"""Interface to the compiler's internal symbol tables"""

import _symtable
from _symtable import (USE, DEF_GLOBAL, DEF_LOCAL, DEF_PARAM,
 DEF_IMPORT, DEF_BOUND, DEF_ANNOT, SCOPE_OFF, SCOPE_MASK, FREE,
 LOCAL, GLOBAL_IMPLICIT, GLOBAL_EXPLICIT, CELL)

import weakref

__all__ = ["symtable", "SymbolTable", "Class", "Function", "Symbol"]

def symtable(code, filename, compile_type):
 top = _symtable.symtable(code, filename, compile_type)
 return _newSymbolTable(top, filename)

class SymbolTableFactory:
 def __init__(self):
 self.__memo = weakref.WeakValueDictionary()

 def new(self, table, filename):
 if table.type == _symtable.TYPE_FUNCTION:
 return Function(table, filename)
 if table.type == _symtable.TYPE_CLASS:
 return Class(table, filename)
 return SymbolTable(table, filename)

 def __call__(self, table, filename):
 key = table, filename
 obj = self.__memo.get(key, None)
 if obj is None:
 obj = self.__memo[key] = self.new(table, filename)
 return obj

_newSymbolTable = SymbolTableFactory()


class SymbolTable(object):

 def __init__(self, raw_table, filename):
 self._table = raw_table
 self._filename = filename
 self._symbols = {}

 def __repr__(self):
 if self.__class__ == SymbolTable:
 kind = ""
 else:
 kind = "%s " % self.__class__.__name__

 if self._table.name == "global":
 return "<{0}SymbolTable for module {1}>".format(kind, self._filename)
 else:
 return "<{0}SymbolTable for {1} in {2}>".format(kind,
 self._table.name,
 self._filename)

 def get_type(self):
 if self._table.type == _symtable.TYPE_MODULE:
 return "module"
 if self._table.type == _symtable.TYPE_FUNCTION:
 return "function"
 if self._table.type == _symtable.TYPE_CLASS:
 return "class"
 assert self._table.type in (1, 2, 3), \
 "unexpected type: {0}".format(self._table.type)

 def get_id(self):
 return self._table.id

 def get_name(self):
 return self._table.name

 def get_lineno(self):
 return self._table.lineno

 def is_optimized(self):
 return bool(self._table.type == _symtable.TYPE_FUNCTION)

 def is_nested(self):
 return bool(self._table.nested)

 def has_children(self):
 return bool(self._table.children)

 def has_exec(self):
 """Return true if the scope uses exec. Deprecated method."""
 return False

 def get_identifiers(self):
 return self._table.symbols.keys()

 def lookup(self, name):
 sym = self._symbols.get(name)
 if sym is None:
 flags = self._table.symbols[name]
 namespaces = self.__check_children(name)
 sym = self._symbols[name] = Symbol(name, flags, namespaces)
 return sym

 def get_symbols(self):
 return [self.lookup(ident) for ident in self.get_identifiers()]

 def __check_children(self, name):
 return [_newSymbolTable(st, self._filename)
 for st in self._table.children
 if st.name == name]

 def get_children(self):
 return [_newSymbolTable(st, self._filename)
 for st in self._table.children]


class Function(SymbolTable):

 # Default values for instance variables
 __params = None
 __locals = None
 __frees = None
 __globals = None

 def __idents_matching(self, test_func):
 return tuple(ident for ident in self.get_identifiers()
 if test_func(self._table.symbols[ident]))

 def get_parameters(self):
 if self.__params is None:
 self.__params = self.__idents_matching(lambda x:x & DEF_PARAM)
 return self.__params

 def get_locals(self):
 if self.__locals is None:
 locs = (LOCAL, CELL)
 test = lambda x: ((x >> SCOPE_OFF) & SCOPE_MASK) in locs
 self.__locals = self.__idents_matching(test)
 return self.__locals

 def get_globals(self):
 if self.__globals is None:
 glob = (GLOBAL_IMPLICIT, GLOBAL_EXPLICIT)
 test = lambda x:((x >> SCOPE_OFF) & SCOPE_MASK) in glob
 self.__globals = self.__idents_matching(test)
 return self.__globals

 def get_frees(self):
 if self.__frees is None:
 is_free = lambda x:((x >> SCOPE_OFF) & SCOPE_MASK) == FREE
 self.__frees = self.__idents_matching(is_free)
 return self.__frees


class Class(SymbolTable):

 __methods = None

 def get_methods(self):
 if self.__methods is None:
 d = {}
 for st in self._table.children:
 d[st.name] = 1
 self.__methods = tuple(d)
 return self.__methods


class Symbol(object):

 def __init__(self, name, flags, namespaces=None):
 self.__name = name
 self.__flags = flags
 self.__scope = (flags >> SCOPE_OFF) & SCOPE_MASK # like PyST_GetScope()
 self.__namespaces = namespaces or ()

 def __repr__(self):
 return "<symbol {0!r}>".format(self.__name)

 def get_name(self):
 return self.__name

 def is_referenced(self):
 return bool(self.__flags & _symtable.USE)

 def is_parameter(self):
 return bool(self.__flags & DEF_PARAM)

 def is_global(self):
 return bool(self.__scope in (GLOBAL_IMPLICIT, GLOBAL_EXPLICIT))

 def is_declared_global(self):
 return bool(self.__scope == GLOBAL_EXPLICIT)

 def is_local(self):
 return bool(self.__flags & DEF_BOUND)

 def is_annotated(self):
 return bool(self.__flags & DEF_ANNOT)

 def is_free(self):
 return bool(self.__scope == FREE)

 def is_imported(self):
 return bool(self.__flags & DEF_IMPORT)

 def is_assigned(self):
 return bool(self.__flags & DEF_LOCAL)

 def is_namespace(self):
 """Returns true if name binding introduces new namespace.

 If the name is used as the target of a function or class
 statement, this will be true.

 Note that a single name can be bound to multiple objects. If
 is_namespace() is true, the name may also be bound to other
 objects, like an int or list, that does not introduce a new
 namespace.
 """
 return bool(self.__namespaces)

 def get_namespaces(self):
 """Return a list of namespaces bound to this name"""
 return self.__namespaces

 def get_namespace(self):
 """Returns the single namespace bound to this name.

 Raises ValueError if the name is bound to multiple namespaces.
 """
 if len(self.__namespaces) != 1:
 raise ValueError("name is bound to multiple namespaces")
 return self.__namespaces[0]

if __name__ == "__main__":
 import os, sys
 with open(sys.argv[0]) as f:
 src = f.read()
 mod = symtable(src, os.path.split(sys.argv[0])[1], "exec")
 for ident in mod.get_identifiers():
 info = mod.lookup(ident)
 print(info, info.is_local(), info.is_namespace())