Merge: Intro Codec

[nit.git] / lib / standard / codecs / codec_base.nit

diff --git a/lib/standard/codecs/codec_base.nit b/lib/standard/codecs/codec_base.nit
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+# This file is part of NIT (http://www.nitlanguage.org).
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#       http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Base for codecs to use with streams
+#
+# A Codec (Coder/Decoder) is a tranformer from a byte-format to another
+#
+# As Nit Strings are UTF-8, a codec works as :
+# - Coder: From a UTF-8 string to a specified format (writing)
+# - Decoder: From a specified format to a UTF-8 string (reading)
+module codec_base
+
+import text
+import bytes
+
+# Codes UTF-8 entities to an external format
+abstract class Coder
+
+       # Transforms `c` to its representation in the format of `self`
+       fun code_char(c: Char): Bytes is abstract
+
+       # Adds a char `c` to bytes `s`
+       fun add_char_to(c: Char, s: Bytes) is abstract
+
+       # Transforms `s` to the format of `self`
+       fun code_string(s: Text): Bytes is abstract
+
+       # Adds a string `s` to bytes `b`
+       fun add_string_to(s: Text, b: Bytes) is abstract
+end
+
+# Decodes entities in an external format to UTF-8
+abstract class Decoder
+
+       # Decodes a char from `b` to a Unicode code-point
+       fun decode_char(b: Bytes): Char is abstract
+
+       # Decodes a string `b` to UTF-8
+       fun decode_string(b: Bytes): String is abstract
+end