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
|
#include <stdio.h>
#include <string.h>
#include "ast.h"
static const int precedence[ATOM_MAX] = {
[ATOM_ALPHABETIC] = 1,
[ATOM_NUMERIC] = 1,
[ATOM_UPPERCASE] = 1,
[ATOM_LOWERCASE] = 1,
[ATOM_CONTROL] = 1,
[ATOM_PUNCTUATION] = 1,
[ATOM_EVERYTHING] = 1,
[ATOM_REPETITION] = 2,
[ATOM_SEQUENCE] = 3,
[ATOM_LITERAL] = 3,
[ATOM_ALTERNATION] = 4,
};
static void print_repeat(const struct repeat *r)
{
if (r->max < 0) {
switch (r->min) {
case 0: printf("*"); break;
case 1: printf("+"); break;
default: printf("{%ld,}", r->min); break;
}
} else if (r->min == 0 && r->max == 1) {
printf("?");
} else if (r->min == r->max) {
printf("{%ld}", r->min);
} else {
printf("{%ld,%ld}", r->min, r->max);
}
}
static void print_literal(const char *s)
{
for (; *s; s++) {
switch (*s) {
case '.':
case '[':
case '{':
case '}':
case '(':
case ')':
case '\\':
case '*':
case '+':
case '?':
case '|':
case '^':
case '$':
putchar('\\');
default:
putchar(*s);
}
}
}
static int get_precedence(const struct atom *a)
{
const struct repeat *r;
switch (a->type) {
case ATOM_LITERAL:
switch (strlen(a->u.literal)) {
case 0: return -1;
case 1: return precedence[ATOM_EVERYTHING];
default: return precedence[ATOM_SEQUENCE];
}
case ATOM_REPETITION:
r = &a->u.repeat.counts;
if (r->min == 1 && r->max == 1)
return get_precedence(a->u.repeat.child);
break;
}
return precedence[a->type];
}
static void print_atom(const struct atom *a);
static void print_child_atom(const struct atom *child, const struct atom *parent)
{
int group = get_precedence(child) > get_precedence(parent);
if (group) printf("(");
print_atom(child);
if (group) printf(")");
}
static void print_atom(const struct atom *a)
{
const struct repeat *r;
switch (a->type) {
case ATOM_ALTERNATION:
print_child_atom(a->u.children[0], a);
printf("|");
print_child_atom(a->u.children[1], a);
break;
case ATOM_SEQUENCE:
print_child_atom(a->u.children[0], a);
print_child_atom(a->u.children[1], a);
break;
case ATOM_REPETITION:
r = &a->u.repeat.counts;
if (r->min == 1 && r->max == 1) {
print_atom(a->u.repeat.child);
} else {
print_child_atom(a->u.repeat.child, a);
print_repeat(r);
}
break;
case ATOM_LITERAL:
print_literal(a->u.literal);
break;
case ATOM_ALPHABETIC: printf("[:alpha:]"); break;
case ATOM_NUMERIC: printf("[:digit:]"); break;
case ATOM_UPPERCASE: printf("[:upper:]"); break;
case ATOM_LOWERCASE: printf("[:lower:]"); break;
case ATOM_CONTROL: printf("[:cntrl:]"); break;
case ATOM_PUNCTUATION: printf("[:punct:]"); break;
case ATOM_EVERYTHING: printf("."); break;
}
}
void print_regex(const struct atom *a)
{
printf("^");
print_atom(a);
printf("$\n");
}
|
