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

import _symtable
from _symtable import (USE, DEF_GLOBAL, DEF_NONLOCAL, 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:

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 == "top":
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)
module_scope = (self._table.name == "top")
sym = self._symbols[name] = Symbol(name, flags, namespaces,
module_scope=module_scope)
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
__nonlocals = 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_nonlocals(self):
if self.__nonlocals is None:
self.__nonlocals = self.__idents_matching(lambda x:x & DEF_NONLOCAL)
return self.__nonlocals

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:

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

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 *True* if the sysmbol is global.
"""
return bool(self.__scope in (GLOBAL_IMPLICIT, GLOBAL_EXPLICIT)
or (self.__module_scope and self.__flags & DEF_BOUND))

def is_nonlocal(self):
return bool(self.__flags & DEF_NONLOCAL)

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

def is_local(self):
"""Return *True* if the symbol is local.
"""
return bool(self.__scope in (LOCAL, CELL)
or (self.__module_scope and 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())