AppPkg/Applications/Python/Python-2.7.10: Initial Checkin part 4/5.

The Lib directory from the cPython 2.7.10 distribution.
These files are unchanged and set the baseline for subsequent commits.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Daryl McDaniel <edk2-lists@mc2research.org>


git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18740 6f19259b-4bc3-4df7-8a09-765794883524

AppPkg/Applications/Python/Python-2.7.10/Lib/encodings/utf_8_sig.py

@@ -0,0 +1,117 @@
+""" Python 'utf-8-sig' Codec
+This work similar to UTF-8 with the following changes:
+
+* On encoding/writing a UTF-8 encoded BOM will be prepended/written as the
+  first three bytes.
+
+* On decoding/reading if the first three bytes are a UTF-8 encoded BOM, these
+  bytes will be skipped.
+"""
+import codecs
+
+### Codec APIs
+
+def encode(input, errors='strict'):
+    return (codecs.BOM_UTF8 + codecs.utf_8_encode(input, errors)[0], len(input))
+
+def decode(input, errors='strict'):
+    prefix = 0
+    if input[:3] == codecs.BOM_UTF8:
+        input = input[3:]
+        prefix = 3
+    (output, consumed) = codecs.utf_8_decode(input, errors, True)
+    return (output, consumed+prefix)
+
+class IncrementalEncoder(codecs.IncrementalEncoder):
+    def __init__(self, errors='strict'):
+        codecs.IncrementalEncoder.__init__(self, errors)
+        self.first = 1
+
+    def encode(self, input, final=False):
+        if self.first:
+            self.first = 0
+            return codecs.BOM_UTF8 + codecs.utf_8_encode(input, self.errors)[0]
+        else:
+            return codecs.utf_8_encode(input, self.errors)[0]
+
+    def reset(self):
+        codecs.IncrementalEncoder.reset(self)
+        self.first = 1
+
+    def getstate(self):
+        return self.first
+
+    def setstate(self, state):
+        self.first = state
+
+class IncrementalDecoder(codecs.BufferedIncrementalDecoder):
+    def __init__(self, errors='strict'):
+        codecs.BufferedIncrementalDecoder.__init__(self, errors)
+        self.first = True
+
+    def _buffer_decode(self, input, errors, final):
+        if self.first:
+            if len(input) < 3:
+                if codecs.BOM_UTF8.startswith(input):
+                    # not enough data to decide if this really is a BOM
+                    # => try again on the next call
+                    return (u"", 0)
+                else:
+                    self.first = None
+            else:
+                self.first = None
+                if input[:3] == codecs.BOM_UTF8:
+                    (output, consumed) = codecs.utf_8_decode(input[3:], errors, final)
+                    return (output, consumed+3)
+        return codecs.utf_8_decode(input, errors, final)
+
+    def reset(self):
+        codecs.BufferedIncrementalDecoder.reset(self)
+        self.first = True
+
+class StreamWriter(codecs.StreamWriter):
+    def reset(self):
+        codecs.StreamWriter.reset(self)
+        try:
+            del self.encode
+        except AttributeError:
+            pass
+
+    def encode(self, input, errors='strict'):
+        self.encode = codecs.utf_8_encode
+        return encode(input, errors)
+
+class StreamReader(codecs.StreamReader):
+    def reset(self):
+        codecs.StreamReader.reset(self)
+        try:
+            del self.decode
+        except AttributeError:
+            pass
+
+    def decode(self, input, errors='strict'):
+        if len(input) < 3:
+            if codecs.BOM_UTF8.startswith(input):
+                # not enough data to decide if this is a BOM
+                # => try again on the next call
+                return (u"", 0)
+        elif input[:3] == codecs.BOM_UTF8:
+            self.decode = codecs.utf_8_decode
+            (output, consumed) = codecs.utf_8_decode(input[3:],errors)
+            return (output, consumed+3)
+        # (else) no BOM present
+        self.decode = codecs.utf_8_decode
+        return codecs.utf_8_decode(input, errors)
+
+### encodings module API
+
+def getregentry():
+    return codecs.CodecInfo(
+        name='utf-8-sig',
+        encode=encode,
+        decode=decode,
+        incrementalencoder=IncrementalEncoder,
+        incrementaldecoder=IncrementalDecoder,
+        streamreader=StreamReader,
+        streamwriter=StreamWriter,
+    )