fd85797033
Added a simple test for fix tables. refs #31 refs #16 --HG-- extra : rebase_source : 26f08d2b3715df318a0965e9c0d0f8b437cd8240
123 lines
2.7 KiB
Python
123 lines
2.7 KiB
Python
# WiredTiger variable-length packing and unpacking functions
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from intpacking import pack_int, unpack_int
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def __get_type(fmt):
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if not fmt:
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return None, fmt
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# Variable-sized encoding is the default (and only supported format in v1)
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if fmt[0] in '.@<>':
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tfmt = fmt[0]
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fmt = fmt[1:]
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else:
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tfmt = '.'
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return tfmt, fmt
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def unpack(fmt, s):
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tfmt, fmt = __get_type(fmt)
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if not fmt:
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return ()
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if tfmt != '.':
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raise ValueError('Only variable-length encoding is currently supported')
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result = []
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havesize = size = 0
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for offset, f in enumerate(fmt):
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if f.isdigit():
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size = (size * 10) + int(f)
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havesize = 1
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continue
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elif f == 'x':
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if not havesize:
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size = 1
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s = s[size:]
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# Note: no value, don't increment i
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elif f in 'Ssu':
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if not havesize:
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if f == 's':
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size = 1
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elif f == 'S':
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size = s.find('\0')
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elif f == 'u':
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if offset == len(fmt) - 1:
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size = len(s)
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else:
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size, s = unpack_int(s)
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result.append(s[:size])
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if f == 'S' and not havesize:
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size += 1
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s = s[size:]
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elif f in 't':
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# bit type, size is number of bits
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if not havesize:
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size = 1
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result.append(ord(s[0:1]))
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s = s[1:]
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else:
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# integral type
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if not havesize:
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size = 1
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for j in xrange(size):
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v, s = unpack_int(s)
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result.append(v)
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havesize = size = 0
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return result
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def pack(fmt, *values):
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tfmt, fmt = __get_type(fmt)
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if not fmt:
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return ()
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if tfmt != '.':
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raise ValueError('Only variable-length encoding is currently supported')
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result = ''
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havesize = i = size = 0
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for offset, f in enumerate(fmt):
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if f.isdigit():
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size = (size * 10) + int(f)
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havesize = 1
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continue
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elif f == 'x':
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if not havesize:
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result += '\0'
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else:
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result += '\0' * size
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# Note: no value, don't increment i
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elif f in 'Ssu':
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if f == 'S' and '\0' in values[i]:
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l = values[i].find('\0')
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else:
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l = len(values[i])
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if havesize:
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if l > size:
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l = size
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elif f == 's':
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havesize = size = 1
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elif f == 'u' and offset != len(fmt) - 1:
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result += pack_int(l)
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result += values[i][:l]
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if f == 'S' and not havesize:
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result += '\0'
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elif size > l:
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result += '\0' * (size - l)
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i += 1
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elif f in 't':
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# bit type, size is number of bits
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if not havesize:
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size = 1
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if size > 8:
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raise ValueError("bit count cannot be greater than 8 for 't' encoding")
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mask = (1 << size) - 1
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val = values[i]
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if (mask & val) != val:
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raise ValueError("value out of range for 't' encoding")
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result += chr(val)
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i += 1
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else:
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# integral type
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if not havesize:
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size = 1
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for j in xrange(size):
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result += pack_int(values[i])
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i += 1
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havesize = size = 0
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return result
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