# Exception handling

import copy

import atexit

import sys

import traceback

import format

import strings

import term

import util

def raise_(e): raise e

def sys_traceback():

    '''Note that Python tracebacks seems to have a bug that truncates them to

    only a few stack frames. See <http://bugs.python.org/issue7378>.'''

    return sys.exc_info()[2]

        # can't just return pointer to traceback because it will change :-(

def has_traceback(e): return hasattr(e, 'traceback_')

def add_traceback(e):

    '''Adds current traceback to an exception if it doesn't already have one'''

    traceback_ = sys_traceback() # get first in case later code throws exception

    if not has_traceback(e): e.traceback_ = traceback_

def get_traceback_str(e):

    try: traceback_ = e.traceback_

    except AttributeError: return ''

    return ''.join(traceback.format_exception(None, None, traceback_)[:-1])

        # remove final "None" line ("exception name")

def add_msg(e, msg): e.args = (strings.ensure_newl(str(e))+msg,)

def repl_msg(e, **repls): e.args = (str(e) % repls,)

def e_ct_exit_status(e_ct): return min(e_ct, 255)

class ExceptionWithCause(Exception):

    def __init__(self, msg, cause=None):

        Exception.__init__(self, msg)

        add_traceback(self)

        if cause != None: add_msg(self, 'cause: '+str_(cause))

def str_(e): return ''.join(traceback.format_exception_only(type(e), e))

def print_ex(e, emph=True):

    msg = strings.ensure_newl(str_(e))+get_traceback_str(e)

    if emph:

        first_line, nl, rest = msg.partition('\n')

        msg = term.error(first_line)+nl+rest

    sys.stderr.write(msg)

class ExTracker:

    def __init__(self):

        self.e_ct = 0

    def msg(self): return 'Encountered '+str(self.e_ct)+' error(s)'

    def track(self, e, **format):

        self.e_ct += 1

        print_ex(e, **format)

    def exit(self):

        if self.e_ct > 0: raise SystemExit(e_ct_exit_status(self.e_ct))

class ExPercentTracker(ExTracker):

    def __init__(self, iter_text='iteration'):

        ExTracker.__init__(self)

        self.iter_text = iter_text

        self.iter_ct = None

    def add_iters(self, iter_ct):

        if self.iter_ct == None: self.iter_ct = 0

        self.iter_ct += iter_ct

    def msg(self):

        msg = ExTracker.msg(self)

        if self.iter_ct != None: msg += ('/'+format.int2str(self.iter_ct)+' '

            +self.iter_text+'(s) = '

            +format.to_percent(float(self.e_ct)/self.iter_ct))

        return msg