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.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23
24 package java.lang;
25
26 /**
27 * Helper for string concatenation. These methods are mostly looked up with private lookups
28 * from {@link java.lang.invoke.StringConcatFactory}, and used in {@link java.lang.invoke.MethodHandle}
29 * combinators there.
30 */
31 final class StringConcatHelper {
32
33 private StringConcatHelper() {
34 // no instantiation
35 }
36
37 /**
38 * Check for overflow, throw the exception on overflow.
39 * @param len String length
40 * @return length
41 */
42 private static int checkOverflow(int len) {
43 if (len < 0) {
44 throw new OutOfMemoryError("Overflow: String length out of range");
45 }
46 return len;
47 }
48
49 /**
50 * Mix value length into current length
51 * @param current current length
52 * @param value value to mix in
53 * @return new length
54 */
55 static int mixLen(int current, boolean value) {
56 return checkOverflow(current + (value ? 4 : 5));
57 }
58
59 /**
60 * Mix value length into current length
61 * @param current current length
62 * @param value value to mix in
63 * @return new length
64 */
65 static int mixLen(int current, byte value) {
66 return mixLen(current, (int)value);
67 }
68
69 /**
70 * Mix value length into current length
71 * @param current current length
72 * @param value value to mix in
73 * @return new length
74 */
75 static int mixLen(int current, char value) {
76 return checkOverflow(current + 1);
77 }
78
79 /**
80 * Mix value length into current length
81 * @param current current length
82 * @param value value to mix in
83 * @return new length
84 */
85 static int mixLen(int current, short value) {
86 return mixLen(current, (int)value);
87 }
88
89 /**
90 * Mix value length into current length
91 * @param current current length
92 * @param value value to mix in
93 * @return new length
94 */
95 static int mixLen(int current, int value) {
96 return checkOverflow(current + Integer.stringSize(value));
97 }
98
99 /**
100 * Mix value length into current length
101 * @param current current length
102 * @param value value to mix in
103 * @return new length
104 */
105 static int mixLen(int current, long value) {
106 return checkOverflow(current + Long.stringSize(value));
107 }
108
109 /**
110 * Mix value length into current length
111 * @param current current length
112 * @param value value to mix in
113 * @return new length
114 */
115 static int mixLen(int current, String value) {
116 return checkOverflow(current + value.length());
117 }
118
119 /**
120 * Mix coder into current coder
121 * @param current current coder
122 * @param value value to mix in
123 * @return new coder
124 */
125 static byte mixCoder(byte current, char value) {
126 return (byte)(current | (StringLatin1.canEncode(value) ? 0 : 1));
127 }
128
129 /**
130 * Mix coder into current coder
131 * @param current current coder
132 * @param value value to mix in
133 * @return new coder
134 */
135 static byte mixCoder(byte current, String value) {
136 return (byte)(current | value.coder());
137 }
138
139 /**
140 * Mix coder into current coder
141 * @param current current coder
142 * @param value value to mix in
143 * @return new coder
144 */
145 static byte mixCoder(byte current, boolean value) {
146 // Booleans are represented with Latin1
147 return current;
148 }
149
150 /**
151 * Mix coder into current coder
152 * @param current current coder
153 * @param value value to mix in
154 * @return new coder
155 */
156 static byte mixCoder(byte current, byte value) {
157 // Bytes are represented with Latin1
158 return current;
159 }
160
161 /**
162 * Mix coder into current coder
163 * @param current current coder
164 * @param value value to mix in
165 * @return new coder
166 */
167 static byte mixCoder(byte current, short value) {
168 // Shorts are represented with Latin1
169 return current;
170 }
171
172 /**
173 * Mix coder into current coder
174 * @param current current coder
175 * @param value value to mix in
176 * @return new coder
177 */
178 static byte mixCoder(byte current, int value) {
179 // Ints are represented with Latin1
180 return current;
181 }
182
183 /**
184 * Mix coder into current coder
185 * @param current current coder
186 * @param value value to mix in
187 * @return new coder
188 */
189 static byte mixCoder(byte current, long value) {
190 // Longs are represented with Latin1
191 return current;
192 }
193
194 /**
195 * Prepends the stringly representation of boolean value into buffer,
196 * given the coder and final index. Index is measured in chars, not in bytes!
197 *
198 * @param index final char index in the buffer
199 * @param buf buffer to append to
200 * @param coder coder to add with
201 * @param value boolean value to encode
202 * @return new index
203 */
204 static int prepend(int index, byte[] buf, byte coder, boolean value) {
205 if (coder == String.LATIN1) {
206 if (value) {
207 buf[--index] = 'e';
208 buf[--index] = 'u';
209 buf[--index] = 'r';
210 buf[--index] = 't';
211 } else {
212 buf[--index] = 'e';
213 buf[--index] = 's';
214 buf[--index] = 'l';
215 buf[--index] = 'a';
216 buf[--index] = 'f';
217 }
218 } else {
219 if (value) {
220 StringUTF16.putChar(buf, --index, 'e');
221 StringUTF16.putChar(buf, --index, 'u');
222 StringUTF16.putChar(buf, --index, 'r');
223 StringUTF16.putChar(buf, --index, 't');
224 } else {
225 StringUTF16.putChar(buf, --index, 'e');
226 StringUTF16.putChar(buf, --index, 's');
227 StringUTF16.putChar(buf, --index, 'l');
228 StringUTF16.putChar(buf, --index, 'a');
229 StringUTF16.putChar(buf, --index, 'f');
230 }
231 }
232 return index;
233 }
234
235 /**
236 * Prepends the stringly representation of byte value into buffer,
237 * given the coder and final index. Index is measured in chars, not in bytes!
238 *
239 * @param index final char index in the buffer
240 * @param buf buffer to append to
241 * @param coder coder to add with
242 * @param value byte value to encode
243 * @return new index
244 */
245 static int prepend(int index, byte[] buf, byte coder, byte value) {
246 return prepend(index, buf, coder, (int)value);
247 }
248
249 /**
250 * Prepends the stringly representation of char value into buffer,
251 * given the coder and final index. Index is measured in chars, not in bytes!
252 *
253 * @param index final char index in the buffer
254 * @param buf buffer to append to
255 * @param coder coder to add with
256 * @param value char value to encode
257 * @return new index
258 */
259 static int prepend(int index, byte[] buf, byte coder, char value) {
260 if (coder == String.LATIN1) {
261 buf[--index] = (byte) (value & 0xFF);
262 } else {
263 StringUTF16.putChar(buf, --index, value);
264 }
265 return index;
266 }
267
268 /**
269 * Prepends the stringly representation of short value into buffer,
270 * given the coder and final index. Index is measured in chars, not in bytes!
271 *
272 * @param index final char index in the buffer
273 * @param buf buffer to append to
274 * @param coder coder to add with
275 * @param value short value to encode
276 * @return new index
277 */
278 static int prepend(int index, byte[] buf, byte coder, short value) {
279 return prepend(index, buf, coder, (int)value);
280 }
281
282 /**
283 * Prepends the stringly representation of integer value into buffer,
284 * given the coder and final index. Index is measured in chars, not in bytes!
285 *
286 * @param index final char index in the buffer
287 * @param buf buffer to append to
288 * @param coder coder to add with
289 * @param value integer value to encode
290 * @return new index
291 */
292 static int prepend(int index, byte[] buf, byte coder, int value) {
293 if (coder == String.LATIN1) {
294 return Integer.getChars(value, index, buf);
295 } else {
296 return StringUTF16.getChars(value, index, buf);
297 }
298 }
299
300 /**
301 * Prepends the stringly representation of long value into buffer,
302 * given the coder and final index. Index is measured in chars, not in bytes!
303 *
304 * @param index final char index in the buffer
305 * @param buf buffer to append to
306 * @param coder coder to add with
307 * @param value long value to encode
308 * @return new index
309 */
310 static int prepend(int index, byte[] buf, byte coder, long value) {
311 if (coder == String.LATIN1) {
312 return Long.getChars(value, index, buf);
313 } else {
314 return StringUTF16.getChars(value, index, buf);
315 }
316 }
317
318 /**
319 * Prepends the stringly representation of String value into buffer,
320 * given the coder and final index. Index is measured in chars, not in bytes!
321 *
322 * @param index final char index in the buffer
323 * @param buf buffer to append to
324 * @param coder coder to add with
325 * @param value String value to encode
326 * @return new index
327 */
328 static int prepend(int index, byte[] buf, byte coder, String value) {
329 index -= value.length();
330 value.getBytes(buf, index, coder);
331 return index;
332 }
333
334 /**
335 * Instantiates the String with given buffer and coder
336 * @param buf buffer to use
337 * @param index remaining index
338 * @param coder coder to use
339 * @return String resulting string
340 */
341 static String newString(byte[] buf, int index, byte coder) {
342 // Use the private, non-copying constructor (unsafe!)
343 if (index != 0) {
344 throw new InternalError("Storage is not completely initialized, " + index + " bytes left");
345 }
346 return new String(buf, coder);
347 }
348
349 /**
350 * Provides the initial coder for the String.
351 * @return initial coder
352 */
353 static byte initialCoder() {
354 return String.COMPACT_STRINGS ? String.LATIN1 : String.UTF16;
355 }
356
357 }