antlr
Class TokenStreamRewriteEngine

java.lang.Object
  extended by 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


Nested Class Summary
(package private) static class TokenStreamRewriteEngine.DeleteOp
           
(package private) static class TokenStreamRewriteEngine.InsertBeforeOp
           
(package private) static class TokenStreamRewriteEngine.ReplaceOp
          I'm going to try replacing range from x..y with (y-x)+1 ReplaceOp instructions.
(package private) static class TokenStreamRewriteEngine.RewriteOperation
           
 
Field Summary
static String DEFAULT_PROGRAM_NAME
           
protected  BitSet discardMask
          Which (whitespace) token(s) to throw out
protected  int index
          track index of tokens
protected  Map lastRewriteTokenIndexes
          Map String (program name) -> Integer index
static int MIN_TOKEN_INDEX
           
static int PROGRAM_INIT_SIZE
           
protected  Map programs
          You may have multiple, named streams of rewrite operations.
protected  TokenStream stream
          Who do we suck tokens from?
protected  List tokens
          Track the incoming list of tokens
 
Constructor Summary
TokenStreamRewriteEngine(TokenStream upstream)
           
TokenStreamRewriteEngine(TokenStream upstream, int initialSize)
           
 
Method Summary
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).
protected  void addToSortedRewriteList(TokenStreamRewriteEngine.RewriteOperation op)
          If op.index > lastRewriteTokenIndexes, just add to the end.
 void delete(int index)
           
 void delete(int from, int to)
           
 void delete(String programName, int from, int to)
           
 void delete(String programName, Token from, Token to)
           
 void delete(Token indexT)
           
 void delete(Token from, Token to)
           
 void deleteProgram()
           
 void deleteProgram(String programName)
          Reset the program so that no instructions exist
 void discard(int ttype)
           
 String getEntireText()
          Returns the entire text input to the lexer.
 int getLastRewriteTokenIndex()
           
protected  int getLastRewriteTokenIndex(String programName)
           
 TokenOffsetInfo getOffsetInfo(Token token)
          Returns the offset information for the token
protected  List getProgram(String name)
           
 TokenWithIndex getToken(int i)
           
 int getTokenStreamSize()
           
 int index()
           
 void insertAfter(int index, String text)
           
 void insertAfter(String programName, int index, String text)
           
 void insertAfter(String programName, Token t, String text)
           
 void insertAfter(Token t, String text)
           
 void insertBefore(int index, String text)
           
 void insertBefore(String programName, int index, String text)
           
 void insertBefore(String programName, Token t, String text)
           
 void insertBefore(Token t, String text)
           
 Token nextToken()
           
 void replace(int from, int to, String text)
           
 void replace(int index, String text)
           
 void replace(String programName, int from, int to, String text)
           
 void replace(String programName, Token from, Token to, String text)
           
 void replace(Token indexT, String text)
           
 void replace(Token from, Token to, String text)
           
 void rollback(int instructionIndex)
           
 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.
protected  void setLastRewriteTokenIndex(String programName, int i)
           
 int size()
           
 String toDebugString()
           
 String toDebugString(int start, int end)
           
 String toOriginalString()
           
 String toOriginalString(int start, int end)
           
 String toString()
           
 String toString(int start, int end)
           
 String toString(String programName)
           
 String toString(String programName, int start, int end)
           
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

MIN_TOKEN_INDEX

public static final int MIN_TOKEN_INDEX
See Also:
Constant Field Values

DEFAULT_PROGRAM_NAME

public static final String DEFAULT_PROGRAM_NAME
See Also:
Constant Field Values

PROGRAM_INIT_SIZE

public static final int PROGRAM_INIT_SIZE
See Also:
Constant Field Values

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 Detail

TokenStreamRewriteEngine

public TokenStreamRewriteEngine(TokenStream upstream)

TokenStreamRewriteEngine

public TokenStreamRewriteEngine(TokenStream upstream,
                                int initialSize)
Method Detail

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