Char::Reader
struct Char::Reader
Overview
A Char::Reader
allows iterating a String
by Chars.
As soon as you instantiate a Char::Reader
it will decode the first char in the String
, which can be accessed by invoking #current_char
. At this point #pos
, the current position in the string, will equal zero. Successive calls to #next_char
return the next chars in the string, advancing #pos
.
Note that the null character '\0'
will be returned in #current_char
when the end is reached (as well as when the string is empty). Thus, #has_next?
will return false
only when #pos
is equal to the string's bytesize, in which case #current_char
will always be '\0'
.
Included Modules
Defined in:
char/reader.crClass Method Summary
- .new(string : String, pos = 0)
Creates a reader with the specified string positioned at byte index pos.
- .new(*, at_end string : String)
Creates a reader that will be positioned at the last char of the given string.
Instance Method Summary
- #current_char : Char
Returns the current character.
- #current_char_width : Int32
Returns the size of the
#current_char
(in bytes) as if it were encoded in UTF-8. - #each(&block) : Nil
- #error : UInt8?
If there was an error decoding the current char because of an invalid UTF-8 byte sequence, returns the byte that produced the invalid encoding.
- #has_next?
Returns
true
if there is a character left to read. - #has_previous?
Returns
true
if there are characters before the current one. - #next_char
Reads the next character in the string,
#pos
is incremented. - #peek_next_char
- #pos : Int32
Returns the position of the current character.
- #pos=(pos)
Sets
#pos
to pos. - #previous_char
Returns the previous character,
#pos
is decremented. - #string : String
Returns the reader's String.
Instance methods inherited from module Enumerable(Char)
all?(&block)all? all?, any?(&block)
any? any?, chunks(&block : T -> U) forall U chunks, compact_map(&block) compact_map, count(&block)
count(item) count, cycle(n, &block)
cycle(&block) cycle, each(&block : T -> _) each, each_cons(count : Int, reuse = false, &block) each_cons, each_slice(count : Int, reuse = false, &block) each_slice, each_with_index(offset = 0, &block) each_with_index, each_with_object(obj, &block) each_with_object, find(if_none = nil, &block) find, first(count : Int)
first first, first? first?, flat_map(&block : T -> Array(U) | Iterator(U) | U) forall U flat_map, grep(pattern) grep, group_by(&block : T -> U) forall U group_by, in_groups_of(size : Int, filled_up_with : U = nil) forall U
in_groups_of(size : Int, filled_up_with : U = nil, reuse = false, &block) forall U in_groups_of, includes?(obj) includes?, index(&block)
index(obj) index, index_by(&block : T -> U) forall U index_by, join(separator, io)
join(separator = "")
join(separator, io, &block)
join(separator = "", &block) join, map(&block : T -> U) forall U map, map_with_index(&block : T, Int32 -> U) forall U map_with_index, max max, max? max?, max_by(&block : T -> U) forall U max_by, max_by?(&block : T -> U) forall U max_by?, max_of(&block : T -> U) forall U max_of, max_of?(&block : T -> U) forall U max_of?, min min, min? min?, min_by(&block : T -> U) forall U min_by, min_by?(&block : T -> U) forall U min_by?, min_of(&block : T -> U) forall U min_of, min_of?(&block : T -> U) forall U min_of?, minmax minmax, minmax? minmax?, minmax_by(&block : T -> U) forall U minmax_by, minmax_by?(&block : T -> U) forall U minmax_by?, minmax_of(&block : T -> U) forall U minmax_of, minmax_of?(&block : T -> U) forall U minmax_of?, none?(&block)
none? none?, one?(&block) one?, partition(&block) partition, product(&block)
product(initial : Number, &block)
product
product(initial : Number) product, reduce(&block)
reduce(memo, &block) reduce, reject(&block : T -> ) reject, select(&block : T -> ) select, size size, skip(count : Int) skip, skip_while(&block) skip_while, sum(initial)
sum
sum(initial, &block)
sum(&block) sum, take_while(&block) take_while, to_a to_a, to_h to_h, to_set to_set
Instance methods inherited from struct Struct
==(other : self) : Bool ==, hash : Int32 hash, inspect(io : IO) : Nil inspect, pretty_print(pp) : Nil pretty_print, to_s(io) to_s Instance methods inherited from struct Value
==(other) ==, dup dup Instance methods inherited from class Object
!=(other) !=, !~(other) !~, ==(other) ==, ===(other : JSON::Any)===(other : YAML::Any)
===(other) ===, =~(other) =~, class class, dup dup, hash hash, inspect(io : IO)
inspect inspect, itself itself, not_nil! not_nil!, pretty_inspect(width = 79, newline = "\n", indent = 0) : String pretty_inspect, pretty_print(pp : PrettyPrint) : Nil pretty_print, tap(&block) tap, to_json(io : IO)
to_json to_json, to_pretty_json(indent : String = " ")
to_pretty_json(io : IO, indent : String = " ") to_pretty_json, to_s
to_s(io : IO) to_s, to_yaml(io : IO)
to_yaml to_yaml, try(&block) try
Class methods inherited from class Object
from_json(string_or_io, root : String) : selffrom_json(string_or_io) : self from_json, from_yaml(string_or_io) : self from_yaml
Class Method Detail
def self.new(string : String, pos = 0)Source
Creates a reader with the specified string positioned at byte index pos.
def self.new(*, at_end string : String)Source
Creates a reader that will be positioned at the last char of the given string.
Instance Method Detail
def current_char : CharSource
Returns the current character.
reader = Char::Reader.new("ab") reader.current_char # => 'a' reader.next_char reader.current_char # => 'b'
def current_char_width : Int32Source
Returns the size of the #current_char
(in bytes) as if it were encoded in UTF-8.
reader = Char::Reader.new("aé") reader.current_char_width # => 1 reader.next_char reader.current_char_width # => 2
def error : UInt8?Source
If there was an error decoding the current char because of an invalid UTF-8 byte sequence, returns the byte that produced the invalid encoding. Otherwise returns nil
.
def has_next?Source
Returns true
if there is a character left to read. The terminating byte '\0'
is considered a valid character by this method.
reader = Char::Reader.new("a") reader.has_next? # => true reader.peek_next_char # => '\0'
def has_previous?Source
Returns true
if there are characters before the current one.
def next_charSource
Reads the next character in the string, #pos
is incremented. Raises IndexError
if the reader is at the end of the #string
.
reader = Char::Reader.new("ab") reader.next_char # => 'b'
def peek_next_charSource
Returns the next character in the #string
without incrementing #pos
. Raises IndexError
if the reader is at the end of the #string
.
reader = Char::Reader.new("ab") reader.peek_next_char # => 'b' reader.current_char # => 'a'
def pos : Int32Source
Returns the position of the current character.
reader = Char::Reader.new("ab") reader.pos # => 0 reader.next_char reader.pos # => 1
def pos=(pos)Source
Sets #pos
to pos.
reader = Char::Reader.new("abc") reader.next_char reader.next_char reader.pos = 0 reader.current_char # => 'a'
def previous_charSource
Returns the previous character, #pos
is decremented. Raises IndexError
if the reader is at the begining of the #string
© 2012–2017 Manas Technology Solutions.
Licensed under the Apache License, Version 2.0.
https://crystal-lang.org/api/0.22.0/Char/Reader.html