neovim

xhistogram.c (9639B)

---

/*
* Copyright (C) 2010, Google Inc.
* and other copyright owners as documented in JGit's IP log.
*
* This program and the accompanying materials are made available
* under the terms of the Eclipse Distribution License v1.0 which
* accompanies this distribution, is reproduced below, and is
* available at http://www.eclipse.org/org/documents/edl-v10.php
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
*
* - Redistributions of source code must retain the above copyright
*   notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above
*   copyright notice, this list of conditions and the following
*   disclaimer in the documentation and/or other materials provided
*   with the distribution.
*
* - Neither the name of the Eclipse Foundation, Inc. nor the
*   names of its contributors may be used to endorse or promote
*   products derived from this software without specific prior
*   written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

#include "xinclude.h"

#define MAX_PTR	INT_MAX
#define MAX_CNT	INT_MAX

#define LINE_END(n) (line##n + count##n - 1)
#define LINE_END_PTR(n) (*line##n + *count##n - 1)

struct histindex {
struct record {
	unsigned int ptr, cnt;
	struct record *next;
} **records, /* an occurrence */
  **line_map; /* map of line to record chain */
chastore_t rcha;
unsigned int *next_ptrs;
unsigned int table_bits,
	     records_size,
	     line_map_size;

unsigned int max_chain_length,
	     key_shift,
	     ptr_shift;

unsigned int cnt,
	     has_common;

xdfenv_t *env;
xpparam_t const *xpp;
};

struct region {
unsigned int begin1, end1;
unsigned int begin2, end2;
};

#define LINE_MAP(i, a) (i->line_map[(a) - i->ptr_shift])

#define NEXT_PTR(index, ptr) \
(index->next_ptrs[(ptr) - index->ptr_shift])

#define CNT(index, ptr) \
((LINE_MAP(index, ptr))->cnt)

#define REC(env, s, l) \
(env->xdf##s.recs[l - 1])

static int cmp_recs(xpparam_t const *xpp,
xrecord_t *r1, xrecord_t *r2)
{
return r1->ha == r2->ha &&
	xdl_recmatch(r1->ptr, r1->size, r2->ptr, r2->size,
		    xpp->flags);
}

#define CMP_ENV(xpp, env, s1, l1, s2, l2) \
(cmp_recs(xpp, REC(env, s1, l1), REC(env, s2, l2)))

#define CMP(i, s1, l1, s2, l2) \
(cmp_recs(i->xpp, REC(i->env, s1, l1), REC(i->env, s2, l2)))

#define TABLE_HASH(index, side, line) \
XDL_HASHLONG((REC(index->env, side, line))->ha, index->table_bits)

static int scanA(struct histindex *index, int line1, int count1)
{
int ptr, tbl_idx;
unsigned int chain_len;
struct record **rec_chain, *rec;

for (ptr = LINE_END(1); line1 <= ptr; ptr--) {
	tbl_idx = TABLE_HASH(index, 1, ptr);
	rec_chain = index->records + tbl_idx;
	rec = *rec_chain;

	chain_len = 0;
	while (rec) {
		if (CMP(index, 1, rec->ptr, 1, ptr)) {
			/*
			 * ptr is identical to another element. Insert
			 * it onto the front of the existing element
			 * chain.
			 */
			NEXT_PTR(index, ptr) = rec->ptr;
			rec->ptr = ptr;
			/* cap rec->cnt at MAX_CNT */
			rec->cnt = XDL_MIN(MAX_CNT, rec->cnt + 1);
			LINE_MAP(index, ptr) = rec;
			goto continue_scan;
		}

		rec = rec->next;
		chain_len++;
	}

	if (chain_len == index->max_chain_length)
		return -1;

	/*
	 * This is the first time we have ever seen this particular
	 * element in the sequence. Construct a new chain for it.
	 */
	if (!(rec = xdl_cha_alloc(&index->rcha)))
		return -1;
	rec->ptr = ptr;
	rec->cnt = 1;
	rec->next = *rec_chain;
	*rec_chain = rec;
	LINE_MAP(index, ptr) = rec;

continue_scan:
	; /* no op */
}

return 0;
}

static int try_lcs(struct histindex *index, struct region *lcs, int b_ptr,
int line1, int count1, int line2, int count2)
{
unsigned int b_next = b_ptr + 1;
struct record *rec = index->records[TABLE_HASH(index, 2, b_ptr)];
unsigned int as, ae, bs, be, np, rc;
int should_break;

for (; rec; rec = rec->next) {
	if (rec->cnt > index->cnt) {
		if (!index->has_common)
			index->has_common = CMP(index, 1, rec->ptr, 2, b_ptr);
		continue;
	}

	as = rec->ptr;
	if (!CMP(index, 1, as, 2, b_ptr))
		continue;

	index->has_common = 1;
	for (;;) {
		should_break = 0;
		np = NEXT_PTR(index, as);
		bs = b_ptr;
		ae = as;
		be = bs;
		rc = rec->cnt;

		while (line1 < (int)as && line2 < (int)bs
			&& CMP(index, 1, as - 1, 2, bs - 1)) {
			as--;
			bs--;
			if (1 < rc)
				rc = XDL_MIN(rc, CNT(index, as));
		}
		while ((int)ae < LINE_END(1) && (int)be < LINE_END(2)
			&& CMP(index, 1, ae + 1, 2, be + 1)) {
			ae++;
			be++;
			if (1 < rc)
				rc = XDL_MIN(rc, CNT(index, ae));
		}

		if (b_next <= be)
			b_next = be + 1;
		if (lcs->end1 - lcs->begin1 < ae - as || rc < index->cnt) {
			lcs->begin1 = as;
			lcs->begin2 = bs;
			lcs->end1 = ae;
			lcs->end2 = be;
			index->cnt = rc;
		}

		if (np == 0)
			break;

		while (np <= ae) {
			np = NEXT_PTR(index, np);
			if (np == 0) {
				should_break = 1;
				break;
			}
		}

		if (should_break)
			break;

		as = np;
	}
}
return b_next;
}

static int fall_back_to_classic_diff(xpparam_t const *xpp, xdfenv_t *env,
	int line1, int count1, int line2, int count2)
{
xpparam_t xpparam;

memset(&xpparam, 0, sizeof(xpparam));
xpparam.flags = xpp->flags & ~XDF_DIFF_ALGORITHM_MASK;

return xdl_fall_back_diff(env, &xpparam,
			  line1, count1, line2, count2);
}

static inline void free_index(struct histindex *index)
{
xdl_free(index->records);
xdl_free(index->line_map);
xdl_free(index->next_ptrs);
xdl_cha_free(&index->rcha);
}

static int find_lcs(xpparam_t const *xpp, xdfenv_t *env,
	    struct region *lcs,
	    int line1, int count1, int line2, int count2)
{
int b_ptr;
int sz, ret = -1;
struct histindex index;

memset(&index, 0, sizeof(index));

index.env = env;
index.xpp = xpp;

index.records = NULL;
index.line_map = NULL;
/* in case of early xdl_cha_free() */
index.rcha.head = NULL;

index.table_bits = xdl_hashbits(count1);
sz = index.records_size = 1 << index.table_bits;
sz *= sizeof(struct record *);
if (!(index.records = (struct record **) xdl_malloc(sz)))
	goto cleanup;
memset(index.records, 0, sz);

sz = index.line_map_size = count1;
sz *= sizeof(struct record *);
if (!(index.line_map = (struct record **) xdl_malloc(sz)))
	goto cleanup;
memset(index.line_map, 0, sz);

sz = index.line_map_size;
sz *= sizeof(unsigned int);
if (!(index.next_ptrs = (unsigned int *) xdl_malloc(sz)))
	goto cleanup;
memset(index.next_ptrs, 0, sz);

/* lines / 4 + 1 comes from xprepare.c:xdl_prepare_ctx() */
if (xdl_cha_init(&index.rcha, sizeof(struct record), count1 / 4 + 1) < 0)
	goto cleanup;

index.ptr_shift = line1;
index.max_chain_length = 64;

if (scanA(&index, line1, count1))
	goto cleanup;

index.cnt = index.max_chain_length + 1;

for (b_ptr = line2; b_ptr <= LINE_END(2); )
	b_ptr = try_lcs(&index, lcs, b_ptr, line1, count1, line2, count2);

if (index.has_common && index.max_chain_length < index.cnt)
	ret = 1;
else
	ret = 0;

cleanup:
free_index(&index);
return ret;
}

static int histogram_diff(xpparam_t const *xpp, xdfenv_t *env,
int line1, int count1, int line2, int count2)
{
struct region lcs;
int lcs_found;
int result;
redo:
result = -1;

if (count1 <= 0 && count2 <= 0)
	return 0;

if (LINE_END(1) >= MAX_PTR)
	return -1;

if (!count1) {
	while(count2--)
		env->xdf2.rchg[line2++ - 1] = 1;
	return 0;
} else if (!count2) {
	while(count1--)
		env->xdf1.rchg[line1++ - 1] = 1;
	return 0;
}

memset(&lcs, 0, sizeof(lcs));
lcs_found = find_lcs(xpp, env, &lcs, line1, count1, line2, count2);
if (lcs_found < 0)
	goto out;
else if (lcs_found)
	result = fall_back_to_classic_diff(xpp, env, line1, count1, line2, count2);
else {
	if (lcs.begin1 == 0 && lcs.begin2 == 0) {
		while (count1--)
			env->xdf1.rchg[line1++ - 1] = 1;
		while (count2--)
			env->xdf2.rchg[line2++ - 1] = 1;
		result = 0;
	} else {
		result = histogram_diff(xpp, env,
					line1, lcs.begin1 - line1,
					line2, lcs.begin2 - line2);
		if (result)
			goto out;
		/*
		 * result = histogram_diff(xpp, env,
		 *            lcs.end1 + 1, LINE_END(1) - lcs.end1,
		 *            lcs.end2 + 1, LINE_END(2) - lcs.end2);
		 * but let's optimize tail recursion ourself:
		*/
		count1 = LINE_END(1) - lcs.end1;
		line1 = lcs.end1 + 1;
		count2 = LINE_END(2) - lcs.end2;
		line2 = lcs.end2 + 1;
		goto redo;
	}
}
out:
return result;
}

int xdl_do_histogram_diff(mmfile_t *file1, mmfile_t *file2,
xpparam_t const *xpp, xdfenv_t *env)
{
if (xdl_prepare_env(file1, file2, xpp, env) < 0)
	return -1;

return histogram_diff(xpp, env,
	env->xdf1.dstart + 1, env->xdf1.dend - env->xdf1.dstart + 1,
	env->xdf2.dstart + 1, env->xdf2.dend - env->xdf2.dstart + 1);
}