SourceBuffer.java

/*
 * Copyright 2003-2011 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.codehaus.groovy.antlr;

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

/**
 * A simple buffer that provides line/col access to chunks of source code
 * held within itself.
 *
 * @author <a href="mailto:groovy@ross-rayner.com">Jeremy Rayner</a>
 * @author Andrew Eisenberg
 * @author Andy Clement
 * @version $Revision: 7922 $
 */
public class SourceBuffer {
    private final List<StringBuilder> lines;
    private StringBuilder current;
    // GRECLIPSE: start
    private final List<Integer> lineEndings;

    // GRECLIPSE-805 Support for unicode escape sequences
    private UnicodeEscapingReader unescaper;
    // end

    public SourceBuffer() {
        lines = new ArrayList<StringBuilder>();
        //lines.add(new StringBuffer()); // dummy row for position [0] in the List
        // GRECLIPSE: start
        lineEndings = new ArrayList<Integer>();
        lineEndings.add(0);
        unescaper = new NoEscaper();
        // end
        current = new StringBuilder();
        lines.add(current);
    }

    /**
     * Obtains a snippet of the source code within the bounds specified
     * @param start (inclusive line/ inclusive column)
     * @param end (inclusive line / exclusive column)
     * @return specified snippet of source code as a String, or null if no source available
     */
    public String getSnippet(LineColumn start, LineColumn end) {
        // preconditions
        if (start == null || end == null) { return null; } // no text to return
        if (start.equals(end)) { return null; } // no text to return
        if (lines.size() == 1 && current.length() == 0) { return null; } // buffer hasn't been filled yet

        // working variables
        int startLine = start.getLine();
        int startColumn = start.getColumn();
        int endLine = end.getLine();
        int endColumn = end.getColumn();

        // reset any out of bounds requests
        if (startLine < 1) { startLine = 1;}
        if (endLine < 1) { endLine = 1;}
        if (startColumn < 1) { startColumn = 1;}
        if (endColumn < 1) { endColumn = 1;}
        if (startLine > lines.size()) { startLine = lines.size(); }
        if (endLine > lines.size()) { endLine = lines.size(); }

        // obtain the snippet from the buffer within specified bounds
        StringBuffer snippet = new StringBuffer();
        for (int i = startLine - 1; i < endLine;i++) {
            String line = (lines.get(i)).toString();
            if (startLine == endLine) {
                // reset any out of bounds requests (again)
                if (startColumn > line.length()) { startColumn = line.length();}
                if (startColumn < 1) { startColumn = 1;}
                if (endColumn > line.length()) { endColumn = line.length() + 1;}
                if (endColumn < 1) { endColumn = 1;}

                line = line.substring(startColumn - 1, endColumn - 1);
            } else {
                if (i == startLine - 1) {
                    if (startColumn - 1 < line.length()) {
                        line = line.substring(startColumn - 1);
                    }
                }
                if (i == endLine - 1) {
                    if (endColumn - 1 < line.length()) {
                        line = line.substring(0,endColumn - 1);
                    }
                }
            }
            snippet.append(line);
        }
        return snippet.toString();
    }

    /**
     * Writes the specified character into the buffer
     * @param c
     */
    // GRECLIPSE: start
    /*{
    public void write(int c) {
        if (c != -1) {
            current.append((char)c);
        }
        if (c == '\n') {
            current = new StringBuffer();
            lines.add(current);
        }
    } 
    }*/
    // newcode:
    public void setUnescaper(UnicodeEscapingReader unicodeEscapingReader) {
        this.unescaper = unicodeEscapingReader;
    }
    
    private boolean prevWasCarriageReturn = false;
    private int col = 0;
    // FIXASC tidy this up, looks slow
    public void write(int c) {
        if (c != -1) {
        	col++;
            current.append((char)c);
        }
        if (c == '\n') {
        	if (!prevWasCarriageReturn) {
	            current = new StringBuilder();
	            lines.add(current);
	            lineEndings.add(col + unescaper.getUnescapedUnicodeOffsetCount());
        	} else {
        		// \r\n was found
        		// back out previous line and add a \n to the line
        		current = new StringBuilder();
        		lines.get(lines.size()-1).append('\n');
        		lineEndings.remove(lineEndings.size()-1);
        		lineEndings.add(col + unescaper.getUnescapedUnicodeOffsetCount());
        	}
        }
        // handle carriage returns as well as newlines
        if (c == '\r') {
        	current = new StringBuilder();
        	lines.add(current);
        	lineEndings.add(col + unescaper.getUnescapedUnicodeOffsetCount());
        	// this may be a \r\n, but may not be
        	prevWasCarriageReturn = true;
        } else {
        	prevWasCarriageReturn = false;
        }
    }
    
    public LocationSupport getLocationSupport() {
    	lineEndings.add(col + unescaper.getUnescapedUnicodeOffsetCount()); // last line ends where the data runs out
    	int[] lineEndingsArray = new int[lineEndings.size()];
    	for (int i=0,max=lineEndings.size();i<max;i++) {
    		lineEndingsArray[i] = lineEndings.get(i).intValue();
    	}
    	return new LocationSupport(lineEndingsArray);
    }
    // end
}