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

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/*
 [The "BSD licence"]
 Copyright (c) 2005-2008 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
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.antlr.runtime;

import java.util.*;

public class CommonTokenStream implements TokenStream {
    protected TokenSource tokenSource;

        protected List tokens;

        protected Map channelOverrideMap;

        protected Set discardSet;

        protected int channel = Token.DEFAULT_CHANNEL;

        protected boolean discardOffChannelTokens = false;

        protected int lastMarker;

    protected int p = -1;

        public CommonTokenStream() {
                tokens = new ArrayList(500);
        }

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

        public CommonTokenStream(TokenSource tokenSource, int channel) {
                this(tokenSource);
                this.channel = channel;
        }

        public void setTokenSource(TokenSource tokenSource) {
                this.tokenSource = tokenSource;
                tokens.clear();
                p = -1;
                channel = Token.DEFAULT_CHANNEL;
        }

        protected void fillBuffer() {
                int index = 0;
                Token t = tokenSource.nextToken();
                while ( t!=null && t.getType()!=CharStream.EOF ) {
                        boolean discard = false;
                        // is there a channel override for token type?
                        if ( channelOverrideMap!=null ) {
                                Integer channelI = (Integer)
                                        channelOverrideMap.get(new Integer(t.getType()));
                                if ( channelI!=null ) {
                                        t.setChannel(channelI.intValue());
                                }
                        }
                        if ( discardSet!=null &&
                                 discardSet.contains(new Integer(t.getType())) )
                        {
                                discard = true;
                        }
                        else if ( discardOffChannelTokens && t.getChannel()!=this.channel ) {
                                discard = true;
                        }
                        if ( !discard ) {
                                t.setTokenIndex(index);
                                tokens.add(t);
                                index++;
                        }
                        t = tokenSource.nextToken();
                }
                // leave p pointing at first token on channel
                p = 0;
                p = skipOffTokenChannels(p);
    }

        public void consume() {
                if ( p<tokens.size() ) {
            p++;
                        p = skipOffTokenChannels(p); // leave p on valid token
        }
    }

        protected int skipOffTokenChannels(int i) {
                int n = tokens.size();
                while ( i<n && ((Token)tokens.get(i)).getChannel()!=channel ) {
                        i++;
                }
                return i;
        }

        protected int skipOffTokenChannelsReverse(int i) {
                while ( i>=0 && ((Token)tokens.get(i)).getChannel()!=channel ) {
                        i--;
                }
                return i;
        }

        public void setTokenTypeChannel(int ttype, int channel) {
                if ( channelOverrideMap==null ) {
                        channelOverrideMap = new HashMap();
                }
        channelOverrideMap.put(new Integer(ttype), new Integer(channel));
        }

        public void discardTokenType(int ttype) {
                if ( discardSet==null ) {
                        discardSet = new HashSet();
                }
        discardSet.add(new Integer(ttype));
        }

        public void discardOffChannelTokens(boolean discardOffChannelTokens) {
                this.discardOffChannelTokens = discardOffChannelTokens;
        }

        public List getTokens() {
                if ( p == -1 ) {
                        fillBuffer();
                }
                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 ) {
                        fillBuffer();
                }
                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 filteredTokens = new ArrayList();
                for (int i=start; i<=stop; i++) {
                        Token t = (Token)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 Token LT(int k) {
                if ( p == -1 ) {
                        fillBuffer();
                }
                if ( k==0 ) {
                        return null;
                }
                if ( k<0 ) {
                        return LB(-k);
                }
                //System.out.print("LT(p="+p+","+k+")=");
                if ( (p+k-1) >= tokens.size() ) {
                        return Token.EOF_TOKEN;
                }
                //System.out.println(tokens.get(p+k-1));
                int i = p;
                int n = 1;
                // find k good tokens
                while ( n<k ) {
                        // skip off-channel tokens
                        i = skipOffTokenChannels(i+1); // leave p on valid token
                        n++;
                }
                if ( i>=tokens.size() ) {
                        return Token.EOF_TOKEN;
                }
        return (Token)tokens.get(i);
    }

        protected Token LB(int k) {
                //System.out.print("LB(p="+p+","+k+") ");
                if ( p == -1 ) {
                        fillBuffer();
                }
                if ( k==0 ) {
                        return null;
                }
                if ( (p-k)<0 ) {
                        return null;
                }

                int i = p;
                int n = 1;
                // find k good tokens looking backwards
                while ( n<=k ) {
                        // skip off-channel tokens
                        i = skipOffTokenChannelsReverse(i-1); // leave p on valid token
                        n++;
                }
                if ( i<0 ) {
                        return null;
                }
                return (Token)tokens.get(i);
        }

        public Token get(int i) {
                return (Token)tokens.get(i);
        }

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

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

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

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

    public int index() {
        return p;
    }

        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 TokenSource getTokenSource() {
                return tokenSource;
        }

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

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

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

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