Analyze return statement

analyzer/expression.go

@@ -613,3 +613,39 @@ func (this *Tree) analyzeBreak (
 
 	return brk, nil
 }
+
+func (this *Tree) analyzeReturn (
+	into entity.Type,
+	mode strictness,
+	ret  *entity.Return,
+) (
+	entity.Expression,
+	error,
+) {
+	if into != nil {
+		return nil, participle.Errorf(ret.Pos, "expected %v", into)
+	}
+
+	ret.Declaration, _ = this.topDeclaration()
+	var ty entity.Type
+	switch ret.Declaration.(type) {
+	case *entity.Function:
+		ty = ret.Declaration.(*entity.Function).Signature.Return
+	case *entity.Method:
+		ty = ret.Declaration.(*entity.Method).Signature.Return
+	}
+
+	if !ty.Equals(&entity.TypeVoid { }) && ret.Value == nil {
+		return nil, participle.Errorf (
+			ret.Pos,
+			"break statement must have value")
+	}
+
+	if ret.Value != nil {
+		value, err := this.analyzeExpression(ty, strict, ret.Value)
+		if err != nil { return nil, err }
+		ret.Value = value
+	}
+
+	return ret, nil
+}

analyzer/function.go

@@ -25,7 +25,7 @@ func (this *Tree) analyzeFunction (
 	}
 
 	// create a new scope context for this function
-	this.pushScopeContext()
+	this.pushScopeContext(function)
 	this.pushScope(function)
 	defer this.popScopeContext()
 	defer this.popScope()

analyzer/method.go

@@ -32,7 +32,7 @@ func (this *Tree) analyzeMethod (
 	}
 
 	// create a new scope context for this function
-	this.pushScopeContext()
+	this.pushScopeContext(method)
 	this.pushScope(method)
 	defer this.popScopeContext()
 	defer this.popScope()

analyzer/scope.go

@@ -7,8 +7,8 @@ import "git.tebibyte.media/sashakoshka/fspl/entity"
 // entity causes the analysis of another.
 type scopeContextManager []scopeContext
 
-func (this *scopeContextManager) pushScopeContext () {
+func (this *scopeContextManager) pushScopeContext (declaration entity.TopLevel) {
-	*this = append(*this, scopeContext { })
+	*this = append(*this, scopeContext { declaration: declaration })
 }
 
 func (this *scopeContextManager) popScopeContext () {
@@ -31,6 +31,11 @@ func (this *scopeContextManager) topLoop () (*entity.Loop, bool) {
 	return (*this)[len(*this) - 1].topLoop()
 }
 
+func (this *scopeContextManager) topDeclaration () (entity.TopLevel, bool) {
+	if len(*this) < 1 { return nil, false }
+	return (*this)[len(*this) - 1].declaration, true
+}
+
 func (this *scopeContextManager) pushScope (scope entity.Scoped) {
 	this.assertPopulated()
 	(*this)[len(*this) - 1].pushScope(scope)
@@ -67,8 +72,9 @@ func (this *scopeContextManager) assertPopulated () {
 // scopeContext is a stack of scopes and loops used when analyzing scoped
 // entities.
 type scopeContext struct {
-	scopes []entity.Scoped
+	scopes      []entity.Scoped
-	loops  []*entity.Loop
+	loops       []*entity.Loop
+	declaration entity.TopLevel
 }
 
 func (this *scopeContext) pushLoop (loop *entity.Loop) {

entity/expression.go

@@ -379,8 +379,12 @@ func (this *Break) String () string {
 // value. In all cases, return statements have no value and may not be assigned
 // to anything. A return statement is never a valid location expression.
 type Return struct {
+	// Syntax
 	Pos   lexer.Position
 	Value Expression `parser:" '[' 'return' @@? ']' "`
+
+	// Semantics
+	Declaration TopLevel
 }
 func (*Return) expression(){}
 func (*Return) statement(){}