"""Extract, format and print information about Python stack traces."""
import linecache
import string
import sys
import types
def _print(file, str='', terminator='\n'):
file.write(str+terminator)
def print_list(extracted_list, file=None):
"""Print the list of tuples as returned by extract_tb() or
extract_stack() as a formatted stack trace to the given file."""
if not file:
file = sys.stderr
for filename, lineno, name, line in extracted_list:
_print(file,
' File "%s", line %d, in %s' % (filename,lineno,name))
if line:
_print(file, ' %s' % string.strip(line))
def format_list(extracted_list):
"""Given a list of tuples as returned by extract_tb() or
extract_stack(), return a list of strings ready for printing.
Each string in the resulting list corresponds to the item with
the same index in the argument list. Each string ends in a
newline; the strings may contain internal newlines as well, for
those items whose source text line is not None."""
list = []
for filename, lineno, name, line in extracted_list:
item = ' File "%s", line %d, in %s\n' % (filename,lineno,name)
if line:
item = item + ' %s\n' % string.strip(line)
list.append(item)
return list
def print_tb(tb, limit=None, file=None):
"""Print up to 'limit' stack trace entries from the traceback 'tb'.
If 'limit' is omitted or None, all entries are printed. If 'file' is
omitted or None, the output goes to sys.stderr; otherwise 'file'
should be an open file or file-like object with a write() method."""
if not file:
file = sys.stderr
if limit is None:
if hasattr(sys, 'tracebacklimit'):
limit = sys.tracebacklimit
n = 0
while tb is not None and (limit is None or n < limit):
f = tb.tb_frame
lineno = tb_lineno(tb)
co = f.f_code
filename = co.co_filename
name = co.co_name
_print(file,
' File "%s", line %d, in %s' % (filename,lineno,name))
line = linecache.getline(filename, lineno)
if line: _print(file, ' ' + string.strip(line))
tb = tb.tb_next
n = n+1
def format_tb(tb, limit = None):
"""A shorthand for 'format_list(extract_stack(f, limit))."""
return format_list(extract_tb(tb, limit))
def extract_tb(tb, limit = None):
"""Return a list of up to 'limit' pre-processed stack trace entries
extracted from the traceback object 'traceback'. This is useful for
alternate formatting of stack traces. If 'limit' is omitted or None,
all entries are extracted. A pre-processed stack trace entry is a
quadruple (filename, line number, function name, text) representing
the information that is usually printed for a stack trace. The text
is a string with leading and trailing whitespace stripped; if the
source is not available it is None."""
if limit is None:
if hasattr(sys, 'tracebacklimit'):
limit = sys.tracebacklimit
list = []
n = 0
while tb is not None and (limit is None or n < limit):
f = tb.tb_frame
lineno = tb_lineno(tb)
co = f.f_code
filename = co.co_filename
name = co.co_name
line = linecache.getline(filename, lineno)
if line: line = string.strip(line)
else: line = None
list.append((filename, lineno, name, line))
tb = tb.tb_next
n = n+1
return list
def print_exception(etype, value, tb, limit=None, file=None):
"""Print exception information and up to 'limit' stack trace entries
from the traceback 'tb' to 'file'. This differs from print_tb() in
the following ways: (1) if traceback is not None, it prints a header
"Traceback (innermost last):"; (2) it prints the exception type and
value after the stack trace; (3) if type is SyntaxError and value has
the appropriate format, it prints the line where the syntax error
occurred with a caret on the next line indicating the approximate
position of the error."""
if not file:
file = sys.stderr
if tb:
_print(file, 'Traceback (innermost last):')
print_tb(tb, limit, file)
lines = format_exception_only(etype, value)
for line in lines[:-1]:
_print(file, line, ' ')
_print(file, lines[-1], '')
def format_exception(etype, value, tb, limit = None):
"""Format a stack trace and the exception information. The arguments
have the same meaning as the corresponding arguments to
print_exception(). The return value is a list of strings, each
ending in a newline and some containing internal newlines. When
these lines are contatenated and printed, exactly the same text is
printed as does print_exception()."""
if tb:
list = ['Traceback (innermost last):\n']
list = list + format_tb(tb, limit)
else:
list = []
list = list + format_exception_only(etype, value)
return list
def format_exception_only(etype, value):
"""Format the exception part of a traceback. The arguments are the
exception type and value such as given by sys.last_type and
sys.last_value. The return value is a list of strings, each ending
in a newline. Normally, the list contains a single string;
however, for SyntaxError exceptions, it contains several lines that
(when printed) display detailed information about where the syntax
error occurred. The message indicating which exception occurred is
the always last string in the list."""
list = []
if type(etype) == types.ClassType:
stype = etype.__name__
else:
stype = etype
if value is None:
list.append(str(stype) + '\n')
else:
if etype is SyntaxError:
try:
msg, (filename, lineno, offset, line) = value
except:
pass
else:
if not filename: filename = "<string>"
list.append(' File "%s", line %d\n' %
(filename, lineno))
i = 0
while i < len(line) and \
line[i] in string.whitespace:
i = i+1
list.append(' %s\n' % string.strip(line))
s = ' '
for c in line[i:offset-1]:
if c in string.whitespace:
s = s + c
else:
s = s + ' '
list.append('%s^\n' % s)
value = msg
list.append('%s: %s\n' % (str(stype), str(value)))
return list
def print_exc(limit=None, file=None):
"""This is a shorthand for 'print_exception(sys.exc_type,
sys.exc_value, sys.exc_traceback, limit, file)'.
(In fact, it uses sys.exc_info() to retrieve the same information
in a thread-safe way.)"""
if not file:
file = sys.stderr
try:
etype, value, tb = sys.exc_info()
print_exception(etype, value, tb, limit, file)
finally:
etype = value = tb = None
def print_last(limit=None, file=None):
"""This is a shorthand for 'print_exception(sys.last_type,
sys.last_value, sys.last_traceback, limit, file)'."""
if not file:
file = sys.stderr
print_exception(sys.last_type, sys.last_value, sys.last_traceback,
limit, file)
def print_stack(f=None, limit=None, file=None):
"""This function prints a stack trace from its invocation point.
The optional 'f' argument can be used to specify an alternate stack
frame at which to start. The optional 'limit' and 'file' arguments
have the same meaning as for print_exception()."""
if f is None:
try:
raise ZeroDivisionError
except ZeroDivisionError:
f = sys.exc_info()[2].tb_frame.f_back
print_list(extract_stack(f, limit), file)
def format_stack(f=None, limit=None):
"""A shorthand for 'format_list(extract_stack(f, limit))'."""
if f is None:
try:
raise ZeroDivisionError
except ZeroDivisionError:
f = sys.exc_info()[2].tb_frame.f_back
return format_list(extract_stack(f, limit))
def extract_stack(f=None, limit = None):
"""Extract the raw traceback from the current stack frame. The
return value has the same format as for extract_tb(). The optional
'f' and 'limit' arguments have the same meaning as for print_stack().
Each item in the list is a quadruple (filename, line number,
function name, text), and the entries are in order from outermost
to innermost stack frame."""
if f is None:
try:
raise ZeroDivisionError
except ZeroDivisionError:
f = sys.exc_info()[2].tb_frame.f_back
if limit is None:
if hasattr(sys, 'tracebacklimit'):
limit = sys.tracebacklimit
list = []
n = 0
while f is not None and (limit is None or n < limit):
lineno = f.f_lineno # XXX Too bad if -O is used
co = f.f_code
filename = co.co_filename
name = co.co_name
line = linecache.getline(filename, lineno)
if line: line = string.strip(line)
else: line = None
list.append((filename, lineno, name, line))
f = f.f_back
n = n+1
list.reverse()
return list
def tb_lineno(tb):
"""Calculate the correct line number of the traceback given in tb
(even with -O on)."""
# Coded by Marc-Andre Lemburg from the example of PyCode_Addr2Line()
# in compile.c.
# Revised version by Jim Hugunin to work with JPython too.
c = tb.tb_frame.f_code
if not hasattr(c, 'co_lnotab'):
return tb.tb_lineno
tab = c.co_lnotab
line = c.co_firstlineno
stopat = tb.tb_lasti
addr = 0
for i in range(0, len(tab), 2):
addr = addr + ord(tab[i])
if addr > stopat:
break
line = line + ord(tab[i+1])
return line
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