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Lexer.javaAPI DocJava SE 5 API16375Fri Aug 26 14:56:08 BST 2005com.sun.org.apache.xpath.internal.compiler

Lexer

public class Lexer extends Object
This class is in charge of lexical processing of the XPath expression into tokens.

Fields Summary
private Compiler
m_compiler
The target XPath.
PrefixResolver
m_namespaceContext
The prefix resolver to map prefixes to namespaces in the XPath.
XPathParser
m_processor
The XPath processor object.
static final int
TARGETEXTRA
This value is added to each element name in the TARGETEXTRA that is a 'target' (right-most top-level element name).
private int[]
m_patternMap
Ignore this, it is going away. This holds a map to the m_tokenQueue that tells where the top-level elements are. It is used for pattern matching so the m_tokenQueue can be walked backwards. Each element that is a 'target', (right-most top level element name) has TARGETEXTRA added to it.
private int
m_patternMapSize
Ignore this, it is going away. The number of elements that m_patternMap maps;
Constructors Summary
Lexer(Compiler compiler, PrefixResolver resolver, XPathParser xpathProcessor)
Create a Lexer object.

param
compiler The owning compiler for this lexer.
param
resolver The prefix resolver for mapping qualified name prefixes to namespace URIs.
param
xpathProcessor The parser that is processing strings to opcodes.


                                                         
     
         
  

    m_compiler = compiler;
    m_namespaceContext = resolver;
    m_processor = xpathProcessor;
Methods Summary
private final voidaddToTokenQueue(java.lang.String s)
Add a token to the token queue.

param
s The token.

    m_compiler.getTokenQueue().addElement(s);
final intgetKeywordToken(java.lang.String key)
Given a string, return the corresponding keyword token.

param
key The keyword.
return
An opcode value.


    int tok;

    try
    {
      Integer itok = (Integer) Keywords.m_keywords.get(key);

      tok = (null != itok) ? itok.intValue() : 0;
    }
    catch (NullPointerException npe)
    {
      tok = 0;
    }
    catch (ClassCastException cce)
    {
      tok = 0;
    }

    return tok;
private intgetTokenQueuePosFromMap(int i)
Given a map pos, return the corresponding token queue pos.

param
i The index in the m_patternMap.
return
the token queue position.


    int pos = m_patternMap[i];

    return (pos >= TARGETEXTRA) ? (pos - TARGETEXTRA) : pos;
private intmapNSTokens(java.lang.String pat, int startSubstring, int posOfNSSep, int posOfScan)
When a seperator token is found, see if there's a element name or the like to map.

param
pat The XPath name string.
param
startSubstring The start of the name string.
param
posOfNSSep The position of the namespace seperator (':').
param
posOfScan The end of the name index.
throws
javax.xml.transform.TransformerException
return
-1 always.


    String prefix = "";
    
    if ((startSubstring >= 0) && (posOfNSSep >= 0))
    {
       prefix = pat.substring(startSubstring, posOfNSSep);
    }
    String uName;

    if ((null != m_namespaceContext) &&!prefix.equals("*")
            &&!prefix.equals("xmlns"))
    {
      try
      {
        if (prefix.length() > 0)
          uName = ((PrefixResolver) m_namespaceContext).getNamespaceForPrefix(
            prefix);
        else
        {

          // Assume last was wildcard. This is not legal according
          // to the draft. Set the below to true to make namespace
          // wildcards work.
          if (false)
          {
            addToTokenQueue(":");

            String s = pat.substring(posOfNSSep + 1, posOfScan);

            if (s.length() > 0)
              addToTokenQueue(s);

            return -1;
          }
          else
          {
            uName =
              ((PrefixResolver) m_namespaceContext).getNamespaceForPrefix(
                prefix);
          }
        }
      }
      catch (ClassCastException cce)
      {
        uName = m_namespaceContext.getNamespaceForPrefix(prefix);
      }
    }
    else
    {
      uName = prefix;
    }

    if ((null != uName) && (uName.length() > 0))
    {
      addToTokenQueue(uName);
      addToTokenQueue(":");

      String s = pat.substring(posOfNSSep + 1, posOfScan);

      if (s.length() > 0)
        addToTokenQueue(s);
    }
    else
    {

      // error("Could not locate namespace for prefix: "+prefix);
      m_processor.error(XPATHErrorResources.ER_PREFIX_MUST_RESOLVE,
                 new String[] {prefix});  //"Prefix must resolve to a namespace: {0}";


      /***  Old code commented out 10-Jan-2001
      addToTokenQueue(prefix);
      addToTokenQueue(":");

      String s = pat.substring(posOfNSSep + 1, posOfScan);

      if (s.length() > 0)
        addToTokenQueue(s);
      ***/
    }

    return -1;
private booleanmapPatternElemPos(int nesting, boolean isStart, boolean isAttrName)
Record the current position on the token queue as long as this is a top-level element. Must be called before the next token is added to the m_tokenQueue.

param
nesting The nesting count for the pattern element.
param
isStart true if this is the start of a pattern.
param
isAttrName true if we have determined that this is an attribute name.
return
true if this is the start of a pattern.


    if (0 == nesting)
    {
      if(m_patternMapSize >= m_patternMap.length)
      {
        int patternMap[] = m_patternMap;
        int len = m_patternMap.length;
        m_patternMap = new int[m_patternMapSize + 100];
        System.arraycopy(patternMap, 0, m_patternMap, 0, len);
      } 
      if (!isStart)
      {
        m_patternMap[m_patternMapSize - 1] -= TARGETEXTRA;
      }
      m_patternMap[m_patternMapSize] =
        (m_compiler.getTokenQueueSize() - (isAttrName ? 1 : 0)) + TARGETEXTRA;

      m_patternMapSize++;

      isStart = false;
    }

    return isStart;
private voidrecordTokenString(java.util.Vector targetStrings)
Record the current token in the passed vector.

param
targetStrings Vector of string.


    int tokPos = getTokenQueuePosFromMap(m_patternMapSize - 1);

    resetTokenMark(tokPos + 1);

    if (m_processor.lookahead('(", 1))
    {
      int tok = getKeywordToken(m_processor.m_token);

      switch (tok)
      {
      case OpCodes.NODETYPE_COMMENT :
        targetStrings.addElement(PsuedoNames.PSEUDONAME_COMMENT);
        break;
      case OpCodes.NODETYPE_TEXT :
        targetStrings.addElement(PsuedoNames.PSEUDONAME_TEXT);
        break;
      case OpCodes.NODETYPE_NODE :
        targetStrings.addElement(PsuedoNames.PSEUDONAME_ANY);
        break;
      case OpCodes.NODETYPE_ROOT :
        targetStrings.addElement(PsuedoNames.PSEUDONAME_ROOT);
        break;
      case OpCodes.NODETYPE_ANYELEMENT :
        targetStrings.addElement(PsuedoNames.PSEUDONAME_ANY);
        break;
      case OpCodes.NODETYPE_PI :
        targetStrings.addElement(PsuedoNames.PSEUDONAME_ANY);
        break;
      default :
        targetStrings.addElement(PsuedoNames.PSEUDONAME_ANY);
      }
    }
    else
    {
      if (m_processor.tokenIs('@"))
      {
        tokPos++;

        resetTokenMark(tokPos + 1);
      }

      if (m_processor.lookahead(':", 1))
      {
        tokPos += 2;
      }

      targetStrings.addElement(m_compiler.getTokenQueue().elementAt(tokPos));
    }
private final voidresetTokenMark(int mark)
Reset token queue mark and m_token to a given position.

param
mark The new position.


    int qsz = m_compiler.getTokenQueueSize();

    m_processor.m_queueMark = (mark > 0)
                              ? ((mark <= qsz) ? mark - 1 : mark) : 0;

    if (m_processor.m_queueMark < qsz)
    {
      m_processor.m_token =
        (String) m_compiler.getTokenQueue().elementAt(m_processor.m_queueMark++);
      m_processor.m_tokenChar = m_processor.m_token.charAt(0);
    }
    else
    {
      m_processor.m_token = null;
      m_processor.m_tokenChar = 0;
    }
voidtokenize(java.lang.String pat)
Walk through the expression and build a token queue, and a map of the top-level elements.

param
pat XSLT Expression.
throws
javax.xml.transform.TransformerException

    tokenize(pat, null);
voidtokenize(java.lang.String pat, java.util.Vector targetStrings)
Walk through the expression and build a token queue, and a map of the top-level elements.

param
pat XSLT Expression.
param
targetStrings Vector to hold Strings, may be null.
throws
javax.xml.transform.TransformerException


    m_compiler.m_currentPattern = pat;
    m_patternMapSize = 0; 

    // This needs to grow too.
    m_compiler.m_opMap = new OpMapVector(OpMap.MAXTOKENQUEUESIZE * 5, OpMap.BLOCKTOKENQUEUESIZE * 5, OpMap.MAPINDEX_LENGTH);

    int nChars = pat.length();
    int startSubstring = -1; 
    int posOfNSSep = -1;
    boolean isStartOfPat = true;
    boolean isAttrName = false;
    boolean isNum = false;

    // Nesting of '[' so we can know if the given element should be
    // counted inside the m_patternMap.
    int nesting = 0;

    // char[] chars = pat.toCharArray();
    for (int i = 0; i < nChars; i++)
    {
      char c = pat.charAt(i);

      switch (c)
      {
      case '\"" :
      {
        if (startSubstring != -1)
        {
          isNum = false;
          isStartOfPat = mapPatternElemPos(nesting, isStartOfPat, isAttrName);
          isAttrName = false;

          if (-1 != posOfNSSep)
          {
            posOfNSSep = mapNSTokens(pat, startSubstring, posOfNSSep, i);
          }
          else
          {
            addToTokenQueue(pat.substring(startSubstring, i));
          }
        }

        startSubstring = i;

        for (i++; (i < nChars) && ((c = pat.charAt(i)) != '\""); i++);

        if (c == '\"" && i < nChars)
        {
          addToTokenQueue(pat.substring(startSubstring, i + 1));

          startSubstring = -1;
        }
        else
        {
          m_processor.error(XPATHErrorResources.ER_EXPECTED_DOUBLE_QUOTE,
                            null);  //"misquoted literal... expected double quote!");
        }
      }
      break;
      case '\'" :
        if (startSubstring != -1)
        {
          isNum = false;
          isStartOfPat = mapPatternElemPos(nesting, isStartOfPat, isAttrName);
          isAttrName = false;

          if (-1 != posOfNSSep)
          {
            posOfNSSep = mapNSTokens(pat, startSubstring, posOfNSSep, i);
          }
          else
          {
            addToTokenQueue(pat.substring(startSubstring, i));
          }
        }

        startSubstring = i;

        for (i++; (i < nChars) && ((c = pat.charAt(i)) != '\'"); i++);

        if (c == '\'" && i < nChars)
        {
          addToTokenQueue(pat.substring(startSubstring, i + 1));

          startSubstring = -1;
        }
        else
        {
          m_processor.error(XPATHErrorResources.ER_EXPECTED_SINGLE_QUOTE,
                            null);  //"misquoted literal... expected single quote!");
        }
        break;
      case 0x0A :
      case 0x0D :
      case ' " :
      case '\t" :
        if (startSubstring != -1)
        {
          isNum = false;
          isStartOfPat = mapPatternElemPos(nesting, isStartOfPat, isAttrName);
          isAttrName = false;

          if (-1 != posOfNSSep)
          {
            posOfNSSep = mapNSTokens(pat, startSubstring, posOfNSSep, i);
          }
          else
          {
            addToTokenQueue(pat.substring(startSubstring, i));
          }

          startSubstring = -1;
        }
        break;
      case '@" :
        isAttrName = true;

      // fall-through on purpose
      case '-" :
        if ('-" == c)
        {
          if (!(isNum || (startSubstring == -1)))
          {
            break;
          }

          isNum = false;
        }

      // fall-through on purpose
      case '(" :
      case '[" :
      case ')" :
      case ']" :
      case '|" :
      case '/" :
      case '*" :
      case '+" :
      case '=" :
      case '," :
      case '\\" :  // Unused at the moment
      case '^" :  // Unused at the moment
      case '!" :  // Unused at the moment
      case '$" :
      case '<" :
      case '>" :
        if (startSubstring != -1)
        {
          isNum = false;
          isStartOfPat = mapPatternElemPos(nesting, isStartOfPat, isAttrName);
          isAttrName = false;

          if (-1 != posOfNSSep)
          {
            posOfNSSep = mapNSTokens(pat, startSubstring, posOfNSSep, i);
          }
          else
          {
            addToTokenQueue(pat.substring(startSubstring, i));
          }

          startSubstring = -1;
        }
        else if (('/" == c) && isStartOfPat)
        {
          isStartOfPat = mapPatternElemPos(nesting, isStartOfPat, isAttrName);
        }
        else if ('*" == c)
        {
          isStartOfPat = mapPatternElemPos(nesting, isStartOfPat, isAttrName);
          isAttrName = false;
        }

        if (0 == nesting)
        {
          if ('|" == c)
          {
            if (null != targetStrings)
            {
              recordTokenString(targetStrings);
            }

            isStartOfPat = true;
          }
        }

        if ((')" == c) || (']" == c))
        {
          nesting--;
        }
        else if (('(" == c) || ('[" == c))
        {
          nesting++;
        }

        addToTokenQueue(pat.substring(i, i + 1));
        break;
      case ':" :
        if (i>0)
        {
          if (posOfNSSep == (i - 1))
          {
            if (startSubstring != -1)
            {
              if (startSubstring < (i - 1))
                addToTokenQueue(pat.substring(startSubstring, i - 1));
            }

            isNum = false;
            isAttrName = false;
            startSubstring = -1;
            posOfNSSep = -1;

            addToTokenQueue(pat.substring(i - 1, i + 1));

            break;
          }
          else
          {
            posOfNSSep = i;
          }
        }

      // fall through on purpose
      default :
        if (-1 == startSubstring)
        {
          startSubstring = i;
          isNum = Character.isDigit(c);
        }
        else if (isNum)
        {
          isNum = Character.isDigit(c);
        }
      }
    }

    if (startSubstring != -1)
    {
      isNum = false;
      isStartOfPat = mapPatternElemPos(nesting, isStartOfPat, isAttrName);

      if ((-1 != posOfNSSep) || 
         ((m_namespaceContext != null) && (m_namespaceContext.handlesNullPrefixes())))
      {
        posOfNSSep = mapNSTokens(pat, startSubstring, posOfNSSep, nChars);
      }
      else
      {
        addToTokenQueue(pat.substring(startSubstring, nChars));
      }
    }

    if (0 == m_compiler.getTokenQueueSize())
    {
      m_processor.error(XPATHErrorResources.ER_EMPTY_EXPRESSION, null);  //"Empty expression!");
    }
    else if (null != targetStrings)
    {
      recordTokenString(targetStrings);
    }

    m_processor.m_queueMark = 0;