1 /*

     2  * diffhelpers.c - helper routines for mpatch

     3  *

     4  * Copyright 2007 Chris Mason <chris.mason@oracle.com>

     5  *

     6  * This software may be used and distributed according to the terms

     7  * of the GNU General Public License v2, incorporated herein by reference.

     8  */

     9 

    10 #include <Python.h>

    11 #include <stdlib.h>

    12 #include <string.h>

    13 

    14 static char diffhelpers_doc[] = "Efficient diff parsing";

    15 static PyObject *diffhelpers_Error;

    16 

    17 

    18 /* fixup the last lines of a and b when the patch has no newline at eof */

    19 static void _fix_newline(PyObject *hunk, PyObject *a, PyObject *b)

    20 {

    21 	int hunksz = PyList_Size(hunk);

    22 	PyObject *s = PyList_GET_ITEM(hunk, hunksz-1);

    23 	char *l = PyString_AS_STRING(s);

    24 	int sz = PyString_GET_SIZE(s);

    25 	int alen = PyList_Size(a);

    26 	int blen = PyList_Size(b);

    27 	char c = l[0];

    28 

    29 	PyObject *hline = PyString_FromStringAndSize(l, sz-1);

    30 	if (c == ' ' || c == '+') {

    31 		PyObject *rline = PyString_FromStringAndSize(l+1, sz-2);

    32 		PyList_SetItem(b, blen-1, rline);

    33 	}

    34 	if (c == ' ' || c == '-') {

    35 		Py_INCREF(hline);

    36 		PyList_SetItem(a, alen-1, hline);

    37 	}

    38 	PyList_SetItem(hunk, hunksz-1, hline);

    39 }

    40 

    41 /* python callable form of _fix_newline */

    42 static PyObject *

    43 fix_newline(PyObject *self, PyObject *args)

    44 {

    45 	PyObject *hunk, *a, *b;

    46 	if (!PyArg_ParseTuple(args, "OOO", &hunk, &a, &b))

    47 		return NULL;

    48 	_fix_newline(hunk, a, b);

    49 	return Py_BuildValue("l", 0);

    50 }

    51 

    52 /*

    53  * read lines from fp into the hunk.  The hunk is parsed into two arrays

    54  * a and b.  a gets the old state of the text, b gets the new state

    55  * The control char from the hunk is saved when inserting into a, but not b

    56  * (for performance while deleting files)

    57  */

    58 static PyObject *

    59 addlines(PyObject *self, PyObject *args)

    60 {

    61 

    62 	PyObject *fp, *hunk, *a, *b, *x;

    63 	int i;

    64 	int lena, lenb;

    65 	int num;

    66 	int todoa, todob;

    67 	char *s, c;

    68 	PyObject *l;

    69 	if (!PyArg_ParseTuple(args, "OOiiOO", &fp, &hunk, &lena, &lenb, &a, &b))

    70 		return NULL;

    71 

    72 	while(1) {

    73 		todoa = lena - PyList_Size(a);

    74 		todob = lenb - PyList_Size(b);

    75 		num = todoa > todob ? todoa : todob;

    76 		if (num == 0)

    77 		    break;

    78 		for (i = 0 ; i < num ; i++) {

    79 			x = PyFile_GetLine(fp, 0);

    80 			s = PyString_AS_STRING(x);

    81 			c = *s;

    82 			if (strcmp(s, "\\ No newline at end of file\n") == 0) {

    83 				_fix_newline(hunk, a, b);

    84 				continue;

    85 			}

    86 			PyList_Append(hunk, x);

    87 			if (c == '+') {

    88 				l = PyString_FromString(s + 1);

    89 				PyList_Append(b, l);

    90 				Py_DECREF(l);

    91 			} else if (c == '-') {

    92 				PyList_Append(a, x);

    93 			} else {

    94 				l = PyString_FromString(s + 1);

    95 				PyList_Append(b, l);

    96 				Py_DECREF(l);

    97 				PyList_Append(a, x);

    98 			}

    99 			Py_DECREF(x);

   100 		}

   101 	}

   102 	return Py_BuildValue("l", 0);

   103 }

   104 

   105 /*

   106  * compare the lines in a with the lines in b.  a is assumed to have

   107  * a control char at the start of each line, this char is ignored in the

   108  * compare

   109  */

   110 static PyObject *

   111 testhunk(PyObject *self, PyObject *args)

   112 {

   113 

   114 	PyObject *a, *b;

   115 	long bstart;

   116 	int alen, blen;

   117 	int i;

   118 	char *sa, *sb;

   119 

   120 	if (!PyArg_ParseTuple(args, "OOl", &a, &b, &bstart))

   121 		return NULL;

   122 	alen = PyList_Size(a);

   123 	blen = PyList_Size(b);

   124 	if (alen > blen - bstart) {

   125 		return Py_BuildValue("l", -1);

   126 	}

   127 	for (i = 0 ; i < alen ; i++) {

   128 		sa = PyString_AS_STRING(PyList_GET_ITEM(a, i));

   129 		sb = PyString_AS_STRING(PyList_GET_ITEM(b, i + bstart));

   130 		if (strcmp(sa+1, sb) != 0)

   131 			return Py_BuildValue("l", -1);

   132 	}

   133 	return Py_BuildValue("l", 0);

   134 }

   135 

   136 static PyMethodDef methods[] = {

   137 	{"addlines", addlines, METH_VARARGS, "add lines to a hunk\n"},

   138 	{"fix_newline", fix_newline, METH_VARARGS, "fixup newline counters\n"},

   139 	{"testhunk", testhunk, METH_VARARGS, "test lines in a hunk\n"},

   140 	{NULL, NULL}

   141 };

   142 

   143 PyMODINIT_FUNC

   144 initdiffhelpers(void)

   145 {

   146 	Py_InitModule3("diffhelpers", methods, diffhelpers_doc);

   147 	diffhelpers_Error = PyErr_NewException("diffhelpers.diffhelpersError",

   148 	                                        NULL, NULL);

   149 }

   150