"""Disassembler of Python byte code into mnemonics."""

import sys

import types

import collections

import io

from opcode import *

from opcode import __all__ as _opcodes_all

__all__ = ["code_info", "dis", "disassemble", "distb", "disco",

           "findlinestarts", "findlabels", "show_code",

           "get_instructions", "Instruction", "Bytecode"] + _opcodes_all

del _opcodes_all

_have_code = (types.MethodType, types.FunctionType, types.CodeType,

              classmethod, staticmethod, type)

FORMAT_VALUE = opmap['FORMAT_VALUE']

def _try_compile(source, name):

    """Attempts to compile the given source, first as an expression and

       then as a statement if the first approach fails.

       Utility function to accept strings in functions that otherwise

       expect code objects

    """

    try:

        c = compile(source, name, 'eval')

    except SyntaxError:

        c = compile(source, name, 'exec')

    return c

def dis(x=None, *, file=None):

    """Disassemble classes, methods, functions, generators, or code.

    With no argument, disassemble the last traceback.

    """

    if x is None:

        distb(file=file)

        return

    if hasattr(x, '__func__'):  # Method

        x = x.__func__

    if hasattr(x, '__code__'):  # Function

        x = x.__code__

    if hasattr(x, 'gi_code'):  # Generator

        x = x.gi_code

    if hasattr(x, '__dict__'):  # Class or module

        items = sorted(x.__dict__.items())

        for name, x1 in items:

            if isinstance(x1, _have_code):

                print("Disassembly of %s:" % name, file=file)

                try:

                    dis(x1, file=file)

                except TypeError as msg:

                    print("Sorry:", msg, file=file)

                print(file=file)

    elif hasattr(x, 'co_code'): # Code object

        disassemble(x, file=file)

    elif isinstance(x, (bytes, bytearray)): # Raw bytecode

        _disassemble_bytes(x, file=file)

    elif isinstance(x, str):    # Source code

        _disassemble_str(x, file=file)

    else:

        raise TypeError("don't know how to disassemble %s objects" %

                        type(x).__name__)

def distb(tb=None, *, file=None):

    """Disassemble a traceback (default: last traceback)."""

    if tb is None:

        try:

            tb = sys.last_traceback

        except AttributeError:

            raise RuntimeError("no last traceback to disassemble")

        while tb.tb_next: tb = tb.tb_next

    disassemble(tb.tb_frame.f_code, tb.tb_lasti, file=file)

# The inspect module interrogates this dictionary to build its

# list of CO_* constants. It is also used by pretty_flags to

# turn the co_flags field into a human readable list.

COMPILER_FLAG_NAMES = {

     1: "OPTIMIZED",

     2: "NEWLOCALS",

     4: "VARARGS",

     8: "VARKEYWORDS",

    16: "NESTED",

    32: "GENERATOR",

    64: "NOFREE",

   128: "COROUTINE",

   256: "ITERABLE_COROUTINE",

   512: "ASYNC_GENERATOR",

}

def pretty_flags(flags):

    """Return pretty representation of code flags."""

    names = []

    for i in range(32):

        flag = 1<

        if flags & flag:

            names.append(COMPILER_FLAG_NAMES.get(flag, hex(flag)))

            flags ^= flag

            if not flags:

                break

    else:

        names.append(hex(flags))

    return ", ".join(names)

def _get_code_object(x):

    """Helper to handle methods, functions, generators, strings and raw code objects"""

    if hasattr(x, '__func__'): # Method

        x = x.__func__

    if hasattr(x, '__code__'): # Function

        x = x.__code__

    if hasattr(x, 'gi_code'):  # Generator

        x = x.gi_code

    if isinstance(x, str):     # Source code

        x = _try_compile(x, "<disassembly>")

    if hasattr(x, 'co_code'):  # Code object

        return x

    raise TypeError("don't know how to disassemble %s objects" %

                    type(x).__name__)

def code_info(x):

    """Formatted details of methods, functions, or code."""

    return _format_code_info(_get_code_object(x))

def _format_code_info(co):

    lines = []

    lines.append("Name:              %s" % co.co_name)

    lines.append("Filename:          %s" % co.co_filename)

    lines.append("Argument count:    %s" % co.co_argcount)

    lines.append("Kw-only arguments: %s" % co.co_kwonlyargcount)

    lines.append("Number of locals:  %s" % co.co_nlocals)

    lines.append("Stack size:        %s" % co.co_stacksize)

    lines.append("Flags:             %s" % pretty_flags(co.co_flags))

    if co.co_consts:

        lines.append("Constants:")

        for i_c in enumerate(co.co_consts):

            lines.append("%4d: %r" % i_c)

    if co.co_names:

        lines.append("Names:")

        for i_n in enumerate(co.co_names):

            lines.append("%4d: %s" % i_n)

    if co.co_varnames:

        lines.append("Variable names:")

        for i_n in enumerate(co.co_varnames):

            lines.append("%4d: %s" % i_n)

    if co.co_freevars:

        lines.append("Free variables:")

        for i_n in enumerate(co.co_freevars):

            lines.append("%4d: %s" % i_n)

    if co.co_cellvars:

        lines.append("Cell variables:")

        for i_n in enumerate(co.co_cellvars):

            lines.append("%4d: %s" % i_n)

    return "\n".join(lines)

def show_code(co, *, file=None):

    """Print details of methods, functions, or code to *file*.

    If *file* is not provided, the output is printed on stdout.

    """

    print(code_info(co), file=file)

_Instruction = collections.namedtuple("_Instruction",

     "opname opcode arg argval argrepr offset starts_line is_jump_target")

_Instruction.opname.__doc__ = "Human readable name for operation"

_Instruction.opcode.__doc__ = "Numeric code for operation"

_Instruction.arg.__doc__ = "Numeric argument to operation (if any), otherwise None"

_Instruction.argval.__doc__ = "Resolved arg value (if known), otherwise same as arg"

_Instruction.argrepr.__doc__ = "Human readable description of operation argument"

_Instruction.offset.__doc__ = "Start index of operation within bytecode sequence"

_Instruction.starts_line.__doc__ = "Line started by this opcode (if any), otherwise None"

_Instruction.is_jump_target.__doc__ = "True if other code jumps to here, otherwise False"

class Instruction(_Instruction):

    """Details for a bytecode operation

       Defined fields:

         opname - human readable name for operation

         opcode - numeric code for operation

         arg - numeric argument to operation (if any), otherwise None

         argval - resolved arg value (if known), otherwise same as arg

         argrepr - human readable description of operation argument

         offset - start index of operation within bytecode sequence

         starts_line - line started by this opcode (if any), otherwise None

         is_jump_target - True if other code jumps to here, otherwise False

    """

    def _disassemble(self, lineno_width=3, mark_as_current=False):

        """Format instruction details for inclusion in disassembly output

        *lineno_width* sets the width of the line number field (0 omits it)

        *mark_as_current* inserts a '-->' marker arrow as part of the line

        """

        fields = []

        # Column: Source code line number

        if lineno_width:

            if self.starts_line is not None:

                lineno_fmt = "%%%dd" % lineno_width

                fields.append(lineno_fmt % self.starts_line)

            else:

                fields.append(' ' * lineno_width)

        # Column: Current instruction indicator

        if mark_as_current:

            fields.append('-->')

        else:

            fields.append('   ')

        # Column: Jump target marker

        if self.is_jump_target:

            fields.append('>>')

        else:

            fields.append('  ')

        # Column: Instruction offset from start of code sequence

        fields.append(repr(self.offset).rjust(4))

        # Column: Opcode name

        fields.append(self.opname.ljust(20))

        # Column: Opcode argument

        if self.arg is not None:

            fields.append(repr(self.arg).rjust(5))

            # Column: Opcode argument details

            if self.argrepr:

                fields.append('(' + self.argrepr + ')')

        return ' '.join(fields).rstrip()

def get_instructions(x, *, first_line=None):

    """Iterator for the opcodes in methods, functions or code

    Generates a series of Instruction named tuples giving the details of

    each operations in the supplied code.

    If *first_line* is not None, it indicates the line number that should

    be reported for the first source line in the disassembled code.

    Otherwise, the source line information (if any) is taken directly from

    the disassembled code object.

    """

    co = _get_code_object(x)

    cell_names = co.co_cellvars + co.co_freevars

    linestarts = dict(findlinestarts(co))

    if first_line is not None:

        line_offset = first_line - co.co_firstlineno

    else:

        line_offset = 0

    return _get_instructions_bytes(co.co_code, co.co_varnames, co.co_names,

                                   co.co_consts, cell_names, linestarts,

                                   line_offset)

def _get_const_info(const_index, const_list):

    """Helper to get optional details about const references

       Returns the dereferenced constant and its repr if the constant

       list is defined.

       Otherwise returns the constant index and its repr().

    """

    argval = const_index

    if const_list is not None:

        argval = const_list[const_index]

    return argval, repr(argval)

def _get_name_info(name_index, name_list):

    """Helper to get optional details about named references

       Returns the dereferenced name as both value and repr if the name

       list is defined.

       Otherwise returns the name index and its repr().

    """

    argval = name_index

    if name_list is not None:

        argval = name_list[name_index]

        argrepr = argval

    else:

        argrepr = repr(argval)

    return argval, argrepr

def _get_instructions_bytes(code, varnames=None, names=None, constants=None,

                      cells=None, linestarts=None, line_offset=0):

    """Iterate over the instructions in a bytecode string.

    Generates a sequence of Instruction namedtuples giving the details of each

    opcode.  Additional information about the code's runtime environment

    (e.g. variable names, constants) can be specified using optional

    arguments.

    """

    labels = findlabels(code)

    starts_line = None

    for offset, op, arg in _unpack_opargs(code):

        if linestarts is not None:

            starts_line = linestarts.get(offset, None)

            if starts_line is not None:

                starts_line += line_offset

        is_jump_target = offset in labels

        argval = None

        argrepr = ''

        if arg is not None:

            #  Set argval to the dereferenced value of the argument when

            #  available, and argrepr to the string representation of argval.

            #    _disassemble_bytes needs the string repr of the

            #    raw name index for LOAD_GLOBAL, LOAD_CONST, etc.

            argval = arg

            if op in hasconst:

                argval, argrepr = _get_const_info(arg, constants)

            elif op in hasname:

                argval, argrepr = _get_name_info(arg, names)

            elif op in hasjrel:

                argval = offset + 2 + arg

                argrepr = "to " + repr(argval)

            elif op in haslocal:

                argval, argrepr = _get_name_info(arg, varnames)

            elif op in hascompare:

                argval = cmp_op[arg]

                argrepr = argval

            elif op in hasfree:

                argval, argrepr = _get_name_info(arg, cells)

            elif op == FORMAT_VALUE:

                argval = ((None, str, repr, ascii)[arg & 0x3], bool(arg & 0x4))

                argrepr = ('', 'str', 'repr', 'ascii')[arg & 0x3]

                if argval[1]:

                    if argrepr:

                        argrepr += ', '

                    argrepr += 'with format'

        yield Instruction(opname[op], op,

                          arg, argval, argrepr,

                          offset, starts_line, is_jump_target)

def disassemble(co, lasti=-1, *, file=None):

    """Disassemble a code object."""

    cell_names = co.co_cellvars + co.co_freevars

    linestarts = dict(findlinestarts(co))

    _disassemble_bytes(co.co_code, lasti, co.co_varnames, co.co_names,

                       co.co_consts, cell_names, linestarts, file=file)

def _disassemble_bytes(code, lasti=-1, varnames=None, names=None,

                       constants=None, cells=None, linestarts=None,

                       *, file=None, line_offset=0):

    # Omit the line number column entirely if we have no line number info

    show_lineno = linestarts is not None

    # TODO?: Adjust width upwards if max(linestarts.values()) >= 1000?

    lineno_width = 3 if show_lineno else 0

    for instr in _get_instructions_bytes(code, varnames, names,

                                         constants, cells, linestarts,

                                         line_offset=line_offset):

        new_source_line = (show_lineno and

                           instr.starts_line is not None and

                           instr.offset > 0)

        if new_source_line:

            print(file=file)

        is_current_instr = instr.offset == lasti

        print(instr._disassemble(lineno_width, is_current_instr), file=file)

def _disassemble_str(source, *, file=None):

    """Compile the source string, then disassemble the code object."""

    disassemble(_try_compile(source, '<dis>'), file=file)

disco = disassemble                     # XXX For backwards compatibility

def _unpack_opargs(code):

    extended_arg = 0

    for i in range(0, len(code), 2):

        op = code[i]

        if op >= HAVE_ARGUMENT:

            arg = code[i+1] | extended_arg

            extended_arg = (arg << 8) if op == EXTENDED_ARG else 0

        else:

            arg = None

        yield (i, op, arg)

def findlabels(code):

    """Detect all offsets in a byte code which are jump targets.

    Return the list of offsets.

    """

    labels = []

    for offset, op, arg in _unpack_opargs(code):

        if arg is not None:

            if op in hasjrel:

                label = offset + 2 + arg

            elif op in hasjabs:

                label = arg

            else:

                continue

            if label not in labels:

                labels.append(label)

    return labels

def findlinestarts(code):

    """Find the offsets in a byte code which are start of lines in the source.

    Generate pairs (offset, lineno) as described in Python/compile.c.

    """

    byte_increments = code.co_lnotab[0::2]

    line_increments = code.co_lnotab[1::2]

    lastlineno = None

    lineno = code.co_firstlineno

    addr = 0

    for byte_incr, line_incr in zip(byte_increments, line_increments):

        if byte_incr:

            if lineno != lastlineno:

                yield (addr, lineno)

                lastlineno = lineno

            addr += byte_incr

        if line_incr >= 0x80:

            # line_increments is an array of 8-bit signed integers

            line_incr -= 0x100

        lineno += line_incr

    if lineno != lastlineno:

        yield (addr, lineno)

class Bytecode:

    """The bytecode operations of a piece of code

    Instantiate this with a function, method, string of code, or a code object

    (as returned by compile()).

    Iterating over this yields the bytecode operations as Instruction instances.

    """

    def __init__(self, x, *, first_line=None, current_offset=None):

        self.codeobj = co = _get_code_object(x)

        if first_line is None:

            self.first_line = co.co_firstlineno

            self._line_offset = 0

        else:

            self.first_line = first_line

            self._line_offset = first_line - co.co_firstlineno

        self._cell_names = co.co_cellvars + co.co_freevars

        self._linestarts = dict(findlinestarts(co))

        self._original_object = x

        self.current_offset = current_offset

    def __iter__(self):

        co = self.codeobj

        return _get_instructions_bytes(co.co_code, co.co_varnames, co.co_names,

                                       co.co_consts, self._cell_names,

                                       self._linestarts,

                                       line_offset=self._line_offset)

    def __repr__(self):

        return "{}({!r})".format(self.__class__.__name__,

                                 self._original_object)

    @classmethod

    def from_traceback(cls, tb):

        """ Construct a Bytecode from the given traceback """

        while tb.tb_next:

            tb = tb.tb_next

        return cls(tb.tb_frame.f_code, current_offset=tb.tb_lasti)

    def info(self):

        """Return formatted information about the code object."""

        return _format_code_info(self.codeobj)

    def dis(self):

        """Return a formatted view of the bytecode operations."""

        co = self.codeobj

        if self.current_offset is not None:

            offset = self.current_offset

        else:

            offset = -1

        with io.StringIO() as output:

            _disassemble_bytes(co.co_code, varnames=co.co_varnames,

                               names=co.co_names, constants=co.co_consts,

                               cells=self._cell_names,

                               linestarts=self._linestarts,

                               line_offset=self._line_offset,

                               file=output,

                               lasti=offset)

            return output.getvalue()

def _test():

    """Simple test program to disassemble a file."""

    import argparse

    parser = argparse.ArgumentParser()

    parser.add_argument('infile', type=argparse.FileType(), nargs='?', default='-')

    args = parser.parse_args()

    with args.infile as infile:

        source = infile.read()

    code = compile(source, args.infile.name, "exec")

    dis(code)

if __name__ == "__main__":

    _test()