Package org.eclipse.php.internal.ui.editor

Source Code of org.eclipse.php.internal.ui.editor.PHPHeuristicScanner

/*******************************************************************************
* Copyright (c) 2009 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
*     IBM Corporation - initial API and implementation
*     Zend Technologies
*******************************************************************************/

package org.eclipse.php.internal.ui.editor;

// taken from package org.eclipse.jdt.internal.ui.text;

import java.util.Arrays;

import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.text.*;
import org.eclipse.php.internal.core.documentModel.parser.regions.IPhpScriptRegion;
import org.eclipse.php.internal.core.documentModel.partitioner.PHPPartitionTypes;
import org.eclipse.wst.sse.core.internal.provisional.text.IStructuredDocumentRegion;
import org.eclipse.wst.sse.core.internal.provisional.text.IStructuredPartitioning;
import org.eclipse.wst.sse.core.internal.provisional.text.ITextRegion;
import org.eclipse.wst.sse.core.internal.text.BasicStructuredDocument;

/**
* Utility methods for heuristic based Java manipulations in an incomplete Java
* source file.
*
* <p>
* An instance holds some internal position in the document and is therefore not
* threadsafe.
* </p>
*
* @see Eclipse 3.0
*/
final class PHPHeuristicScanner implements Symbols {
  /**
   * Returned by all methods when the requested position could not be found,
   * or if a {@link BadLocationException} was thrown while scanning.
   */
  public static final int NOT_FOUND = -1;

  /**
   * Special bound parameter that means either -1 (backward scanning) or
   * <code>fDocument.getLength()</code> (forward scanning).
   */
  public static final int UNBOUND = -2;

  /* character constants */
  private static final char LBRACE = '{';
  private static final char RBRACE = '}';
  private static final char LPAREN = '(';
  private static final char RPAREN = ')';
  private static final char SEMICOLON = ';';
  private static final char COLON = ':';
  private static final char COMMA = ',';
  private static final char LBRACKET = '[';
  private static final char RBRACKET = ']';
  private static final char QUESTIONMARK = '?';
  private static final char EQUAL = '=';
  private static final char LANGLE = '<';
  private static final char RANGLE = '>';

  /**
   * Specifies the stop condition, upon which the <code>scanXXX</code> methods
   * will decide whether to keep scanning or not. This interface may
   * implemented by clients.
   */
  private static abstract class StopCondition {
    /**
     * Instructs the scanner to return the current position.
     *
     * @param ch
     *            the char at the current position
     * @param position
     *            the current position
     * @param forward
     *            the iteration direction
     * @return <code>true</code> if the stop condition is met.
     */
    public abstract boolean stop(char ch, int position, boolean forward);

    /**
     * Asks the condition to return the next position to query. The default
     * is to return the next/previous position.
     *
     * @return the next position to scan
     */
    public int nextPosition(int position, boolean forward) {
      return forward ? position + 1 : position - 1;
    }
  }

  /**
   * Stops upon a non-whitespace (as defined by
   * {@link Character#isWhitespace(char)}) character.
   */
  private static class NonWhitespace extends StopCondition {
    /*
     * @see
     * org.eclipse.jdt.internal.ui.text.JavaHeuristicScanner.StopCondition
     * #stop(char)
     */
    public boolean stop(char ch, int position, boolean forward) {
      return !Character.isWhitespace(ch);
    }
  }

  /**
   * Stops upon a non-whitespace character in the default partition.
   *
   * @see NonWhitespace
   */
  private final class NonWhitespaceDefaultPartition extends NonWhitespace {
    /*
     * @see
     * org.eclipse.jdt.internal.ui.text.JavaHeuristicScanner.StopCondition
     * #stop(char)
     */
    public boolean stop(char ch, int position, boolean forward) {
      return super.stop(ch, position, true)
          && isDefaultPartition(position);
    }

    /*
     * @see
     * org.eclipse.jdt.internal.ui.text.JavaHeuristicScanner.StopCondition
     * #nextPosition(int, boolean)
     */
    public int nextPosition(int position, boolean forward) {
      ITypedRegion partition = getPartition(position);
      if (fPartition.equals(partition.getType()))
        return super.nextPosition(position, forward);

      if (forward) {
        int end = partition.getOffset() + partition.getLength();
        if (position < end)
          return end;
      } else {
        int offset = partition.getOffset();
        if (position > offset)
          return offset - 1;
      }
      return super.nextPosition(position, forward);
    }
  }

  /**
   * Stops upon a non-java identifier (as defined by
   * {@link Character#isJavaIdentifierPart(char)}) character.
   */
  private static class NonJavaIdentifierPart extends StopCondition {
    /*
     * @see
     * org.eclipse.jdt.internal.ui.text.JavaHeuristicScanner.StopCondition
     * #stop(char)
     */
    public boolean stop(char ch, int position, boolean forward) {
      return !Character.isJavaIdentifierPart(ch);
    }
  }

  /**
   * Stops upon a non-java identifier character in the default partition.
   *
   * @see NonJavaIdentifierPart
   */
  private final class NonJavaIdentifierPartDefaultPartition extends
      NonJavaIdentifierPart {
    /*
     * @see
     * org.eclipse.jdt.internal.ui.text.JavaHeuristicScanner.StopCondition
     * #stop(char)
     */
    public boolean stop(char ch, int position, boolean forward) {
      return super.stop(ch, position, true)
          || !isDefaultPartition(position);
    }

    /*
     * @see
     * org.eclipse.jdt.internal.ui.text.JavaHeuristicScanner.StopCondition
     * #nextPosition(int, boolean)
     */
    public int nextPosition(int position, boolean forward) {
      ITypedRegion partition = getPartition(position);
      if (fPartition.equals(partition.getType()))
        return super.nextPosition(position, forward);

      if (forward) {
        int end = partition.getOffset() + partition.getLength();
        if (position < end)
          return end;
      } else {
        int offset = partition.getOffset();
        if (position > offset)
          return offset - 1;
      }
      return super.nextPosition(position, forward);
    }
  }

  /**
   * Stops upon a character in the default partition that matches the given
   * character list.
   */
  private final class CharacterMatch extends StopCondition {
    private final char[] fChars;

    /**
     * Creates a new instance.
     *
     * @param ch
     *            the single character to match
     */
    public CharacterMatch(char ch) {
      this(new char[] { ch });
    }

    /**
     * Creates a new instance.
     *
     * @param chars
     *            the chars to match.
     */
    public CharacterMatch(char[] chars) {
      Assert.isNotNull(chars);
      Assert.isTrue(chars.length > 0);
      fChars = chars;
      Arrays.sort(chars);
    }

    /*
     * @see
     * org.eclipse.jdt.internal.ui.text.JavaHeuristicScanner.StopCondition
     * #stop(char, int)
     */
    public boolean stop(char ch, int position, boolean forward) {
      return Arrays.binarySearch(fChars, ch) >= 0
          && isDefaultPartition(position);
    }

    /*
     * @see
     * org.eclipse.jdt.internal.ui.text.JavaHeuristicScanner.StopCondition
     * #nextPosition(int, boolean)
     */
    public int nextPosition(int position, boolean forward) {
      // only match char in the same string
      if (fTextRegion != null
          && !fTextRegion.equals(getTextRegion(position))) {
        if (forward) {
          return fDocument.getLength();
        } else {
          return -1;
        }
      }
      ITypedRegion partition = getPartition(position);
      if (fPartition.equals(partition.getType()))
        return super.nextPosition(position, forward);

      if (forward) {
        int end = partition.getOffset() + partition.getLength();
        if (position < end)
          return end;
      } else {
        int offset = partition.getOffset();
        if (position > offset)
          return offset - 1;
      }
      return super.nextPosition(position, forward);
    }
  }

  /** The document being scanned. */
  private IDocument fDocument;
  /** The partitioning being used for scanning. */
  private String fPartitioning;
  /** The partition to scan in. */
  private String fPartition;

  /**
   * this is only not null for PHPPartitionTypes.PHP_QUOTED_STRING
   * fPartition,to judge if the to be matched and the matched result in the
   * same region.https://bugs.eclipse.org/bugs/show_bug.cgi?id=280133
   */
  private ITextRegion fTextRegion;
  /* internal scan state */

  /** the most recently read character. */
  private char fChar;
  /** the most recently read position. */
  private int fPos;

  /* preset stop conditions */
  private final StopCondition fNonWSDefaultPart = new NonWhitespaceDefaultPartition();
  private final static StopCondition fNonWS = new NonWhitespace();
  private final StopCondition fNonIdent = new NonJavaIdentifierPartDefaultPartition();

  /**
   * Creates a new instance.
   *
   * @param document
   *            the document to scan
   * @param partitioning
   *            the partitioning to use for scanning
   * @param partition
   *            the partition to scan in
   */
  public PHPHeuristicScanner(IDocument document, String partitioning,
      String partition) {
    Assert.isNotNull(document);
    Assert.isNotNull(partitioning);
    Assert.isNotNull(partition);
    fDocument = document;
    fPartitioning = partitioning;
    fPartition = partition;
  }

  /**
   * Calls
   * <code>this(document, IPhpPartitions.JAVA_PARTITIONING, IDocument.DEFAULT_CONTENT_TYPE)</code>
   * .
   *
   * @param document
   *            the document to scan.
   */
  public PHPHeuristicScanner(IDocument document) {
    this(document, IStructuredPartitioning.DEFAULT_STRUCTURED_PARTITIONING,
        IDocument.DEFAULT_CONTENT_TYPE);
  }

  /**
   * Creates a PHPHeuristicScanner with a default partition type set to -
   * PHPPartitionTypes.PHP_COMMENT, PHPPartitionTypes.PHP_QUOTED_STRING or
   * PHPPartitionTypes.PHP_DEFAULT. Matching open/close symbol will only be
   * looked for in the same partition type, so that for example a closing
   * bracket in a commented line will not match an opening bracket in the
   * code.
   *
   * @param document
   *            the document to scan
   * @param offset
   *            the offset in the document
   * @return the PHPHeuristicScanner for the given document and offset
   * @throws BadLocationException
   */
  public static PHPHeuristicScanner createHeuristicScanner(
      IDocument document, int offset) throws BadLocationException {
    // Create a scanner with default values
    PHPHeuristicScanner scanner = new PHPHeuristicScanner(document);
    // Calculate the partition in the given offset and classify it
    // accordingly
    ITypedRegion partition = scanner.getPartition(offset);
    // Update the default partition in the scanner
    scanner.fPartition = partition.getType();
    if (PHPPartitionTypes.PHP_QUOTED_STRING.equals(scanner.fPartition)) {
      scanner.fTextRegion = scanner.getTextRegion(offset);
    }
    return scanner;
  }

  /**
   * Returns the most recent internal scan position.
   *
   * @return the most recent internal scan position.
   */
  public int getPosition() {
    return fPos;
  }

  /**
   * Returns the next token in forward direction, starting at
   * <code>start</code>, and not extending further than <code>bound</code>.
   * The return value is one of the constants defined in {@link Symbols}.
   * After a call, {@link #getPosition()} will return the position just after
   * the scanned token (i.e. the next position that will be scanned).
   *
   * @param start
   *            the first character position in the document to consider
   * @param bound
   *            the first position not to consider any more
   * @return a constant from {@link Symbols} describing the next token
   */
  public int nextToken(int start, int bound) {
    int pos = scanForward(start, bound, fNonWSDefaultPart);
    if (pos == NOT_FOUND)
      return TokenEOF;

    fPos++;

    switch (fChar) {
    case LBRACE:
      return TokenLBRACE;
    case RBRACE:
      return TokenRBRACE;
    case LBRACKET:
      return TokenLBRACKET;
    case RBRACKET:
      return TokenRBRACKET;
    case LPAREN:
      return TokenLPAREN;
    case RPAREN:
      return TokenRPAREN;
    case SEMICOLON:
      return TokenSEMICOLON;
    case COMMA:
      return TokenCOMMA;
    case QUESTIONMARK:
      return TokenQUESTIONMARK;
    case EQUAL:
      return TokenEQUAL;
    case LANGLE:
      return TokenLESSTHAN;
    case RANGLE:
      return TokenGREATERTHAN;
    }

    // else
    if (Character.isJavaIdentifierPart(fChar)) {
      // assume an ident or keyword
      int from = pos, to;
      pos = scanForward(pos + 1, bound, fNonIdent);
      if (pos == NOT_FOUND)
        to = bound == UNBOUND ? fDocument.getLength() : bound;
      else
        to = pos;

      String identOrKeyword;
      try {
        identOrKeyword = fDocument.get(from, to - from);
      } catch (BadLocationException e) {
        return TokenEOF;
      }

      return getToken(identOrKeyword);

    }
    // operators, number literals etc
    return TokenOTHER;
  }

  /**
   * Returns the next token in backward direction, starting at
   * <code>start</code>, and not extending further than <code>bound</code>.
   * The return value is one of the constants defined in {@link Symbols}.
   * After a call, {@link #getPosition()} will return the position just before
   * the scanned token starts (i.e. the next position that will be scanned).
   *
   * @param start
   *            the first character position in the document to consider
   * @param bound
   *            the first position not to consider any more
   * @return a constant from {@link Symbols} describing the previous token
   */
  public int previousToken(int start, int bound) {
    int pos = scanBackward(start, bound, fNonWSDefaultPart);
    if (pos == NOT_FOUND)
      return TokenEOF;

    fPos--;

    switch (fChar) {
    case LBRACE:
      return TokenLBRACE;
    case RBRACE:
      return TokenRBRACE;
    case LBRACKET:
      return TokenLBRACKET;
    case RBRACKET:
      return TokenRBRACKET;
    case LPAREN:
      return TokenLPAREN;
    case RPAREN:
      return TokenRPAREN;
    case SEMICOLON:
      return TokenSEMICOLON;
    case COLON:
      return TokenCOLON;
    case COMMA:
      return TokenCOMMA;
    case QUESTIONMARK:
      return TokenQUESTIONMARK;
    case EQUAL:
      return TokenEQUAL;
    case LANGLE:
      return TokenLESSTHAN;
    case RANGLE:
      return TokenGREATERTHAN;
    }

    // else
    if (Character.isJavaIdentifierPart(fChar)) {
      // assume an ident or keyword
      int from, to = pos + 1;
      pos = scanBackward(pos - 1, bound, fNonIdent);
      if (pos == NOT_FOUND)
        from = bound == UNBOUND ? 0 : bound + 1;
      else
        from = pos + 1;

      String identOrKeyword;
      try {
        identOrKeyword = fDocument.get(from, to - from);
      } catch (BadLocationException e) {
        return TokenEOF;
      }

      return getToken(identOrKeyword);

    }
    // operators, number literals etc
    return TokenOTHER;
  }

  /**
   * Returns one of the keyword constants or <code>TokenIDENT</code> for a
   * scanned identifier.
   *
   * @param s
   *            a scanned identifier
   * @return one of the constants defined in {@link Symbols}
   */
  private int getToken(String s) {
    Assert.isNotNull(s);

    switch (s.length()) {
    case 2:
      if ("if".equals(s)) //$NON-NLS-1$
        return TokenIF;
      if ("do".equals(s)) //$NON-NLS-1$
        return TokenDO;
      break;
    case 3:
      if ("for".equals(s)) //$NON-NLS-1$
        return TokenFOR;
      if ("try".equals(s)) //$NON-NLS-1$
        return TokenTRY;
      if ("new".equals(s)) //$NON-NLS-1$
        return TokenNEW;
      break;
    case 4:
      if ("case".equals(s)) //$NON-NLS-1$
        return TokenCASE;
      if ("else".equals(s)) //$NON-NLS-1$
        return TokenELSE;
      if ("enum".equals(s)) //$NON-NLS-1$
        return TokenENUM;
      if ("goto".equals(s)) //$NON-NLS-1$
        return TokenGOTO;
      break;
    case 5:
      if ("break".equals(s)) //$NON-NLS-1$
        return TokenBREAK;
      if ("catch".equals(s)) //$NON-NLS-1$
        return TokenCATCH;
      if ("class".equals(s)) //$NON-NLS-1$
        return TokenCLASS;
      if ("while".equals(s)) //$NON-NLS-1$
        return TokenWHILE;
      break;
    case 6:
      if ("return".equals(s)) //$NON-NLS-1$
        return TokenRETURN;
      if ("static".equals(s)) //$NON-NLS-1$
        return TokenSTATIC;
      if ("switch".equals(s)) //$NON-NLS-1$
        return TokenSWITCH;
      break;
    case 7:
      if ("default".equals(s)) //$NON-NLS-1$
        return TokenDEFAULT;
      if ("finally".equals(s)) //$NON-NLS-1$
        return TokenFINALLY;
      break;
    case 9:
      if ("interface".equals(s)) //$NON-NLS-1$
        return TokenINTERFACE;
      break;
    case 12:
      if ("synchronized".equals(s)) //$NON-NLS-1$
        return TokenSYNCHRONIZED;
      break;
    }
    return TokenIDENT;
  }

  /**
   * Returns the position of the closing peer character (forward search). Any
   * scopes introduced by opening peers are skipped. All peers accounted for
   * must reside in the default partition.
   *
   * <p>
   * Note that <code>start</code> must not point to the opening peer, but to
   * the first character being searched.
   * </p>
   *
   * @param start
   *            the start position
   * @param openingPeer
   *            the opening peer character (e.g. '{')
   * @param closingPeer
   *            the closing peer character (e.g. '}')
   * @return the matching peer character position, or <code>NOT_FOUND</code>
   */
  public int findClosingPeer(int start, final char openingPeer,
      final char closingPeer) {
    Assert.isNotNull(fDocument);
    Assert.isTrue(start >= 0);

    try {
      int depth = 1;
      start -= 1;
      while (true) {
        start = scanForward(start + 1, UNBOUND, new CharacterMatch(
            new char[] { openingPeer, closingPeer }));
        if (start == NOT_FOUND)
          return NOT_FOUND;

        if (fDocument.getChar(start) == openingPeer)
          depth++;
        else
          depth--;

        if (depth == 0)
          return start;
      }

    } catch (BadLocationException e) {
      return NOT_FOUND;
    }
  }

  /**
   * Returns the position of the opening peer character (backward search). Any
   * scopes introduced by closing peers are skipped. All peers accounted for
   * must reside in the default partition.
   *
   * <p>
   * Note that <code>start</code> must not point to the closing peer, but to
   * the first character being searched.
   * </p>
   *
   * @param start
   *            the start position
   * @param openingPeer
   *            the opening peer character (e.g. '{')
   * @param closingPeer
   *            the closing peer character (e.g. '}')
   * @return the matching peer character position, or <code>NOT_FOUND</code>
   */
  public int findOpeningPeer(int start, char openingPeer, char closingPeer) {
    Assert.isTrue(start < fDocument.getLength());

    try {
      int depth = 1;
      start += 1;
      while (true) {
        start = scanBackward(start - 1, UNBOUND, new CharacterMatch(
            new char[] { openingPeer, closingPeer }));
        if (start == NOT_FOUND)
          return NOT_FOUND;

        if (fDocument.getChar(start) == closingPeer)
          depth++;
        else
          depth--;

        if (depth == 0)
          return start;
      }

    } catch (BadLocationException e) {
      return NOT_FOUND;
    }
  }

  /**
   * Computes the surrounding block around <code>offset</code>. The search is
   * started at the beginning of <code>offset</code>, i.e. an opening brace at
   * <code>offset</code> will not be part of the surrounding block, but a
   * closing brace will.
   *
   * @param offset
   *            the offset for which the surrounding block is computed
   * @return a region describing the surrounding block, or <code>null</code>
   *         if none can be found
   */
  public IRegion findSurroundingBlock(int offset) {
    if (offset < 1 || offset >= fDocument.getLength())
      return null;

    int begin = findOpeningPeer(offset - 1, LBRACE, RBRACE);
    int end = findClosingPeer(offset, LBRACE, RBRACE);
    if (begin == NOT_FOUND || end == NOT_FOUND)
      return null;
    return new Region(begin, end + 1 - begin);
  }

  /**
   * Finds the smallest position in <code>fDocument</code> such that the
   * position is &gt;= <code>position</code> and &lt; <code>bound</code> and
   * <code>Character.isWhitespace(fDocument.getChar(pos))</code> evaluates to
   * <code>false</code> and the position is in the default partition.
   *
   * @param position
   *            the first character position in <code>fDocument</code> to be
   *            considered
   * @param bound
   *            the first position in <code>fDocument</code> to not consider
   *            any more, with <code>bound</code> &gt; <code>position</code>,
   *            or <code>UNBOUND</code>
   * @return the smallest position of a non-whitespace character in [
   *         <code>position</code>, <code>bound</code>) that resides in a Java
   *         partition, or <code>NOT_FOUND</code> if none can be found
   */
  public int findNonWhitespaceForward(int position, int bound) {
    return scanForward(position, bound, fNonWSDefaultPart);
  }

  /**
   * Finds the smallest position in <code>fDocument</code> such that the
   * position is &gt;= <code>position</code> and &lt; <code>bound</code> and
   * <code>Character.isWhitespace(fDocument.getChar(pos))</code> evaluates to
   * <code>false</code>.
   *
   * @param position
   *            the first character position in <code>fDocument</code> to be
   *            considered
   * @param bound
   *            the first position in <code>fDocument</code> to not consider
   *            any more, with <code>bound</code> &gt; <code>position</code>,
   *            or <code>UNBOUND</code>
   * @return the smallest position of a non-whitespace character in [
   *         <code>position</code>, <code>bound</code>), or
   *         <code>NOT_FOUND</code> if none can be found
   */
  public int findNonWhitespaceForwardInAnyPartition(int position, int bound) {
    return scanForward(position, bound, fNonWS);
  }

  /**
   * Finds the highest position in <code>fDocument</code> such that the
   * position is &lt;= <code>position</code> and &gt; <code>bound</code> and
   * <code>Character.isWhitespace(fDocument.getChar(pos))</code> evaluates to
   * <code>false</code> and the position is in the default partition.
   *
   * @param position
   *            the first character position in <code>fDocument</code> to be
   *            considered
   * @param bound
   *            the first position in <code>fDocument</code> to not consider
   *            any more, with <code>bound</code> &lt; <code>position</code>,
   *            or <code>UNBOUND</code>
   * @return the highest position of a non-whitespace character in (
   *         <code>bound</code>, <code>position</code>] that resides in a Java
   *         partition, or <code>NOT_FOUND</code> if none can be found
   */
  public int findNonWhitespaceBackward(int position, int bound) {
    return scanBackward(position, bound, fNonWSDefaultPart);
  }

  /**
   * Finds the lowest position <code>p</code> in <code>fDocument</code> such
   * that <code>start</code> &lt;= p &lt; <code>bound</code> and
   * <code>condition.stop(fDocument.getChar(p), p)</code> evaluates to
   * <code>true</code>.
   *
   * @param start
   *            the first character position in <code>fDocument</code> to be
   *            considered
   * @param bound
   *            the first position in <code>fDocument</code> to not consider
   *            any more, with <code>bound</code> &gt; <code>start</code>, or
   *            <code>UNBOUND</code>
   * @param condition
   *            the <code>StopCondition</code> to check
   * @return the lowest position in [<code>start</code>, <code>bound</code>)
   *         for which <code>condition</code> holds, or <code>NOT_FOUND</code>
   *         if none can be found
   */
  public int scanForward(int start, int bound, StopCondition condition) {
    Assert.isTrue(start >= 0);

    if (bound == UNBOUND)
      bound = fDocument.getLength();

    Assert.isTrue(bound <= fDocument.getLength());

    try {
      fPos = start;
      while (fPos < bound) {

        fChar = fDocument.getChar(fPos);
        if (condition.stop(fChar, fPos, true))
          return fPos;

        fPos = condition.nextPosition(fPos, true);
      }
    } catch (BadLocationException e) {
    }
    return NOT_FOUND;
  }

  /**
   * Finds the lowest position in <code>fDocument</code> such that the
   * position is &gt;= <code>position</code> and &lt; <code>bound</code> and
   * <code>fDocument.getChar(position) == ch</code> evaluates to
   * <code>true</code> and the position is in the default partition.
   *
   * @param position
   *            the first character position in <code>fDocument</code> to be
   *            considered
   * @param bound
   *            the first position in <code>fDocument</code> to not consider
   *            any more, with <code>bound</code> &gt; <code>position</code>,
   *            or <code>UNBOUND</code>
   * @param ch
   *            the <code>char</code> to search for
   * @return the lowest position of <code>ch</code> in (<code>bound</code>,
   *         <code>position</code>] that resides in a Java partition, or
   *         <code>NOT_FOUND</code> if none can be found
   */
  public int scanForward(int position, int bound, char ch) {
    return scanForward(position, bound, new CharacterMatch(ch));
  }

  /**
   * Finds the lowest position in <code>fDocument</code> such that the
   * position is &gt;= <code>position</code> and &lt; <code>bound</code> and
   * <code>fDocument.getChar(position) == ch</code> evaluates to
   * <code>true</code> for at least one ch in <code>chars</code> and the
   * position is in the default partition.
   *
   * @param position
   *            the first character position in <code>fDocument</code> to be
   *            considered
   * @param bound
   *            the first position in <code>fDocument</code> to not consider
   *            any more, with <code>bound</code> &gt; <code>position</code>,
   *            or <code>UNBOUND</code>
   * @param chars
   *            an array of <code>char</code> to search for
   * @return the lowest position of a non-whitespace character in [
   *         <code>position</code>, <code>bound</code>) that resides in a Java
   *         partition, or <code>NOT_FOUND</code> if none can be found
   */
  public int scanForward(int position, int bound, char[] chars) {
    return scanForward(position, bound, new CharacterMatch(chars));
  }

  /**
   * Finds the highest position <code>p</code> in <code>fDocument</code> such
   * that <code>bound</code> &lt; <code>p</code> &lt;= <code>start</code> and
   * <code>condition.stop(fDocument.getChar(p), p)</code> evaluates to
   * <code>true</code>.
   *
   * @param start
   *            the first character position in <code>fDocument</code> to be
   *            considered
   * @param bound
   *            the first position in <code>fDocument</code> to not consider
   *            any more, with <code>bound</code> &lt; <code>start</code>, or
   *            <code>UNBOUND</code>
   * @param condition
   *            the <code>StopCondition</code> to check
   * @return the highest position in (<code>bound</code>, <code>start</code>
   *         for which <code>condition</code> holds, or <code>NOT_FOUND</code>
   *         if none can be found
   */
  public int scanBackward(int start, int bound, StopCondition condition) {
    if (bound == UNBOUND)
      bound = -1;

    Assert.isTrue(bound >= -1);
    Assert.isTrue(start < fDocument.getLength());

    try {
      fPos = start;
      while (fPos > bound) {

        fChar = fDocument.getChar(fPos);
        if (condition.stop(fChar, fPos, false))
          return fPos;

        fPos = condition.nextPosition(fPos, false);
      }
    } catch (BadLocationException e) {
    }
    return NOT_FOUND;
  }

  /**
   * Finds the highest position in <code>fDocument</code> such that the
   * position is &lt;= <code>position</code> and &gt; <code>bound</code> and
   * <code>fDocument.getChar(position) == ch</code> evaluates to
   * <code>true</code> for at least one ch in <code>chars</code> and the
   * position is in the default partition.
   *
   * @param position
   *            the first character position in <code>fDocument</code> to be
   *            considered
   * @param bound
   *            the first position in <code>fDocument</code> to not consider
   *            any more, with <code>bound</code> &lt; <code>position</code>,
   *            or <code>UNBOUND</code>
   * @param ch
   *            the <code>char</code> to search for
   * @return the highest position of one element in <code>chars</code> in (
   *         <code>bound</code>, <code>position</code>] that resides in a Java
   *         partition, or <code>NOT_FOUND</code> if none can be found
   */
  public int scanBackward(int position, int bound, char ch) {
    return scanBackward(position, bound, new CharacterMatch(ch));
  }

  /**
   * Finds the highest position in <code>fDocument</code> such that the
   * position is &lt;= <code>position</code> and &gt; <code>bound</code> and
   * <code>fDocument.getChar(position) == ch</code> evaluates to
   * <code>true</code> for at least one ch in <code>chars</code> and the
   * position is in the default partition.
   *
   * @param position
   *            the first character position in <code>fDocument</code> to be
   *            considered
   * @param bound
   *            the first position in <code>fDocument</code> to not consider
   *            any more, with <code>bound</code> &lt; <code>position</code>,
   *            or <code>UNBOUND</code>
   * @param chars
   *            an array of <code>char</code> to search for
   * @return the highest position of one element in <code>chars</code> in (
   *         <code>bound</code>, <code>position</code>] that resides in a Java
   *         partition, or <code>NOT_FOUND</code> if none can be found
   */
  public int scanBackward(int position, int bound, char[] chars) {
    return scanBackward(position, bound, new CharacterMatch(chars));
  }

  /**
   * Checks whether <code>position</code> resides in a default (Java)
   * partition of <code>fDocument</code>.
   *
   * @param position
   *            the position to be checked
   * @return <code>true</code> if <code>position</code> is in the default
   *         partition of <code>fDocument</code>, <code>false</code> otherwise
   */
  public boolean isDefaultPartition(int position) {
    Assert.isTrue(position >= 0);
    Assert.isTrue(position <= fDocument.getLength());
    ITypedRegion partition = getPartition(position);
    return fPartition.equals(partition.getType());
  }

  /**
   * Returns the partition at <code>position</code>. Classify the partition as
   * - PHPPartitionTypes.PHP_COMMENT, PHPPartitionTypes.PHP_QUOTED_STRING or
   * PHPPartitionTypes.PHP_DEFAULT. Matching open/close symbol will only be
   * looked for in the same partition type, so that for example a closing
   * bracket in a commented line will not match an opening bracket in the
   * code.
   *
   * @param position
   *            the position to get the partition for
   * @return the partition at <code>position</code> or a dummy zero-length
   *         partition if accessing the document fails
   */
  private ITypedRegion getPartition(int position) {
    Assert.isTrue(position >= 0);
    Assert.isTrue(position <= fDocument.getLength());

    try {
      // If we have a structured document - extract the text region from
      // the document and classify it
      if (fDocument instanceof BasicStructuredDocument) {
        IStructuredDocumentRegion sdRegion = ((BasicStructuredDocument) fDocument)
            .getRegionAtCharacterOffset(position);
        ITextRegion textRegion = sdRegion
            .getRegionAtCharacterOffset(position);
        if (textRegion instanceof IPhpScriptRegion) {
          IPhpScriptRegion phpScriptRegion = (IPhpScriptRegion) textRegion;
          textRegion = phpScriptRegion.getPhpToken(position
              - sdRegion.getStartOffset()
              - phpScriptRegion.getStart());
          // handle comments
          if (PHPPartitionTypes.isPHPCommentState(textRegion
              .getType())) {
            return new TypedRegion(position, 0,
                PHPPartitionTypes.PHP_COMMENT);
          }
          // handle strings
          else if (PHPPartitionTypes.isPHPQuotesState(textRegion
              .getType())) {
            return new TypedRegion(position, 0,
                PHPPartitionTypes.PHP_QUOTED_STRING);
          }
          // handle the rest
          else if (PHPPartitionTypes.isPHPRegularState(textRegion
              .getType())) {
            return new TypedRegion(position, 0,
                PHPPartitionTypes.PHP_DEFAULT);
          }
        }
      }

      return TextUtilities.getPartition(fDocument, fPartitioning,
          position, false);
    } catch (BadLocationException e) {
      return new TypedRegion(position, 0, "__no_partition_at_all"); //$NON-NLS-1$
    }

  }

  private ITextRegion getTextRegion(int position) {
    Assert.isTrue(position >= 0);
    Assert.isTrue(position <= fDocument.getLength());
    try {
      // If we have a structured document - extract the text region from
      // the document and classify it
      if (fDocument instanceof BasicStructuredDocument) {
        IStructuredDocumentRegion sdRegion = ((BasicStructuredDocument) fDocument)
            .getRegionAtCharacterOffset(position);
        ITextRegion textRegion = sdRegion
            .getRegionAtCharacterOffset(position);
        if (textRegion instanceof IPhpScriptRegion) {
          IPhpScriptRegion phpScriptRegion = (IPhpScriptRegion) textRegion;
          textRegion = phpScriptRegion.getPhpToken(position
              - sdRegion.getStartOffset()
              - phpScriptRegion.getStart());
          return textRegion;
        }
      }

      return null;
    } catch (BadLocationException e) {
      return null; //$NON-NLS-1$
    }

  }

  /**
   * Checks if the line seems to be an open condition not followed by a block
   * (i.e. an if, while, or for statement with just one following statement,
   * see example below).
   *
   * <pre>
   * if (condition)
   *   doStuff();
   * </pre>
   *
   * <p>
   * Algorithm: if the last non-WS, non-Comment code on the line is an if
   * (condition), while (condition), for( expression), do, else, and there is
   * no statement after that
   * </p>
   *
   * @param position
   *            the insert position of the new character
   * @param bound
   *            the lowest position to consider
   * @return <code>true</code> if the code is a conditional statement or loop
   *         without a block, <code>false</code> otherwise
   */
  public boolean isBracelessBlockStart(int position, int bound) {
    if (position < 1)
      return false;

    switch (previousToken(position, bound)) {
    case TokenDO:
    case TokenELSE:
      return true;
    case TokenRPAREN:
      position = findOpeningPeer(fPos, LPAREN, RPAREN);
      if (position > 0) {
        switch (previousToken(position - 1, bound)) {
        case TokenIF:
        case TokenFOR:
        case TokenWHILE:
          return true;
        }
      }
    }

    return false;
  }
}
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