LocationSupport.java

 /*
 * Copyright 2009-2017 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.List;

/**
 * Maps lines/columns to offsets in a text file.  Assumes '\n' is the newline
 * delimiter.  The newline character is included as the last char on the line.
 * Lines and columns are both 1 based
 *
 * <ul>
 * <li> "" -> [0,0]
 * <li> "a" -> [0,1]
 * <li> "\n" -> [0,1], [1,0]
 * <li> "a\n" -> [0,2], [2,0]
 * <li> "a\nb" -> [0,2], [2,1]
 * <li> "a\nbc\n" -> [0,2], [2,3], [5,0]
 * </ul>
 *
 * @author Andrew Eisenberg
 */
public class LocationSupport {

    public static final LocationSupport NO_LOCATIONS = new LocationSupport();

    private static final int[] NO_LINE_ENDINGS = new int[0];

    private final int[] lineEndings;

    public LocationSupport() {
        lineEndings = NO_LINE_ENDINGS;
    }

    public LocationSupport(int[] lineEndings) {
        this.lineEndings = lineEndings;
    }

    public LocationSupport(List<StringBuffer> lines) {
        if (lines != null) {
            lineEndings = processLineEndings(lines);
        } else {
            lineEndings = NO_LINE_ENDINGS;
        }
    }

    private int[] processLineEndings(List<? extends CharSequence> lines) {
        int[] newLineEndings = new int[lines.size() + 1]; // last index stores end of file
        int total = 0;
        int current = 1;
        for (CharSequence line : lines) {
            newLineEndings[current++] = (total += (line.length()));
        }
        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, n = lineEndings.length; i < n; i += 1) {
            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;
    }
}