trunk/js/jsstr.h

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla Communicator client code, released
 * March 31, 1998.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

#ifndef jsstr_h___
#define jsstr_h___
/*
 * JS string type implementation.
 *
 * A JS string is a counted array of unicode characters.  To support handoff
 * of API client memory, the chars are allocated separately from the length,
 * necessitating a pointer after the count, to form a separately allocated
 * string descriptor.  String descriptors are GC'ed, while their chars are
 * allocated from the malloc heap.
 */
#include <ctype.h>
#include "jspubtd.h"
#include "jsprvtd.h"

JS_BEGIN_EXTERN_C

/*
 * The GC-thing "string" type.
 *
 * When the JSSTRFLAG_DEPENDENT bit of the length field is unset, the u.chars
 * field points to a flat character array owned by its GC-thing descriptor.
 * The array is terminated at index length by a zero character and the size of
 * the array in bytes is (length + 1) * sizeof(jschar). The terminator is
 * purely a backstop, in case the chars pointer flows out to native code that
 * requires \u0000 termination.
 *
 * A flat string with JSSTRFLAG_MUTABLE set means that the string is accessible
 * only from one thread and it is possible to turn it into a dependent string
 * of the same length to optimize js_ConcatStrings. It is also possible to grow
 * such a string, but extreme care must be taken to ensure that no other code
 * relies on the original length of the string.
 *
 * A flat string with JSSTRFLAG_ATOMIZED set means that the string is hashed as
 * an atom. This flag is used to avoid re-hashing the already-atomized string.
 *
 * Any string with JSSTRFLAG_DEFLATED set means that the string has an entry
 * in the deflated string cache. The GC uses this flag to optimize string 
 * finalization and avoid an expensive cache lookup for strings that were 
 * never deflated.
 *
 * When JSSTRFLAG_DEPENDENT is set, the string depends on characters of another
 * string strongly referenced by the u.base field. The base member may point to
 * another dependent string if JSSTRING_CHARS has not been called yet.
 *
 * JSSTRFLAG_PREFIX determines the kind of the dependent string. When the flag
 * is unset, the length field encodes both starting position relative to the
 * base string and the number of characters in the dependent string, see
 * JSSTRDEP_START_MASK and JSSTRDEP_LENGTH_MASK macros below for details.
 *
 * When JSSTRFLAG_PREFIX is set, the dependent string is a prefix of the base
 * string. The number of characters in the prefix is encoded using all non-flag
 * bits of the length field and spans the same 0 .. SIZE_T_MAX/4 range as the
 * length of the flat string.
 *
 * NB: Always use the JSSTRING_LENGTH and JSSTRING_CHARS accessor macros.
 */
struct JSString {
    size_t          length;
    union {
        jschar      *chars;
        JSString    *base;
    } u;
};

/*
 * Definitions for flags stored in the high order bits of JSString.length.
 * JSSTRFLAG_PREFIX and JSSTRFLAG_MUTABLE are two aliases for the same value.
 * JSSTRFLAG_PREFIX should be used only if JSSTRFLAG_DEPENDENT is set and
 * JSSTRFLAG_MUTABLE should be used only if the string is flat.
 * JSSTRFLAG_ATOMIZED is used only with the flat immutable strings.
 */
#define JSSTRFLAG_DEPENDENT         JSSTRING_BIT(JS_BITS_PER_WORD - 1)
#define JSSTRFLAG_PREFIX            JSSTRING_BIT(JS_BITS_PER_WORD - 2)
#define JSSTRFLAG_MUTABLE           JSSTRFLAG_PREFIX
#define JSSTRFLAG_ATOMIZED          JSSTRING_BIT(JS_BITS_PER_WORD - 3)
#define JSSTRFLAG_DEFLATED          JSSTRING_BIT(JS_BITS_PER_WORD - 4)

#define JSSTRING_LENGTH_BITS        (JS_BITS_PER_WORD - 4)
#define JSSTRING_LENGTH_MASK        JSSTRING_BITMASK(JSSTRING_LENGTH_BITS)

/* Universal JSString type inquiry and accessor macros. */
#define JSSTRING_BIT(n)             ((size_t)1 << (n))
#define JSSTRING_BITMASK(n)         (JSSTRING_BIT(n) - 1)
#define JSSTRING_HAS_FLAG(str,flg)  ((str)->length & (flg))
#define JSSTRING_IS_DEPENDENT(str)  JSSTRING_HAS_FLAG(str, JSSTRFLAG_DEPENDENT)
#define JSSTRING_IS_FLAT(str)       (!JSSTRING_IS_DEPENDENT(str))
#define JSSTRING_IS_MUTABLE(str)    (((str)->length & (JSSTRFLAG_DEPENDENT |  \
                                                       JSSTRFLAG_MUTABLE)) == \
                                     JSSTRFLAG_MUTABLE)
#define JSSTRING_IS_ATOMIZED(str)   (((str)->length & (JSSTRFLAG_DEPENDENT |  \
                                                       JSSTRFLAG_ATOMIZED)) ==\
                                     JSSTRFLAG_ATOMIZED)

#define JSSTRING_CHARS(str)         (JSSTRING_IS_DEPENDENT(str)               \
                                     ? JSSTRDEP_CHARS(str)                    \
                                     : JSFLATSTR_CHARS(str))
#define JSSTRING_LENGTH(str)        (JSSTRING_IS_DEPENDENT(str)               \
                                     ? JSSTRDEP_LENGTH(str)                   \
                                     : JSFLATSTR_LENGTH(str))

JS_STATIC_ASSERT(sizeof(size_t) == sizeof(jsword));

#define JSSTRING_IS_DEFLATED(str)   ((str)->length & JSSTRFLAG_DEFLATED)

#define JSSTRING_SET_DEFLATED(str)                                            \
    JS_ATOMIC_SET_MASK((jsword*)&(str)->length, JSSTRFLAG_DEFLATED)

#define JSSTRING_CHARS_AND_LENGTH(str, chars_, length_)                       \
    ((void)(JSSTRING_IS_DEPENDENT(str)                                        \
            ? ((length_) = JSSTRDEP_LENGTH(str),                              \
               (chars_) = JSSTRDEP_CHARS(str))                                \
            : ((length_) = JSFLATSTR_LENGTH(str),                             \
               (chars_) = JSFLATSTR_CHARS(str))))

#define JSSTRING_CHARS_AND_END(str, chars_, end)                              \
    ((void)((end) = JSSTRING_IS_DEPENDENT(str)                                \
                  ? JSSTRDEP_LENGTH(str) + ((chars_) = JSSTRDEP_CHARS(str))   \
                  : JSFLATSTR_LENGTH(str) + ((chars_) = JSFLATSTR_CHARS(str))))

/* Specific flat string initializer and accessor macros. */
#define JSFLATSTR_INIT(str, chars_, length_)                                  \
    ((void)(JS_ASSERT(((length_) & ~JSSTRING_LENGTH_MASK) == 0),              \
            (str)->length = (length_), (str)->u.chars = (chars_)))

#define JSFLATSTR_LENGTH(str)                                                 \
    (JS_ASSERT(JSSTRING_IS_FLAT(str)), (str)->length & JSSTRING_LENGTH_MASK)

#define JSFLATSTR_CHARS(str)                                                  \
    (JS_ASSERT(JSSTRING_IS_FLAT(str)), (str)->u.chars)

/* 
 * Special flat string initializer that preserves the JSSTR_DEFLATED flag.
 * Use this macro when reinitializing an existing string (which may be
 * hashed to its deflated bytes. Newborn strings must use JSFLATSTR_INIT.
 */
#define JSFLATSTR_REINIT(str, chars_, length_)                                \
    ((void)(JS_ASSERT(((length_) & ~JSSTRING_LENGTH_MASK) == 0),              \
            (str)->length = ((str)->length & JSSTRFLAG_DEFLATED) |            \
                             (length_ & ~JSSTRFLAG_DEFLATED),                 \
            (str)->u.chars = (chars_)))

/*
 * Macros to manipulate atomized and mutable flags of flat strings. It is safe
 * to use these without extra locking due to the following properties:
 *
 *   * We do not have a macro like JSFLATSTR_CLEAR_ATOMIZED as a string
 *     remains atomized until the GC collects it.
 *
 *   * A thread may call JSFLATSTR_SET_MUTABLE only when it is the only thread
 *     accessing the string until a later call to JSFLATSTR_CLEAR_MUTABLE.
 *
 *   * Multiple threads can call JSFLATSTR_CLEAR_MUTABLE but the macro
 *     actually clears the mutable flag only when the flag is set -- in which
 *     case only one thread can access the string (see previous property).
 *
 * Thus, when multiple threads access the string, JSFLATSTR_SET_ATOMIZED is
 * the only macro that can update the length field of the string by changing
 * the mutable bit from 0 to 1. We call the macro only after the string has
 * been hashed. When some threads in js_ValueToStringId see that the flag is
 * set, it knows that the string was atomized.
 *
 * On the other hand, if the thread sees that the flag is unset, it could be
 * seeing a stale value when another thread has just atomized the string and
 * set the flag. But this can lead only to an extra call to js_AtomizeString.
 * This function would find that the string was already hashed and return it
 * with the atomized bit set.
 */
#define JSFLATSTR_SET_ATOMIZED(str)                                           \
    JS_BEGIN_MACRO                                                            \
        JS_ASSERT(JSSTRING_IS_FLAT(str) && !JSSTRING_IS_MUTABLE(str));        \
        JS_ATOMIC_SET_MASK((jsword*) &(str)->length, JSSTRFLAG_ATOMIZED);     \
    JS_END_MACRO

#define JSFLATSTR_SET_MUTABLE(str)                                            \
    ((void)(JS_ASSERT(JSSTRING_IS_FLAT(str) && !JSSTRING_IS_ATOMIZED(str)),   \
            (str)->length |= JSSTRFLAG_MUTABLE))

#define JSFLATSTR_CLEAR_MUTABLE(str)                                          \
    ((void)(JS_ASSERT(JSSTRING_IS_FLAT(str)),                                 \
            JSSTRING_HAS_FLAG(str, JSSTRFLAG_MUTABLE) &&                      \
            ((str)->length &= ~JSSTRFLAG_MUTABLE)))

/* Specific dependent string shift/mask accessor and mutator macros. */
#define JSSTRDEP_START_BITS         (JSSTRING_LENGTH_BITS-JSSTRDEP_LENGTH_BITS)
#define JSSTRDEP_START_SHIFT        JSSTRDEP_LENGTH_BITS
#define JSSTRDEP_START_MASK         JSSTRING_BITMASK(JSSTRDEP_START_BITS)
#define JSSTRDEP_LENGTH_BITS        (JSSTRING_LENGTH_BITS / 2)
#define JSSTRDEP_LENGTH_MASK        JSSTRING_BITMASK(JSSTRDEP_LENGTH_BITS)

#define JSSTRDEP_IS_PREFIX(str)     JSSTRING_HAS_FLAG(str, JSSTRFLAG_PREFIX)

#define JSSTRDEP_START(str)         (JSSTRDEP_IS_PREFIX(str) ? 0              \
                                     : (((str)->length                        \
                                         >> JSSTRDEP_START_SHIFT)             \
                                        & JSSTRDEP_START_MASK))
#define JSSTRDEP_LENGTH(str)        ((str)->length                            \
                                     & (JSSTRDEP_IS_PREFIX(str)               \
                                        ? JSSTRING_LENGTH_MASK                \
                                        : JSSTRDEP_LENGTH_MASK))

#define JSSTRDEP_INIT(str,bstr,off,len)                                       \
    ((str)->length = JSSTRFLAG_DEPENDENT                                      \
                   | ((off) << JSSTRDEP_START_SHIFT)                          \
                   | (len),                                                   \
     (str)->u.base = (bstr))

/* See JSFLATSTR_INIT. */
#define JSSTRDEP_REINIT(str,bstr,off,len)                                     \
    ((str)->length = JSSTRFLAG_DEPENDENT                                      \
                   | ((str->length) & JSSTRFLAG_DEFLATED)                     \
                   | ((off) << JSSTRDEP_START_SHIFT)                          \
                   | (len),                                                   \
     (str)->u.base = (bstr))

#define JSPREFIX_INIT(str,bstr,len)                                           \
    ((str)->length = JSSTRFLAG_DEPENDENT | JSSTRFLAG_PREFIX | (len),          \
     (str)->u.base = (bstr))

/* See JSFLATSTR_INIT. */
#define JSPREFIX_REINIT(str,bstr,len)                                         \
    ((str)->length = JSSTRFLAG_DEPENDENT | JSSTRFLAG_PREFIX |                 \
                     ((str->length) & JSSTRFLAG_DEFLATED) | (len),            \
     (str)->u.base = (bstr))

#define JSSTRDEP_BASE(str)          ((str)->u.base)
#define JSPREFIX_BASE(str)          JSSTRDEP_BASE(str)
#define JSPREFIX_SET_BASE(str,bstr) ((str)->u.base = (bstr))

#define JSSTRDEP_CHARS(str)                                                   \
    (JSSTRING_IS_DEPENDENT(JSSTRDEP_BASE(str))                                \
     ? js_GetDependentStringChars(str)                                        \
     : JSFLATSTR_CHARS(JSSTRDEP_BASE(str)) + JSSTRDEP_START(str))

extern size_t
js_MinimizeDependentStrings(JSString *str, int level, JSString **basep);

extern jschar *
js_GetDependentStringChars(JSString *str);

extern const jschar *
js_GetStringChars(JSContext *cx, JSString *str);

extern JSString * JS_FASTCALL
js_ConcatStrings(JSContext *cx, JSString *left, JSString *right);

extern const jschar *
js_UndependString(JSContext *cx, JSString *str);

extern JSBool
js_MakeStringImmutable(JSContext *cx, JSString *str);

extern JSString* JS_FASTCALL
js_toLowerCase(JSContext *cx, JSString *str);

extern JSString* JS_FASTCALL
js_toUpperCase(JSContext *cx, JSString *str);

typedef struct JSCharBuffer {
    size_t          length;
    jschar          *chars;
} JSCharBuffer;

struct JSSubString {
    size_t          length;
    const jschar    *chars;
};

extern jschar      js_empty_ucstr[];
extern JSSubString js_EmptySubString;

/* Unicode character attribute lookup tables. */
extern const uint8 js_X[];
extern const uint8 js_Y[];
extern const uint32 js_A[];

/* Enumerated Unicode general category types. */
typedef enum JSCharType {
    JSCT_UNASSIGNED             = 0,
    JSCT_UPPERCASE_LETTER       = 1,
    JSCT_LOWERCASE_LETTER       = 2,
    JSCT_TITLECASE_LETTER       = 3,
    JSCT_MODIFIER_LETTER        = 4,
    JSCT_OTHER_LETTER           = 5,
    JSCT_NON_SPACING_MARK       = 6,
    JSCT_ENCLOSING_MARK         = 7,
    JSCT_COMBINING_SPACING_MARK = 8,
    JSCT_DECIMAL_DIGIT_NUMBER   = 9,
    JSCT_LETTER_NUMBER          = 10,
    JSCT_OTHER_NUMBER           = 11,
    JSCT_SPACE_SEPARATOR        = 12,
    JSCT_LINE_SEPARATOR         = 13,
    JSCT_PARAGRAPH_SEPARATOR    = 14,
    JSCT_CONTROL                = 15,
    JSCT_FORMAT                 = 16,
    JSCT_PRIVATE_USE            = 18,
    JSCT_SURROGATE              = 19,
    JSCT_DASH_PUNCTUATION       = 20,
    JSCT_START_PUNCTUATION      = 21,
    JSCT_END_PUNCTUATION        = 22,
    JSCT_CONNECTOR_PUNCTUATION  = 23,
    JSCT_OTHER_PUNCTUATION      = 24,
    JSCT_MATH_SYMBOL            = 25,
    JSCT_CURRENCY_SYMBOL        = 26,
    JSCT_MODIFIER_SYMBOL        = 27,
    JSCT_OTHER_SYMBOL           = 28
} JSCharType;

/* Character classifying and mapping macros, based on java.lang.Character. */
#define JS_CCODE(c)     (js_A[js_Y[(js_X[(uint16)(c)>>6]<<6)|((c)&0x3F)]])
#define JS_CTYPE(c)     (JS_CCODE(c) & 0x1F)

#define JS_ISALPHA(c)   ((((1 << JSCT_UPPERCASE_LETTER) |                     \
                           (1 << JSCT_LOWERCASE_LETTER) |                     \
                           (1 << JSCT_TITLECASE_LETTER) |                     \
                           (1 << JSCT_MODIFIER_LETTER) |                      \
                           (1 << JSCT_OTHER_LETTER))                          \
                          >> JS_CTYPE(c)) & 1)

#define JS_ISALNUM(c)   ((((1 << JSCT_UPPERCASE_LETTER) |                     \
                           (1 << JSCT_LOWERCASE_LETTER) |                     \
                           (1 << JSCT_TITLECASE_LETTER) |                     \
                           (1 << JSCT_MODIFIER_LETTER) |                      \
                           (1 << JSCT_OTHER_LETTER) |                         \
                           (1 << JSCT_DECIMAL_DIGIT_NUMBER))                  \
                          >> JS_CTYPE(c)) & 1)

/* A unicode letter, suitable for use in an identifier. */
#define JS_ISLETTER(c)   ((((1 << JSCT_UPPERCASE_LETTER) |                    \
                            (1 << JSCT_LOWERCASE_LETTER) |                    \
                            (1 << JSCT_TITLECASE_LETTER) |                    \
                            (1 << JSCT_MODIFIER_LETTER) |                     \
                            (1 << JSCT_OTHER_LETTER) |                        \
                            (1 << JSCT_LETTER_NUMBER))                        \
                           >> JS_CTYPE(c)) & 1)

/*
 * 'IdentifierPart' from ECMA grammar, is Unicode letter or combining mark or
 * digit or connector punctuation.
 */
#define JS_ISIDPART(c)  ((((1 << JSCT_UPPERCASE_LETTER) |                     \
                           (1 << JSCT_LOWERCASE_LETTER) |                     \
                           (1 << JSCT_TITLECASE_LETTER) |                     \
                           (1 << JSCT_MODIFIER_LETTER) |                      \
                           (1 << JSCT_OTHER_LETTER) |                         \
                           (1 << JSCT_LETTER_NUMBER) |                        \
                           (1 << JSCT_NON_SPACING_MARK) |                     \
                           (1 << JSCT_COMBINING_SPACING_MARK) |               \
                           (1 << JSCT_DECIMAL_DIGIT_NUMBER) |                 \
                           (1 << JSCT_CONNECTOR_PUNCTUATION))                 \
                          >> JS_CTYPE(c)) & 1)

/* Unicode control-format characters, ignored in input */
#define JS_ISFORMAT(c) (((1 << JSCT_FORMAT) >> JS_CTYPE(c)) & 1)

/*
 * Per ECMA-262 15.10.2.6, these characters are the only ones that make up a
 * "word", as far as a RegExp is concerned.  If we want a Unicode-friendlier
 * definition of "word", we should rename this macro to something regexp-y.
 */
#define JS_ISWORD(c)    ((c) < 128 && (isalnum(c) || (c) == '_'))

#define JS_ISIDSTART(c) (JS_ISLETTER(c) || (c) == '_' || (c) == '$')
#define JS_ISIDENT(c)   (JS_ISIDPART(c) || (c) == '_' || (c) == '$')

#define JS_ISXMLSPACE(c)        ((c) == ' ' || (c) == '\t' || (c) == '\r' ||  \
                                 (c) == '\n')
#define JS_ISXMLNSSTART(c)      ((JS_CCODE(c) & 0x00000100) || (c) == '_')
#define JS_ISXMLNS(c)           ((JS_CCODE(c) & 0x00000080) || (c) == '.' ||  \
                                 (c) == '-' || (c) == '_')
#define JS_ISXMLNAMESTART(c)    (JS_ISXMLNSSTART(c) || (c) == ':')
#define JS_ISXMLNAME(c)         (JS_ISXMLNS(c) || (c) == ':')

#define JS_ISDIGIT(c)   (JS_CTYPE(c) == JSCT_DECIMAL_DIGIT_NUMBER)

/* XXXbe unify on A/X/Y tbls, avoid ctype.h? */
/* XXXbe fs, etc. ? */
#define JS_ISSPACE(c)   ((JS_CCODE(c) & 0x00070000) == 0x00040000)
#define JS_ISPRINT(c)   ((c) < 128 && isprint(c))

#define JS_ISUPPER(c)   (JS_CTYPE(c) == JSCT_UPPERCASE_LETTER)
#define JS_ISLOWER(c)   (JS_CTYPE(c) == JSCT_LOWERCASE_LETTER)

#define JS_TOUPPER(c)   ((jschar) ((JS_CCODE(c) & 0x00100000)                 \
                                   ? (c) - ((int32)JS_CCODE(c) >> 22)         \
                                   : (c)))
#define JS_TOLOWER(c)   ((jschar) ((JS_CCODE(c) & 0x00200000)                 \
                                   ? (c) + ((int32)JS_CCODE(c) >> 22)         \
                                   : (c)))

/*
 * Shorthands for ASCII (7-bit) decimal and hex conversion.
 * Manually inline isdigit for performance; MSVC doesn't do this for us.
 */
#define JS7_ISDEC(c)    ((((unsigned)(c)) - '0') <= 9)
#define JS7_UNDEC(c)    ((c) - '0')
#define JS7_ISHEX(c)    ((c) < 128 && isxdigit(c))
#define JS7_UNHEX(c)    (uintN)(JS7_ISDEC(c) ? (c) - '0' : 10 + tolower(c) - 'a')
#define JS7_ISLET(c)    ((c) < 128 && isalpha(c))

/* Initialize per-runtime string state for the first context in the runtime. */
extern JSBool
js_InitRuntimeStringState(JSContext *cx);

extern JSBool
js_InitDeflatedStringCache(JSRuntime *rt);

/*
 * Maximum character code for which we will create a pinned unit string on
 * demand -- see JSRuntime.unitStrings in jscntxt.h.
 */
#define UNIT_STRING_LIMIT 256U

/*
 * Get the independent string containing only character code at index in str
 * (backstopped with a zero character as usual for independent strings).
 */
extern JSString *
js_GetUnitString(JSContext *cx, JSString *str, size_t index);

/*
 * Get the independent string containing only the character code c, which must
 * be less than UNIT_STRING_LIMIT.
 */
extern JSString *
js_GetUnitStringForChar(JSContext *cx, jschar c);

extern void
js_FinishUnitStrings(JSRuntime *rt);

extern void
js_FinishRuntimeStringState(JSContext *cx);

extern void
js_FinishDeflatedStringCache(JSRuntime *rt);

/* Initialize the String class, returning its prototype object. */
extern JSClass js_StringClass;

extern JSObject *
js_InitStringClass(JSContext *cx, JSObject *obj);

extern const char js_escape_str[];
extern const char js_unescape_str[];
extern const char js_uneval_str[];
extern const char js_decodeURI_str[];
extern const char js_encodeURI_str[];
extern const char js_decodeURIComponent_str[];
extern const char js_encodeURIComponent_str[];

/* GC-allocate a string descriptor for the given malloc-allocated chars. */
extern JSString *
js_NewString(JSContext *cx, jschar *chars, size_t length);

extern JSString *
js_NewDependentString(JSContext *cx, JSString *base, size_t start,
                      size_t length);

/* Copy a counted string and GC-allocate a descriptor for it. */
extern JSString *
js_NewStringCopyN(JSContext *cx, const jschar *s, size_t n);

/* Copy a C string and GC-allocate a descriptor for it. */
extern JSString *
js_NewStringCopyZ(JSContext *cx, const jschar *s);

/*
 * Free the chars held by str when it is finalized by the GC. When type is
 * less then zero, it denotes an internal string. Otherwise it denotes the
 * type of the external string allocated with JS_NewExternalString.
 *
 * This function always needs rt but can live with null cx.
 */
extern void
js_FinalizeStringRT(JSRuntime *rt, JSString *str, intN type, JSContext *cx);

/*
 * Convert a value to a printable C string.
 */
typedef JSString *(*JSValueToStringFun)(JSContext *cx, jsval v);

extern JS_FRIEND_API(const char *)
js_ValueToPrintable(JSContext *cx, jsval v, JSValueToStringFun v2sfun);

#define js_ValueToPrintableString(cx,v) \
    js_ValueToPrintable(cx, v, js_ValueToString)

#define js_ValueToPrintableSource(cx,v) \
    js_ValueToPrintable(cx, v, js_ValueToSource)

/*
 * Convert a value to a string, returning null after reporting an error,
 * otherwise returning a new string reference.
 */
extern JS_FRIEND_API(JSString *)
js_ValueToString(JSContext *cx, jsval v);

/*
 * Convert a value to its source expression, returning null after reporting
 * an error, otherwise returning a new string reference.
 */
extern JS_FRIEND_API(JSString *)
js_ValueToSource(JSContext *cx, jsval v);

/*
 * Compute a hash function from str. The caller can call this function even if
 * str is not a GC-allocated thing.
 */
extern uint32
js_HashString(JSString *str);

/*
 * Test if strings are equal. The caller can call the function even if str1
 * or str2 are not GC-allocated things.
 */
extern JSBool JS_FASTCALL
js_EqualStrings(JSString *str1, JSString *str2);

/*
 * Return less than, equal to, or greater than zero depending on whether
 * str1 is less than, equal to, or greater than str2.
 */
extern int32 JS_FASTCALL
js_CompareStrings(JSString *str1, JSString *str2);

/*
 * Boyer-Moore-Horspool superlinear search for pat:patlen in text:textlen.
 * The patlen argument must be positive and no greater than BMH_PATLEN_MAX.
 * The start argument tells where in text to begin the search.
 *
 * Return the index of pat in text, or -1 if not found.
 */
#define BMH_CHARSET_SIZE 256    /* ISO-Latin-1 */
#define BMH_PATLEN_MAX   255    /* skip table element is uint8 */

#define BMH_BAD_PATTERN  (-2)   /* return value if pat is not ISO-Latin-1 */

extern jsint
js_BoyerMooreHorspool(const jschar *text, jsint textlen,
                      const jschar *pat, jsint patlen,
                      jsint start);

extern size_t
js_strlen(const jschar *s);

extern jschar *
js_strchr(const jschar *s, jschar c);

extern jschar *
js_strchr_limit(const jschar *s, jschar c, const jschar *limit);

#define js_strncpy(t, s, n)     memcpy((t), (s), (n) * sizeof(jschar))

/*
 * Return s advanced past any Unicode white space characters.
 */
extern const jschar *
js_SkipWhiteSpace(const jschar *s, const jschar *end);

/*
 * Inflate bytes to JS chars and vice versa.  Report out of memory via cx
 * and return null on error, otherwise return the jschar or byte vector that
 * was JS_malloc'ed. length is updated with the length of the new string in jschars.
 */
extern jschar *
js_InflateString(JSContext *cx, const char *bytes, size_t *length);

extern char *
js_DeflateString(JSContext *cx, const jschar *chars, size_t length);

/*
 * Inflate bytes to JS chars into a buffer. 'chars' must be large enough for
 * 'length' jschars. The buffer is NOT null-terminated. The destination length
 * must be be initialized with the buffer size and will contain on return the
 * number of copied chars.
 */
extern JSBool
js_InflateStringToBuffer(JSContext* cx, const char *bytes, size_t length,
                         jschar *chars, size_t* charsLength);

/*
 * Get number of bytes in the deflated sequence of characters.
 */
extern size_t
js_GetDeflatedStringLength(JSContext *cx, const jschar *chars,
                           size_t charsLength);

/*
 * Deflate JS chars to bytes into a buffer. 'bytes' must be large enough for
 * 'length chars. The buffer is NOT null-terminated. The destination length
 * must to be initialized with the buffer size and will contain on return the
 * number of copied bytes.
 */
extern JSBool
js_DeflateStringToBuffer(JSContext* cx, const jschar *chars,
                         size_t charsLength, char *bytes, size_t* length);

/*
 * Associate bytes with str in the deflated string cache, returning true on
 * successful association, false on out of memory.
 */
extern JSBool
js_SetStringBytes(JSContext *cx, JSString *str, char *bytes, size_t length);

/*
 * Find or create a deflated string cache entry for str that contains its
 * characters chopped from Unicode code points into bytes.
 */
extern const char *
js_GetStringBytes(JSContext *cx, JSString *str);

/* Remove a deflated string cache entry associated with str if any. */
extern void
js_PurgeDeflatedStringCache(JSRuntime *rt, JSString *str);

/* Export a few natives and a helper to other files in SpiderMonkey. */
extern JSBool
js_str_escape(JSContext *cx, JSObject *obj, uintN argc, jsval *argv,
              jsval *rval);

extern JSBool
js_StringReplaceHelper(JSContext *cx, uintN argc, JSObject *lambda,
                       JSString *repstr, jsval *vp);

/*
 * Convert one UCS-4 char and write it into a UTF-8 buffer, which must be at
 * least 6 bytes long.  Return the number of UTF-8 bytes of data written.
 */
extern int
js_OneUcs4ToUtf8Char(uint8 *utf8Buffer, uint32 ucs4Char);

/*
 * Write str into buffer escaping any non-printable or non-ASCII character.
 * Guarantees that a NUL is at the end of the buffer. Returns the length of
 * the written output, NOT including the NUL. If buffer is null, just returns
 * the length of the output. If quote is not 0, it must be a single or double
 * quote character that will quote the output.
 *
 * The function is only defined for debug builds.
*/
#define js_PutEscapedString(buffer, bufferSize, str, quote)                   \
    js_PutEscapedStringImpl(buffer, bufferSize, NULL, str, quote)

/*
 * Write str into file escaping any non-printable or non-ASCII character.
 * Returns the number of bytes written to file. If quote is not 0, it must
 * be a single or double quote character that will quote the output.
 *
 * The function is only defined for debug builds.
*/
#define js_FileEscapedString(file, str, quote)                                \
    (JS_ASSERT(file), js_PutEscapedStringImpl(NULL, 0, file, str, quote))

extern JS_FRIEND_API(size_t)
js_PutEscapedStringImpl(char *buffer, size_t bufferSize, FILE *fp,
                        JSString *str, uint32 quote);

extern JSBool
js_String(JSContext *cx, JSObject *obj, uintN argc, jsval *argv, jsval *rval);

JS_END_EXTERN_C

#endif /* jsstr_h___ */