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100 lines
2.7 KiB
Python
100 lines
2.7 KiB
Python
import logging
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import re
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logger = logging.getLogger('structure')
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UNESCAPE = re.compile(r'(?<!\\)\\(.)')
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INT_TYPES = "".join(
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("int", "uint", "int8", "uint8", "int16", "uint16", "int32", "uint32", "int64", "uint64")
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)
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class Structure(object):
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"""
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Gst Structure parser.
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Has publicly accesible members representing the structure data:
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name -- the structure name
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types -- a dictionary keyed by the field name
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values -- a dictionary keyed by the field name
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"""
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def __init__(self, text):
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self.text = text
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self.name, self.types, self.values = Structure._parse(text)
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def __repr__(self):
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return self.text
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@staticmethod
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def _find_eos(s):
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# find next '"' without preceeding '\'
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i = 0
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# logger.debug("find_eos: '%s'", s)
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while True: # faster than regexp for '[^\\]\"'
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p = s.index('"')
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i += p + 1
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if s[p - 1] != '\\':
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# logger.debug("... ok : '%s'", s[p:])
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return i
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s = s[(p + 1):]
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# logger.debug("... : '%s'", s)
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return -1
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@staticmethod
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def _parse(s):
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types = {}
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values = {}
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scan = True
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# logger.debug("===: '%s'", s)
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# parse id
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p = s.find(',')
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if p == -1:
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p = s.index(';')
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scan = False
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name = s[:p]
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# parse fields
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while scan:
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s = s[(p + 2):] # skip 'name, ' / 'value, '
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# logger.debug("...: '%s'", s)
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p = s.index('=')
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k = s[:p]
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if not s[p + 1] == '(':
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raise ValueError
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s = s[(p + 2):] # skip 'key=('
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p = s.index(')')
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t = s[:p]
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s = s[(p + 1):] # skip 'type)'
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if s[0] == '"':
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s = s[1:] # skip '"'
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p = Structure._find_eos(s)
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if p == -1:
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raise ValueError
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v = s[:(p - 1)]
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if s[p] == ';':
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scan = False
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# unescape \., but not \\. (using a backref)
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# need a reverse for re.escape()
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v = v.replace('\\\\', '\\')
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v = UNESCAPE.sub(r'\1', v)
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else:
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p = s.find(',')
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if p == -1:
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p = s.index(';')
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scan = False
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v = s[:p]
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if t == 'structure':
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v = Structure(v)
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elif t == 'string' and v[0] == '"':
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v = v[1:-1]
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elif t == 'boolean':
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v = (v == '1')
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elif t in INT_TYPES:
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v = int(v)
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types[k] = t
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values[k] = v
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return (name, types, values)
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