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  #   ˆl–ßi~”Ji?u2 \¸®å1hßÁ„M<ÿÀ¿ 8™    """Module symbol-table generator"""

from compiler import ast
from compiler.consts import SC_LOCAL, SC_GLOBAL_IMPLICIT, SC_GLOBAL_EXPLICIT, \
    SC_FREE, SC_CELL, SC_UNKNOWN
from compiler.misc import mangle
import types


import sys

MANGLE_LEN = 256

class Scope:
    # XXX how much information do I need about each name?
    def __init__(self, name, module, klass=None):
        self.name = name
        self.module = module
        self.defs = {}
        self.uses = {}
        self.globals = {}
        self.params = {}
        self.frees = {}
        self.cells = {}
        self.children = []
        # nested is true if the class could contain free variables,
        # i.e. if it is nested within another function.
        self.nested = None
        self.generator = None
        self.klass = None
        if klass is not None:
            for i in range(len(klass)):
                if klass[i] != '_':
                    self.klass = klass[i:]
                    break

    def __repr__(self):
        return "<%s: %s>" % (self.__class__.__name__, self.name)

    def mangle(self, name):
        if self.klass is None:
            return name
        return mangle(name, self.klass)

    def add_def(self, name):
        self.defs[self.mangle(name)] = 1

    def add_use(self, name):
        self.uses[self.mangle(name)] = 1

    def add_global(self, name):
        name = self.mangle(name)
        if name in self.uses or name in self.defs:
            pass # XXX warn about global following def/use
        if name in self.params:
            raise SyntaxError, "%s in %s is global and parameter" % \
                  (name, self.name)
        self.globals[name] = 1
        self.module.add_def(name)

    def add_param(self, name):
        name = self.mangle(name)
        self.defs[name] = 1
        self.params[name] = 1

    def get_names(self):
        d = {}
        d.update(self.defs)
        d.update(self.uses)
        d.update(self.globals)
        return d.keys()

    def add_child(self, child):
        self.children.append(child)

    def get_children(self):
        return self.children

    def DEBUG(self):
        print >> sys.stderr, self.name, self.nested and "nested" or ""
        print >> sys.stderr, "\tglobals: ", self.globals
        print >> sys.stderr, "\tcells: ", self.cells
        print >> sys.stderr, "\tdefs: ", self.defs
        print >> sys.stderr, "\tuses: ", self.uses
        print >> sys.stderr, "\tfrees:", self.frees

    def check_name(self, name):
        """Return scope of name.

        The scope of a name could be LOCAL, GLOBAL, FREE, or CELL.
        """
        if name in self.globals:
            return SC_GLOBAL_EXPLICIT
        if name in self.cells:
            return SC_CELL
        if name in self.defs:
            return SC_LOCAL
        if self.nested and (name in self.frees or name in self.uses):
            return SC_FREE
        if self.nested:
            return SC_UNKNOWN
        else:
            return SC_GLOBAL_IMPLICIT

    def get_free_vars(self):
        if not self.nested:
            return ()
        free = {}
        free.update(self.frees)
        for name in self.uses.keys():
            if name not in self.defs and name not in self.globals:
                free[name] = 1
        return free.keys()

    def handle_children(self):
        for child in self.children:
            frees = child.get_free_vars()
            globals = self.add_frees(frees)
            for name in globals:
                child.force_global(name)

    def force_global(self, name):
        """Force name to be global in scope.

        Some child of the current node had a free reference to name.
        When the child was processed, it was labelled a free
        variable.  Now that all its enclosing scope have been
        processed, the name is known to be a global or builtin.  So
        walk back down the child chain and set the name to be global
        rather than free.

        Be careful to stop if a child does not think the name is