Class ANTLRStringStream

java.lang.Object
org.antlr.runtime.ANTLRStringStream
All Implemented Interfaces:
CharStream, IntStream
Direct Known Subclasses:
ANTLRFileStream, ANTLRReaderStream

public class ANTLRStringStream extends Object implements CharStream
A pretty quick CharStream that pulls all data from an array directly. Every method call counts in the lexer. Java's strings aren't very good so I'm avoiding.
  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected int
    The index of the character relative to the beginning of the line 0..n-1
    protected char[]
    The data being scanned
    protected int
    Track the last mark() call result value for use in rewind().
    protected int
    line number 1..n within the input
    protected int
    tracks how deep mark() calls are nested
    A list of CharStreamState objects that tracks the stream state values line, charPositionInLine, and p that can change as you move through the input stream.
    protected int
    How many characters are actually in the buffer
    What is name or source of this char stream?
    protected int
    0..n-1 index into string of next char

    Fields inherited from interface org.antlr.runtime.CharStream

    EOF
  • Constructor Summary

    Constructors
    Constructor
    Description
     
    ANTLRStringStream(char[] data, int numberOfActualCharsInArray)
    This is the preferred constructor as no data is copied
    Copy data in string to a local char array
  • Method Summary

    Modifier and Type
    Method
    Description
    void
     
    int
    The index of the character relative to the beginning of the line 0..n-1
    int
    ANTLR tracks the line information automatically
    Where are you getting symbols from? Normally, implementations will pass the buck all the way to the lexer who can ask its input stream for the file name or whatever.
    int
    Return the current input symbol index 0..n where n indicates the last symbol has been read.
    int
    LA(int i)
    Get int at current input pointer + i ahead where i=1 is next int.
    int
    LT(int i)
    Get the ith character of lookahead.
    int
    Tell the stream to start buffering if it hasn't already.
    void
    release(int marker)
    You may want to commit to a backtrack but don't want to force the stream to keep bookkeeping objects around for a marker that is no longer necessary.
    void
    Reset the stream so that it's in the same state it was when the object was created *except* the data array is not touched.
    void
    Rewind to the input position of the last marker.
    void
    rewind(int m)
    Reset the stream so that next call to index would return marker.
    void
    seek(int index)
    consume() ahead until p==index; can't just set p=index as we must update line and charPositionInLine.
    void
     
    void
    setLine(int line)
    Because this stream can rewind, we need to be able to reset the line
    int
    Only makes sense for streams that buffer everything up probably, but might be useful to display the entire stream or for testing.
    substring(int start, int stop)
    For infinite streams, you don't need this; primarily I'm providing a useful interface for action code.
     

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
  • Field Details

    • data

      protected char[] data
      The data being scanned
    • n

      protected int n
      How many characters are actually in the buffer
    • p

      protected int p
      0..n-1 index into string of next char
    • line

      protected int line
      line number 1..n within the input
    • charPositionInLine

      protected int charPositionInLine
      The index of the character relative to the beginning of the line 0..n-1
    • markDepth

      protected int markDepth
      tracks how deep mark() calls are nested
    • markers

      protected List<CharStreamState> markers
      A list of CharStreamState objects that tracks the stream state values line, charPositionInLine, and p that can change as you move through the input stream. Indexed from 1..markDepth. A null is kept @ index 0. Create upon first call to mark().
    • lastMarker

      protected int lastMarker
      Track the last mark() call result value for use in rewind().
    • name

      public String name
      What is name or source of this char stream?
  • Constructor Details

    • ANTLRStringStream

      public ANTLRStringStream()
    • ANTLRStringStream

      public ANTLRStringStream(String input)
      Copy data in string to a local char array
    • ANTLRStringStream

      public ANTLRStringStream(char[] data, int numberOfActualCharsInArray)
      This is the preferred constructor as no data is copied
  • Method Details

    • reset

      public void reset()
      Reset the stream so that it's in the same state it was when the object was created *except* the data array is not touched.
    • consume

      public void consume()
      Specified by:
      consume in interface IntStream
    • LA

      public int LA(int i)
      Description copied from interface: IntStream
      Get int at current input pointer + i ahead where i=1 is next int. Negative indexes are allowed. LA(-1) is previous token (token just matched). LA(-i) where i is before first token should yield -1, invalid char / EOF.
      Specified by:
      LA in interface IntStream
    • LT

      public int LT(int i)
      Description copied from interface: CharStream
      Get the ith character of lookahead. This is the same usually as LA(i). This will be used for labels in the generated lexer code. I'd prefer to return a char here type-wise, but it's probably better to be 32-bit clean and be consistent with LA.
      Specified by:
      LT in interface CharStream
    • index

      public int index()
      Return the current input symbol index 0..n where n indicates the last symbol has been read. The index is the index of char to be returned from LA(1).
      Specified by:
      index in interface IntStream
    • size

      public int size()
      Description copied from interface: IntStream
      Only makes sense for streams that buffer everything up probably, but might be useful to display the entire stream or for testing. This value includes a single EOF.
      Specified by:
      size in interface IntStream
    • mark

      public int mark()
      Description copied from interface: IntStream
      Tell the stream to start buffering if it hasn't already. Return current input position, index(), or some other marker so that when passed to rewind() you get back to the same spot. rewind(mark()) should not affect the input cursor. The Lexer track line/col info as well as input index so its markers are not pure input indexes. Same for tree node streams.
      Specified by:
      mark in interface IntStream
    • rewind

      public void rewind(int m)
      Description copied from interface: IntStream
      Reset the stream so that next call to index would return marker. The marker will usually be index() but it doesn't have to be. It's just a marker to indicate what state the stream was in. This is essentially calling release() and seek(). If there are markers created after this marker argument, this routine must unroll them like a stack. Assume the state the stream was in when this marker was created.
      Specified by:
      rewind in interface IntStream
    • rewind

      public void rewind()
      Description copied from interface: IntStream
      Rewind to the input position of the last marker. Used currently only after a cyclic DFA and just before starting a sem/syn predicate to get the input position back to the start of the decision. Do not "pop" the marker off the state. mark(i) and rewind(i) should balance still. It is like invoking rewind(last marker) but it should not "pop" the marker off. It's like seek(last marker's input position).
      Specified by:
      rewind in interface IntStream
    • release

      public void release(int marker)
      Description copied from interface: IntStream
      You may want to commit to a backtrack but don't want to force the stream to keep bookkeeping objects around for a marker that is no longer necessary. This will have the same behavior as rewind() except it releases resources without the backward seek. This must throw away resources for all markers back to the marker argument. So if you're nested 5 levels of mark(), and then release(2) you have to release resources for depths 2..5.
      Specified by:
      release in interface IntStream
    • seek

      public void seek(int index)
      consume() ahead until p==index; can't just set p=index as we must update line and charPositionInLine.
      Specified by:
      seek in interface IntStream
    • substring

      public String substring(int start, int stop)
      Description copied from interface: CharStream
      For infinite streams, you don't need this; primarily I'm providing a useful interface for action code. Just make sure actions don't use this on streams that don't support it.
      Specified by:
      substring in interface CharStream
    • getLine

      public int getLine()
      Description copied from interface: CharStream
      ANTLR tracks the line information automatically
      Specified by:
      getLine in interface CharStream
    • getCharPositionInLine

      public int getCharPositionInLine()
      Description copied from interface: CharStream
      The index of the character relative to the beginning of the line 0..n-1
      Specified by:
      getCharPositionInLine in interface CharStream
    • setLine

      public void setLine(int line)
      Description copied from interface: CharStream
      Because this stream can rewind, we need to be able to reset the line
      Specified by:
      setLine in interface CharStream
    • setCharPositionInLine

      public void setCharPositionInLine(int pos)
      Specified by:
      setCharPositionInLine in interface CharStream
    • getSourceName

      public String getSourceName()
      Description copied from interface: IntStream
      Where are you getting symbols from? Normally, implementations will pass the buck all the way to the lexer who can ask its input stream for the file name or whatever.
      Specified by:
      getSourceName in interface IntStream
    • toString

      public String toString()
      Overrides:
      toString in class Object