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1 package org.jruby.util;
2
3 import java.util.regex.Matcher  ;
4 import java.util.regex.Pattern ;
5
6
10 public class StringScanner {
11
12 private CharSequence string;
13 private Matcher matcher;
14 private int pos = 0;
15 private int lastPos = -1;
16 private int matchStart = -1;
17 private int matchEnd = -1;
18
19
22 public StringScanner() {
23 this("");
24 }
25
26 public StringScanner(CharSequence string) {
27 this.string = string;
28 }
29
30 public boolean isEndOfString() {
31 return pos == string.length();
32 }
33
34 public boolean isBeginningOfLine() {
35 return pos == 0 || string.charAt(pos - 1) == '\n';
36 }
37
38 public CharSequence getString() {
39 return string;
40 }
41
42 private void resetMatchData() {
43 matcher = null;
44 matchStart = -1;
45 matchEnd = -1;
46 }
47
48 public void terminate() {
49 pos = string.length();
50 lastPos = -1;
51 resetMatchData();
52 }
53
54 public void reset() {
55 pos = 0;
56 lastPos = -1;
57 resetMatchData();
58 }
59
60 public void setString(CharSequence string) {
61 this.string = string;
62 reset();
63 }
64
65 public void append(CharSequence string) {
66 StringBuffer buf = new StringBuffer ();
67 buf.append(this.string);
69 buf.append(string);
70 this.string = buf.toString();
71 }
72
73 public CharSequence rest() {
74 return string.subSequence(pos, string.length());
75 }
76
77 public int getPos() {
78 return pos;
79 }
80
81 public void setPos(int pos) {
82 if (pos > string.length()) {
83 throw new IllegalArgumentException ("index out of range.");
84 }
85 this.pos = pos;
86 }
87
88 public char getChar() {
89 if (isEndOfString()) {
90 return 0;
91 } else {
92 matcher = null;
93 matchStart = pos;
94 matchEnd = pos + 1;
95 lastPos = pos;
96 return string.charAt(pos++);
97 }
98 }
99
100 public boolean matched() {
101 return matchStart > -1;
102 }
103
104 public CharSequence group(int n) {
105 if (!matched()) {
106 return null;
107 }
108 if (matcher == null && matchEnd - matchStart == 1) {
109 return string.subSequence(matchStart, matchEnd);
111 }
112 if (n > matcher.groupCount()) {
113 return null;
114 }
115 return matcher.group(n);
116 }
117
118 public CharSequence preMatch() {
119 if (matched()) {
120 return string.subSequence(0, matchStart);
121 } else {
122 return null;
123 }
124 }
125
126 public CharSequence postMatch() {
127 if (matched()) {
128 return string.subSequence(matchEnd, string.length());
129 } else {
130 return null;
131 }
132 }
133
134 public CharSequence matchedValue() {
135 if (matched()) {
136 return string.subSequence(matchStart, matchEnd);
137 } else {
138 return null;
139 }
140 }
141
142 public int matchedSize() {
143 if (matcher == null) {
144 return -1;
145 } else {
146 return matchEnd - matchStart;
147 }
148 }
149
150 public void unscan() {
151 if (lastPos != -1) {
152 pos = lastPos;
153 resetMatchData();
154 } else {
155 throw new IllegalStateException ("unscan() cannot be called after an unmached scan.");
156 }
157 }
158
159 public int matches(Pattern pattern) {
160 if (!isEndOfString()) {
161 matcher = pattern.matcher(string.subSequence(pos, string.length()));
162 if (matcher.lookingAt()) {
163 matchStart = pos;
164 matchEnd = matcher.end();
165 return matchEnd;
166 } else {
167 resetMatchData();
168 }
169 }
170
171 return -1;
172 }
173
174 public CharSequence scanUntil(Pattern pattern) {
175 if (!isEndOfString()) {
176 matcher = pattern.matcher(string);
177 if (matcher.find(pos)) {
178 lastPos = pos;
179 matchStart = matcher.start();
180 matchEnd = matcher.end();
181 pos = matchEnd;
182 return string.subSequence(lastPos, pos);
183 } else {
184 lastPos = -1;
185 resetMatchData();
186 }
187 }
188
189 return null;
190 }
191
192 public CharSequence scan(Pattern pattern) {
193 if (!isEndOfString()) {
194 matcher = pattern.matcher(string.subSequence(pos, string.length()));
195 if (matcher.lookingAt()) {
196 lastPos = pos;
197 matchStart = pos;
198 pos += matcher.end();
199 matchEnd = pos;
200 return matcher.group();
201 } else {
202 lastPos = -1;
203 resetMatchData();
204 }
205 }
206
207 return null;
208 }
209
210 public CharSequence check(Pattern pattern) {
211 if (!isEndOfString()) {
212 matcher = pattern.matcher(string.subSequence(pos, string.length()));
213 if (matcher.lookingAt()) {
214 matchStart = pos;
215 matchEnd = matchStart + matcher.end();
216 return matcher.group();
217 } else {
218 resetMatchData();
219 }
220 }
221
222 return null;
223 }
224
225 public CharSequence checkUntil(Pattern pattern) {
226 if (!isEndOfString()) {
227 matcher = pattern.matcher(string);
228 if (matcher.find(pos)) {
229 matchStart = matcher.start();
230 matchEnd = matcher.end();
231 return string.subSequence(pos, matcher.end());
232 } else {
233 resetMatchData();
234 }
235 }
236
237 return null;
238 }
239
240 public int skip(Pattern pattern) {
241 if (!isEndOfString()) {
242 matcher = pattern.matcher(string.subSequence(pos, string.length()));
243 if (matcher.lookingAt()) {
244 lastPos = pos;
245 matchStart = pos;
246 int end = matcher.end();
247 pos += end;
248 matchEnd = pos;
249 return end;
250 } else {
251 resetMatchData();
252 }
253 }
254
255 return -1;
256 }
257
258 public int skipUntil(Pattern pattern) {
259 if (!isEndOfString()) {
260 matcher = pattern.matcher(string);
261 if (matcher.find(pos)) {
262 lastPos = pos;
263 pos = matcher.end();
264 matchStart = matcher.start();
265 matchEnd = pos;
266 return pos - lastPos;
267 } else {
268 resetMatchData();
269 }
270 }
271
272 return -1;
273 }
274
275 public int exists(Pattern pattern) {
276 if (!isEndOfString()) {
277 matcher = pattern.matcher(string);
278 if (matcher.find(pos)) {
279 matchStart = matcher.start();
280 matchEnd = matcher.end();
281 return matchEnd - pos;
282 } else {
283 resetMatchData();
284 }
285 }
286
287 return -1;
288 }
289
290 public CharSequence peek(int length) {
291 int end = pos + length;
292 if (end > string.length()) {
293 end = string.length();
294 }
295 return string.subSequence(pos, end);
296 }
297 } |
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