mercurial/bdiff_module.c

color: add a 'ui.color' option to control color behavior

This new option control whether or not color will be used. It mirror the behavior
of '--color'. I usually avoid adding new option to '[ui]' as the section is
already filled with many option. However, I feel like 'color' is central enough
to deserves a spot in this '[ui]' section.

For now the option is not documented so it is still marked as experimental. Once
it get documented and official, we should be able to deprecate the color
extensions.

There is more cleanup to do before that documentation is written, but we need
this option early to made them. Having that option will allow for more cleanup
of the initialisation process and proper separation between color
configuration.

/*
 bdiff.c - efficient binary diff extension for Mercurial

 Copyright 2005, 2006 Matt Mackall <[e-mail]>

 This software may be used and distributed according to the terms of
 the GNU General Public License, incorporated herein by reference.

 Based roughly on Python difflib
*/

#define PY_SSIZE_T_CLEAN
#include <Python.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>

#include "bdiff.h"
#include "bitmanipulation.h"
#include "util.h"


static PyObject *blocks(PyObject *self, PyObject *args)
{
	PyObject *sa, *sb, *rl = NULL, *m;
	struct bdiff_line *a, *b;
	struct bdiff_hunk l, *h;
	int an, bn, count, pos = 0;

	l.next = NULL;

	if (!PyArg_ParseTuple(args, "SS:bdiff", &sa, &sb))
		return NULL;

	an = bdiff_splitlines(PyBytes_AsString(sa), PyBytes_Size(sa), &a);
	bn = bdiff_splitlines(PyBytes_AsString(sb), PyBytes_Size(sb), &b);

	if (!a || !b)
		goto nomem;

	count = bdiff_diff(a, an, b, bn, &l);
	if (count < 0)
		goto nomem;

	rl = PyList_New(count);
	if (!rl)
		goto nomem;

	for (h = l.next; h; h = h->next) {
		m = Py_BuildValue("iiii", h->a1, h->a2, h->b1, h->b2);
		PyList_SetItem(rl, pos, m);
		pos++;
	}

nomem:
	free(a);
	free(b);
	bdiff_freehunks(l.next);
	return rl ? rl : PyErr_NoMemory();
}

static PyObject *bdiff(PyObject *self, PyObject *args)
{
	char *sa, *sb, *rb, *ia, *ib;
	PyObject *result = NULL;
	struct bdiff_line *al, *bl;
	struct bdiff_hunk l, *h;
	int an, bn, count;
	Py_ssize_t len = 0, la, lb, li = 0, lcommon = 0, lmax;
	PyThreadState *_save;

	l.next = NULL;

	if (!PyArg_ParseTuple(args, "s#s#:bdiff", &sa, &la, &sb, &lb))
		return NULL;

	if (la > UINT_MAX || lb > UINT_MAX) {
		PyErr_SetString(PyExc_ValueError, "bdiff inputs too large");
		return NULL;
	}

	_save = PyEval_SaveThread();

	lmax = la > lb ? lb : la;
	for (ia = sa, ib = sb;
	     li < lmax && *ia == *ib;
	     ++li, ++ia, ++ib)
		if (*ia == '\n')
			lcommon = li + 1;
	/* we can almost add: if (li == lmax) lcommon = li; */

	an = bdiff_splitlines(sa + lcommon, la - lcommon, &al);
	bn = bdiff_splitlines(sb + lcommon, lb - lcommon, &bl);
	if (!al || !bl)
		goto nomem;

	count = bdiff_diff(al, an, bl, bn, &l);
	if (count < 0)
		goto nomem;

	/* calculate length of output */
	la = lb = 0;
	for (h = l.next; h; h = h->next) {
		if (h->a1 != la || h->b1 != lb)
			len += 12 + bl[h->b1].l - bl[lb].l;
		la = h->a2;
		lb = h->b2;
	}
	PyEval_RestoreThread(_save);
	_save = NULL;

	result = PyBytes_FromStringAndSize(NULL, len);

	if (!result)
		goto nomem;

	/* build binary patch */
	rb = PyBytes_AsString(result);
	la = lb = 0;

	for (h = l.next; h; h = h->next) {
		if (h->a1 != la || h->b1 != lb) {
			len = bl[h->b1].l - bl[lb].l;
			putbe32((uint32_t)(al[la].l + lcommon - al->l), rb);
			putbe32((uint32_t)(al[h->a1].l + lcommon - al->l), rb + 4);
			putbe32((uint32_t)len, rb + 8);
			memcpy(rb + 12, bl[lb].l, len);
			rb += 12 + len;
		}
		la = h->a2;
		lb = h->b2;
	}

nomem:
	if (_save)
		PyEval_RestoreThread(_save);
	free(al);
	free(bl);
	bdiff_freehunks(l.next);
	return result ? result : PyErr_NoMemory();
}

/*
 * If allws != 0, remove all whitespace (' ', \t and \r). Otherwise,
 * reduce whitespace sequences to a single space and trim remaining whitespace
 * from end of lines.
 */
static PyObject *fixws(PyObject *self, PyObject *args)
{
	PyObject *s, *result = NULL;
	char allws, c;
	const char *r;
	Py_ssize_t i, rlen, wlen = 0;
	char *w;

	if (!PyArg_ParseTuple(args, "Sb:fixws", &s, &allws))
		return NULL;
	r = PyBytes_AsString(s);
	rlen = PyBytes_Size(s);

	w = (char *)malloc(rlen ? rlen : 1);
	if (!w)
		goto nomem;

	for (i = 0; i != rlen; i++) {
		c = r[i];
		if (c == ' ' || c == '\t' || c == '\r') {
			if (!allws && (wlen == 0 || w[wlen - 1] != ' '))
				w[wlen++] = ' ';
		} else if (c == '\n' && !allws
			  && wlen > 0 && w[wlen - 1] == ' ') {
			w[wlen - 1] = '\n';
		} else {
			w[wlen++] = c;
		}
	}

	result = PyBytes_FromStringAndSize(w, wlen);

nomem:
	free(w);
	return result ? result : PyErr_NoMemory();
}


static char mdiff_doc[] = "Efficient binary diff.";

static PyMethodDef methods[] = {
	{"bdiff", bdiff, METH_VARARGS, "calculate a binary diff\n"},
	{"blocks", blocks, METH_VARARGS, "find a list of matching lines\n"},
	{"fixws", fixws, METH_VARARGS, "normalize diff whitespaces\n"},
	{NULL, NULL}
};

#ifdef IS_PY3K
static struct PyModuleDef bdiff_module = {
	PyModuleDef_HEAD_INIT,
	"bdiff",
	mdiff_doc,
	-1,
	methods
};

PyMODINIT_FUNC PyInit_bdiff(void)
{
	return PyModule_Create(&bdiff_module);
}
#else
PyMODINIT_FUNC initbdiff(void)
{
	Py_InitModule3("bdiff", methods, mdiff_doc);
}
#endif