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1"""Interface to the compiler's internal symbol tables"""
2
3import _symtable
4from _symtable import (USE, DEF_GLOBAL, DEF_NONLOCAL, DEF_LOCAL, DEF_PARAM,
5     DEF_IMPORT, DEF_BOUND, DEF_ANNOT, SCOPE_OFF, SCOPE_MASK, FREE,
6     LOCAL, GLOBAL_IMPLICIT, GLOBAL_EXPLICIT, CELL)
7
8import weakref
9
10__all__ = ["symtable", "SymbolTable", "Class", "Function", "Symbol"]
11
12def symtable(code, filename, compile_type):
13    top = _symtable.symtable(code, filename, compile_type)
14    return _newSymbolTable(top, filename)
15
16class SymbolTableFactory:
17    def __init__(self):
18        self.__memo = weakref.WeakValueDictionary()
19
20    def new(self, table, filename):
21        if table.type == _symtable.TYPE_FUNCTION:
22            return Function(table, filename)
23        if table.type == _symtable.TYPE_CLASS:
24            return Class(table, filename)
25        return SymbolTable(table, filename)
26
27    def __call__(self, table, filename):
28        key = table, filename
29        obj = self.__memo.get(key, None)
30        if obj is None:
31            obj = self.__memo[key] = self.new(table, filename)
32        return obj
33
34_newSymbolTable = SymbolTableFactory()
35
36
37class SymbolTable(object):
38
39    def __init__(self, raw_table, filename):
40        self._table = raw_table
41        self._filename = filename
42        self._symbols = {}
43
44    def __repr__(self):
45        if self.__class__ == SymbolTable:
46            kind = ""
47        else:
48            kind = "%s " % self.__class__.__name__
49
50        if self._table.name == "global":
51            return "<{0}SymbolTable for module {1}>".format(kind, self._filename)
52        else:
53            return "<{0}SymbolTable for {1} in {2}>".format(kind,
54                                                            self._table.name,
55                                                            self._filename)
56
57    def get_type(self):
58        if self._table.type == _symtable.TYPE_MODULE:
59            return "module"
60        if self._table.type == _symtable.TYPE_FUNCTION:
61            return "function"
62        if self._table.type == _symtable.TYPE_CLASS:
63            return "class"
64        assert self._table.type in (1, 2, 3), \
65               "unexpected type: {0}".format(self._table.type)
66
67    def get_id(self):
68        return self._table.id
69
70    def get_name(self):
71        return self._table.name
72
73    def get_lineno(self):
74        return self._table.lineno
75
76    def is_optimized(self):
77        return bool(self._table.type == _symtable.TYPE_FUNCTION)
78
79    def is_nested(self):
80        return bool(self._table.nested)
81
82    def has_children(self):
83        return bool(self._table.children)
84
85    def has_exec(self):
86        """Return true if the scope uses exec.  Deprecated method."""
87        return False
88
89    def get_identifiers(self):
90        return self._table.symbols.keys()
91
92    def lookup(self, name):
93        sym = self._symbols.get(name)
94        if sym is None:
95            flags = self._table.symbols[name]
96            namespaces = self.__check_children(name)
97            sym = self._symbols[name] = Symbol(name, flags, namespaces)
98        return sym
99
100    def get_symbols(self):
101        return [self.lookup(ident) for ident in self.get_identifiers()]
102
103    def __check_children(self, name):
104        return [_newSymbolTable(st, self._filename)
105                for st in self._table.children
106                if st.name == name]
107
108    def get_children(self):
109        return [_newSymbolTable(st, self._filename)
110                for st in self._table.children]
111
112
113class Function(SymbolTable):
114
115    # Default values for instance variables
116    __params = None
117    __locals = None
118    __frees = None
119    __globals = None
120    __nonlocals = None
121
122    def __idents_matching(self, test_func):
123        return tuple(ident for ident in self.get_identifiers()
124                     if test_func(self._table.symbols[ident]))
125
126    def get_parameters(self):
127        if self.__params is None:
128            self.__params = self.__idents_matching(lambda x:x & DEF_PARAM)
129        return self.__params
130
131    def get_locals(self):
132        if self.__locals is None:
133            locs = (LOCAL, CELL)
134            test = lambda x: ((x >> SCOPE_OFF) & SCOPE_MASK) in locs
135            self.__locals = self.__idents_matching(test)
136        return self.__locals
137
138    def get_globals(self):
139        if self.__globals is None:
140            glob = (GLOBAL_IMPLICIT, GLOBAL_EXPLICIT)
141            test = lambda x:((x >> SCOPE_OFF) & SCOPE_MASK) in glob
142            self.__globals = self.__idents_matching(test)
143        return self.__globals
144
145    def get_nonlocals(self):
146        if self.__nonlocals is None:
147            self.__nonlocals = self.__idents_matching(lambda x:x & DEF_NONLOCAL)
148        return self.__nonlocals
149
150    def get_frees(self):
151        if self.__frees is None:
152            is_free = lambda x:((x >> SCOPE_OFF) & SCOPE_MASK) == FREE
153            self.__frees = self.__idents_matching(is_free)
154        return self.__frees
155
156
157class Class(SymbolTable):
158
159    __methods = None
160
161    def get_methods(self):
162        if self.__methods is None:
163            d = {}
164            for st in self._table.children:
165                d[st.name] = 1
166            self.__methods = tuple(d)
167        return self.__methods
168
169
170class Symbol(object):
171
172    def __init__(self, name, flags, namespaces=None):
173        self.__name = name
174        self.__flags = flags
175        self.__scope = (flags >> SCOPE_OFF) & SCOPE_MASK # like PyST_GetScope()
176        self.__namespaces = namespaces or ()
177
178    def __repr__(self):
179        return "<symbol {0!r}>".format(self.__name)
180
181    def get_name(self):
182        return self.__name
183
184    def is_referenced(self):
185        return bool(self.__flags & _symtable.USE)
186
187    def is_parameter(self):
188        return bool(self.__flags & DEF_PARAM)
189
190    def is_global(self):
191        return bool(self.__scope in (GLOBAL_IMPLICIT, GLOBAL_EXPLICIT))
192
193    def is_nonlocal(self):
194        return bool(self.__flags & DEF_NONLOCAL)
195
196    def is_declared_global(self):
197        return bool(self.__scope == GLOBAL_EXPLICIT)
198
199    def is_local(self):
200        return bool(self.__flags & DEF_BOUND)
201
202    def is_annotated(self):
203        return bool(self.__flags & DEF_ANNOT)
204
205    def is_free(self):
206        return bool(self.__scope == FREE)
207
208    def is_imported(self):
209        return bool(self.__flags & DEF_IMPORT)
210
211    def is_assigned(self):
212        return bool(self.__flags & DEF_LOCAL)
213
214    def is_namespace(self):
215        """Returns true if name binding introduces new namespace.
216
217        If the name is used as the target of a function or class
218        statement, this will be true.
219
220        Note that a single name can be bound to multiple objects.  If
221        is_namespace() is true, the name may also be bound to other
222        objects, like an int or list, that does not introduce a new
223        namespace.
224        """
225        return bool(self.__namespaces)
226
227    def get_namespaces(self):
228        """Return a list of namespaces bound to this name"""
229        return self.__namespaces
230
231    def get_namespace(self):
232        """Returns the single namespace bound to this name.
233
234        Raises ValueError if the name is bound to multiple namespaces.
235        """
236        if len(self.__namespaces) != 1:
237            raise ValueError("name is bound to multiple namespaces")
238        return self.__namespaces[0]
239
240if __name__ == "__main__":
241    import os, sys
242    with open(sys.argv[0]) as f:
243        src = f.read()
244    mod = symtable(src, os.path.split(sys.argv[0])[1], "exec")
245    for ident in mod.get_identifiers():
246        info = mod.lookup(ident)
247        print(info, info.is_local(), info.is_namespace())
248