added basic dataflow analysis to skslc

src/sksl/SkSLParser.cpp

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
  
 #include "stdio.h"
 #include "SkSLParser.h"
 #include "SkSLToken.h"
@@ skipping 788 matching lines @@
     if (!this->expect(Token::FOR, "'for'", &start)) {
         return nullptr;
     }
     if (!this->expect(Token::LPAREN, "'('")) {
         return nullptr;
     }
     std::unique_ptr<ASTStatement> initializer;
     Token nextToken = this->peek();
     switch (nextToken.fKind) {
         case Token::SEMICOLON: 
+            this->nextToken();
             break;
         case Token::CONST:
             initializer = std::unique_ptr<ASTStatement>(new ASTVarDeclarationStatement(
                                                                           this->varDeclarations()));
             break;
         case Token::IDENTIFIER: 
             if (this->isType(nextToken.fText)) {
                 initializer = std::unique_ptr<ASTStatement>(new ASTVarDeclarationStatement(
                                                                           this->varDeclarations()));
                 break;
             }
             // fall through
         default:
             initializer = this->expressionStatement();
     }
     std::unique_ptr<ASTExpression> test;
     if (this->peek().fKind != Token::SEMICOLON) {
         test = this->expression();
         if (!test) {
             return nullptr;
         }
     }
     if (!this->expect(Token::SEMICOLON, "';'")) {
         return nullptr;
     }
     std::unique_ptr<ASTExpression> next;
-    if (this->peek().fKind != Token::SEMICOLON) {
+    if (this->peek().fKind != Token::RPAREN) {
         next = this->expression();
         if (!next) {
             return nullptr;
         }
     }
     if (!this->expect(Token::RPAREN, "')'")) {
         return nullptr;
     }
     std::unique_ptr<ASTStatement> statement(this->statement());
     if (!statement) {
@@ skipping 588 matching lines @@
 bool Parser::identifier(std::string* dest) {
     Token t;
     if (this->expect(Token::IDENTIFIER, "identifier", &t)) {
         *dest = t.fText; 
         return true;
     }
     return false;
 }
 
 } // namespace