Package com.yahoo.prelude.semantics.parser

Class AbstractCharStream

java.lang.Object
com.yahoo.prelude.semantics.parser.AbstractCharStream
All Implemented Interfaces:
CharStream
Direct Known Subclasses:
SimpleCharStream
public abstract class AbstractCharStream extends Object implements CharStream
An implementation of interface CharStream, where the stream is assumed to contain only ASCII characters (without unicode processing).

  • Field Details

    • DEFAULT_BUF_SIZE

      public static final int DEFAULT_BUF_SIZE
      Default buffer size if nothing is specified
      See Also:

    • buffer

      protected char[] buffer
      Internal circular buffer

    • bufsize

      protected int bufsize
      Overall buffer size - same as buffer.length

    • bufpos

      protected int bufpos
      Current read position in buffer.

    • available

      protected int available
      The number of unoccupied buffer array positions

    • tokenBegin

      protected int tokenBegin
      The first array index (of `buffer`) that the current token starts

    • inBuf

      protected int inBuf
      Characters in the backup/pushBack buffer

    • maxNextCharInd

      protected int maxNextCharInd

  • Constructor Details

    • AbstractCharStream

      public AbstractCharStream(int nStartLine, int nStartColumn, int nBufferSize)
      Constructor.

  • Method Details

    • reInit

      public final void reInit(int nStartLine, int nStartColumn, int nBufferSize)
      Reinitialise.

    • streamRead

      protected abstract int streamRead(char[] aBuf, int nOfs, int nLen) throws IOException
      Read from the underlying stream.
      Parameters:
      aBuf - the buffer to be filled
      nOfs - The offset into the buffer. 0-based
      nLen - Number of chars to read.
      Returns:
      Number of effective chars read, or -1 on error.
      Throws:
      IOException

    • streamClose

      protected abstract void streamClose() throws IOException
      Close the underlying stream.
      Throws:
      IOException - If closing fails.

    • getBufSizeAfterExpansion

      protected int getBufSizeAfterExpansion()

    • expandBuff

      protected void expandBuff(boolean bWrapAround)

    • internalAdjustBuffSize

      protected final void internalAdjustBuffSize()

    • fillBuff

      protected void fillBuff() throws IOException
      Throws:
      IOException

    • internalSetBufLineColumn

      protected final void internalSetBufLineColumn(int nLine, int nColumn)

    • internalUpdateLineColumn

      protected final void internalUpdateLineColumn(char c)

    • readChar

      public char readChar() throws IOException
      Description copied from interface: CharStream
      Get the next character from the selected input. The method of selecting the input is the responsibility of the class implementing this interface.
      Specified by:
      readChar in interface CharStream
      Returns:
      the next character from the selected input
      Throws:
      IOException - on IO error

    • beginToken

      public char beginToken() throws IOException
      Specified by:
      beginToken in interface CharStream
      Returns:
      the next character that marks the beginning of the next token. All characters must remain in the buffer between two successive calls to this method to implement backup correctly.
      Throws:
      IOException

    • getBeginColumn

      public int getBeginColumn()
      Specified by:
      getBeginColumn in interface CharStream
      Returns:
      the column number of the first character for current token (being matched after the last call to beginToken).

    • getBeginLine

      public int getBeginLine()
      Specified by:
      getBeginLine in interface CharStream
      Returns:
      the line number of the first character for current token (being matched after the last call to BeginToken).

    • getEndColumn

      public int getEndColumn()
      Specified by:
      getEndColumn in interface CharStream
      Returns:
      the column number of the last character for current token (being matched after the last call to BeginToken).

    • getEndLine

      public int getEndLine()
      Specified by:
      getEndLine in interface CharStream
      Returns:
      the line number of the last character for current token (being matched after the last call to BeginToken).

    • backup

      public void backup(int nAmount)
      Description copied from interface: CharStream
      Backs up the input stream by amount steps. Lexer calls this method if it had already read some characters, but could not use them to match a (longer) token. So, they will be used again as the prefix of the next token and it is the implemetation's responsibility to do this right.
      Specified by:
      backup in interface CharStream
      Parameters:
      nAmount - Number of chars to back up.

    • getImage

      public String getImage()
      Specified by:
      getImage in interface CharStream
      Returns:
      a string made up of characters from the marked token beginning to the current buffer position. Implementations have the choice of returning anything that they want to. For example, for efficiency, one might decide to just return null, which is a valid implementation.

    • getSuffix

      public char[] getSuffix(int len)
      Specified by:
      getSuffix in interface CharStream
      Returns:
      an array of characters that make up the suffix of length 'len' for the currently matched token. This is used to build up the matched string for use in actions in the case of MORE. A simple and inefficient implementation of this is as follows: 
         {
      String t = getImage();
      return t.substring(t.length() - len, t.length()).toCharArray();
   }

    • done

      public void done()
      Description copied from interface: CharStream
      The lexer calls this function to indicate that it is done with the stream and hence implementations can free any resources held by this class. Again, the body of this function can be just empty and it will not affect the lexer's operation.
      Specified by:
      done in interface CharStream

    • getTabSize

      public final int getTabSize()
      Specified by:
      getTabSize in interface CharStream
      Returns:
      Current tab size.

    • setTabSize

      public final void setTabSize(int nTabSize)
      Description copied from interface: CharStream
      Set the tab size to use.
      Specified by:
      setTabSize in interface CharStream
      Parameters:
      nTabSize - spaces per tab

    • adjustBeginLineColumn

      public final void adjustBeginLineColumn(int nNewLine, int newCol)
      Method to adjust line and column numbers for the start of a token. This is used internally to

    • getLine

      protected final int getLine()
      Returns:
      the current line number. 0-based.

    • getColumn

      protected final int getColumn()
      Returns:
      the current column number. 0-based.

    • isTrackLineColumn

      public final boolean isTrackLineColumn()
      Specified by:
      isTrackLineColumn in interface CharStream
      Returns:
      true if line number and column numbers should be tracked.

    • setTrackLineColumn

      public final void setTrackLineColumn(boolean bTrackLineColumn)
      Description copied from interface: CharStream
      Enable or disable line number and column number tracking.
      Specified by:
      setTrackLineColumn in interface CharStream
      Parameters:
      bTrackLineColumn - true to track it, false to not do it.