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

import _symtable

from _symtable import (USE, DEF_GLOBAL, DEF_LOCAL, DEF_PARAM,

     DEF_IMPORT, DEF_BOUND, OPT_IMPORT_STAR, OPT_EXEC, OPT_BARE_EXEC,

     SCOPE_OFF, SCOPE_MASK, FREE, GLOBAL_IMPLICIT, GLOBAL_EXPLICIT)

import warnings

import weakref

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

def symtable(code, filename, compile_type):

    raw = _symtable.symtable(code, filename, compile_type)

    for top in raw.itervalues():

        if top.name == 'top':

            break

    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

                    and not self._table.optimized)

    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"""

        return bool(self._table.optimized & (OPT_EXEC | OPT_BARE_EXEC))

    def has_import_star(self):

        """Return true if the scope uses import *"""

        return bool(self._table.optimized & OPT_IMPORT_STAR)

    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:

            self.__locals = self.__idents_matching(lambda x:x & DEF_BOUND)

        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_vararg(self):

        warnings.warn("is_vararg() is obsolete and will be removed",

                      DeprecationWarning, 2)

        return False

    def is_keywordarg(self):

        warnings.warn("is_keywordarg() is obsolete and will be removed",

                      DeprecationWarning, 2)

        return False

    def is_local(self):

        return bool(self.__flags & DEF_BOUND)

    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_in_tuple(self):

        warnings.warn("is_in_tuple() is obsolete and will be removed",

                      DeprecationWarning, 2)

    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

    src = open(sys.argv[0]).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()