/* vim: set ts=4 sw=4 tw=99 et:

  *

  * Copyright (C) 2012 David Anderson

  *

  * This file is part of JITCraft.

  *

  * JITCraft is free software: you can redistribute it and/or modify it under

  * the terms of the GNU General Public License as published by the Free

  * Software Foundation, either version 3 of the License, or (at your option)

  * any later version.

  * 

  * Foobar is distributed in the hope that it will be useful, but WITHOUT ANY

  * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

  * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

  *

  * You should have received a copy of the GNU General Public License along with

  * JITCraft. If not, see http://www.gnu.org/licenses/.

  */

 #ifndef _include_semantic_analysis_h_

 #define _include_semantic_analysis_h_

 #include <assert.h>

 #include "AST.h"

 namespace ke {

 class SemanticAnalysis : public AstVisitor

 {

     Zone *zone_;

     CompileContext &cc_;

     ParseTree *tree_;

     Scope *scope_;

     ScopedRoot<Type> function_;

     enum ReturnStatus

     {

         Returns_Never,

         Returns_Sometimes,

         Returns_Always

     };

     // Tuple that describes whether a path terminates control flow, and

     // if it is guaranteed to end in a return.

     class ControlStatus

     {

         bool terminates_;

         ReturnStatus returns_;

       public:

         ControlStatus(bool terminates, ReturnStatus returns)

           : terminates_(terminates),

             returns_(returns)

         {

         }

         bool terminates() const {

             return terminates_;

         }

         ReturnStatus returns() const {

             return returns_;

         }

     };

     // Used to keep track of terminating control flow and return statements

     // inside control structures.

     class ControlScope

     {

         ReturnStatus returns_;

         ControlScope **prevp_;

         ControlScope *prev_;

         bool terminates_;

       public:

         ControlScope(ControlScope **prev)

           : returns_(Returns_Never),

             prevp_(prev),

             prev_(*prev),

             terminates_(false)

         {

             *prevp_ = this;

         }

         ControlStatus status() const {

             return ControlStatus(terminates_, returns_);

         }

         // We allow multiple terminators, but only the first one takes effect.

         // For example, |break; continue;| is legal but the continue is

         // unreachable.

         void returns(ReturnStatus status) {

             if (terminates_)

                 return;

             if (status > returns_)

                 returns_ = status;

         }

         void terminate(ReturnStatus status) {

             if (terminates_)

                 return;

             terminates_ = true;

             returns_ = status;

         }

         void merge(const ControlStatus &left, const ControlStatus &right);

         ~ControlScope()

         {

             *prevp_ = prev_;

         }

     };

     class LoopScope

     {

         LoopScope **prevp_;

         LoopScope *prev_;

         unsigned breaks_;

         unsigned continues_;

       public:

         LoopScope(LoopScope **prev)

           : prevp_(prev),

             prev_(*prev),

             breaks_(0),

             continues_(0)

         {

             *prevp_ = this;

         }

         ~LoopScope()

         {

             *prevp_ = prev_;

         }

         void addBreak() {

             breaks_++;

         }

         void addContinue() {

             continues_++;

         }

         unsigned breaks() const {

             return breaks_;

         }

         unsigned continues() const {

             return continues_;

         }

     };

     ControlScope *control_;

     LoopScope *loop_;

   private:

     bool canTest(AstNode *node, Handle<Type> type);

     void unaryTypeError(AstNode *node, TokenKind token, Handle<Type> type);

     void binaryTypeError(AstNode *node, TokenKind token, Handle<Type> left, Handle<Type> right);

     Type *typeCheckBinary(AstNode *node, TokenKind token, Handle<Type> left, Handle<Type> right);

     // These check if one type is compatible with another type, for various

     // purposes, like:

     //      return (expr) matches function return type

     //      call(a, b)    matches expected arg type

     //      a = b         matches declared type

     //

     bool typeCheckArrayAssignment(AstNode *node, Handle<Type> given, Handle<Type> actual, bool forAssign);

     bool typeCheckAssignment(AstNode *node, Handle<Type> given, Handle<Type> actual, bool forAssign);

     bool typeCheckParameter(AstNode *node, Handle<Type> given, Handle<Type> actual);

     Type *visitForLoad(Expression *expression);

     bool preanalyze(FunctionStatement *node);

     Type *visitForLValue(Expression *expression);

     Type *visitAndApplyType(Expression *expression);

     ControlStatus visitForControl(Statement *statement);

     void markCallResultUsed(CallExpression *call);

   public:

     SemanticAnalysis(Zone *zone, CompileContext &cc, ParseTree *tree);

     bool analyze();

   public:

     void visit(NameProxy *name);

     void visit(Assignment *node);

     void visit(BinaryExpression *node);

     void visit(ReturnStatement *node);

     void visit(ForStatement *node);

     void visit(BlockStatement *node);

     void visit(VariableDeclaration *node);

     void visit(IntegerLiteral *node);

     void visit(ExpressionStatement *node);

     void visit(FunctionStatement *node);

     void visit(CallExpression *node);

     void visit(IfStatement *node);

     void visit(IndexExpression *node);

     void visit(EnumStatement *node);

     void visit(FloatLiteral *node);

     void visit(WhileStatement *node);

     void visit(BreakStatement *node);

     void visit(ContinueStatement *node);

     void visit(StringLiteral *node);

     void visit(IncDecExpression *node);

     void visit(UnaryExpression *node);

     void visit(TernaryExpression *node);

 };

 } // namespace ke

 #endif // _include_semantic_analysis_h_