blob: ad92f591bc4d6320d91986b1d27191dac2415674 (
plain)
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
|
#
# Regular Definitions
#
rl rl_ws /[ \t\n\r\v]+/
rl rl_id /[a-zA-Z_][a-zA-Z0-9_]*/
rl rl_num /[0-9]+/
#
# Tokens
#
lex start
{
# Ignore whitespace.
ignore /rl_ws/
# Tokens.
token id /rl_id/
token number /rl_num/
}
#
# Productions
#
# Arbitrary item.
def item
[id]
| [number]
# List production one. The condition stops the
# greedy list when it has gone too far.
def count_items
target: int
count: int
[count_items item]
{
# Pass up the data
lhs.target = r1.target
lhs.count = r1.count + 1
if lhs.count > lhs.target {
reject
}
}
# List production two, the base.
| [number]
{
match lhs [Number: number]
lhs.target = Number.data.atoi()
lhs.count = 0
}
# Wrapper which prevents short lists from getting through if the parser
# encounters an error and needs to backtrack over counted list.
def counted_list
[count_items]
{
if r1.count < r1.target {
reject
}
}
def start
[counted_list*]
{
for List: counted_list in lhs {
match List [CountItems:count_items]
print( 'num items: ' CountItems.target '\n' )
i: int = 1
for Item:item in CountItems {
print( ' item ' i ': ' ^Item '\n' )
i = i + 1
}
}
}
parse start( stdin )
|
