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
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
|
/* ISC license. */
#include <string.h>
#include <skalibs/allreadwrite.h>
#include <skalibs/types.h>
#include <skalibs/strerr2.h>
#define USAGE "s6-expr arithmetic expression"
#define bail() strerr_dief1x(2, "invalid expression")
enum opnum
{
T_DATA,
T_AND,
T_OR,
T_LEFTP,
T_RIGHTP,
T_EQUAL,
T_NEQUAL,
T_GREATER,
T_GREATERE,
T_LESSER,
T_LESSERE,
T_PLUS,
T_MINUS,
T_TIMES,
T_DIV,
T_MOD
} ;
struct token
{
char const *string ;
enum opnum op ;
unsigned int type ;
} ;
struct node
{
enum opnum op ;
unsigned int type ;
unsigned int arg1 ;
unsigned int arg2 ;
long data ;
} ;
static unsigned int lex (struct node *tree, char const *const *argv)
{
static struct token const tokens[16] =
{
{ "+", T_PLUS, 3 },
{ "-", T_MINUS, 3 },
{ "*", T_TIMES, 2 },
{ "/", T_DIV, 2 },
{ "%", T_MOD, 2 },
{ "(", T_LEFTP, 7 },
{ ")", T_RIGHTP, 8 },
{ "=", T_EQUAL, 4 },
{ "!=", T_NEQUAL, 4 },
{ "<", T_LESSER, 4 },
{ "<=", T_LESSERE, 4 },
{ ">", T_GREATER, 4 },
{ ">=", T_GREATERE, 4 },
{ "|", T_OR, 6 },
{ "&", T_AND, 5 },
{ 0, 0, 0 }
} ;
unsigned int pos = 0 ;
for (; argv[pos] ; pos++)
{
unsigned int i = 0 ;
for (i = 0 ; tokens[i].string ; i++)
if (!strcmp(argv[pos], tokens[i].string))
{
tree[pos].op = tokens[i].op ;
tree[pos].type = tokens[i].type ;
break ;
}
if (!tokens[i].string)
{
tree[pos].op = T_DATA ;
tree[pos].type = 0 ;
if (!long_scan(argv[pos], &tree[pos].data)) bail() ;
}
}
return pos ;
}
static void reduce (struct node *tree, unsigned int *stack, unsigned int *sp, unsigned int type)
{
if (tree[stack[*sp-1]].type == type)
{
tree[stack[*sp-1]].arg1 = stack[*sp-2] ;
tree[stack[*sp-1]].arg2 = stack[*sp] ;
stack[*sp-2] = stack[*sp-1] ;
*sp -= 2 ;
}
tree[stack[*sp]].type = type + 7 ;
}
static unsigned int parse (struct node *tree, unsigned int n)
{
static char const table[9][15] =
{
"xsssssssxzzzzzz",
"xxxxxxxx!zzzzzz",
"mxxxxxxxMszzzzz",
"mxxxxxxxMaszzzz",
"mxxxxxxxMacszzz",
"mxxxxxxxMacAszz",
"mxxxxxxxMacAOsz",
"xsssssssxzzzzzz",
"mxxxxxxxMacAOEs"
} ;
unsigned int stack[n] ;
unsigned int sp = 0, pos = 0 ;
char cont = 1 ;
stack[0] = n + 1 ;
tree[n].type = 8 ; /* add ) for the final reduce */
tree[n+1].type = 1 ; /* add EOF */
while (cont)
{
switch (table[tree[pos].type][tree[stack[sp]].type])
{
case 'x' : bail() ;
case '!' : cont = 0 ; break ;
case 's' : stack[++sp] = pos++ ; break ;
case 'M' :
if (tree[stack[sp-2]].type != 7) bail() ;
stack[sp-2] = stack[sp-1] ;
sp -= 2 ;
case 'm' : reduce(tree, stack, &sp, 2) ; break ;
case 'a' : reduce(tree, stack, &sp, 3) ; break ;
case 'c' : reduce(tree, stack, &sp, 4) ; break ;
case 'A' : reduce(tree, stack, &sp, 5) ; break ;
case 'O' : reduce(tree, stack, &sp, 6) ; break ;
case 'E' : tree[stack[sp]].type = 14 ; break ;
case 'z' :
default : strerr_dief1x(101, "internal error in parse, please submit a bug-report.") ; /* can't happen */
}
}
if (sp != 2) bail() ;
return stack[1] ;
}
static long run (struct node const *tree, unsigned int root)
{
switch (tree[root].op)
{
case T_DATA :
return tree[root].data ;
case T_OR :
{
long r = run(tree, tree[root].arg1) ;
return r ? r : run(tree, tree[root].arg2) ;
}
case T_AND :
{
long r = run(tree, tree[root].arg1) ;
return r ? run(tree, tree[root].arg2) ? r : 0 : 0 ;
}
case T_EQUAL :
return run(tree, tree[root].arg1) == run(tree, tree[root].arg2) ;
case T_NEQUAL :
return run(tree, tree[root].arg1) != run(tree, tree[root].arg2) ;
case T_GREATER :
return run(tree, tree[root].arg1) > run(tree, tree[root].arg2) ;
case T_GREATERE :
return run(tree, tree[root].arg1) >= run(tree, tree[root].arg2) ;
case T_LESSER :
return run(tree, tree[root].arg1) < run(tree, tree[root].arg2) ;
case T_LESSERE :
return run(tree, tree[root].arg1) <= run(tree, tree[root].arg2) ;
case T_PLUS :
return run(tree, tree[root].arg1) + run(tree, tree[root].arg2) ;
case T_MINUS :
return run(tree, tree[root].arg1) - run(tree, tree[root].arg2) ;
case T_TIMES :
return run(tree, tree[root].arg1) * run(tree, tree[root].arg2) ;
case T_DIV :
return run(tree, tree[root].arg1) / run(tree, tree[root].arg2) ;
case T_MOD :
return run(tree, tree[root].arg1) % run(tree, tree[root].arg2) ;
default : strerr_dief1x(101, "internal error in run, please submit a bug-report") ;
}
}
int main (int argc, char const *const *argv)
{
char fmt[LONG_FMT] ;
long val ;
size_t len ;
PROG = "s6-expr" ;
if (argc <= 1) return 2 ;
{
struct node tree[argc + 1] ;
val = run(tree, parse(tree, lex(tree, argv+1))) ;
}
len = long_fmt(fmt, val) ;
fmt[len++] = '\n' ;
if (allwrite(1, fmt, len) < len)
strerr_diefu1sys(111, "write to stdout") ;
return !val ;
}
|
