TagSetParselet.java

/*
 * Copyright (c) 2013 Patrick Scheibe
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

package de.halirutan.mathematica.parsing.prattparser.parselets;

import com.intellij.lang.PsiBuilder;
import com.intellij.psi.tree.IElementType;
import de.halirutan.mathematica.parsing.MathematicaElementTypes;
import de.halirutan.mathematica.parsing.ParserBundle;
import de.halirutan.mathematica.parsing.prattparser.CriticalParserError;
import de.halirutan.mathematica.parsing.prattparser.MathematicaParser;

/**
 * Parselet for all <em>tag setting operations</em> like a /: b = c or a /: b =.
 *
 * @author patrick (3/27/13)
 */
public class TagSetParselet implements InfixParselet {

  private final int myPrecedence;

  public TagSetParselet(int precedence) {
    this.myPrecedence = precedence;
  }

  @Override
  public MathematicaParser.Result parse(MathematicaParser parser, MathematicaParser.Result left) throws CriticalParserError {
    PsiBuilder.Marker tagSetMark = left.getMark().precede();
    if (parser.matchesToken(MathematicaElementTypes.TAG_SET)) {
      parser.advanceLexer();
    } else {
      tagSetMark.drop();
      throw new CriticalParserError(ParserBundle.message("Critical.tagset"));
    }
    // In the next line we parse expr1 of expr0/:expr1 and we reduce the precedence by one because it is
    // right associative. Using SetDelayed (:=) which has the same precedence the following expression:
    // a /: b := c := d is then correctly parsed as a /: b := (c := d)
    MathematicaParser.Result expr1 = parser.parseExpression(myPrecedence);

    if (!expr1.isValid()) {
      parser.error(ParserBundle.message("TagSet.missing.pattern"));
      tagSetMark.done(MathematicaElementTypes.TAG_SET_EXPRESSION);
      return MathematicaParser.result(tagSetMark, MathematicaElementTypes.TAG_SET_EXPRESSION, false);
    }

//    IElementType tokenType = parser.getTokenTypeSave(tagSetMark);
    IElementType tokenType = parser.getTokenType();

    if (tokenType == null) {
      parser.error(ParserBundle.message("TagSet.missing.set"));
      tagSetMark.done(MathematicaElementTypes.TAG_SET_EXPRESSION);
      return MathematicaParser.result(tagSetMark, MathematicaElementTypes.TAG_SET_EXPRESSION, false);
    }

    // Form expr0 /: expr1 =. where nothing needs to be parsed right of the =.
    if (tokenType.equals(MathematicaElementTypes.UNSET)) {
      parser.advanceLexer();
      tagSetMark.done(MathematicaElementTypes.TAG_UNSET_EXPRESSION);
      return MathematicaParser.result(tagSetMark, MathematicaElementTypes.TAG_UNSET_EXPRESSION, expr1.isParsed());
    }

    // Form expr0 /: expr1 := expr2 or expr0 /: expr1 = expr2 where we need to parse expr2
    if ((tokenType.equals(MathematicaElementTypes.SET)) || (tokenType.equals(MathematicaElementTypes.SET_DELAYED))) {
      parser.advanceLexer();
      MathematicaParser.Result expr2 = parser.parseExpression(myPrecedence);
      IElementType endType = tokenType.equals(MathematicaElementTypes.SET) ? MathematicaElementTypes.TAG_SET_EXPRESSION : MathematicaElementTypes.TAG_SET_DELAYED_EXPRESSION;
      if (!expr2.isValid()) {
        parser.error(ParserBundle.message("General.expr.expected"));
      }

      tagSetMark.done(endType);
      return MathematicaParser.result(tagSetMark, endType, expr1.isParsed() && expr2.isParsed());
    }

    // if we are here, the second operator (:=, = or =.) is missing and we give up
    parser.error(ParserBundle.message("TagSet.missing.set"));
    tagSetMark.done(MathematicaElementTypes.TAG_SET_EXPRESSION);
    return MathematicaParser.result(tagSetMark, MathematicaElementTypes.TAG_SET_EXPRESSION, false);
  }

  @Override
  public int getMyPrecedence() {
    return myPrecedence;
  }
}