Initial commit

text_codecs/alphanumeric.py

@@ -0,0 +1,39 @@
+import string
+import codecs
+from custom_codecs.register import register_codec
+from easybits import Bits
+
+allowed_characters = string.ascii_letters + string.digits
+
+def encode(text):
+    """A (very) lossy encoder which only saves ASCII letters, numbers, and spaces.
+    Everything else is discarded. All whitespace (e.g. tabs) is converted into spaces.
+    """
+    ascii_characters = []
+    last_character_was_space = False
+    for char in text:
+        if char in allowed_characters:
+            ascii_characters.append(char)
+            last_character_was_space = False
+        elif char in string.whitespace and not last_character_was_space:
+            ascii_characters.append(' ')
+            last_character_was_space = True
+    ascii_text = ''.join(ascii_characters)
+    return Bits(ascii_text).bytes
+
+def decode(data):
+    """A decoder which reads bytes and returns (string, length), 
+    where length is the length of bytes consumed
+    """
+    text = ""
+    for i, byte in enumerate(data):
+        try:
+            text += Bits(byte, length=8).ascii
+        except OverflowError:
+            print(i, byte)
+            print(text + '|')
+            print("Error")
+            breakpoint()
+    return text
+    
+register_codec(encode, decode, "alphanumeric")