1 /*
2  * Copyright (c) 2020 Neels Hofmeyr <neels@hofmeyr.de>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #define DEBUG 0
18 
19 #if DEBUG
20 #include <stdio.h>
21 #include <unistd.h>
22 #define print(args...) fprintf(stderr, ##args)
23 #define debug print
24 #define debug_dump dump
25 #define debug_dump_atom dump_atom
26 #define debug_dump_atoms dump_atoms
27 
28 static inline void
29 print_atom_byte(unsigned char c) {
30 	if (c == '\r')
31 		print("\\r");
32 	else if (c == '\n')
33 		print("\\n");
34 	else if ((c < 32 || c >= 127) && (c != '\t'))
35 		print("\\x%02x", c);
36 	else
37 		print("%c", c);
38 }
39 
40 static inline void
41 dump_atom(const struct diff_data *left, const struct diff_data *right,
42 	  const struct diff_atom *atom)
43 {
44 	if (!atom) {
45 		print("NULL atom\n");
46 		return;
47 	}
48 	if (left)
49 		print(" %3u", diff_atom_root_idx(left, atom));
50 	if (right && atom->patience.pos_in_other)
51 		print(" %3u",
52 		      diff_atom_root_idx(right, atom->patience.pos_in_other));
53 
54 	print(" %s%s '",
55 	      atom->patience.unique_in_both ? "u" : " ");
56 	if (atom->at == NULL) {
57 		off_t remain = atom->len;
58 		if (fseek(atom->d->root->f, atom->pos, SEEK_SET) == -1)
59 			abort(); /* cannot return error */
60 		while (remain > 0) {
61 			char buf[16];
62 			size_t r;
63 			int i;
64 			r = fread(buf, 1, MIN(remain, sizeof(buf)),
65 			    atom->d->root->f);
66 			if (r == -1)
67 				abort(); /* cannot return error */
68 			if (r == 0)
69 				break;
70 			remain -= r;
71 			for (i = 0; i < r; i++)
72 				print_atom_byte(buf[i]);
73 		}
74 	} else {
75 		const char *s;
76 		for (s = atom->at; s < (const char*)(atom->at + atom->len); s++)
77 			print_atom_byte(*s);
78 	}
79 	print("'\n");
80 }
81 
82 static inline void
83 dump_atoms(const struct diff_data *d, struct diff_atom *atom,
84 	   unsigned int count)
85 {
86 	if (count > 42) {
87 		dump_atoms(d, atom, 20);
88 		print("[%u lines skipped]\n", count - 20 - 20);
89 		dump_atoms(d, atom + count - 20, 20);
90 		return;
91 	} else {
92 		struct diff_atom *i;
93 		foreach_diff_atom(i, atom, count) {
94 			dump_atom(d, NULL, i);
95 		}
96 	}
97 }
98 
99 static inline void
100 dump(struct diff_data *d)
101 {
102 	dump_atoms(d, d->atoms.head, d->atoms.len);
103 }
104 
105 /* kd is a quadratic space myers matrix from the original Myers algorithm.
106  * kd_forward and kd_backward are linear slices of a myers matrix from the Myers
107  * Divide algorithm.
108  */
109 static inline void
110 dump_myers_graph(const struct diff_data *l, const struct diff_data *r,
111 		 int *kd, int *kd_forward, int kd_forward_d,
112 		 int *kd_backward, int kd_backward_d)
113 {
114 	#define COLOR_YELLOW "\033[1;33m"
115 	#define COLOR_GREEN "\033[1;32m"
116 	#define COLOR_BLUE "\033[1;34m"
117 	#define COLOR_RED "\033[1;31m"
118 	#define COLOR_END "\033[0;m"
119 	int x;
120 	int y;
121 	print("   ");
122 	for (x = 0; x <= l->atoms.len; x++)
123 		print("%2d", x % 100);
124 	print("\n");
125 
126 	for (y = 0; y <= r->atoms.len; y++) {
127 		print("%3d ", y);
128 		for (x = 0; x <= l->atoms.len; x++) {
129 
130 			/* print d advancements from kd, if any. */
131 			char label = 'o';
132 			char *color = NULL;
133 			if (kd) {
134 				int max = l->atoms.len + r->atoms.len;
135 				size_t kd_len = max + 1 + max;
136 				int *kd_pos = kd;
137 				int di;
138 #define xk_to_y(X, K) ((X) - (K))
139 				for (di = 0; di < max; di++) {
140 					int ki;
141 					for (ki = di; ki >= -di; ki -= 2) {
142 						if (x != kd_pos[ki]
143 						    || y != xk_to_y(x, ki))
144 							continue;
145 						label = '0' + (di % 10);
146 						color = COLOR_YELLOW;
147 						break;
148 					}
149 					if (label != 'o')
150 						break;
151 					kd_pos += kd_len;
152 				}
153 			}
154 			if (kd_forward && kd_forward_d >= 0) {
155 #define xc_to_y(X, C, DELTA) ((X) - (C) + (DELTA))
156 				int ki;
157 				for (ki = kd_forward_d;
158 				     ki >= -kd_forward_d;
159 				     ki -= 2) {
160 					if (x != kd_forward[ki])
161 						continue;
162 					if (y != xk_to_y(x, ki))
163 						continue;
164 					label = 'F';
165 					color = COLOR_GREEN;
166 					break;
167 				}
168 			}
169 			if (kd_backward && kd_backward_d >= 0) {
170 				int delta = (int)r->atoms.len
171 					    - (int)l->atoms.len;
172 				int ki;
173 				for (ki = kd_backward_d;
174 				     ki >= -kd_backward_d;
175 				     ki -= 2) {
176 					if (x != kd_backward[ki])
177 						continue;
178 					if (y != xc_to_y(x, ki, delta))
179 						continue;
180 					if (label == 'o') {
181 						label = 'B';
182 						color = COLOR_BLUE;
183 					} else {
184 						label = 'X';
185 						color = COLOR_RED;
186 					}
187 					break;
188 				}
189 			}
190 			if (color)
191 				print("%s", color);
192 			print("%c", label);
193 			if (color)
194 				print("%s", COLOR_END);
195 			if (x < l->atoms.len)
196 				print("-");
197 		}
198 		print("\n");
199 		if (y == r->atoms.len)
200 			break;
201 
202 		print("    ");
203 		for (x = 0; x < l->atoms.len; x++) {
204 			bool same;
205 			diff_atom_same(&same, &l->atoms.head[x],
206 			    &r->atoms.head[y]);
207 			if (same)
208 				print("|\\");
209 			else
210 				print("| ");
211 		}
212 		print("|\n");
213 	}
214 }
215 
216 static inline void
217 debug_dump_myers_graph(const struct diff_data *l, const struct diff_data *r,
218 		       int *kd, int *kd_forward, int kd_forward_d,
219 		       int *kd_backward, int kd_backward_d)
220 {
221 	if (l->atoms.len > 99 || r->atoms.len > 99)
222 		return;
223 	dump_myers_graph(l, r, kd, kd_forward, kd_forward_d,
224 			 kd_backward, kd_backward_d);
225 }
226 
227 #else
228 #define debug(args...)
229 #define debug_dump(args...)
230 #define debug_dump_atom(args...)
231 #define debug_dump_atoms(args...)
232 #define debug_dump_myers_graph(args...)
233 #endif