lib/core/codecs/codec_base.nit

   1 # This file is part of NIT (http://www.nitlanguage.org).
   2 #
   3 # Licensed under the Apache License, Version 2.0 (the "License");
   4 # you may not use this file except in compliance with the License.
   5 # You may obtain a copy of the License at
   6 #
   7 #        http://www.apache.org/licenses/LICENSE-2.0
   8 #
   9 # Unless required by applicable law or agreed to in writing, software
  10 # distributed under the License is distributed on an "AS IS" BASIS,
  11 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12 # See the License for the specific language governing permissions and
  13 # limitations under the License.
  14
  15 # Base for codecs to use with streams
  16 #
  17 # A Codec (Coder/Decoder) is a tranformer from a byte-format to another
  18 #
  19 # As Nit Strings are UTF-8, a codec works as :
  20 # - Coder: From a UTF-8 string to a specified format (writing)
  21 # - Decoder: From a specified format to a UTF-8 string (reading)
  22 module codec_base
  23
  24 import text
  25 import bytes
  26
  27 # Codes UTF-8 entities to an external format
  28 abstract class Coder
  29
  30         # Transforms `c` to its representation in the format of `self`
  31         fun code_char(c: Char): Bytes is abstract
  32
  33         # Adds a char `c` to bytes `s`
  34         fun add_char_to(c: Char, s: Bytes) is abstract
  35
  36         # Transforms `s` to the format of `self`
  37         fun code_string(s: Text): Bytes is abstract
  38
  39         # Adds a string `s` to bytes `b`
  40         fun add_string_to(s: Text, b: Bytes) is abstract
  41 end
  42
  43 # Decodes entities in an external format to UTF-8
  44 abstract class Decoder
  45
  46         # Decodes a char from `b` to a Unicode code-point
  47         fun decode_char(b: Bytes): Char is abstract
  48
  49         # Decodes a string `b` to UTF-8
  50         fun decode_string(b: Bytes): String is abstract
  51 end