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comparison graal/com.oracle.truffle.api/src/com/oracle/truffle/api/source/TextMap.java @ 13455:69d2e4baa215

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Truffle: new infrastructure related to instrumentation, and in particular debugging: support for managing Source objects; framework for generalized "instrumentation proxy nodes" (to be inserted into ASTs with no runtime cost when inactive), and "probes" (which can be attached to proxy nodes to receive event notification); a rudimentary interface and abstract implementation for a "debug manager" (mostly a placeholder at this point); and the beginning of a language-agnostic ExecutionContext interface.
author Michael Van De Vanter <michael.van.de.vanter@oracle.com>
date Tue, 17 Dec 2013 20:22:45 -0800
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13306:dfb780080923 13455:69d2e4baa215
1 /*
2 * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25 package com.oracle.truffle.api.source;
26
27 import java.util.*;
28
29 /**
30 * A utility for converting between coordinate systems in a string of text interspersed with newline
31 * characters. The coordinate systems are:
32 * <ul>
33 * <li>0-based character offset from the beginning of the text, where newline characters count as a
34 * single character and the first character in the text occupies position 0.</li>
35 * <li>1-based position in the 2D space of lines and columns, in which the first position in the
36 * text is at (1,1).</li>
37 * </ul>
38 * <p>
39 * This utility is based on positions occupied by characters, not text stream positions as in a text
40 * editor. The distinction shows up in editors where you can put the cursor just past the last
41 * character in a buffer; this is necessary, among other reasons, so that you can put the edit
42 * cursor in a new (empty) buffer. For the purposes of this utility, however, there are no character
43 * positions in an empty text string and there are no lines in an empty text string.
44 * <p>
45 * A newline character designates the end of a line and occupies a column position.
46 * <p>
47 * If the text ends with a character other than a newline, then the characters following the final
48 * newline character count as a line, even though not newline-terminated.
49 * <p>
50 * <strong>Limitations:</strong>
51 * <ul>
52 * <li>Does not handle multiple character encodings correctly.</li>
53 * <li>Treats tabs as occupying 1 column.</li>
54 * <li>Does not handle multiple-character line termination sequences correctly.</li>
55 * </ul>
56 */
57 public final class TextMap {
58
59 // 0-based offsets of newline characters in the text, with sentinel
60 private final int[] nlOffsets;
61
62 // The number of characters in the text, including newlines (which count as 1).
63 private final int textLength;
64
65 // Is the final text character a newline?
66 final boolean finalNL;
67
68 /**
69 * Constructs map permitting translation between 0-based character offsets and 1-based
70 * lines/columns.
71 */
72 public TextMap(String text) {
73 this.textLength = text.length();
74 final ArrayList<Integer> lines = new ArrayList<>();
75 lines.add(0);
76 int offset = 0;
77
78 while (offset < text.length()) {
79 final int nlIndex = text.indexOf('\n', offset);
80 if (nlIndex >= 0) {
81 offset = nlIndex + 1;
82 lines.add(offset);
83 } else {
84 break;
85 }
86 }
87 lines.add(Integer.MAX_VALUE);
88
89 nlOffsets = new int[lines.size()];
90 for (int line = 0; line < lines.size(); line++) {
91 nlOffsets[line] = lines.get(line);
92 }
93
94 finalNL = textLength > 0 && (textLength == nlOffsets[nlOffsets.length - 2]);
95 }
96
97 /**
98 * Converts 0-based character offset to 1-based number of the line containing the character.
99 *
100 * @throws IllegalArgumentException if the offset is outside the string.
101 */
102 public int offsetToLine(int offset) throws IllegalArgumentException {
103 if (offset < 0 || offset >= textLength) {
104 throw new IllegalArgumentException("offset out of bounds");
105 }
106 int line = 1;
107 while (offset >= nlOffsets[line]) {
108 line++;
109 }
110 return line;
111 }
112
113 /**
114 * Converts 0-based character offset to 1-based number of the column occupied by the character.
115 * <p>
116 * Tabs are not expanded; they occupy 1 column.
117 *
118 * @throws IllegalArgumentException if the offset is outside the string.
119 */
120 public int offsetToCol(int offset) throws IllegalArgumentException {
121 return 1 + offset - nlOffsets[offsetToLine(offset) - 1];
122 }
123
124 /**
125 * The number of lines in the text; if characters appear after the final newline, then they also
126 * count as a line, even though not newline-terminated.
127 */
128 public int lineCount() {
129 if (textLength == 0) {
130 return 0;
131 }
132 return finalNL ? nlOffsets.length - 2 : nlOffsets.length - 1;
133 }
134
135 /**
136 * Converts 1-based line number to the 0-based offset of the line's first character; this would
137 * be the offset of a newline if the line is empty.
138 *
139 * @throws IllegalArgumentException if there is no such line in the text.
140 */
141 public int lineStartOffset(int line) throws IllegalArgumentException {
142 if (textLength == 0 || lineOutOfRange(line)) {
143 throw new IllegalArgumentException("line out of bounds");
144 }
145 return nlOffsets[line - 1];
146 }
147
148 /**
149 * Gets the number of characters in a line, identified by 1-based line number; <em>does not</em>
150 * include the final newline, if any.
151 *
152 * @throws IllegalArgumentException if there is no such line in the text.
153 */
154 public int lineLength(int line) throws IllegalArgumentException {
155 if (textLength == 0 || lineOutOfRange(line)) {
156 throw new IllegalArgumentException("line out of bounds");
157 }
158 if (line == nlOffsets.length - 1 && !finalNL) {
159 return textLength - nlOffsets[line - 1];
160 }
161 return (nlOffsets[line] - nlOffsets[line - 1]) - 1;
162
163 }
164
165 /**
166 * Is the line number out of range.
167 */
168 private boolean lineOutOfRange(int line) {
169 return line <= 0 || line >= nlOffsets.length || (line == nlOffsets.length - 1 && finalNL);
170 }
171
172 }