• file
• revisions
• annotate
• diff
• comparison
• raw

js/src/ds/Sort.h@129ffea94266 (annotated)

js/src/ds/Sort.h

Sat, 03 Jan 2015 20:18:00 +0100

author

Michael Schloh von Bennewitz <michael@schloh.com>

date

Sat, 03 Jan 2015 20:18:00 +0100

branch

TOR_BUG_3246

changeset 7

129ffea94266

permissions

-rw-r--r--

Conditionally enable double key logic according to:
private browsing mode or privacy.thirdparty.isolate preference and
implement in GetCookieStringCommon and FindCookie where it counts...
With some reservations of how to convince FindCookie users to test
condition and pass a nullptr when disabling double key logic.

michael@0	1	/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
michael@0	2	* vim: set ts=8 sts=4 et sw=4 tw=99:
michael@0	3	* This Source Code Form is subject to the terms of the Mozilla Public
michael@0	4	* License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0	5	* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0	6
michael@0	7	#ifndef ds_Sort_h
michael@0	8	#define ds_Sort_h
michael@0	9
michael@0	10	#include "jstypes.h"
michael@0	11
michael@0	12	namespace js {
michael@0	13
michael@0	14	namespace detail {
michael@0	15
michael@0	16	template<typename T>
michael@0	17	MOZ_ALWAYS_INLINE void
michael@0	18	CopyNonEmptyArray(T *dst, const T *src, size_t nelems)
michael@0	19	{
michael@0	20	JS_ASSERT(nelems != 0);
michael@0	21	const T *end = src + nelems;
michael@0	22	do {
michael@0	23	*dst++ = *src++;
michael@0	24	} while (src != end);
michael@0	25	}
michael@0	26
michael@0	27	/* Helper function for MergeSort. */
michael@0	28	template<typename T, typename Comparator>
michael@0	29	MOZ_ALWAYS_INLINE bool
michael@0	30	MergeArrayRuns(T *dst, const T *src, size_t run1, size_t run2, Comparator c)
michael@0	31	{
michael@0	32	JS_ASSERT(run1 >= 1);
michael@0	33	JS_ASSERT(run2 >= 1);
michael@0	34
michael@0	35	/* Copy runs already in sorted order. */
michael@0	36	const T *b = src + run1;
michael@0	37	bool lessOrEqual;
michael@0	38	if (!c(b[-1], b[0], &lessOrEqual))
michael@0	39	return false;
michael@0	40
michael@0	41	if (!lessOrEqual) {
michael@0	42	/* Runs are not already sorted, merge them. */
michael@0	43	for (const T *a = src;;) {
michael@0	44	if (!c(*a, *b, &lessOrEqual))
michael@0	45	return false;
michael@0	46	if (lessOrEqual) {
michael@0	47	*dst++ = *a++;
michael@0	48	if (!--run1) {
michael@0	49	src = b;
michael@0	50	break;
michael@0	51	}
michael@0	52	} else {
michael@0	53	*dst++ = *b++;
michael@0	54	if (!--run2) {
michael@0	55	src = a;
michael@0	56	break;
michael@0	57	}
michael@0	58	}
michael@0	59	}
michael@0	60	}
michael@0	61	CopyNonEmptyArray(dst, src, run1 + run2);
michael@0	62	return true;
michael@0	63	}
michael@0	64
michael@0	65	} /* namespace detail */
michael@0	66
michael@0	67	/*
michael@0	68	* Sort the array using the merge sort algorithm. The scratch should point to
michael@0	69	* a temporary storage that can hold nelems elements.
michael@0	70	*
michael@0	71	* The comparator must provide the () operator with the following signature:
michael@0	72	*
michael@0	73	* bool operator()(const T& a, const T& a, bool *lessOrEqualp);
michael@0	74	*
michael@0	75	* It should return true on success and set *lessOrEqualp to the result of
michael@0	76	* a <= b operation. If it returns false, the sort terminates immediately with
michael@0	77	* the false result. In this case the content of the array and scratch is
michael@0	78	* arbitrary.
michael@0	79	*/
michael@0	80	template<typename T, typename Comparator>
michael@0	81	bool
michael@0	82	MergeSort(T *array, size_t nelems, T *scratch, Comparator c)
michael@0	83	{
michael@0	84	const size_t INS_SORT_LIMIT = 3;
michael@0	85
michael@0	86	if (nelems <= 1)
michael@0	87	return true;
michael@0	88
michael@0	89	/*
michael@0	90	* Apply insertion sort to small chunks to reduce the number of merge
michael@0	91	* passes needed.
michael@0	92	*/
michael@0	93	for (size_t lo = 0; lo < nelems; lo += INS_SORT_LIMIT) {
michael@0	94	size_t hi = lo + INS_SORT_LIMIT;
michael@0	95	if (hi >= nelems)
michael@0	96	hi = nelems;
michael@0	97	for (size_t i = lo + 1; i != hi; i++) {
michael@0	98	for (size_t j = i; ;) {
michael@0	99	bool lessOrEqual;
michael@0	100	if (!c(array[j - 1], array[j], &lessOrEqual))
michael@0	101	return false;
michael@0	102	if (lessOrEqual)
michael@0	103	break;
michael@0	104	T tmp = array[j - 1];
michael@0	105	array[j - 1] = array[j];
michael@0	106	array[j] = tmp;
michael@0	107	if (--j == lo)
michael@0	108	break;
michael@0	109	}
michael@0	110	}
michael@0	111	}
michael@0	112
michael@0	113	T *vec1 = array;
michael@0	114	T *vec2 = scratch;
michael@0	115	for (size_t run = INS_SORT_LIMIT; run < nelems; run *= 2) {
michael@0	116	for (size_t lo = 0; lo < nelems; lo += 2 * run) {
michael@0	117	size_t hi = lo + run;
michael@0	118	if (hi >= nelems) {
michael@0	119	detail::CopyNonEmptyArray(vec2 + lo, vec1 + lo, nelems - lo);
michael@0	120	break;
michael@0	121	}
michael@0	122	size_t run2 = (run <= nelems - hi) ? run : nelems - hi;
michael@0	123	if (!detail::MergeArrayRuns(vec2 + lo, vec1 + lo, run, run2, c))
michael@0	124	return false;
michael@0	125	}
michael@0	126	T *swap = vec1;
michael@0	127	vec1 = vec2;
michael@0	128	vec2 = swap;
michael@0	129	}
michael@0	130	if (vec1 == scratch)
michael@0	131	detail::CopyNonEmptyArray(array, scratch, nelems);
michael@0	132	return true;
michael@0	133	}
michael@0	134
michael@0	135	} /* namespace js */
michael@0	136
michael@0	137	#endif /* ds_Sort_h */