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 
51 	if (atom->at == NULL) {
52 		off_t remain = atom->len;
53 		if (fseek(atom->root->f, atom->pos, SEEK_SET) == -1)
54 			abort(); /* cannot return error */
55 		while (remain > 0) {
56 			char buf[16];
57 			size_t r;
58 			int i;
59 			r = fread(buf, 1, MIN(remain, sizeof(buf)),
60 			    atom->root->f);
61 			if (r == -1)
62 				abort(); /* cannot return error */
63 			if (r == 0)
64 				break;
65 			remain -= r;
66 			for (i = 0; i < r; i++)
67 				print_atom_byte(buf[i]);
68 		}
69 	} else {
70 		const char *s;
71 		for (s = atom->at; s < (const char*)(atom->at + atom->len); s++)
72 			print_atom_byte(*s);
73 	}
74 	print("'\n");
75 }
76 
77 static inline void
78 dump_atoms(const struct diff_data *d, struct diff_atom *atom,
79 	   unsigned int count)
80 {
81 	if (count > 42) {
82 		dump_atoms(d, atom, 20);
83 		print("[%u lines skipped]\n", count - 20 - 20);
84 		dump_atoms(d, atom + count - 20, 20);
85 		return;
86 	} else {
87 		struct diff_atom *i;
88 		foreach_diff_atom(i, atom, count) {
89 			dump_atom(d, NULL, i);
90 		}
91 	}
92 }
93 
94 static inline void
95 dump(struct diff_data *d)
96 {
97 	dump_atoms(d, d->atoms.head, d->atoms.len);
98 }
99 
100 /* kd is a quadratic space myers matrix from the original Myers algorithm.
101  * kd_forward and kd_backward are linear slices of a myers matrix from the Myers
102  * Divide algorithm.
103  */
104 static inline void
105 dump_myers_graph(const struct diff_data *l, const struct diff_data *r,
106 		 int *kd, int *kd_forward, int kd_forward_d,
107 		 int *kd_backward, int kd_backward_d)
108 {
109 	#define COLOR_YELLOW "\033[1;33m"
110 	#define COLOR_GREEN "\033[1;32m"
111 	#define COLOR_BLUE "\033[1;34m"
112 	#define COLOR_RED "\033[1;31m"
113 	#define COLOR_END "\033[0;m"
114 	int x;
115 	int y;
116 	print("   ");
117 	for (x = 0; x <= l->atoms.len; x++)
118 		print("%2d", x % 100);
119 	print("\n");
120 
121 	for (y = 0; y <= r->atoms.len; y++) {
122 		print("%3d ", y);
123 		for (x = 0; x <= l->atoms.len; x++) {
124 
125 			/* print d advancements from kd, if any. */
126 			char label = 'o';
127 			char *color = NULL;
128 			if (kd) {
129 				int max = l->atoms.len + r->atoms.len;
130 				size_t kd_len = max + 1 + max;
131 				int *kd_pos = kd;
132 				int di;
133 #define xk_to_y(X, K) ((X) - (K))
134 				for (di = 0; di < max; di++) {
135 					int ki;
136 					for (ki = di; ki >= -di; ki -= 2) {
137 						if (x != kd_pos[ki]
138 						    || y != xk_to_y(x, ki))
139 							continue;
140 						label = '0' + (di % 10);
141 						color = COLOR_YELLOW;
142 						break;
143 					}
144 					if (label != 'o')
145 						break;
146 					kd_pos += kd_len;
147 				}
148 			}
149 			if (kd_forward && kd_forward_d >= 0) {
150 #define xc_to_y(X, C, DELTA) ((X) - (C) + (DELTA))
151 				int ki;
152 				for (ki = kd_forward_d;
153 				     ki >= -kd_forward_d;
154 				     ki -= 2) {
155 					if (x != kd_forward[ki])
156 						continue;
157 					if (y != xk_to_y(x, ki))
158 						continue;
159 					label = 'F';
160 					color = COLOR_GREEN;
161 					break;
162 				}
163 			}
164 			if (kd_backward && kd_backward_d >= 0) {
165 				int delta = (int)r->atoms.len
166 					    - (int)l->atoms.len;
167 				int ki;
168 				for (ki = kd_backward_d;
169 				     ki >= -kd_backward_d;
170 				     ki -= 2) {
171 					if (x != kd_backward[ki])
172 						continue;
173 					if (y != xc_to_y(x, ki, delta))
174 						continue;
175 					if (label == 'o') {
176 						label = 'B';
177 						color = COLOR_BLUE;
178 					} else {
179 						label = 'X';
180 						color = COLOR_RED;
181 					}
182 					break;
183 				}
184 			}
185 			if (color)
186 				print("%s", color);
187 			print("%c", label);
188 			if (color)
189 				print("%s", COLOR_END);
190 			if (x < l->atoms.len)
191 				print("-");
192 		}
193 		print("\n");
194 		if (y == r->atoms.len)
195 			break;
196 
197 		print("    ");
198 		for (x = 0; x < l->atoms.len; x++) {
199 			bool same;
200 			diff_atom_same(&same, &l->atoms.head[x],
201 			    &r->atoms.head[y]);
202 			if (same)
203 				print("|\\");
204 			else
205 				print("| ");
206 		}
207 		print("|\n");
208 	}
209 }
210 
211 static inline void
212 debug_dump_myers_graph(const struct diff_data *l, const struct diff_data *r,
213 		       int *kd, int *kd_forward, int kd_forward_d,
214 		       int *kd_backward, int kd_backward_d)
215 {
216 	if (l->atoms.len > 99 || r->atoms.len > 99)
217 		return;
218 	dump_myers_graph(l, r, kd, kd_forward, kd_forward_d,
219 			 kd_backward, kd_backward_d);
220 }
221 
222 #else
223 #define debug(args...)
224 #define debug_dump(args...)
225 #define debug_dump_atom(args...)
226 #define debug_dump_atoms(args...)
227 #define debug_dump_myers_graph(args...)
228 #endif