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
|
=begin
= strscan user manual
== What is this library?
strscan is a lexical scan library.
Here is the simplest usage example of this library:
s = StringScanner.new('This is an example string')
s.eos? #=> false
p s.scan(/\w+/) #=> "This"
p s.scan(/\w+/) #=> nil
p s.scan(/\s+/) #=> " "
p s.scan(/\s+/) #=> nil
p s.scan(/\w+/) #=> "is"
s.eos? #=> false
p s.scan(/\s+/) #=> " "
p s.scan(/\w+/) #=> "an"
p s.scan(/\s+/) #=> " "
p s.scan(/\w+/) #=> "example"
p s.scan(/\s+/) #=> " "
p s.scan(/\w+/) #=> "string"
s.eos? #=> true
p s.scan(/\s+/) #=> nil
p s.scan(/\w+/) #=> nil
In a word, StringScanner is a set of "scan pointer" and
a string. "scan pointer" is, in another word, an index.
## a string and a scan pointer ("_" = scan pointer)
s = StringScanner.new('This is an example string')
_This is an example string s.eos? = false
s.scan(/\w+/)
This_ is an example string s.eos? = false
s.scan(/\s+/)
This _is an example string s.eos? = false
s.scan(/\w+/)
This is_ an example string s.eos? = false
s.scan(/\s+/)
This is _an example string s.eos? = false
s.scan(/\w+/)
This is an_ example string s.eos? = false
s.scan(/\s+/)
This is an _example string s.eos? = false
s.scan(/\w+/)
This is an example_ string s.eos? = false
s.scan(/\s+/)
This is an example _string s.eos? = false
s.scan(/\w+/)
This is an example string_ s.eos? = true
== WARNING!!!!!
StringScanner DOES NOT set regexp variables like $~, $&, $1, $2, etc.
Use StringScanner's methods instead (e.g. scanner[n], scanner.matched?).
== class StringScanner
=== Class Methods
: new( str: String, dup: bool = true ) -> StringScanner
creates a new StringScanner object. STR is a string to scan.
If DUP is true, duplicates STR and use freeze it.
If DUP is false, does not duplicate and freeze it.
=== Instance Methods
: scan( pattern: Regexp ) -> String
tries matching with PATTERN only on the scan pointer.
If matched, the scanner advances "scan pointer" and
returns a matched string. Else, the scanner returns nil.
s = StringScanner.new('test string')
p s.scan(/\w+/) #=> "test"
p s.scan(/\w+/) #=> nil
p s.scan(/\s+/) #=> " "
p s.scan(/\w+/) #=> "string"
p s.scan(/./) #=> nil
: skip( pattern: Regexp ) -> Integer
tries matching with PATTERN, only on the scan pointer.
If matched, the scanner advances "scan pointer" and
returns length of matched string. Else, the scanner
returns nil.
s = StringScanner.new('test string')
p s.skip(/\w+/) #=> 4
p s.skip(/\w+/) #=> nil
p s.skip(/\s+/) #=> 1
p s.skip(/\w+/) #=> 6
p s.skip(/./) #=> nil
: match?( pattern: Regexp ) -> Integer
tries matching with PATTERN, only on the scan pointer.
If matched, the scanner keep "scan pointer" un-touched
and returns the length of the matched string. Else, the
scanner returns nil.
s = StringScanner.new('test string')
p s.match?(/\w+/) #=> 4
p s.match?(/\w+/) #=> 4
p s.match?(/\s+/) #=> nil
: getch -> String
scans one character and returns it.
: get_byte -> String
scans one byte and returns it.
: peek( len: Integer ) -> String
extracts a string which is corresponding to string[pos, len]
: eos? -> bool
returns true if the scan pointer is on the end of the string.
: string -> String
returns the scanning string itself.
: matched? -> bool
returns true if last matching had been successed.
: pre_match -> String
: post_match -> String
: self[ n: Integer ] -> String
returns N-th content of regexp register (indecated by paren in regexp).
If previous scanning had been failed, the scanner raises ScanError.
: matched -> String
returns the entire matched string.
: reset
reset scan pointer (index 0) and clear matching data.
: terminate
set scan pointer the end of the string and clear matching data.
: unscan
set scan pointer the previous position.
This method is valid only once for one scanning method call.
=end
|
