Package antlr

Class TokenStreamRewriteEngine

java.lang.Object
antlr.TokenStreamRewriteEngine
All Implemented Interfaces:
IASDebugStream, TokenStream
public class TokenStreamRewriteEngine extends Object implements TokenStream, IASDebugStream
This token stream tracks the *entire* token stream coming from a lexer, but does not pass on the whitespace (or whatever else you want to discard) to the parser. This class can then be asked for the ith token in the input stream. Useful for dumping out the input stream exactly after doing some augmentation or other manipulations. Tokens are index from 0..n-1 You can insert stuff, replace, and delete chunks. Note that the operations are done lazily--only if you convert the buffer to a String. This is very efficient because you are not moving data around all the time. As the buffer of tokens is converted to strings, the toString() method(s) check to see if there is an operation at the current index. If so, the operation is done and then normal String rendering continues on the buffer. This is like having multiple Turing machine instruction streams (programs) operating on a single input tape. :) Since the operations are done lazily at toString-time, operations do not screw up the token index values. That is, an insert operation at token index i does not change the index values for tokens i+1..n-1. Because operations never actually alter the buffer, you may always get the original token stream back without undoing anything. Since the instructions are queued up, you can easily simulate transactions and roll back any changes if there is an error just by removing instructions. For example, TokenStreamRewriteEngine rewriteEngine = new TokenStreamRewriteEngine(lexer); JavaRecognizer parser = new JavaRecognizer(rewriteEngine); ... rewriteEngine.insertAfter("pass1", t, "foobar");} rewriteEngine.insertAfter("pass2", u, "start");} System.out.println(rewriteEngine.toString("pass1")); System.out.println(rewriteEngine.toString("pass2")); You can also have multiple "instruction streams" and get multiple rewrites from a single pass over the input. Just name the instruction streams and use that name again when printing the buffer. This could be useful for generating a C file and also its header file--all from the same buffer. If you don't use named rewrite streams, a "default" stream is used. Terence Parr, parrt at antlr.org University of San Francisco February 2004

  • Field Details

    • MIN_TOKEN_INDEX

      public static final int MIN_TOKEN_INDEX
      See Also:

    • DEFAULT_PROGRAM_NAME

      public static final String DEFAULT_PROGRAM_NAME
      See Also:

    • PROGRAM_INIT_SIZE

      public static final int PROGRAM_INIT_SIZE
      See Also:

    • tokens

      protected List tokens
      Track the incoming list of tokens

    • programs

      protected Map programs
      You may have multiple, named streams of rewrite operations. I'm calling these things "programs." Maps String (name) -> rewrite (List)

    • lastRewriteTokenIndexes

      protected Map lastRewriteTokenIndexes
      Map String (program name) -> Integer index

    • index

      protected int index
      track index of tokens

    • stream

      protected TokenStream stream
      Who do we suck tokens from?

    • discardMask

      protected BitSet discardMask
      Which (whitespace) token(s) to throw out

  • Constructor Details

    • TokenStreamRewriteEngine

      public TokenStreamRewriteEngine(TokenStream upstream)

    • TokenStreamRewriteEngine

      public TokenStreamRewriteEngine(TokenStream upstream, int initialSize)

  • Method Details

    • nextToken

      public Token nextToken() throws TokenStreamException
      Specified by:
      nextToken in interface TokenStream
      Throws:
      TokenStreamException

    • rollback

      public void rollback(int instructionIndex)

    • rollback

      public void rollback(String programName, int instructionIndex)
      Rollback the instruction stream for a program so that the indicated instruction (via instructionIndex) is no longer in the stream. UNTESTED!

    • deleteProgram

      public void deleteProgram()

    • deleteProgram

      public void deleteProgram(String programName)
      Reset the program so that no instructions exist

    • addToSortedRewriteList

      protected void addToSortedRewriteList(TokenStreamRewriteEngine.RewriteOperation op)
      If op.index > lastRewriteTokenIndexes, just add to the end. Otherwise, do linear

    • addToSortedRewriteList

      protected void addToSortedRewriteList(String programName, TokenStreamRewriteEngine.RewriteOperation op)
      Add an instruction to the rewrite instruction list ordered by the instruction number (use a binary search for efficiency). The list is ordered so that toString() can be done efficiently. When there are multiple instructions at the same index, the instructions must be ordered to ensure proper behavior. For example, a delete at index i must kill any replace operation at i. Insert-before operations must come before any replace / delete instructions. If there are multiple insert instructions for a single index, they are done in reverse insertion order so that "insert foo" then "insert bar" yields "foobar" in front rather than "barfoo". This is convenient because I can insert new InsertOp instructions at the index returned by the binary search. A ReplaceOp kills any previous replace op. Since delete is the same as replace with null text, i can check for ReplaceOp and cover DeleteOp at same time. :)

    • insertAfter

      public void insertAfter(Token t, String text)

    • insertAfter

      public void insertAfter(int index, String text)

    • insertAfter

      public void insertAfter(String programName, Token t, String text)

    • insertAfter

      public void insertAfter(String programName, int index, String text)

    • insertBefore

      public void insertBefore(Token t, String text)

    • insertBefore

      public void insertBefore(int index, String text)

    • insertBefore

      public void insertBefore(String programName, Token t, String text)

    • insertBefore

      public void insertBefore(String programName, int index, String text)

    • replace

      public void replace(int index, String text)

    • replace

      public void replace(int from, int to, String text)

    • replace

      public void replace(Token indexT, String text)

    • replace

      public void replace(Token from, Token to, String text)

    • replace

      public void replace(String programName, int from, int to, String text)

    • replace

      public void replace(String programName, Token from, Token to, String text)

    • delete

      public void delete(int index)

    • delete

      public void delete(int from, int to)

    • delete

      public void delete(Token indexT)

    • delete

      public void delete(Token from, Token to)

    • delete

      public void delete(String programName, int from, int to)

    • delete

      public void delete(String programName, Token from, Token to)

    • discard

      public void discard(int ttype)

    • getToken

      public TokenWithIndex getToken(int i)

    • getTokenStreamSize

      public int getTokenStreamSize()

    • toOriginalString

      public String toOriginalString()

    • toOriginalString

      public String toOriginalString(int start, int end)

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • toString

      public String toString(String programName)

    • toString

      public String toString(int start, int end)

    • toString

      public String toString(String programName, int start, int end)

    • toDebugString

      public String toDebugString()

    • toDebugString

      public String toDebugString(int start, int end)

    • getLastRewriteTokenIndex

      public int getLastRewriteTokenIndex()

    • getLastRewriteTokenIndex

      protected int getLastRewriteTokenIndex(String programName)

    • setLastRewriteTokenIndex

      protected void setLastRewriteTokenIndex(String programName, int i)

    • getProgram

      protected List getProgram(String name)

    • size

      public int size()

    • index

      public int index()

    • getEntireText

      public String getEntireText()
      Description copied from interface: IASDebugStream
      Returns the entire text input to the lexer.
      Specified by:
      getEntireText in interface IASDebugStream
      Returns:
      The entire text or null, if error occured or System.in was used.

    • getOffsetInfo

      public TokenOffsetInfo getOffsetInfo(Token token)
      Description copied from interface: IASDebugStream
      Returns the offset information for the token
      Specified by:
      getOffsetInfo in interface IASDebugStream
      Parameters:
      token - the token whose information need to be retrieved
      Returns:
      offset info, or null