| Submitter | Boris Feld |
|---|---|
| Date | Jan. 19, 2018, 11:47 p.m. |
| Message ID | <5dbc3c53c923b8d11b5e.1516405627@FB> |
| Download | mbox | patch |
| Permalink | /patch/26985/ |
| State | Accepted |
| Headers | show |
Comments
On Sat, Jan 20, 2018 at 12:47:07AM +0100, Boris Feld wrote: > # HG changeset patch > # User Gregory Szorc <gregory.szorc@gmail.com> > # Date 1516398755 -3600 > # Fri Jan 19 22:52:35 2018 +0100 > # Node ID 5dbc3c53c923b8d11b5efcaf0f415b3d8c8c5180 > # Parent 15f7795f96a5f9acb3ed2e640fcec82f3ccd6f53 > # EXP-Topic b2-stream > # Available At https://bitbucket.org/octobus/mercurial-devel/ > # hg pull https://bitbucket.org/octobus/mercurial-devel/ -r 5dbc3c53c923 > util: implement varint functions > also candidates for netutil imo, or maybe protoutil (readexactly also fits in the same bucket) > This will be useful in an incoming version-2 of the stream format. > > diff --git a/mercurial/util.py b/mercurial/util.py > --- a/mercurial/util.py > +++ b/mercurial/util.py > @@ -3874,3 +3874,73 @@ def readexactly(stream, n): > " (got %d bytes, expected %d)") > % (len(s), n)) > return s > + > +def uvarintencode(value): > + """Encode an unsigned integer value to a varint. > + > + A varint is a variable length integer of 1 or more bytes. Each byte > + except the last has the most significant bit set. The lower 7 bits of > + each byte store the 2's complement representation, least significant group > + first. > + > + >>> uvarintencode(0) > + '\\x00' > + >>> uvarintencode(1) > + '\\x01' > + >>> uvarintencode(127) > + '\\x7f' > + >>> uvarintencode(1337) > + '\\xb9\\n' > + >>> uvarintencode(65536) > + '\\x80\\x80\\x04' > + >>> uvarintencode(-1) > + Traceback (most recent call last): > + ... > + ProgrammingError: negative value for uvarint: -1 > + """ > + if value < 0: > + raise error.ProgrammingError('negative value for uvarint: %d' > + % value) > + bits = value & 0x7f > + value >>= 7 > + bytes = [] > + while value: > + bytes.append(pycompat.bytechr(0x80 | bits)) > + bits = value & 0x7f > + value >>= 7 > + bytes.append(pycompat.bytechr(bits)) > + > + return ''.join(bytes) > + > +def uvarintdecodestream(fh): > + """Decode an unsigned variable length integer from a stream. > + > + The passed argument is anything that has a ``.read(N)`` method. > + > + >>> try: > + ... from StringIO import StringIO as BytesIO > + ... except ImportError: > + ... from io import BytesIO > + >>> uvarintdecodestream(BytesIO(b'\\x00')) > + 0 > + >>> uvarintdecodestream(BytesIO(b'\\x01')) > + 1 > + >>> uvarintdecodestream(BytesIO(b'\\x7f')) > + 127 > + >>> uvarintdecodestream(BytesIO(b'\\xb9\\n')) > + 1337 > + >>> uvarintdecodestream(BytesIO(b'\\x80\\x80\\x04')) > + 65536 > + >>> uvarintdecodestream(BytesIO(b'\\x80')) > + Traceback (most recent call last): > + ... > + Abort: stream ended unexpectedly (got 0 bytes, expected 1) > + """ > + result = 0 > + shift = 0 > + while True: > + byte = ord(readexactly(fh, 1)) > + result |= ((byte & 0x7f) << shift) > + if not (byte & 0x80): > + return result > + shift += 7
Patch
diff --git a/mercurial/util.py b/mercurial/util.py --- a/mercurial/util.py +++ b/mercurial/util.py @@ -3874,3 +3874,73 @@ def readexactly(stream, n): " (got %d bytes, expected %d)") % (len(s), n)) return s + +def uvarintencode(value): + """Encode an unsigned integer value to a varint. + + A varint is a variable length integer of 1 or more bytes. Each byte + except the last has the most significant bit set. The lower 7 bits of + each byte store the 2's complement representation, least significant group + first. + + >>> uvarintencode(0) + '\\x00' + >>> uvarintencode(1) + '\\x01' + >>> uvarintencode(127) + '\\x7f' + >>> uvarintencode(1337) + '\\xb9\\n' + >>> uvarintencode(65536) + '\\x80\\x80\\x04' + >>> uvarintencode(-1) + Traceback (most recent call last): + ... + ProgrammingError: negative value for uvarint: -1 + """ + if value < 0: + raise error.ProgrammingError('negative value for uvarint: %d' + % value) + bits = value & 0x7f + value >>= 7 + bytes = [] + while value: + bytes.append(pycompat.bytechr(0x80 | bits)) + bits = value & 0x7f + value >>= 7 + bytes.append(pycompat.bytechr(bits)) + + return ''.join(bytes) + +def uvarintdecodestream(fh): + """Decode an unsigned variable length integer from a stream. + + The passed argument is anything that has a ``.read(N)`` method. + + >>> try: + ... from StringIO import StringIO as BytesIO + ... except ImportError: + ... from io import BytesIO + >>> uvarintdecodestream(BytesIO(b'\\x00')) + 0 + >>> uvarintdecodestream(BytesIO(b'\\x01')) + 1 + >>> uvarintdecodestream(BytesIO(b'\\x7f')) + 127 + >>> uvarintdecodestream(BytesIO(b'\\xb9\\n')) + 1337 + >>> uvarintdecodestream(BytesIO(b'\\x80\\x80\\x04')) + 65536 + >>> uvarintdecodestream(BytesIO(b'\\x80')) + Traceback (most recent call last): + ... + Abort: stream ended unexpectedly (got 0 bytes, expected 1) + """ + result = 0 + shift = 0 + while True: + byte = ord(readexactly(fh, 1)) + result |= ((byte & 0x7f) << shift) + if not (byte & 0x80): + return result + shift += 7