js/src/jsstrinlines.h

   1 /* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
   2  *
   3  * ***** BEGIN LICENSE BLOCK *****
   4  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   5  *
   6  * The contents of this file are subject to the Mozilla Public License Version
   7  * 1.1 (the "License"); you may not use this file except in compliance with
   8  * the License. You may obtain a copy of the License at
   9  * http://www.mozilla.org/MPL/
  10  *
  11  * Software distributed under the License is distributed on an "AS IS" basis,
  12  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  13  * for the specific language governing rights and limitations under the
  14  * License.
  15  *
  16  * The Original Code is Mozilla Communicator client code, released
  17  * March 31, 1998.
  18  *
  19  * The Initial Developer of the Original Code is
  20  * Netscape Communications Corporation.
  21  * Portions created by the Initial Developer are Copyright (C) 1998
  22  * the Initial Developer. All Rights Reserved.
  23  *
  24  * Contributor(s):
  25  *
  26  * Alternatively, the contents of this file may be used under the terms of
  27  * either of the GNU General Public License Version 2 or later (the "GPL"),
  28  * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  29  * in which case the provisions of the GPL or the LGPL are applicable instead
  30  * of those above. If you wish to allow use of your version of this file only
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  35  * the provisions above, a recipient may use your version of this file under
  36  * the terms of any one of the MPL, the GPL or the LGPL.
  37  *
  38  * ***** END LICENSE BLOCK ***** */
  39
  40 #ifndef jsstrinlines_h___
  41 #define jsstrinlines_h___
  42
  43 #include "jsstr.h"
  44 #include "jscntxtinlines.h"
  45
  46 namespace js {
  47
  48 static inline bool
  49 CheckStringLength(JSContext *cx, size_t length)
  50 {
  51     if (JS_UNLIKELY(length > JSString::MAX_LENGTH)) {
  52         js_ReportAllocationOverflow(cx);
  53         return false;
  54     }
  55
  56     return true;
  57 }
  58
  59 /*
  60  * String builder that eagerly checks for over-allocation past the maximum
  61  * string length.
  62  *
  63  * Note: over-allocation is not checked for when using the infallible
  64  * |replaceRawBuffer|, so the implementation of |finishString| also must check
  65  * for over-allocation.
  66  */
  67 class StringBuffer
  68 {
  69     typedef Vector<jschar, 32> CharBuffer;
  70     CharBuffer cb;
  71
  72     static inline bool checkLength(JSContext *cx, size_t length);
  73     inline bool checkLength(size_t length);
  74     JSContext *context() const { return cb.allocPolicy().context(); }
  75
  76   public:
  77     explicit inline StringBuffer(JSContext *cx);
  78     bool reserve(size_t len);
  79     bool resize(size_t len);
  80     bool append(const jschar c);
  81     bool append(const jschar *chars, size_t len);
  82     bool append(const jschar *begin, const jschar *end);
  83     bool append(JSString *str);
  84     bool append(JSAtom *atom);
  85     bool appendN(const jschar c, size_t n);
  86     bool appendInflated(const char *cstr, size_t len);
  87     JSAtom *atomize(uintN flags = 0);
  88     static JSAtom *atomize(JSContext *cx, const CharBuffer &cb, uintN flags = 0);
  89     static JSAtom *atomize(JSContext *cx, const jschar *begin, size_t length, uintN flags = 0);
  90
  91     void replaceRawBuffer(jschar *chars, size_t len) { cb.replaceRawBuffer(chars, len); }
  92     jschar *begin() { return cb.begin(); }
  93     jschar *end() { return cb.end(); }
  94     const jschar *begin() const { return cb.begin(); }
  95     const jschar *end() const { return cb.end(); }
  96     bool empty() const { return cb.empty(); }
  97     inline jsint length() const;
  98
  99     /*
 100      * Produces a string, resetting the buffer to an empty state.
 101      * This method takes responsibility for adding the terminating '\0'
 102      * required by js_NewString.
 103      */
 104     JSFlatString *finishString();
 105
 106     template <size_t ArrayLength>
 107     bool append(const char (&array)[ArrayLength]) {
 108         return cb.append(array, array + ArrayLength - 1); /* No trailing '\0'. */
 109     }
 110 };
 111
 112 inline
 113 StringBuffer::StringBuffer(JSContext *cx)
 114   : cb(cx)
 115 {}
 116
 117 inline bool
 118 StringBuffer::reserve(size_t len)
 119 {
 120     if (!checkLength(len))
 121         return false;
 122     return cb.reserve(len);
 123 }
 124
 125 inline bool
 126 StringBuffer::resize(size_t len)
 127 {
 128     if (!checkLength(len))
 129         return false;
 130     return cb.resize(len);
 131 }
 132
 133 inline bool
 134 StringBuffer::append(const jschar c)
 135 {
 136     if (!checkLength(cb.length() + 1))
 137         return false;
 138     return cb.append(c);
 139 }
 140
 141 inline bool
 142 StringBuffer::append(const jschar *chars, size_t len)
 143 {
 144     if (!checkLength(cb.length() + len))
 145         return false;
 146     return cb.append(chars, len);
 147 }
 148
 149 inline bool
 150 StringBuffer::append(const jschar *begin, const jschar *end)
 151 {
 152     if (!checkLength(cb.length() + (end - begin)))
 153         return false;
 154     return cb.append(begin, end);
 155 }
 156
 157 inline bool
 158 StringBuffer::append(JSString *str)
 159 {
 160     JSLinearString *linear = str->ensureLinear(context());
 161     size_t strLen = linear->length();
 162     if (!checkLength(cb.length() + strLen))
 163         return false;
 164     return cb.append(linear->chars(), strLen);
 165 }
 166
 167 inline bool
 168 StringBuffer::append(JSAtom *atom)
 169 {
 170     size_t strLen = atom->length();
 171     if (!checkLength(cb.length() + strLen))
 172         return false;
 173     return cb.append(atom->chars(), strLen);
 174 }
 175
 176 inline bool
 177 StringBuffer::appendN(const jschar c, size_t n)
 178 {
 179     if (!checkLength(cb.length() + n))
 180         return false;
 181     return cb.appendN(c, n);
 182 }
 183
 184 inline bool
 185 StringBuffer::appendInflated(const char *cstr, size_t cstrlen)
 186 {
 187     size_t lengthBefore = length();
 188     if (!cb.growByUninitialized(cstrlen))
 189         return false;
 190 #if DEBUG
 191     size_t oldcstrlen = cstrlen;
 192     bool ok =
 193 #endif
 194     js_InflateStringToBuffer(context(), cstr, cstrlen, begin() + lengthBefore, &cstrlen);
 195     JS_ASSERT(ok && oldcstrlen == cstrlen);
 196     return true;
 197 }
 198
 199 inline jsint
 200 StringBuffer::length() const
 201 {
 202     JS_STATIC_ASSERT(jsint(JSString::MAX_LENGTH) == JSString::MAX_LENGTH);
 203     JS_ASSERT(cb.length() <= JSString::MAX_LENGTH);
 204     return jsint(cb.length());
 205 }
 206
 207 inline bool
 208 StringBuffer::checkLength(size_t length)
 209 {
 210     return CheckStringLength(context(), length);
 211 }
 212
 213 } /* namespace js */
 214
 215 inline JSFlatString *
 216 JSString::unitString(jschar c)
 217 {
 218     JS_ASSERT(c < UNIT_STRING_LIMIT);
 219     return const_cast<JSString *>(&unitStringTable[c])->assertIsFlat();
 220 }
 221
 222 inline JSLinearString *
 223 JSString::getUnitString(JSContext *cx, JSString *str, size_t index)
 224 {
 225     JS_ASSERT(index < str->length());
 226     const jschar *chars = str->getChars(cx);
 227     if (!chars)
 228         return NULL;
 229     jschar c = chars[index];
 230     if (c < UNIT_STRING_LIMIT)
 231         return unitString(c);
 232     return js_NewDependentString(cx, str, index, 1);
 233 }
 234
 235 inline JSFlatString *
 236 JSString::length2String(jschar c1, jschar c2)
 237 {
 238     JS_ASSERT(fitsInSmallChar(c1));
 239     JS_ASSERT(fitsInSmallChar(c2));
 240     return const_cast<JSString *> (
 241              &length2StringTable[(((size_t)toSmallChar[c1]) << 6) + toSmallChar[c2]]
 242            )->assertIsFlat();
 243 }
 244
 245 inline JSFlatString *
 246 JSString::length2String(uint32 i)
 247 {
 248     JS_ASSERT(i < 100);
 249     return length2String('0' + i / 10, '0' + i % 10);
 250 }
 251
 252 inline JSFlatString *
 253 JSString::intString(jsint i)
 254 {
 255     jsuint u = jsuint(i);
 256     JS_ASSERT(u < INT_STRING_LIMIT);
 257     return const_cast<JSString *>(JSString::intStringTable[u])->assertIsFlat();
 258 }
 259
 260 /* Get a static atomized string for chars if possible. */
 261 inline JSFlatString *
 262 JSString::lookupStaticString(const jschar *chars, size_t length)
 263 {
 264     if (length == 1) {
 265         if (chars[0] < UNIT_STRING_LIMIT)
 266             return unitString(chars[0]);
 267     }
 268
 269     if (length == 2) {
 270         if (fitsInSmallChar(chars[0]) && fitsInSmallChar(chars[1]))
 271             return length2String(chars[0], chars[1]);
 272     }
 273
 274     /*
 275      * Here we know that JSString::intStringTable covers only 256 (or at least
 276      * not 1000 or more) chars. We rely on order here to resolve the unit vs.
 277      * int string/length-2 string atom identity issue by giving priority to unit
 278      * strings for "0" through "9" and length-2 strings for "10" through "99".
 279      */
 280     JS_STATIC_ASSERT(INT_STRING_LIMIT <= 999);
 281     if (length == 3) {
 282         if ('1' <= chars[0] && chars[0] <= '9' &&
 283             '0' <= chars[1] && chars[1] <= '9' &&
 284             '0' <= chars[2] && chars[2] <= '9') {
 285             jsint i = (chars[0] - '0') * 100 +
 286                       (chars[1] - '0') * 10 +
 287                       (chars[2] - '0');
 288
 289             if (jsuint(i) < INT_STRING_LIMIT)
 290                 return intString(i);
 291         }
 292     }
 293
 294     return NULL;
 295 }
 296
 297 inline void
 298 JSString::finalize(JSContext *cx) {
 299     JS_ASSERT(!JSString::isStatic(this));
 300     JS_RUNTIME_UNMETER(cx->runtime, liveStrings);
 301     if (isDependent()) {
 302         JS_RUNTIME_UNMETER(cx->runtime, liveDependentStrings);
 303     } else if (isFlat()) {
 304         /*
 305          * flatChars for stillborn string is null, but cx->free checks
 306          * for a null pointer on its own.
 307          */
 308         cx->runtime->stringMemoryUsed -= length() * 2;
 309         cx->free(const_cast<jschar *>(flatChars()));
 310     }
 311 }
 312
 313 inline void
 314 JSShortString::finalize(JSContext *cx)
 315 {
 316     JS_ASSERT(!JSString::isStatic(&mHeader));
 317     JS_ASSERT(mHeader.isFlat());
 318     JS_RUNTIME_UNMETER(cx->runtime, liveStrings);
 319 }
 320
 321 inline void
 322 JSExternalString::finalize(JSContext *cx)
 323 {
 324     JS_ASSERT(unsigned(externalStringType) < JS_ARRAY_LENGTH(str_finalizers));
 325     JS_ASSERT(!isStatic(this));
 326     JS_ASSERT(isFlat());
 327     JS_RUNTIME_UNMETER(cx->runtime, liveStrings);
 328
 329     /* A stillborn string has null chars. */
 330     jschar *chars = const_cast<jschar *>(flatChars());
 331     if (!chars)
 332         return;
 333     JSStringFinalizeOp finalizer = str_finalizers[externalStringType];
 334     if (finalizer)
 335         finalizer(cx, this);
 336 }
 337
 338 inline void
 339 JSExternalString::finalize()
 340 {
 341     JS_ASSERT(unsigned(externalStringType) < JS_ARRAY_LENGTH(str_finalizers));
 342     JSStringFinalizeOp finalizer = str_finalizers[externalStringType];
 343     if (finalizer) {
 344         /*
 345          * Assume that the finalizer for the permanently interned
 346          * string knows how to deal with null context.
 347          */
 348         finalizer(NULL, this);
 349     }
 350 }
 351
 352 namespace js {
 353
 354 class RopeBuilder {
 355     JSContext *cx;
 356     JSString *res;
 357
 358   public:
 359     RopeBuilder(JSContext *cx)
 360       : cx(cx), res(cx->runtime->emptyString)
 361     {}
 362
 363     inline bool append(JSString *str) {
 364         res = js_ConcatStrings(cx, res, str);
 365         return !!res;
 366     }
 367
 368     inline JSString *result() {
 369         return res;
 370     }
 371 };
 372
 373 class StringSegmentRange
 374 {
 375     /*
 376      * If malloc() shows up in any profiles from this vector, we can add a new
 377      * StackAllocPolicy which stashes a reusable freed-at-gc buffer in the cx.
 378      */
 379     Vector<JSString *, 32> stack;
 380     JSString *cur;
 381
 382     bool settle(JSString *str) {
 383         while (str->isRope()) {
 384             if (!stack.append(str->ropeRight()))
 385                 return false;
 386             str = str->ropeLeft();
 387         }
 388         cur = str;
 389         return true;
 390     }
 391
 392   public:
 393     StringSegmentRange(JSContext *cx)
 394       : stack(cx), cur(NULL)
 395     {}
 396
 397     JS_WARN_UNUSED_RESULT bool init(JSString *str) {
 398         JS_ASSERT(stack.empty());
 399         return settle(str);
 400     }
 401
 402     bool empty() const {
 403         return cur == NULL;
 404     }
 405
 406     JSString *front() const {
 407         JS_ASSERT(!cur->isRope());
 408         return cur;
 409     }
 410
 411     JS_WARN_UNUSED_RESULT bool popFront() {
 412         JS_ASSERT(!empty());
 413         if (stack.empty()) {
 414             cur = NULL;
 415             return true;
 416         }
 417         return settle(stack.popCopy());
 418     }
 419 };
 420
 421 }  /* namespace js */
 422
 423 #endif /* jsstrinlines_h___ */