/Users/parrt/antlr/code/antlr/main/runtime/Java/src/main/java/org/antlr/runtime/BufferedTokenStream.java

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/*
 [The "BSD license"]
 Copyright (c) 2005-2009 Terence Parr
 All rights reserved.

 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions
 are met:
 1. Redistributions of source code must retain the above copyright
     notice, this list of conditions and the following disclaimer.
 2. Redistributions in binary form must reproduce the above copyright
     notice, this list of conditions and the following disclaimer in the
     documentation and/or other materials provided with the distribution.
 3. The name of the author may not be used to endorse or promote products
     derived from this software without specific prior written permission.

 THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.antlr.runtime;

import java.util.List;
import java.util.ArrayList;
import java.util.NoSuchElementException;

public class BufferedTokenStream implements TokenStream {
    protected TokenSource tokenSource;

    protected List<Token> tokens = new ArrayList<Token>(100);

    protected int lastMarker;

    protected int p = -1;

        protected int range = -1; // how deep have we gone?

    public BufferedTokenStream() {;}

    public BufferedTokenStream(TokenSource tokenSource) {
        this.tokenSource = tokenSource;
    }

    public TokenSource getTokenSource() { return tokenSource; }

        public int index() { return p; }

        public int range() { return range; }

    public int mark() {
        if ( p == -1 ) setup();
                lastMarker = index();
                return lastMarker;
        }

        public void release(int marker) {
                // no resources to release
        }

    public void rewind(int marker) {
        seek(marker);
    }

    public void rewind() {
        seek(lastMarker);
    }

    public void reset() {
        p = 0;
        lastMarker = 0;
    }

    public void seek(int index) { p = index; }

    public int size() { return tokens.size(); }

    public void consume() {
        if ( p == -1 ) setup();
        p++;
        sync(p);
    }

    protected void sync(int i) {
        int n = i - tokens.size() + 1; // how many more elements we need?
        //System.out.println("sync("+i+") needs "+n);
        if ( n > 0 ) fetch(n);
    }

    protected void fetch(int n) {
        for (int i=1; i<=n; i++) {
            Token t = tokenSource.nextToken();
            t.setTokenIndex(tokens.size());
            //System.out.println("adding "+t+" at index "+tokens.size());
            tokens.add(t);
            if ( t.getType()==Token.EOF ) break;
        }
    }

    public Token get(int i) {
        if ( i < 0 || i >= tokens.size() ) {
            throw new NoSuchElementException("token index "+i+" out of range 0.."+(tokens.size()-1));
        }
        return tokens.get(i);
    }

        public List get(int start, int stop) {
                if ( start<0 || stop<0 ) return null;
                if ( p == -1 ) setup();
                List subset = new ArrayList();
                if ( stop>=tokens.size() ) stop = tokens.size()-1;
                for (int i = start; i <= stop; i++) {
                        Token t = tokens.get(i);
                        if ( t.getType()==Token.EOF ) break;
                        subset.add(t);
                }
                return subset;
        }

        public int LA(int i) { return LT(i).getType(); }

    protected Token LB(int k) {
        if ( (p-k)<0 ) return null;
        return tokens.get(p-k);
    }

    public Token LT(int k) {
        if ( p == -1 ) setup();
        if ( k==0 ) return null;
        if ( k < 0 ) return LB(-k);

                int i = p + k - 1;
                sync(i);
        if ( i >= tokens.size() ) { // return EOF token
            // EOF must be last token
            return tokens.get(tokens.size()-1);
        }
                if ( i>range ) range = i;               
        return tokens.get(i);
    }

    protected void setup() { sync(0); p = 0; }

    public void setTokenSource(TokenSource tokenSource) {
        this.tokenSource = tokenSource;
        tokens.clear();
        p = -1;
    }
    
    public List getTokens() { return tokens; }

    public List getTokens(int start, int stop) {
        return getTokens(start, stop, (BitSet)null);
    }

    public List getTokens(int start, int stop, BitSet types) {
        if ( p == -1 ) setup();
        if ( stop>=tokens.size() ) stop=tokens.size()-1;
        if ( start<0 ) start=0;
        if ( start>stop ) return null;

        // list = tokens[start:stop]:{Token t, t.getType() in types}
        List<Token> filteredTokens = new ArrayList<Token>();
        for (int i=start; i<=stop; i++) {
            Token t = tokens.get(i);
            if ( types==null || types.member(t.getType()) ) {
                filteredTokens.add(t);
            }
        }
        if ( filteredTokens.size()==0 ) {
            filteredTokens = null;
        }
        return filteredTokens;
    }

    public List getTokens(int start, int stop, List types) {
        return getTokens(start,stop,new BitSet(types));
    }

    public List getTokens(int start, int stop, int ttype) {
        return getTokens(start,stop,BitSet.of(ttype));
    }

    public String getSourceName() {     return tokenSource.getSourceName();     }

    public String toString() {
        if ( p == -1 ) setup();
        fill();
        return toString(0, tokens.size()-1);
    }

    public String toString(int start, int stop) {
        if ( start<0 || stop<0 ) return null;
        if ( p == -1 ) setup();
        if ( stop>=tokens.size() ) stop = tokens.size()-1;
        StringBuffer buf = new StringBuffer();
        for (int i = start; i <= stop; i++) {
            Token t = tokens.get(i);
            if ( t.getType()==Token.EOF ) break;
            buf.append(t.getText());
        }
        return buf.toString();
    }

    public String toString(Token start, Token stop) {
        if ( start!=null && stop!=null ) {
            return toString(start.getTokenIndex(), stop.getTokenIndex());
        }
        return null;
    }

    public void fill() {
        if ( p == -1 ) setup();
        if ( tokens.get(p).getType()==Token.EOF ) return;

        int i = p+1;
        sync(i);
        while ( tokens.get(i).getType()!=Token.EOF ) {
            i++;
            sync(i);
        }
    }
}

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