class StringScanner
Overview
StringScanner
provides for lexical scanning operations on a String
.
NOTE To use StringScanner
, you must explicitly import it with require "string_scanner"
Example
require "string_scanner"
s = StringScanner.new("This is an example string")
s.eos? # => false
s.scan(/\w+/) # => "This"
s.scan(/\w+/) # => nil
s.scan(/\s+/) # => " "
s.scan(/\s+/) # => nil
s.scan(/\w+/) # => "is"
s.eos? # => false
s.scan(/\s+/) # => " "
s.scan(/\w+/) # => "an"
s.scan(/\s+/) # => " "
s.scan(/\w+/) # => "example"
s.scan(/\s+/) # => " "
s.scan(/\w+/) # => "string"
s.eos? # => true
s.scan(/\s+/) # => nil
s.scan(/\w+/) # => nil
Scanning a string means remembering the position of a scan offset, which is just an index. Scanning moves the offset forward, and matches are sought after the offset; usually immediately after it.
Method Categories
Methods that advance the scan offset:
Methods that look ahead:
Methods that deal with the position of the offset:
Methods that deal with the last match:
Miscellaneous methods:
Defined in:
string_scanner.crConstructors
Instance Method Summary
-
#[](n) : String
Returns the n-th subgroup in the most recent match.
-
#[]?(n) : String | Nil
Returns the nilable n-th subgroup in the most recent match.
-
#check(pattern : String) : String | Nil
Returns the value that
#scan
would return, without advancing the scan offset. -
#check(pattern : Char) : String | Nil
Returns the value that
#scan
would return, without advancing the scan offset. -
#check(pattern : Regex, *, options : Regex::MatchOptions = Regex::MatchOptions::None) : String | Nil
Returns the value that
#scan
would return, without advancing the scan offset. -
#check_until(pattern : String) : String | Nil
Returns the value that
#scan_until
would return, without advancing the scan offset. -
#check_until(pattern : Char) : String | Nil
Returns the value that
#scan_until
would return, without advancing the scan offset. -
#check_until(pattern : Regex, *, options : Regex::MatchOptions = Regex::MatchOptions::None) : String | Nil
Returns the value that
#scan_until
would return, without advancing the scan offset. -
#eos? : Bool
Returns
true
if the scan offset is at the end of the string. -
#inspect(io : IO) : Nil
Writes a representation of the scanner.
-
#offset : Int32
Returns the current position of the scan offset.
-
#offset=(position : Int)
Sets the position of the scan offset.
-
#peek(len) : String
Extracts a string corresponding to string[offset,len], without advancing the scan offset.
-
#reset
Resets the scan offset to the beginning and clears the last match.
-
#rest : String
Returns the remainder of the string after the scan offset.
-
#scan(pattern : String) : String | Nil
Tries to match with pattern at the current position.
-
#scan(pattern : Char) : String | Nil
Tries to match with pattern at the current position.
-
#scan(pattern : Regex, *, options : Regex::MatchOptions = Regex::MatchOptions::None) : String | Nil
Tries to match with pattern at the current position.
-
#scan_until(pattern : String) : String | Nil
Scans the string until the pattern is matched.
-
#scan_until(pattern : Char) : String | Nil
Scans the string until the pattern is matched.
-
#scan_until(pattern : Regex, *, options : Regex::MatchOptions = Regex::MatchOptions::None) : String | Nil
Scans the string until the pattern is matched.
-
#skip(pattern : String) : Int32 | Nil
Attempts to skip over the given pattern beginning with the scan offset.
-
#skip(pattern : Char) : Int32 | Nil
Attempts to skip over the given pattern beginning with the scan offset.
-
#skip(pattern : Regex, *, options : Regex::MatchOptions = Regex::MatchOptions::None) : Int32 | Nil
Attempts to skip over the given pattern beginning with the scan offset.
-
#skip_until(pattern : String) : Int32 | Nil
Attempts to skip until the given pattern is found after the scan offset.
-
#skip_until(pattern : Char) : Int32 | Nil
Attempts to skip until the given pattern is found after the scan offset.
-
#skip_until(pattern : Regex, *, options : Regex::MatchOptions = Regex::MatchOptions::None) : Int32 | Nil
Attempts to skip until the given pattern is found after the scan offset.
-
#string : String
Returns the string being scanned.
-
#terminate
Moves the scan offset to the end of the string and clears the last match.
Instance methods inherited from class Reference
==(other : self)==(other : JSON::Any)
==(other : YAML::Any)
==(other) ==, dup dup, hash(hasher) hash, initialize initialize, inspect(io : IO) : Nil inspect, object_id : UInt64 object_id, pretty_print(pp) : Nil pretty_print, same?(other : Reference) : Bool
same?(other : Nil) same?, to_s(io : IO) : Nil to_s
Constructor methods inherited from class Reference
new
new,
unsafe_construct(address : Pointer, *args, **opts) : self
unsafe_construct
Class methods inherited from class Reference
pre_initialize(address : Pointer)
pre_initialize
Instance methods inherited from class Object
! : Bool
!,
!=(other)
!=,
!~(other)
!~,
==(other)
==,
===(other : JSON::Any)===(other : YAML::Any)
===(other) ===, =~(other) =~, as(type : Class) as, as?(type : Class) as?, class class, dup dup, hash(hasher)
hash hash, in?(collection : Object) : Bool
in?(*values : Object) : Bool in?, inspect(io : IO) : Nil
inspect : String inspect, is_a?(type : Class) : Bool is_a?, itself itself, nil? : Bool nil?, not_nil!(message)
not_nil! not_nil!, pretty_inspect(width = 79, newline = "\n", indent = 0) : String pretty_inspect, pretty_print(pp : PrettyPrint) : Nil pretty_print, responds_to?(name : Symbol) : Bool responds_to?, tap(&) tap, to_json(io : IO) : Nil
to_json : String to_json, to_pretty_json(indent : String = " ") : String
to_pretty_json(io : IO, indent : String = " ") : Nil to_pretty_json, to_s(io : IO) : Nil
to_s : String to_s, to_yaml(io : IO) : Nil
to_yaml : String to_yaml, try(&) try, unsafe_as(type : T.class) forall T unsafe_as
Class methods inherited from class Object
from_json(string_or_io, root : String)from_json(string_or_io) from_json, from_yaml(string_or_io : String | IO) from_yaml
Constructor Detail
Instance Method Detail
Returns the n-th subgroup in the most recent match.
Raises an exception if there was no last match or if there is no subgroup.
require "string_scanner"
s = StringScanner.new("Fri Dec 12 1975 14:39")
regex = /(?<wday>\w+) (?<month>\w+) (?<day>\d+)/
s.scan(regex) # => "Fri Dec 12"
s[0] # => "Fri Dec 12"
s[1] # => "Fri"
s[2] # => "Dec"
s[3] # => "12"
s["wday"] # => "Fri"
s["month"] # => "Dec"
s["day"] # => "12"
Returns the nilable n-th subgroup in the most recent match.
Returns nil
if there was no last match or if there is no subgroup.
require "string_scanner"
s = StringScanner.new("Fri Dec 12 1975 14:39")
regex = /(?<wday>\w+) (?<month>\w+) (?<day>\d+)/
s.scan(regex) # => "Fri Dec 12"
s[0]? # => "Fri Dec 12"
s[1]? # => "Fri"
s[2]? # => "Dec"
s[3]? # => "12"
s[4]? # => nil
s["wday"]? # => "Fri"
s["month"]? # => "Dec"
s["day"]? # => "12"
s["year"]? # => nil
s.scan(/more/) # => nil
s[0]? # => nil
Returns the value that #scan
would return, without advancing the scan
offset. The last match is still saved, however.
require "string_scanner"
s = StringScanner.new("this is a string")
s.offset = 5
s.check(/\w+/) # => "is"
s.check(/\w+/) # => "is"
Returns the value that #scan
would return, without advancing the scan
offset. The last match is still saved, however.
require "string_scanner"
s = StringScanner.new("this is a string")
s.offset = 5
s.check(/\w+/) # => "is"
s.check(/\w+/) # => "is"
Returns the value that #scan
would return, without advancing the scan
offset. The last match is still saved, however.
require "string_scanner"
s = StringScanner.new("this is a string")
s.offset = 5
s.check(/\w+/) # => "is"
s.check(/\w+/) # => "is"
Returns the value that #scan_until
would return, without advancing the
scan offset. The last match is still saved, however.
require "string_scanner"
s = StringScanner.new("test string")
s.check_until(/tr/) # => "test str"
s.check_until(/g/) # => "test string"
Returns the value that #scan_until
would return, without advancing the
scan offset. The last match is still saved, however.
require "string_scanner"
s = StringScanner.new("test string")
s.check_until(/tr/) # => "test str"
s.check_until(/g/) # => "test string"
Returns the value that #scan_until
would return, without advancing the
scan offset. The last match is still saved, however.
require "string_scanner"
s = StringScanner.new("test string")
s.check_until(/tr/) # => "test str"
s.check_until(/g/) # => "test string"
Returns true
if the scan offset is at the end of the string.
require "string_scanner"
s = StringScanner.new("this is a string")
s.eos? # => false
s.scan(/(\w+\s?){4}/) # => "this is a string"
s.eos? # => true
Writes a representation of the scanner.
Includes the current position of the offset, the total size of the string, and five characters near the current position.
Extracts a string corresponding to string[offset,len], without advancing the scan offset.
Returns the remainder of the string after the scan offset.
require "string_scanner"
s = StringScanner.new("this is a string")
s.scan(/(\w+\s?){2}/) # => "this is "
s.rest # => "a string"
Tries to match with pattern at the current position. If there's a match,
the scanner advances the scan offset, the last match is saved, and it
returns the matched string. Otherwise, the scanner returns nil
.
require "string_scanner"
s = StringScanner.new("test string")
s.scan(/\w+/) # => "test"
s.scan(/\w+/) # => nil
s.scan(/\s\w/) # => " s"
s.scan('t') # => "t"
s.scan("ring") # => "ring"
s.scan(/.*/) # => ""
Tries to match with pattern at the current position. If there's a match,
the scanner advances the scan offset, the last match is saved, and it
returns the matched string. Otherwise, the scanner returns nil
.
require "string_scanner"
s = StringScanner.new("test string")
s.scan(/\w+/) # => "test"
s.scan(/\w+/) # => nil
s.scan(/\s\w/) # => " s"
s.scan('t') # => "t"
s.scan("ring") # => "ring"
s.scan(/.*/) # => ""
Tries to match with pattern at the current position. If there's a match,
the scanner advances the scan offset, the last match is saved, and it
returns the matched string. Otherwise, the scanner returns nil
.
require "string_scanner"
s = StringScanner.new("test string")
s.scan(/\w+/) # => "test"
s.scan(/\w+/) # => nil
s.scan(/\s\w/) # => " s"
s.scan('t') # => "t"
s.scan("ring") # => "ring"
s.scan(/.*/) # => ""
Scans the string until the pattern is matched. Returns the substring up
to and including the end of the match, the last match is saved, and
advances the scan offset. Returns nil
if no match.
require "string_scanner"
s = StringScanner.new("test string")
s.scan_until(/ s/) # => "test s"
s.scan_until(/ s/) # => nil
s.scan_until('r') # => "tr"
s.scan_until("ng") # => "ing"
Scans the string until the pattern is matched. Returns the substring up
to and including the end of the match, the last match is saved, and
advances the scan offset. Returns nil
if no match.
require "string_scanner"
s = StringScanner.new("test string")
s.scan_until(/ s/) # => "test s"
s.scan_until(/ s/) # => nil
s.scan_until('r') # => "tr"
s.scan_until("ng") # => "ing"
Scans the string until the pattern is matched. Returns the substring up
to and including the end of the match, the last match is saved, and
advances the scan offset. Returns nil
if no match.
require "string_scanner"
s = StringScanner.new("test string")
s.scan_until(/ s/) # => "test s"
s.scan_until(/ s/) # => nil
s.scan_until('r') # => "tr"
s.scan_until("ng") # => "ing"
Attempts to skip over the given pattern beginning with the scan offset. In other words, the pattern is not anchored to the current scan offset.
If there's a match, the scanner advances the scan offset, the last match is
saved, and it returns the size of the skipped match. Otherwise it returns
nil
and does not advance the offset.
This method is the same as #scan
, but without returning the matched
string.
Attempts to skip over the given pattern beginning with the scan offset. In other words, the pattern is not anchored to the current scan offset.
If there's a match, the scanner advances the scan offset, the last match is
saved, and it returns the size of the skipped match. Otherwise it returns
nil
and does not advance the offset.
This method is the same as #scan
, but without returning the matched
string.
Attempts to skip over the given pattern beginning with the scan offset. In other words, the pattern is not anchored to the current scan offset.
If there's a match, the scanner advances the scan offset, the last match is
saved, and it returns the size of the skipped match. Otherwise it returns
nil
and does not advance the offset.
This method is the same as #scan
, but without returning the matched
string.
Attempts to skip until the given pattern is found after the scan offset. In other words, the pattern is not anchored to the current scan offset.
If there's a match, the scanner advances the scan offset, the last match is
saved, and it returns the size of the skip. Otherwise it returns nil
and does not advance the
offset.
This method is the same as #scan_until
, but without returning the matched
string.
Attempts to skip until the given pattern is found after the scan offset. In other words, the pattern is not anchored to the current scan offset.
If there's a match, the scanner advances the scan offset, the last match is
saved, and it returns the size of the skip. Otherwise it returns nil
and does not advance the
offset.
This method is the same as #scan_until
, but without returning the matched
string.
Attempts to skip until the given pattern is found after the scan offset. In other words, the pattern is not anchored to the current scan offset.
If there's a match, the scanner advances the scan offset, the last match is
saved, and it returns the size of the skip. Otherwise it returns nil
and does not advance the
offset.
This method is the same as #scan_until
, but without returning the matched
string.