 
 var _ Expression = &For { }
+var _ Breakable  = &For { }
 // For is a special kind of loop that evaluates an expression for each element
 // of an array or slice. It accepts an index declaration and an element
 // declaration, which are scoped to the loop's body and are set to the index of
@@ -486,6 +495,7 @@ type For struct {
 	Ty Type
 }
 func (*For) expression(){}
+func (*For) breakable(){}
 func (this *For) Position () errors.Position { return this.Pos }
 func (this *For) Type () Type { return this.Ty }
 func (this *For) HasExplicitType () bool {
@@ -511,7 +521,7 @@ type Break struct {
 	Value Expression
 
 	// Semantics
-	Loop *Loop
+	Loop Breakable
 }
 func (*Break) expression(){}
 func (this *Break) Position () errors.Position { return this.Pos }