struct Char::Reader

• Char::Reader
• Struct
• Value
• Object

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

• Enumerable(Char)

Defined in:

Constructors

• .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

  Yields successive characters from #string starting from #pos.

• #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

  Returns the next character in the #string without incrementing #pos.

• #pos : Int32

  Returns the position of the current character.

• #pos=(pos)

  Sets #pos to pos.

• #previous_char : Char

  Returns the previous character, #pos is decremented.

• #string : String

  Returns the reader's String.

Constructor Detail

Instance Method Detail

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

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

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

B
C

reader = Char::Reader.new("a")
reader.has_next?      # => true
reader.peek_next_char # => '\0'

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

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

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

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