First cut at a high-level symbol table interface

1 files changed, 258 insertions, 0 deletions

diff --git a/Lib/symtable.py b/Lib/symtable.py
new file mode 100644
index 0000000..3133633
--- /dev/null
+++ b/Lib/symtable.py
@@ -0,0 +1,258 @@
+"""Interface to the compiler's internal symbol tables"""
+from __future__ import nested_scopes
+
+import _symtable
+from _symtable import USE, DEF_GLOBAL, DEF_LOCAL, DEF_PARAM, \
+     DEF_STAR, DEF_DOUBLESTAR, DEF_INTUPLE, DEF_FREE, \
+     DEF_FREE_GLOBAL, DEF_FREE_CLASS, DEF_IMPORT, DEF_BOUND
+
+import weakref
+
+__all__ = ["symtable", "SymbolTable", "newSymbolTable"]
+
+def symtable(code, filename, compile_type):
+    raw = _symtable.symtable(code, filename, compile_type)
+    return newSymbolTable(raw[0], 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()
+    
+def bool(x):
+    """Helper to force boolean result to 1 or 0"""
+    if x:
+        return 1
+    return 0
+
+def is_free(flags):
+    if (flags & (USE | DEF_FREE)) \
+       and (flags & (DEF_LOCAL | DEF_PARAM | DEF_GLOBAL)):
+        return 1
+    if flags & DEF_FREE_CLASS:
+        return 1
+    return 0
+
+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 == "global":
+            return "<%sSymbolTable for module %s>" % (kind, self._filename)
+        else:
+            return "<%sSymbolTable for %s in %s>" % (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: %s" % 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 bool()
+
+    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]
+
+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 = DEF_GLOBAL | DEF_FREE_GLOBAL
+            self.__globals = self.__idents_matching(lambda x:x & glob)
+        return self.__globals
+
+    def get_frees(self):
+        if self.__frees is None:
+            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.keys())
+        return self.__methods
+
+class Symbol:
+    def __init__(self, name, flags, namespaces=None):
+        self.__name = name
+        self.__flags = flags
+        self.__namespaces = namespaces or ()
+
+    def __repr__(self):
+        return "<symbol '%s'>" % 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.__flags & DEF_GLOBAL) 
+                    or (self.__flags & DEF_FREE_GLOBAL))
+
+    def is_vararg(self):
+        return bool(self.flag & DEF_STAR)
+
+    def is_keywordarg(self):
+        return bool(self.__flags & DEF_STARSTAR)
+
+    def is_local(self):
+        return bool(self.__flags & DEF_BOUND)
+
+    def is_free(self):
+        if (self.__flags & (USE | DEF_FREE)) \
+            and (self.__flags & (DEF_LOCAL | DEF_PARAM | DEF_GLOBAL)):
+            return 1
+        if self.__flags & DEF_FREE_CLASS:
+            return 1
+        return 0
+
+    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):
+        return bool(self.__flags & DEF_INTUPLE)
+
+    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 __debug__:
+    class Foo:
+        version = 1
+
+    class Foo:
+        version = 2
+
+    class Foo:
+        version = 3
+
+    def execfunc(x):
+        exec x in y
+    
+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()