# Copyright (c) 2015-2018 by Rocky Bernstein
"""
Python 2.7 bytecode ingester.

This massages tokenized 2.7 bytecode to make it more amenable for
grammar parsing.
"""


from __future__ import print_function

from uncompyle6.scanners.scanner2 import Scanner2

from uncompyle6 import PYTHON3
if PYTHON3:
    import sys
    intern = sys.intern

# bytecode verification, verify(), uses JUMP_OPs from here
from xdis.opcodes import opcode_27
JUMP_OPS = opcode_27.JUMP_OPs

class Scanner27(Scanner2):
    def __init__(self, show_asm=False, is_pypy=False):
        super(Scanner27, self).__init__(2.7, show_asm, is_pypy)

        # opcodes that start statements
        self.stmt_opcodes = frozenset([
            self.opc.SETUP_LOOP,       self.opc.BREAK_LOOP,
            self.opc.SETUP_FINALLY,    self.opc.END_FINALLY,
            self.opc.SETUP_EXCEPT,
            self.opc.POP_BLOCK,        self.opc.STORE_FAST, self.opc.DELETE_FAST,
            self.opc.STORE_DEREF,      self.opc.STORE_GLOBAL,
            self.opc.DELETE_GLOBAL,    self.opc.STORE_NAME,
            self.opc.DELETE_NAME,      self.opc.STORE_ATTR,
            self.opc.DELETE_ATTR,      self.opc.STORE_SUBSCR,
            self.opc.DELETE_SUBSCR,    self.opc.RETURN_VALUE,
            self.opc.RAISE_VARARGS,    self.opc.POP_TOP,
            self.opc.PRINT_EXPR,       self.opc.PRINT_ITEM,
            self.opc.PRINT_NEWLINE,    self.opc.PRINT_ITEM_TO,
            self.opc.PRINT_NEWLINE_TO, self.opc.CONTINUE_LOOP,
            self.opc.JUMP_ABSOLUTE,    self.opc.EXEC_STMT,
            # New in 2.7
            self.opc.SETUP_WITH,
            self.opc.STORE_SLICE_0,    self.opc.STORE_SLICE_1,
            self.opc.STORE_SLICE_2,    self.opc.STORE_SLICE_3,
            self.opc.DELETE_SLICE_0,   self.opc.DELETE_SLICE_1,
            self.opc.DELETE_SLICE_2,   self.opc.DELETE_SLICE_3,
        ])

        # opcodes which expect a variable number pushed values and whose
        # count is in the opcode. For parsing we generally change the
        # opcode name to include that number.
        varargs_ops = set([
            self.opc.BUILD_LIST,           self.opc.BUILD_TUPLE,
            self.opc.BUILD_SLICE,          self.opc.UNPACK_SEQUENCE,
            self.opc.MAKE_FUNCTION,        self.opc.CALL_FUNCTION,
            self.opc.MAKE_CLOSURE,         self.opc.CALL_FUNCTION_VAR,
            self.opc.CALL_FUNCTION_KW,     self.opc.CALL_FUNCTION_VAR_KW,
            self.opc.DUP_TOPX,             self.opc.RAISE_VARARGS,
            # New in Python 2.7
            self.opc.BUILD_SET,            self.opc.BUILD_MAP])

        if is_pypy:
            varargs_ops.add(self.opc.CALL_METHOD)
        self.varargs_ops = frozenset(varargs_ops)

        # "setup" opcodes
        self.setup_ops = frozenset([
            self.opc.SETUP_EXCEPT, self.opc.SETUP_FINALLY,
            # New in 2.7
            self.opc.SETUP_WITH])

        # opcodes that store values into a variable
        self.designator_ops = frozenset([
            self.opc.STORE_FAST,    self.opc.STORE_NAME,
            self.opc.STORE_GLOBAL,  self.opc.STORE_DEREF,   self.opc.STORE_ATTR,
            self.opc.STORE_SLICE_0, self.opc.STORE_SLICE_1, self.opc.STORE_SLICE_2,
            self.opc.STORE_SLICE_3, self.opc.STORE_SUBSCR,  self.opc.UNPACK_SEQUENCE,
            self.opc.JUMP_ABSOLUTE
        ])

        self.pop_jump_if_or_pop = frozenset([self.opc.JUMP_IF_FALSE_OR_POP,
                                             self.opc.JUMP_IF_TRUE_OR_POP])

        return

    def patch_continue(self, tokens, offset, op):
        if op in (self.opc.JUMP_FORWARD, self.opc.JUMP_ABSOLUTE):
            # FIXME: this is a hack to catch stuff like:
            #   for ...
            #     try: ...
            #     except: continue
            # the "continue" is not on a new line.
            n = len(tokens)
            if (n > 2 and
                tokens[-1].kind == 'JUMP_BACK' and
                self.code[offset+3] == self.opc.END_FINALLY):
                tokens[-1].kind = intern('CONTINUE')

    pass

if __name__ == "__main__":
    from uncompyle6 import PYTHON_VERSION
    if PYTHON_VERSION == 2.7:
        import inspect
        co = inspect.currentframe().f_code
        tokens, customize = Scanner27().ingest(co)
        for t in tokens:
            print(t)
        pass
    else:
        print("Need to be Python 2.7 to demo; I am %s." %
              PYTHON_VERSION)