1 /*
2 * Copyright (c) 2015, 2017, 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
26 package java.lang;
27
28 /**
29 * Helper for string concatenation. These methods are mostly looked up with private lookups
30 * from {@link java.lang.invoke.StringConcatFactory}, and used in {@link java.lang.invoke.MethodHandle}
31 * combinators there.
32 */
33 final class StringConcatHelper {
34
35 private StringConcatHelper() {
36 // no instantiation
37 }
38
39 /**
40 * Check for overflow, throw the exception on overflow.
41 * @param len String length
42 * @return length
43 */
44 private static int checkOverflow(int len) {
45 if (len < 0) {
46 throw new OutOfMemoryError("Overflow: String length out of range");
47 }
48 return len;
49 }
50
51 /**
52 * Mix value length into current length
53 * @param current current length
54 * @param value value to mix in
55 * @return new length
56 */
57 static int mixLen(int current, boolean value) {
58 return checkOverflow(current + (value ? 4 : 5));
59 }
60
61 /**
62 * Mix value length into current length
63 * @param current current length
64 * @param value value to mix in
65 * @return new length
66 */
67 static int mixLen(int current, byte value) {
68 return mixLen(current, (int)value);
69 }
70
71 /**
72 * Mix value length into current length
73 * @param current current length
74 * @param value value to mix in
75 * @return new length
76 */
77 static int mixLen(int current, char value) {
78 return checkOverflow(current + 1);
79 }
80
81 /**
82 * Mix value length into current length
83 * @param current current length
84 * @param value value to mix in
85 * @return new length
86 */
87 static int mixLen(int current, short value) {
88 return mixLen(current, (int)value);
89 }
90
91 /**
92 * Mix value length into current length
93 * @param current current length
94 * @param value value to mix in
95 * @return new length
96 */
97 static int mixLen(int current, int value) {
98 return checkOverflow(current + Integer.stringSize(value));
99 }
100
101 /**
102 * Mix value length into current length
103 * @param current current length
104 * @param value value to mix in
105 * @return new length
106 */
107 static int mixLen(int current, long value) {
108 return checkOverflow(current + Long.stringSize(value));
109 }
110
111 /**
112 * Mix value length into current length
113 * @param current current length
114 * @param value value to mix in
115 * @return new length
116 */
117 static int mixLen(int current, String value) {
118 return checkOverflow(current + value.length());
119 }
120
121 /**
122 * Mix coder into current coder
123 * @param current current coder
124 * @param value value to mix in
125 * @return new coder
126 */
127 static byte mixCoder(byte current, char value) {
128 return (byte)(current | (StringLatin1.canEncode(value) ? 0 : 1));
129 }
130
131 /**
132 * Mix coder into current coder
133 * @param current current coder
134 * @param value value to mix in
135 * @return new coder
136 */
137 static byte mixCoder(byte current, String value) {
138 return (byte)(current | value.coder());
139 }
140
141 /**
142 * Mix coder into current coder
143 * @param current current coder
144 * @param value value to mix in
145 * @return new coder
146 */
147 static byte mixCoder(byte current, boolean value) {
148 // Booleans are represented with Latin1
149 return current;
150 }
151
152 /**
153 * Mix coder into current coder
154 * @param current current coder
155 * @param value value to mix in
156 * @return new coder
157 */
158 static byte mixCoder(byte current, byte value) {
159 // Bytes are represented with Latin1
160 return current;
161 }
162
163 /**
164 * Mix coder into current coder
165 * @param current current coder
166 * @param value value to mix in
167 * @return new coder
168 */
169 static byte mixCoder(byte current, short value) {
170 // Shorts are represented with Latin1
171 return current;
172 }
173
174 /**
175 * Mix coder into current coder
176 * @param current current coder
177 * @param value value to mix in
178 * @return new coder
179 */
180 static byte mixCoder(byte current, int value) {
181 // Ints are represented with Latin1
182 return current;
183 }
184
185 /**
186 * Mix coder into current coder
187 * @param current current coder
188 * @param value value to mix in
189 * @return new coder
190 */
191 static byte mixCoder(byte current, long value) {
192 // Longs are represented with Latin1
193 return current;
194 }
195
196 /**
197 * Prepends the stringly representation of boolean value into buffer,
198 * given the coder and final index. Index is measured in chars, not in bytes!
199 *
200 * @param index final char index in the buffer
201 * @param buf buffer to append to
202 * @param coder coder to add with
203 * @param value boolean value to encode
204 * @return new index
205 */
206 static int prepend(int index, byte[] buf, byte coder, boolean value) {
207 if (coder == String.LATIN1) {
208 if (value) {
209 buf[--index] = 'e';
210 buf[--index] = 'u';
211 buf[--index] = 'r';
212 buf[--index] = 't';
213 } else {
214 buf[--index] = 'e';
215 buf[--index] = 's';
216 buf[--index] = 'l';
217 buf[--index] = 'a';
218 buf[--index] = 'f';
219 }
220 } else {
221 if (value) {
222 StringUTF16.putChar(buf, --index, 'e');
223 StringUTF16.putChar(buf, --index, 'u');
224 StringUTF16.putChar(buf, --index, 'r');
225 StringUTF16.putChar(buf, --index, 't');
226 } else {
227 StringUTF16.putChar(buf, --index, 'e');
228 StringUTF16.putChar(buf, --index, 's');
229 StringUTF16.putChar(buf, --index, 'l');
230 StringUTF16.putChar(buf, --index, 'a');
231 StringUTF16.putChar(buf, --index, 'f');
232 }
233 }
234 return index;
235 }
236
237 /**
238 * Prepends the stringly representation of byte value into buffer,
239 * given the coder and final index. Index is measured in chars, not in bytes!
240 *
241 * @param index final char index in the buffer
242 * @param buf buffer to append to
243 * @param coder coder to add with
244 * @param value byte value to encode
245 * @return new index
246 */
247 static int prepend(int index, byte[] buf, byte coder, byte value) {
248 return prepend(index, buf, coder, (int)value);
249 }
250
251 /**
252 * Prepends the stringly representation of char value into buffer,
253 * given the coder and final index. Index is measured in chars, not in bytes!
254 *
255 * @param index final char index in the buffer
256 * @param buf buffer to append to
257 * @param coder coder to add with
258 * @param value char value to encode
259 * @return new index
260 */
261 static int prepend(int index, byte[] buf, byte coder, char value) {
262 if (coder == String.LATIN1) {
263 buf[--index] = (byte) (value & 0xFF);
264 } else {
265 StringUTF16.putChar(buf, --index, value);
266 }
267 return index;
268 }
269
270 /**
271 * Prepends the stringly representation of short value into buffer,
272 * given the coder and final index. Index is measured in chars, not in bytes!
273 *
274 * @param index final char index in the buffer
275 * @param buf buffer to append to
276 * @param coder coder to add with
277 * @param value short value to encode
278 * @return new index
279 */
280 static int prepend(int index, byte[] buf, byte coder, short value) {
281 return prepend(index, buf, coder, (int)value);
282 }
283
284 /**
285 * Prepends the stringly representation of integer value into buffer,
286 * given the coder and final index. Index is measured in chars, not in bytes!
287 *
288 * @param index final char index in the buffer
289 * @param buf buffer to append to
290 * @param coder coder to add with
291 * @param value integer value to encode
292 * @return new index
293 */
294 static int prepend(int index, byte[] buf, byte coder, int value) {
295 if (coder == String.LATIN1) {
296 return Integer.getChars(value, index, buf);
297 } else {
298 return StringUTF16.getChars(value, index, buf);
299 }
300 }
301
302 /**
303 * Prepends the stringly representation of long value into buffer,
304 * given the coder and final index. Index is measured in chars, not in bytes!
305 *
306 * @param index final char index in the buffer
307 * @param buf buffer to append to
308 * @param coder coder to add with
309 * @param value long value to encode
310 * @return new index
311 */
312 static int prepend(int index, byte[] buf, byte coder, long value) {
313 if (coder == String.LATIN1) {
314 return Long.getChars(value, index, buf);
315 } else {
316 return StringUTF16.getChars(value, index, buf);
317 }
318 }
319
320 /**
321 * Prepends the stringly representation of String value into buffer,
322 * given the coder and final index. Index is measured in chars, not in bytes!
323 *
324 * @param index final char index in the buffer
325 * @param buf buffer to append to
326 * @param coder coder to add with
327 * @param value String value to encode
328 * @return new index
329 */
330 static int prepend(int index, byte[] buf, byte coder, String value) {
331 index -= value.length();
332 value.getBytes(buf, index, coder);
333 return index;
334 }
335
336 /**
337 * Instantiates the String with given buffer and coder
338 * @param buf buffer to use
339 * @param index remaining index
340 * @param coder coder to use
341 * @return String resulting string
342 */
343 static String newString(byte[] buf, int index, byte coder) {
344 // Use the private, non-copying constructor (unsafe!)
345 if (index != 0) {
346 throw new InternalError("Storage is not completely initialized, " + index + " bytes left");
347 }
348 return new String(buf, coder);
349 }
350
351 /**
352 * Provides the initial coder for the String.
353 * @return initial coder
354 */
355 static byte initialCoder() {
356 return String.COMPACT_STRINGS ? String.LATIN1 : String.UTF16;
357 }
358
359 }