1"""Interface to the compiler's internal symbol tables"""
2
3import _symtable
4from _symtable import (USE, DEF_GLOBAL, 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
121    def __idents_matching(self, test_func):
122        return tuple(ident for ident in self.get_identifiers()
123                     if test_func(self._table.symbols[ident]))
124
125    def get_parameters(self):
126        if self.__params is None:
127            self.__params = self.__idents_matching(lambda x:x & DEF_PARAM)
128        return self.__params
129
130    def get_locals(self):
131        if self.__locals is None:
132            locs = (LOCAL, CELL)
133            test = lambda x: ((x >> SCOPE_OFF) & SCOPE_MASK) in locs
134            self.__locals = self.__idents_matching(test)
135        return self.__locals
136
137    def get_globals(self):
138        if self.__globals is None:
139            glob = (GLOBAL_IMPLICIT, GLOBAL_EXPLICIT)
140            test = lambda x:((x >> SCOPE_OFF) & SCOPE_MASK) in glob
141            self.__globals = self.__idents_matching(test)
142        return self.__globals
143
144    def get_frees(self):
145        if self.__frees is None:
146            is_free = lambda x:((x >> SCOPE_OFF) & SCOPE_MASK) == FREE
147            self.__frees = self.__idents_matching(is_free)
148        return self.__frees
149
150
151class Class(SymbolTable):
152
153    __methods = None
154
155    def get_methods(self):
156        if self.__methods is None:
157            d = {}
158            for st in self._table.children:
159                d[st.name] = 1
160            self.__methods = tuple(d)
161        return self.__methods
162
163
164class Symbol(object):
165
166    def __init__(self, name, flags, namespaces=None):
167        self.__name = name
168        self.__flags = flags
169        self.__scope = (flags >> SCOPE_OFF) & SCOPE_MASK # like PyST_GetScope()
170        self.__namespaces = namespaces or ()
171
172    def __repr__(self):
173        return "<symbol {0!r}>".format(self.__name)
174
175    def get_name(self):
176        return self.__name
177
178    def is_referenced(self):
179        return bool(self.__flags & _symtable.USE)
180
181    def is_parameter(self):
182        return bool(self.__flags & DEF_PARAM)
183
184    def is_global(self):
185        return bool(self.__scope in (GLOBAL_IMPLICIT, GLOBAL_EXPLICIT))
186
187    def is_declared_global(self):
188        return bool(self.__scope == GLOBAL_EXPLICIT)
189
190    def is_local(self):
191        return bool(self.__scope in (LOCAL, CELL))
192
193    def is_annotated(self):
194        return bool(self.__flags & DEF_ANNOT)
195
196    def is_free(self):
197        return bool(self.__scope == FREE)
198
199    def is_imported(self):
200        return bool(self.__flags & DEF_IMPORT)
201
202    def is_assigned(self):
203        return bool(self.__flags & DEF_LOCAL)
204
205    def is_namespace(self):
206        """Returns true if name binding introduces new namespace.
207
208        If the name is used as the target of a function or class
209        statement, this will be true.
210
211        Note that a single name can be bound to multiple objects.  If
212        is_namespace() is true, the name may also be bound to other
213        objects, like an int or list, that does not introduce a new
214        namespace.
215        """
216        return bool(self.__namespaces)
217
218    def get_namespaces(self):
219        """Return a list of namespaces bound to this name"""
220        return self.__namespaces
221
222    def get_namespace(self):
223        """Returns the single namespace bound to this name.
224
225        Raises ValueError if the name is bound to multiple namespaces.
226        """
227        if len(self.__namespaces) != 1:
228            raise ValueError("name is bound to multiple namespaces")
229        return self.__namespaces[0]
230
231if __name__ == "__main__":
232    import os, sys
233    with open(sys.argv[0]) as f:
234        src = f.read()
235    mod = symtable(src, os.path.split(sys.argv[0])[1], "exec")
236    for ident in mod.get_identifiers():
237        info = mod.lookup(ident)
238        print(info, info.is_local(), info.is_namespace())
239