/****************************************************************************

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** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).

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** This file is part of the QtScript module of the Qt Toolkit.

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****************************************************************************/

#include "qscriptsyntaxchecker_p.h"

#include "qscriptlexer_p.h"

#include "qscriptparser_p.h"

QT_BEGIN_NAMESPACE

namespace QScript {

SyntaxChecker::SyntaxChecker():

    tos(0),

    stack_size(0),

    state_stack(0)

{

}

SyntaxChecker::~SyntaxChecker()

{

    if (stack_size) {

        qFree(state_stack);

    }

}

bool SyntaxChecker::automatic(QScript::Lexer *lexer, int token) const

{

    return token == T_RBRACE || token == 0 || lexer->prevTerminator();

}

SyntaxChecker::Result SyntaxChecker::checkSyntax(const QString &code)

{

  const int INITIAL_STATE = 0;

  QScript::Lexer lexer (/*engine=*/ 0);

  lexer.setCode(code, /*lineNo*/ 1);

  int yytoken = -1;

  int saved_yytoken = -1;

  QString error_message;

  int error_lineno = -1;

  int error_column = -1;

  State checkerState = Valid;

  reallocateStack();

  tos = 0;

  state_stack[++tos] = INITIAL_STATE;

  while (true)

    {

      const int state = state_stack [tos];

      if (yytoken == -1 && - TERMINAL_COUNT != action_index [state])

        {

          if (saved_yytoken == -1)

            yytoken = lexer.lex();

          else

            {

              yytoken = saved_yytoken;

              saved_yytoken = -1;

            }

        }

      int act = t_action (state, yytoken);

      if (act == ACCEPT_STATE) {

          if (lexer.error() == QScript::Lexer::UnclosedComment)

              checkerState = Intermediate;

          else

              checkerState = Valid;

          break;

      } else if (act > 0) {

          if (++tos == stack_size)

            reallocateStack();

          state_stack [tos] = act;

          yytoken = -1;

        }

      else if (act < 0)

        {

          int r = - act - 1;

          tos -= rhs [r];

          act = state_stack [tos++];

          if ((r == Q_SCRIPT_REGEXPLITERAL_RULE1)

              || (r == Q_SCRIPT_REGEXPLITERAL_RULE2)) {

              // Skip the rest of the RegExp literal

              bool rx = lexer.scanRegExp();

              if (!rx) {

                  checkerState = Intermediate;

                  break;

              }

          }

          state_stack [tos] = nt_action (act, lhs [r] - TERMINAL_COUNT);

        }

      else

        {

          if (saved_yytoken == -1 && automatic (&lexer, yytoken) && t_action (state, T_AUTOMATIC_SEMICOLON) > 0)

            {

              saved_yytoken = yytoken;

              yytoken = T_SEMICOLON;

              continue;

            }

          else if ((state == INITIAL_STATE) && (yytoken == 0)) {

              // accept empty input

              yytoken = T_SEMICOLON;

              continue;

          }

          int ers = state;

          int shifts = 0;

          int reduces = 0;

          int expected_tokens [3];

          for (int tk = 0; tk < TERMINAL_COUNT; ++tk)

            {

              int k = t_action (ers, tk);

              if (! k)

                continue;

              else if (k < 0)

                ++reduces;

              else if (spell [tk])

                {

                  if (shifts < 3)

                    expected_tokens [shifts] = tk;

                  ++shifts;

                }

            }

          error_message.clear ();

          if (shifts && shifts < 3)

            {

              bool first = true;

              for (int s = 0; s < shifts; ++s)

                {

                  if (first)

                    error_message += QLatin1String ("Expected ");

                  else

                    error_message += QLatin1String (", ");

                  first = false;

                  error_message += QLatin1Char('`');

                  error_message += QLatin1String (spell [expected_tokens [s]]);

                  error_message += QLatin1Char('\'');

                }

            }

          if (error_message.isEmpty())

              error_message = lexer.errorMessage();

          error_lineno = lexer.startLineNo();

          error_column = lexer.startColumnNo();

          checkerState = Error;

          break;

        }

    }

  if (checkerState == Error) {

      if (lexer.error() == QScript::Lexer::UnclosedComment)

          checkerState = Intermediate;

      else if (yytoken == 0)

          checkerState = Intermediate;

  }

  return Result(checkerState, error_lineno, error_column, error_message);

}

} // namespace QScript

QT_END_NAMESPACE