jsstr.h

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/* -*- 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
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 * decision by deleting the provisions above and replace them with the notice
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 * 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.
 *
 * When a string is treated as an object (by following it with . or []), the
 * runtime wraps it with a JSObject whose valueOf method returns the unwrapped
 * string descriptor.
 */
#include <ctype.h>
#include "jspubtd.h"
#include "jsprvtd.h"
#include "jshash.h"

JS_BEGIN_EXTERN_C

/*
 * The original GC-thing "string" type, a flat character string owned by its
 * GC-thing descriptor.  The chars member points to a vector having byte size
 * (length + 1) * sizeof(jschar), terminated at index length by a zero jschar.
 * The terminator is purely a backstop, in case the chars pointer flows out to
 * native code that requires \u0000 termination.
 *
 * NB: Always use the JSSTRING_LENGTH and JSSTRING_CHARS accessor macros,
 * unless you guard str->member uses with !JSSTRING_IS_DEPENDENT(str).
 */
struct JSString {
    size_t          length;
    jschar          *chars;
};

/*
 * Overlay structure for a string that depends on another string's characters.
 * Distinguished by the JSSTRFLAG_DEPENDENT bit being set in length.  The base
 * member may point to another dependent string if JSSTRING_CHARS has not been
 * called yet.  The length chars in a dependent string are stored starting at
 * base->chars + start, and are not necessarily zero-terminated.  If start is
 * 0, it is not stored, length is a full size_t (minus the JSSTRFLAG_* bits in
 * the high two positions), and the JSSTRFLAG_PREFIX flag is set.
 */
struct JSDependentString {
    size_t          length;
    JSString        *base;
};

/* Definitions for flags stored in the high order bits of JSString.length. */
#define JSSTRFLAG_BITS              2
#define JSSTRFLAG_SHIFT(flg)        ((size_t)(flg) << JSSTRING_LENGTH_BITS)
#define JSSTRFLAG_MASK              JSSTRFLAG_SHIFT(JS_BITMASK(JSSTRFLAG_BITS))
#define JSSTRFLAG_DEPENDENT         JSSTRFLAG_SHIFT(1)
#define JSSTRFLAG_PREFIX            JSSTRFLAG_SHIFT(2)

/* 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_PREFIX(str)     JSSTRING_HAS_FLAG(str, JSSTRFLAG_PREFIX)
#define JSSTRING_CHARS(str)         (JSSTRING_IS_DEPENDENT(str)               \
                                     ? JSSTRDEP_CHARS(str)                    \
                                     : (str)->chars)
#define JSSTRING_LENGTH(str)        (JSSTRING_IS_DEPENDENT(str)               \
                                     ? JSSTRDEP_LENGTH(str)                   \
                                     : (str)->length)
#define JSSTRING_LENGTH_BITS        (sizeof(size_t) * JS_BITS_PER_BYTE        \
                                     - JSSTRFLAG_BITS)
#define JSSTRING_LENGTH_MASK        JSSTRING_BITMASK(JSSTRING_LENGTH_BITS)

/* Specific JSDependentString 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(str)               ((JSDependentString *)(str))
#define JSSTRDEP_START(str)         (JSSTRING_IS_PREFIX(str) ? 0              \
                                     : ((JSSTRDEP(str)->length                \
                                         >> JSSTRDEP_START_SHIFT)             \
                                        & JSSTRDEP_START_MASK))
#define JSSTRDEP_LENGTH(str)        (JSSTRDEP(str)->length                    \
                                     & (JSSTRING_IS_PREFIX(str)               \
                                        ? JSSTRING_LENGTH_MASK                \
                                        : JSSTRDEP_LENGTH_MASK))

#define JSSTRDEP_SET_START_AND_LENGTH(str,off,len)                            \
    (JSSTRDEP(str)->length = JSSTRFLAG_DEPENDENT                              \
                           | ((off) << JSSTRDEP_START_SHIFT)                  \
                           | (len))
#define JSPREFIX_SET_LENGTH(str,len)                                          \
    (JSSTRDEP(str)->length = JSSTRFLAG_DEPENDENT | JSSTRFLAG_PREFIX | (len))

#define JSSTRDEP_BASE(str)          (JSSTRDEP(str)->base)
#define JSSTRDEP_SET_BASE(str,bstr) (JSSTRDEP(str)->base = (bstr))
#define JSPREFIX_BASE(str)          JSSTRDEP_BASE(str)
#define JSPREFIX_SET_BASE(str,bstr) JSSTRDEP_SET_BASE(str,bstr)

#define JSSTRDEP_CHARS(str)                                                   \
    (JSSTRING_IS_DEPENDENT(JSSTRDEP_BASE(str))                                \
     ? js_GetDependentStringChars(str)                                        \
     : JSSTRDEP_BASE(str)->chars + JSSTRDEP_START(str))

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

extern jschar *
js_GetDependentStringChars(JSString *str);

extern jschar *
js_GetStringChars(JSString *str);

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

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

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) |                     \