/
arith.go
202 lines (193 loc) · 3.79 KB
/
arith.go
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
// Copyright (c) 2017, Daniel Martí <mvdan@mvdan.cc>
// See LICENSE for licensing information
package expand
import (
"fmt"
"strconv"
"mvdan.cc/sh/syntax"
)
func Arithm(cfg *Config, expr syntax.ArithmExpr) (int, error) {
switch x := expr.(type) {
case *syntax.Word:
str, err := Literal(cfg, x)
if err != nil {
return 0, err
}
// recursively fetch vars
i := 0
for str != "" && syntax.ValidName(str) {
val := cfg.envGet(str)
if val == "" {
break
}
if i++; i >= maxNameRefDepth {
break
}
str = val
}
// default to 0
return atoi(str), nil
case *syntax.ParenArithm:
return Arithm(cfg, x.X)
case *syntax.UnaryArithm:
switch x.Op {
case syntax.Inc, syntax.Dec:
name := x.X.(*syntax.Word).Lit()
old := atoi(cfg.envGet(name))
val := old
if x.Op == syntax.Inc {
val++
} else {
val--
}
cfg.envSet(name, strconv.Itoa(val))
if x.Post {
return old, nil
}
return val, nil
}
val, err := Arithm(cfg, x.X)
if err != nil {
return 0, err
}
switch x.Op {
case syntax.Not:
return oneIf(val == 0), nil
case syntax.Plus:
return val, nil
default: // syntax.Minus
return -val, nil
}
case *syntax.BinaryArithm:
switch x.Op {
case syntax.Assgn, syntax.AddAssgn, syntax.SubAssgn,
syntax.MulAssgn, syntax.QuoAssgn, syntax.RemAssgn,
syntax.AndAssgn, syntax.OrAssgn, syntax.XorAssgn,
syntax.ShlAssgn, syntax.ShrAssgn:
return cfg.assgnArit(x)
case syntax.Quest: // Colon can't happen here
cond, err := Arithm(cfg, x.X)
if err != nil {
return 0, err
}
b2 := x.Y.(*syntax.BinaryArithm) // must have Op==Colon
if cond == 1 {
return Arithm(cfg, b2.X)
}
return Arithm(cfg, b2.Y)
}
left, err := Arithm(cfg, x.X)
if err != nil {
return 0, err
}
right, err := Arithm(cfg, x.Y)
if err != nil {
return 0, err
}
return binArit(x.Op, left, right), nil
default:
panic(fmt.Sprintf("unexpected arithm expr: %T", x))
}
}
func oneIf(b bool) int {
if b {
return 1
}
return 0
}
// atoi is just a shorthand for strconv.Atoi that ignores the error,
// just like shells do.
func atoi(s string) int {
n, _ := strconv.Atoi(s)
return n
}
func (cfg *Config) assgnArit(b *syntax.BinaryArithm) (int, error) {
name := b.X.(*syntax.Word).Lit()
val := atoi(cfg.envGet(name))
arg, err := Arithm(cfg, b.Y)
if err != nil {
return 0, err
}
switch b.Op {
case syntax.Assgn:
val = arg
case syntax.AddAssgn:
val += arg
case syntax.SubAssgn:
val -= arg
case syntax.MulAssgn:
val *= arg
case syntax.QuoAssgn:
val /= arg
case syntax.RemAssgn:
val %= arg
case syntax.AndAssgn:
val &= arg
case syntax.OrAssgn:
val |= arg
case syntax.XorAssgn:
val ^= arg
case syntax.ShlAssgn:
val <<= uint(arg)
case syntax.ShrAssgn:
val >>= uint(arg)
}
cfg.envSet(name, strconv.Itoa(val))
return val, nil
}
func intPow(a, b int) int {
p := 1
for b > 0 {
if b&1 != 0 {
p *= a
}
b >>= 1
a *= a
}
return p
}
func binArit(op syntax.BinAritOperator, x, y int) int {
switch op {
case syntax.Add:
return x + y
case syntax.Sub:
return x - y
case syntax.Mul:
return x * y
case syntax.Quo:
return x / y
case syntax.Rem:
return x % y
case syntax.Pow:
return intPow(x, y)
case syntax.Eql:
return oneIf(x == y)
case syntax.Gtr:
return oneIf(x > y)
case syntax.Lss:
return oneIf(x < y)
case syntax.Neq:
return oneIf(x != y)
case syntax.Leq:
return oneIf(x <= y)
case syntax.Geq:
return oneIf(x >= y)
case syntax.And:
return x & y
case syntax.Or:
return x | y
case syntax.Xor:
return x ^ y
case syntax.Shr:
return x >> uint(y)
case syntax.Shl:
return x << uint(y)
case syntax.AndArit:
return oneIf(x != 0 && y != 0)
case syntax.OrArit:
return oneIf(x != 0 || y != 0)
default: // syntax.Comma
// x is executed but its result discarded
return y
}
}