1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
|
/* Copyright Vladimir Prus 2004. Distributed under the Boost */
/* Software License, Version 1.0. (See accompanying */
/* file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) */
#include "../native.h"
#include "../lists.h"
#include "../strings.h"
#include "../newstr.h"
#include "../variable.h"
/* Use quite klugy approach: when we add order dependency from 'a' to 'b',
just append 'b' to of value of variable 'a'.
*/
LIST *add_pair( PARSE *parse, FRAME *frame )
{
LIST* arg = lol_get( frame->args, 0 );
var_set(arg->string, list_copy(0, arg->next), VAR_APPEND);
return L0;
}
/** Given a list and a value, returns position of that value in
the list, or -1 if not found.
*/
int list_index(LIST* list, const char* value)
{
int result = 0;
for(; list; list = list->next, ++result) {
if (strcmp(list->string, value) == 0)
return result;
}
return -1;
}
enum colors { white, gray, black };
/* Main routite of topological sort. Calls itself recursively on all
adjacent vertices which were not yet visited. After that, 'current_vertex'
is added to '*result_ptr'.
*/
void do_ts(int** graph, int current_vertex, int* colors, int** result_ptr)
{
int i;
colors[current_vertex] = gray;
for(i = 0; graph[current_vertex][i] != -1; ++i) {
int adjacent_vertex = graph[current_vertex][i];
if (colors[adjacent_vertex] == white)
do_ts(graph, adjacent_vertex, colors, result_ptr);
/* The vertex is either black, in which case we don't have to do
anything, a gray, in which case we have a loop. If we have a loop,
it's not clear what useful diagnostic we can emit, so we emit
nothing. */
}
colors[current_vertex] = black;
**result_ptr = current_vertex;
(*result_ptr)++;
}
void topological_sort(int** graph, int num_vertices, int* result)
{
int i;
int* colors = (int*)BJAM_CALLOC(num_vertices, sizeof(int));
for (i = 0; i < num_vertices; ++i)
colors[i] = white;
for(i = 0; i < num_vertices; ++i)
if (colors[i] == white)
do_ts(graph, i, colors, &result);
BJAM_FREE(colors);
}
LIST *order( PARSE *parse, FRAME *frame )
{
LIST* arg = lol_get( frame->args, 0 );
LIST* tmp;
LIST* result = 0;
int src;
/* We need to create a graph of order dependencies between
the passed objects. We assume that there are no duplicates
passed to 'add_pair'.
*/
int length = list_length(arg);
int** graph = (int**)BJAM_CALLOC(length, sizeof(int*));
int* order = (int*)BJAM_MALLOC((length+1)*sizeof(int));
for(tmp = arg, src = 0; tmp; tmp = tmp->next, ++src) {
/* For all object this one depend upon, add elements
to 'graph' */
LIST* dependencies = var_get(tmp->string);
int index = 0;
graph[src] = (int*)BJAM_CALLOC(list_length(dependencies)+1, sizeof(int));
for(; dependencies; dependencies = dependencies->next) {
int dst = list_index(arg, dependencies->string);
if (dst != -1)
graph[src][index++] = dst;
}
graph[src][index] = -1;
}
topological_sort(graph, length, order);
{
int index = length-1;
for(; index >= 0; --index) {
int i;
tmp = arg;
for (i = 0; i < order[index]; ++i, tmp = tmp->next);
result = list_new(result, tmp->string);
}
}
/* Clean up */
{
int i;
for(i = 0; i < length; ++i)
BJAM_FREE(graph[i]);
BJAM_FREE(graph);
BJAM_FREE(order);
}
return result;
}
void init_order()
{
{
char* args[] = { "first", "second", 0 };
declare_native_rule("class@order", "add-pair", args, add_pair, 1);
}
{
char* args[] = { "objects", "*", 0 };
declare_native_rule("class@order", "order", args, order, 1);
}
}
|
