Class FeatStructParser

x.__init__(...) initializes x; see x.__class__.__doc__ for signature

Overrides: object.__init__

(inherited documentation)

Convert a string representation of a feature structure (as displayed by repr) into a FeatStruct. This parse imposes the following restrictions on the string representation:

• Feature names cannot contain any of the following: whitespace, parenthases, quote marks, equals signs, dashes, commas, and square brackets. Feature names may not begin with plus signs or minus signs.
• Only the following basic feature value are supported: strings, integers, variables, None, and unquoted alphanumeric strings.
• For reentrant values, the first mention must specify a reentrance identifier and a value; and any subsequent mentions must use arrows ('->') to reference the reentrance identifier.

Helper function that parses a feature structure.

Parameters:

• s - The string to parse.
• position - The position in the string to start parsing.
• reentrances - A dictionary from reentrance ids to values. Defaults to an empty dictionary.

Returns:

A tuple (val, pos) of the feature structure created by parsing and the position where the parsed feature structure ends.

VALUE_HANDLERS

A table indicating how feature values should be parsed. Each entry in the table is a pair (handler, regexp). The first entry with a matching regexp will have its handler called. Handlers should have the following signature:

  def handler(s, position, reentrances, match): ...

and should return a tuple (value, position), where position is the string position where the value ended. (n.b.: order is important here!)

Value:

[('parse_fstruct_value', re.compile(r'\s*(?:\((\d+)\)\s*)?(\??[\w-]+)?(\[)')), ('parse_var_value', re.compile(r'\?[a-zA-Z_][a-zA-Z0-9_]*')), ('parse_str_value', re.compile(r'[uU]?[rR]?([\'"])')), ('parse_int_value', re.compile(r'-?\d+')), ('parse_sym_value', re.compile(r'[a-zA-Z_][a-zA-Z0-9_]*')), ('parse_app_value', re.compile(r'<(app)\((\?[a-z][a-z]*)\s*,\s*(\?[a-z][a-z]*)\)>')), ...