1
2	#### recursive arith: one level
3	shopt -s eval_unsafe_arith
4	a='b=123'
5	echo $((a))
6	## stdout: 123
7	## N-I dash status: 2
8	## N-I dash stdout-json: ""
9	## N-I yash stdout: b=123
10
11	#### recursive arith: two levels
12	shopt -s eval_unsafe_arith
13	a='b=c' c='d=123'
14	echo $((a))
15	## stdout: 123
16	## N-I dash status: 2
17	## N-I dash stdout-json: ""
18	## N-I yash stdout: b=c
19
20	#### recursive arith: short circuit &&, ||
21	# Note: mksh R52 has a bug. Even though it supports a short circuit like
22	# "echo $((cond&&(a=1)))", it doesn't work with "x=a=1; echo
23	# $((cond&&x))". It is fixed at least in mksh R57.
24	# Note: "busybox sh" doesn't support short circuit.
25	shopt -s eval_unsafe_arith
26	a=b=123
27	echo $((1||a)):$((b))
28	echo $((0||a)):$((b))
29	c=d=321
30	echo $((0&&c)):$((d))
31	echo $((1&&c)):$((d))
32	## stdout-json: "1:0\n1:123\n0:0\n1:321\n"
33	## BUG mksh stdout-json: "1:123\n1:123\n0:321\n1:321\n"
34	## N-I ash stdout-json: "1:123\n1:123\n0:321\n1:321\n"
35	## N-I dash/yash status: 2
36	## N-I dash/yash stdout-json: "1:0\n"
37
38	#### recursive arith: short circuit ?:
39	# Note: "busybox sh" behaves strangely.
40	shopt -s eval_unsafe_arith
41	y=a=123 n=a=321
42	echo $((1?(y):(n))):$((a))
43	echo $((0?(y):(n))):$((a))
44	## stdout-json: "123:123\n321:321\n"
45	## BUG ash stdout-json: "123:123\n321:123\n"
46	## N-I dash status: 2
47	## N-I dash stdout-json: ""
48	## N-I yash stdout-json: "a=123:0\na=321:0\n"
49
50	#### recursive arith: side effects
51	# In Zsh and Busybox sh, the side effect of inner arithmetic
52	# evaluations seems to take effect only after the whole evaluation.
53	shopt -s eval_unsafe_arith
54	a='b=c' c='d=123'
55	echo $((a,d)):$((d))
56	## stdout: 123:123
57	## BUG zsh/ash stdout: 0:123
58	## N-I dash/yash status: 2
59	## N-I dash/yash stdout-json: ""
60
61	#### recursive arith: recursion
62	shopt -s eval_unsafe_arith
63	loop='i<=100&&(s+=i,i++,loop)' s=0 i=0
64	echo $((a=loop,s))
65	## stdout: 5050
66	## N-I mksh status: 1
67	## N-I mksh stdout-json: ""
68	## N-I ash/dash/yash status: 2
69	## N-I ash/dash/yash stdout-json: ""
70
71	#### recursive arith: array elements
72	shopt -s eval_unsafe_arith
73	text[1]='d=123'
74	text[2]='text[1]'
75	text[3]='text[2]'
76	echo $((a=text[3]))
77	## stdout: 123
78	## N-I ash/dash/yash status: 2
79	## N-I ash/dash/yash stdout-json: ""
80
81	#### dynamic arith varname: assign
82	shopt -s parse_dynamic_arith # for LHS
83
84	vec2_set () {
85	local this=$1 x=$2 y=$3
86	: $(( ${this}_x = $2 ))
87	: $(( ${this}_y = y ))
88	}
89	vec2_set a 3 4
90	vec2_set b 5 12
91	echo a_x=$a_x a_y=$a_y
92	echo b_x=$b_x b_y=$b_y
93	## STDOUT:
94	a_x=3 a_y=4
95	b_x=5 b_y=12
96	## END
97
98	#### dynamic arith varname: read
99	shopt -s eval_unsafe_arith # for RHS
100
101	vec2_load() {
102	local this=$1
103	x=$(( ${this}_x ))
104	: $(( y = ${this}_y ))
105	}
106	a_x=12 a_y=34
107	vec2_load a
108	echo x=$x y=$y
109	## STDOUT:
110	x=12 y=34
111	## END
112
113	#### dynamic arith varname: copy/add
114	shopt -s parse_dynamic_arith # for LHS
115	shopt -s eval_unsafe_arith # for RHS
116
117	vec2_copy () {
118	local this=$1 rhs=$2
119	: $(( ${this}_x = $(( ${rhs}_x )) ))
120	: $(( ${this}_y = ${rhs}_y ))
121	}
122	vec2_add () {
123	local this=$1 rhs=$2
124	: $(( ${this}_x += $(( ${rhs}_x )) ))
125	: $(( ${this}_y += ${rhs}_y ))
126	}
127	a_x=3 a_y=4
128	b_x=4 b_y=20
129	vec2_copy c a
130	echo c_x=$c_x c_y=$c_y
131	vec2_add c b
132	echo c_x=$c_x c_y=$c_y
133	## STDOUT:
134	c_x=3 c_y=4
135	c_x=7 c_y=24
136	## END
137
138	#### is-array with ${var@a}
139	case $SH in (mksh|ash|dash|yash) exit 1 ;; esac
140
141	function ble/is-array { [[ ${!1@a} == *a* ]]; }
142
143	ble/is-array undef
144	echo undef $?
145
146	string=''
147	ble/is-array string
148	echo string $?
149
150	array=(one two three)
151	ble/is-array array
152	echo array $?
153	## STDOUT:
154	undef 1
155	string 1
156	array 0
157	## END
158	## N-I zsh/mksh/ash/dash/yash status: 1
159	## N-I zsh/mksh/ash/dash/yash stdout-json: ""