org.eclim.util.file.FileOffsets.java Source code

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Here is the source code for org.eclim.util.file.FileOffsets.java

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/**
 * Copyright (C) 2005 - 2009  Eric Van Dewoestine
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.eclim.util.file;

import java.io.InputStream;
import java.io.InputStreamReader;

import java.util.ArrayList;

import org.apache.commons.vfs.FileObject;
import org.apache.commons.vfs.FileSystemManager;
import org.apache.commons.vfs.VFS;

import org.eclim.Services;

import org.eclim.util.IOUtils;

/**
 * Compiles a list of char offsets to line numbers and stores them for quick
 * translation of offset to line number and column.
 *
 * @author Eric Van Dewoestine
 */
public class FileOffsets {
    private Integer[] offsets;
    private String[] multiByteLines;

    private FileOffsets() {
    }

    /**
     * Reads the supplied file and compiles a list of offsets.
     *
     * @param filename The file to compile a list of offsets for.
     * @return The FileOffsets instance.
     */
    public static FileOffsets compile(String filename) {
        try {
            FileSystemManager fsManager = VFS.getManager();
            FileObject file = fsManager.resolveFile(filename);

            // disable caching (the cache seems to become invalid at some point
            // causing vfs errors).
            //fsManager.getFilesCache().clear(file.getFileSystem());

            if (!file.exists()) {
                throw new IllegalArgumentException(Services.getMessage("file.not.found", filename));
            }
            return compile(file.getContent().getInputStream());
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * Reads the supplied input stream and compiles a list of offsets.
     *
     * @param in The InputStream to compile a list of offsets for.
     * @return The FileOffsets instance.
     */
    public static FileOffsets compile(InputStream in) {
        FileOffsets offsets = new FileOffsets();
        offsets.compileOffsets(in);
        return offsets;
    }

    /**
     * Reads the supplied input stream and compiles a list of offsets.
     *
     * @param in The InputStream to compile a list of offsets for.
     */
    private void compileOffsets(InputStream in) {
        BufferedReader reader = null;
        try {
            reader = new BufferedReader(new InputStreamReader(in));

            ArrayList<Integer> lines = new ArrayList<Integer>();
            lines.add(new Integer(0));
            ArrayList<String> byteLines = new ArrayList<String>();
            byteLines.add(null);

            int offset = 0;
            String line = null;
            while ((line = reader.readLine()) != null) {
                offset += line.length();
                lines.add(new Integer(offset));
                if (line.length() != line.getBytes().length) {
                    byteLines.add(line);
                } else {
                    byteLines.add(null);
                }
            }

            offsets = (Integer[]) lines.toArray(new Integer[lines.size()]);
            multiByteLines = (String[]) byteLines.toArray(new String[byteLines.size()]);
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            IOUtils.closeQuietly(reader);
        }
    }

    /**
     * Converts the supplied offset into an int array where the first element is
     * the line number and the second is the column number.
     *
     * @param offset The offset.
     * @return The line and column int array.
     */
    public int[] offsetToLineColumn(int offset) {
        if (offset <= 0) {
            return new int[] { 1, 1 };
        }

        int bot = -1;
        int top = offsets.length - 1;
        while (top - bot > 1) {
            int mid = (top + bot) / 2;
            if (offsets[mid].intValue() < offset) {
                bot = mid;
            } else {
                top = mid;
            }
        }
        if (offsets[top].intValue() > offset) {
            top--;
        }
        int line = top + 1;
        int column = 1 + offset - offsets[top].intValue();
        String value = multiByteLines.length > line ? multiByteLines[line] : null;
        if (value != null) {
            column = value.substring(0, column).getBytes().length;
        }
        return new int[] { line, column };
    }

    /**
     * Gets the offset where the supplied line starts.
     *
     * @param line The line.
     * @return The starting offset.
     */
    public int getLineStart(int line) {
        return offsets[line - 1].intValue();
    }

    /**
     * Gets the offset where the supplied line ends.
     *
     * @param line The line.
     * @return The ending offset.
     */
    public int getLineEnd(int line) {
        if (offsets.length == line) {
            return offsets[offsets.length - 1].intValue();
        }
        return offsets[line].intValue() - 1;
    }
}