001/*
002 * Copyright (C) 2009-2011 Mathias Doenitz
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.parboiled.buffers;
018
019import org.parboiled.common.IntArrayStack;
020import org.parboiled.errors.ParserRuntimeException;
021import org.parboiled.support.Chars;
022import org.parboiled.support.IndexRange;
023import org.parboiled.support.Position;
024import org.parboiled.common.IntArrayStack;
025import org.parboiled.common.Preconditions;
026import org.parboiled.errors.ParserRuntimeException;
027import org.parboiled.support.Chars;
028import org.parboiled.support.IndexRange;
029import org.parboiled.support.Position;
030
031import java.util.Arrays;
032
033import static org.parboiled.common.Preconditions.checkArgNotNull;
034import static org.parboiled.common.Preconditions.checkArgument;
035
036/**
037 * Immutable default implementation of an InputBuffer.
038 */
039public class DefaultInputBuffer implements InputBuffer {
040    private final int length;
041    private final char[] buffer;
042
043    // the indices of the newline characters in the buffer
044    // built lazily, since the newline information is normally only needed in the case of parse errors when
045    // error messages need to be generated
046    private int[] newlines;
047
048    /**
049     * Constructs a new DefaultInputBuffer wrapping the given char array.
050     * CAUTION: For performance reasons the given char array is not defensively copied.
051     *
052     * @param buffer the chars
053     */
054    public DefaultInputBuffer(char[] buffer) {
055        Preconditions.checkArgNotNull(buffer, "buffer");
056        this.buffer = buffer;
057        this.length = buffer.length;
058    }
059
060    public char charAt(int index) {
061        return 0 <= index && index < length ? buffer[index] :
062                index - length > 100000 ? throwParsingException() : Chars.EOI;
063    }
064
065    private char throwParsingException() {
066        throw new ParserRuntimeException("Parser read more than 100K chars beyond EOI, " +
067                "verify that your grammar does not consume EOI indefinitely!");
068    }
069
070    public boolean test(int index, char[] characters) {
071        int len = characters.length;
072        if (index < 0 || index > length - len) {
073            return false;
074        }
075        for (int i = 0; i < len; i++) {
076            if (buffer[index + i] != characters[i]) return false;
077        }
078        return true;
079    }
080
081    public String extract(int start, int end) {
082        if (start < 0) start = 0;
083        if (end >= length) end = length;
084        if (end <= start) return "";
085        return new String(buffer, start, end - start);
086    }
087
088    public String extract(IndexRange range) {
089        return new String(buffer, range.start, Math.min(range.end, length) - range.start);
090    }
091
092    public Position getPosition(int index) {
093        buildNewlines();
094        int line = getLine0(newlines, index);
095        int column = index - (line > 0 ? newlines[line - 1] : -1);
096        return new Position(line + 1, column);
097    }
098
099    public int getOriginalIndex(int index) {
100        return index;
101    }
102
103    // returns the zero based input line number the character with the given index is found in
104    private static int getLine0(int[] newlines, int index) {
105        int j = Arrays.binarySearch(newlines, index);
106        return j >= 0 ? j : -(j + 1);
107    }
108
109    public String extractLine(int lineNumber) {
110        buildNewlines();
111        Preconditions.checkArgument(0 < lineNumber && lineNumber <= newlines.length + 1);
112        int start = lineNumber > 1 ? newlines[lineNumber - 2] + 1 : 0;
113        int end = lineNumber <= newlines.length ? newlines[lineNumber - 1] : length;
114        if (charAt(end - 1) == '\r') end--;
115        return extract(start, end);
116    }
117
118    public int getLineCount() {
119        buildNewlines();
120        return newlines.length + 1;
121    }
122
123    private void buildNewlines() {
124        if (newlines == null) {
125            IntArrayStack newlines = new IntArrayStack();
126            for (int i = 0; i < length; i++) {
127                if (buffer[i] == '\n') {
128                    newlines.push(i);
129                }
130            }
131            this.newlines = new int[newlines.size()];
132            newlines.getElements(this.newlines, 0);
133        }
134    }
135}
136