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 /*
 * Copyright 2009 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;


/**
 * @author Andrew Eisenberg
 * @created Jun 4, 2009
 * 
 * Maps Line/Columns to offsets in a text file.  Assumes that '\n' is the newline delimiter.
 * The newline character is included as the last char on the current line.
 * Both columns and lines are 1 based
 *
 * 
 *  "" -> [0,0]
 * 
 "a" -> [0,1]
 * 
 "\n" -> [0,1], [1,0]
 * 
 "a\n" -> [0,2], [2,0]
 * 
 "a\nb" -> [0,2], [2,1]
 * 
 "a\nbc\n" -> [0,2], [2,3], [5,0]
 * 
 */
public class LocationSupport {
	
	private static final int[] NO_LINE_ENDINGS = new int[0];

	public static final LocationSupport NO_LOCATIONS = new LocationSupport();
	
    private final int[] lineEndings;
    
    // not used
    public LocationSupport(char[] contents) {
    	if (contents != null) {
    		lineEndings = processLineEndings(contents);
    	} else {
    		lineEndings = NO_LINE_ENDINGS;
    	}
    }
    
    public LocationSupport(List lines) {
    	if (lines != null) {
    		lineEndings = processLineEndings(lines);
    	} else {
    		lineEndings = NO_LINE_ENDINGS;
    	}
    }

    public LocationSupport(int[] lineEndings) {
    	this.lineEndings = lineEndings;
    }
    
    public LocationSupport() {
        lineEndings = NO_LINE_ENDINGS;
    }
    
    private int[] processLineEndings(List lines) {
        int[] newLineEndings = new int[lines.size()+1];  // last index stores end of file
        int total = 0;
        int current = 1;
        for (StringBuffer line : lines) {
        	newLineEndings[current++] = total += (line.length());
        }
        return newLineEndings;
    }
    
    
    private int[] processLineEndings(char[] contents) {
        List l = new ArrayList();
        for (int i = 0; i < contents.length; i++) {
        	
            if (contents[i] == '\n') {
                l.add(i);
            } else if (contents[i] == '\r') {
            	l.add(i);
            	if (i < contents.length && contents[i] == '\n') {
            		i++;
            	}
            }
        }
        
        int[] newLineEndings = new int[l.size()];
        int i = 0;
        for (Integer integer : l) {
        	newLineEndings[i] = integer.intValue();
        }
        return newLineEndings;
    }

    // TODO maybe should throw exception if out of bounds?
    public int findOffset(int row, int col) {
        return row <= lineEndings.length && row > 0 ? lineEndings[row-1] + col-1 : 0;
    }
    public int getEnd() {
        return lineEndings.length > 0 ? 
                lineEndings[lineEndings.length-1] :
                0;
    }
    public int getEndColumn() {
        if (lineEndings.length > 1) {
            return lineEndings[lineEndings.length-1] - lineEndings[lineEndings.length-2];
        } else if (lineEndings.length > 0) {
            return lineEndings[0];
        } else {
            return 0;
        }
    }
    public int getEndLine() {
        return lineEndings.length > 0 ?
                lineEndings.length-1 : 0;  // last index contains length of document
    }
    
    public int[] getRowCol(int offset) {
        for (int i = 1; i < lineEndings.length; i++) {
            if (lineEndings[i] > offset) {
                return new int[] { i, offset - lineEndings[i-1] +1};
            }
        }
        // after end of document
        throw new RuntimeException("Location is after end of document.  Offset : " + offset);
    }
    
    public boolean isPopulated() {
        return lineEndings.length > 0;
    }
}