"""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