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.cr

Constructors

Instance Method Summary

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 -> UNDERSCORE) 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) : Bool ==, hash(hasher) hash, inspect(io : IO) : Nil inspect, pretty_print(pp) : Nil pretty_print, to_s(io) to_s

Instance methods inherited from struct Value

==(other : JSON::Any)
==(other : YAML::Any)
==(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(hasher)
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, unsafe_as(type : T.class) forall T unsafe_as

Constructor methods inherited from class Object

from_json(string_or_io, root : String) : self
from_json(string_or_io) : self
from_json
, from_yaml(string_or_io : String | IO) : self from_yaml

Constructor Detail

def self.new(string : String, pos = 0) #

Creates a reader with the specified string positioned at byte index pos.


[View source]
def self.new(*, at_end string : String) #

Creates a reader that will be positioned at the last char of the given string.


[View source]

Instance Method Detail

def current_char : Char #

Returns the current character.

reader = Char::Reader.new("ab")
reader.current_char # => 'a'
reader.next_char
reader.current_char # => 'b'

[View source]
def current_char_width : Int32 #

Returns the size of the #current_char (in bytes) as if it were encoded in UTF-8.

reader = Char::Reader.new("aƩ")
reader.current_char_width # => 1
reader.next_char
reader.current_char_width # => 2

[View source]
def each(&block) : Nil #

Yields successive characters from #string starting from #pos.

reader = Char::Reader.new("abc")
reader.next_char
reader.each do |c|
  puts c.upcase
end
B
C

[View source]
def 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. Returns 0 if the char would've been out of bounds. Otherwise returns nil.


[View source]
def has_next? #

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'

[View source]
def has_previous? #

Returns true if there are characters before the current one.


[View source]
def next_char #

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'

[View source]
def peek_next_char #

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'

[View source]
def pos : Int32 #

Returns the position of the current character.

reader = Char::Reader.new("ab")
reader.pos # => 0
reader.next_char
reader.pos # => 1

[View source]
def pos=(pos) #

Sets #pos to pos.

reader = Char::Reader.new("abc")
reader.next_char
reader.next_char
reader.pos = 0
reader.current_char # => 'a'

[View source]
def previous_char : Char #

Returns the previous character, #pos is decremented. Raises IndexError if the reader is at the begining of the #string


[View source]
def string : String #

Returns the reader's String.


[View source]