scanning/reading_a_string.rb

tests/_examples/scanning/reading_a_string.rb in the metorex repository.

# A StringScanner walks a string with a cursor, matching patterns at the
# place it has reached.
require 'strscan'

scanner = StringScanner.new("This is a test")

p scanner.scan(/\w+/)
p scanner.pos
p scanner.scan(/\s+/)
p scanner.scan(/\d+/)
p scanner.check(/is/)
p scanner.pos
p scanner.match?(/is/)
p scanner.skip(/is/)
p scanner.rest
p scanner.rest_size
p scanner.eos?

scanner.reset
p scanner.pos
p scanner.scan_until(/is/)
p scanner.pre_match
p scanner.post_match
p scanner.matched
p scanner.matched?
p scanner.matched_size
p scanner.unscan.pos

p scanner.scan("This")
p scanner.exist?(/test/)
p scanner.check_until(/a/)
p scanner.skip_until(/a/)
p scanner.rest

grouped = StringScanner.new("2024-05-06")
p grouped.scan(/(?<year>\d+)-(?<month>\d+)/)
p grouped[0]
p grouped[1]
p grouped[:year]
p grouped.captures
p grouped.named_captures
p grouped.values_at(0, 1, 2)
p grouped.size

reading = StringScanner.new("abc")
p reading.getch
p reading.peek(2)
p reading.peek_byte
p reading.scan_byte
p reading.beginning_of_line?
p reading.terminate.eos?
p reading.inspect

begin
  StringScanner.new("x").scan_until("literal")
rescue TypeError => error
  p error.class
end

begin
  StringScanner.new("x").unscan
rescue StringScanner::Error => error
  p error.class
end

Output:

"This"
4
" "
nil
"is"
5
2
2
" a test"
7
false
0
"This"
"Th"
" is a test"
"is"
true
2
0
"This"
10
" is a"
5
" test"
"2024-05"
"2024-05"
"2024"
"2024"
["2024", "05"]
{"year" => "2024", "month" => "05"}
["2024-05", "2024", "05"]
3
"a"
"bc"
98
98
false
true
"#<StringScanner fin>"
TypeError
ScanError