aria/utils/exceptions.py

# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements.  See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License.  You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""
Utilities for extracting and formatting Python exceptions.
"""

import sys
import linecache
import StringIO
import traceback as tb

import jsonpickle

from .console import (puts, indent, Colored)


ENTRY_FORMAT = 'File "{filename}", line {lineno}, in {name}'


def print_exception(e, full=True, cause=False, traceback=None):
    """
    Prints the exception with nice colors and such.
    """
    def format_heading(e):
        return '{0}{1}: {2}'.format(
            Colored.red('Caused by ') if cause else '',
            Colored.red(e.__class__.__name__, bold=True),
            Colored.red(e))

    puts(format_heading(e))
    if full:
        if cause:
            if traceback:
                print_traceback(traceback, True)
        else:
            print_traceback()
    if hasattr(e, 'cause') and e.cause:
        traceback = e.cause_traceback if hasattr(e, 'cause_traceback') else None
        print_exception(e.cause, full=full, cause=True, traceback=traceback)


def print_traceback(traceback=None, print_last_stack=False):
    """
    Prints the traceback with nice colors and such.
    """

    if traceback is None:
        _, _, traceback = sys.exc_info()
    while traceback is not None:
        frame = traceback.tb_frame
        code = frame.f_code
        filename = code.co_filename
        lineno = traceback.tb_lineno
        name = code.co_name
        with indent(2):
            puts(ENTRY_FORMAT.format(filename=Colored.blue(filename),
                                     lineno=Colored.cyan(lineno),
                                     name=Colored.cyan(name)))
            linecache.checkcache(filename)
            line = linecache.getline(filename, lineno, frame.f_globals)
            if line:
                with indent(2):
                    puts(line.strip())
        traceback = traceback.tb_next
        if print_last_stack and (traceback is None):
            # Print stack of *last* traceback
            _print_stack(frame)


def _print_stack(frame):
    entries = tb.extract_stack(frame)
    if not entries:
        return
    puts(Colored.red('Call stack:'))
    with indent(2):
        for filename, lineno, name, line in entries:
            puts(ENTRY_FORMAT.format(filename=Colored.blue(filename),
                                     lineno=Colored.cyan(lineno),
                                     name=Colored.cyan(name)))
            with indent(2):
                puts(line)


def get_exception_as_string(exc_type, exc_val, traceback):
    s_traceback = StringIO.StringIO()
    tb.print_exception(
        etype=exc_type,
        value=exc_val,
        tb=traceback,
        file=s_traceback)
    return s_traceback.getvalue()


class _WrappedException(Exception):

    def __init__(self, exception_type, exception_str):
        super(_WrappedException, self).__init__(exception_type, exception_str)
        self.exception_type = exception_type
        self.exception_str = exception_str


def wrap_if_needed(exception):
    try:
        jsonpickle.loads(jsonpickle.dumps(exception))
        return exception
    except BaseException:
        return _WrappedException(type(exception).__name__, str(exception))