Python _ast 模块，While() 实例源码

def semicolon(self, stmt):
        if not isinstance(stmt, _ast.If) and not isinstance(stmt, _ast.While) and not isinstance(stmt, _ast.For):
            return ";"
        else:
            return ""

def handleNodeDelete(self, node):

        def on_conditional_branch():
            """
            Return `True` if node is part of a conditional body.
            """
            current = getattr(node, 'parent', None)
            while current:
                if isinstance(current, (ast.If, ast.While, ast.IfExp)):
                    return True
                current = getattr(current, 'parent', None)
            return False

        name = getNodeName(node)
        if not name:
            return

        if on_conditional_branch():
            # We cannot predict if this conditional branch is going to
            # be executed.
            return

        if isinstance(self.scope, FunctionScope) and name in self.scope.globals:
            self.scope.globals.remove(name)
        else:
            try:
                del self.scope[name]
            except KeyError:
                self.report(messages.UndefinedName, node, name)

def handleNodeDelete(self, node):

        def on_conditional_branch():
            """
            Return `True` if node is part of a conditional body.
            """
            current = getattr(node, 'parent', None)
            while current:
                if isinstance(current, (ast.If, ast.While, ast.IfExp)):
                    return True
                current = getattr(current, 'parent', None)
            return False

        name = getNodeName(node)
        if not name:
            return

        if on_conditional_branch():
            # We cannot predict if this conditional branch is going to
            # be executed.
            return

        if isinstance(self.scope, FunctionScope) and name in self.scope.globals:
            self.scope.globals.remove(name)
        else:
            try:
                del self.scope[name]
            except KeyError:
                self.report(messages.UndefinedName, node, name)

def handleNodeDelete(self, node):

        def on_conditional_branch():
            """
            Return `True` if node is part of a conditional body.
            """
            current = getattr(node, 'parent', None)
            while current:
                if isinstance(current, (ast.If, ast.While, ast.IfExp)):
                    return True
                current = getattr(current, 'parent', None)
            return False

        name = getNodeName(node)
        if not name:
            return

        if on_conditional_branch():
            # We can not predict if this conditional branch is going to
            # be executed.
            return

        if isinstance(self.scope, FunctionScope) and name in self.scope.globals:
            self.scope.globals.remove(name)
        else:
            try:
                del self.scope[name]
            except KeyError:
                self.report(messages.UndefinedName, node, name)

def while_loop(self, instr, loop_block):

        kw = dict(lineno=instr.lineno, col_offset=0)

        loop_block_map = {instr.i:instr.op for instr in loop_block}

        first_i = loop_block[0].i

        func = lambda instr: instr.opname == 'JUMP_ABSOLUTE' and instr.oparg == first_i
        body_index = rfind_index(loop_block[:-1], func)

        if body_index is None:
            const_while = True
            body_index = len(loop_block) - 1
        else:
            if body_index + 1 < len(loop_block): 
                pop_block = loop_block[body_index + 1]
                const_while = pop_block.opname != 'POP_BLOCK'
                const_else = True
            else:
                const_while = True
                const_else = False

        if const_while:
            test = _ast.Num(1, **kw)
            body_ = self.decompile_block(loop_block[:body_index]).stmnt()

            else_block = loop_block[body_index + 1:]
            if else_block:
                else_ = self.decompile_block(else_block).stmnt()
            else:
                else_ = []
        else:
            pop_block = loop_block[body_index + 1]

            func = lambda instr: instr.opname in ['POP_JUMP_IF_FALSE', 'POP_JUMP_IF_TRUE'] and instr.oparg == pop_block.i
            idx = rfind_index(loop_block[:body_index], func)
            cond_block = loop_block[:idx]

            iter_stmnt = self.decompile_block(cond_block).stmnt()
            assert len(iter_stmnt) == 1
            test = iter_stmnt[0]

            body_ = self.decompile_block(loop_block[idx + 1:body_index]).stmnt()

            else_block = loop_block[body_index + 2:]
            if else_block:
                else_ = self.decompile_block(else_block[:]).stmnt()
            else:
                else_ = []

        while_ = _ast.While(test=test, body=body_, orelse=else_, **kw)

        self.ast_stack.append(while_)