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# This file is part of pex_config. 

# 

# Developed for the LSST Data Management System. 

# This product includes software developed by the LSST Project 

# (http://www.lsst.org). 

# See the COPYRIGHT file at the top-level directory of this distribution 

# for details of code ownership. 

# 

# This software is dual licensed under the GNU General Public License and also 

# under a 3-clause BSD license. Recipients may choose which of these licenses 

# to use; please see the files gpl-3.0.txt and/or bsd_license.txt, 

# respectively. If you choose the GPL option then the following text applies 

# (but note that there is still no warranty even if you opt for BSD instead): 

# 

# This program is free software: you can redistribute it and/or modify 

# it under the terms of the GNU General Public License as published by 

# the Free Software Foundation, either version 3 of the License, or 

# (at your option) any later version. 

# 

# This program is distributed in the hope that it will be useful, 

# but WITHOUT ANY WARRANTY; without even the implied warranty of 

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 

# GNU General Public License for more details. 

# 

# You should have received a copy of the GNU General Public License 

# along with this program. If not, see <http://www.gnu.org/licenses/>. 

 

__all__ = ['getCallerFrame', 'getStackFrame', 'StackFrame', 'getCallStack'] 

 

import inspect 

import linecache 

 

 

def getCallerFrame(relative=0): 

"""Get the frame for the user's caller. 

 

Parameters 

---------- 

relative : `int`, optional 

Number of frames (0 or more) above the caller to retrieve. 

Default is 0. 

 

Returns 

------- 

frame : `__builtin__.Frame` 

Frame for the caller. 

 

Notes 

----- 

This function is excluded from the frame. 

""" 

frame = inspect.currentframe().f_back.f_back # Our caller's caller 

for ii in range(relative): 

frame = frame.f_back 

return frame 

 

 

def getStackFrame(relative=0): 

"""Get the `StackFrame` for the user's caller. 

 

Parameters 

---------- 

relative : `int`, optional 

Number of frames (0 or more) above the caller to retrieve. 

 

Returns 

------- 

frame : `StackFrame` 

Stack frame for the caller. 

""" 

frame = getCallerFrame(relative + 1) 

return StackFrame.fromFrame(frame) 

 

 

class StackFrame: 

"""A single element of the stack trace. 

 

This differs slightly from the standard system mechanisms for getting a 

stack trace by the fact that it does not look up the source code until it 

is absolutely necessary, reducing the I/O. 

 

Parameters 

---------- 

filename : `str` 

Name of file containing the code being executed. 

lineno : `int` 

Line number of file being executed. 

function : `str` 

Function name being executed. 

content : `str`, optional 

The actual content being executed. If not provided, it will be loaded 

from the file. 

 

Notes 

----- 

This differs slightly from the standard system mechanisms for getting a 

stack trace by the fact that it does not look up the source code until it 

is absolutely necessary, reducing the I/O. 

 

See also 

-------- 

getStackFrame 

""" 

 

_STRIP = "/python/lsst/" 

"""String to strip from the ``filename`` in the constructor.""" 

 

def __init__(self, filename, lineno, function, content=None): 

loc = filename.rfind(self._STRIP) 

if loc > 0: 

filename = filename[loc + len(self._STRIP):] 

self.filename = filename 

self.lineno = lineno 

self.function = function 

self._content = content 

 

@property 

def content(self): 

"""Content being executed (loaded on demand) (`str`). 

""" 

if self._content is None: 

self._content = linecache.getline(self.filename, self.lineno).strip() 

return self._content 

 

@classmethod 

def fromFrame(cls, frame): 

"""Construct from a Frame object. 

 

Parameters 

---------- 

frame : `Frame` 

Frame object to interpret, such as from `inspect.currentframe`. 

 

Returns 

------- 

stackFrame : `StackFrame` 

A `StackFrame` instance. 

 

Examples 

-------- 

`inspect.currentframe` provides a Frame object. This is a convenience 

constructor to interpret that Frame object: 

 

>>> import inspect 

>>> stackFrame = StackFrame.fromFrame(inspect.currentframe()) 

""" 

filename = frame.f_code.co_filename 

lineno = frame.f_lineno 

function = frame.f_code.co_name 

return cls(filename, lineno, function) 

 

def __repr__(self): 

return "%s(%s, %s, %s)" % (self.__class__.__name__, self.filename, self.lineno, self.function) 

 

def format(self, full=False): 

"""Format for printing. 

 

Parameters 

---------- 

full : `bool`, optional 

If `True`, output includes the conentent (`StackFrame.content`) 

being executed. Default is `False`. 

 

Returns 

------- 

result : `str` 

Formatted string. 

""" 

result = " File %s:%s (%s)" % (self.filename, self.lineno, self.function) 

if full: 

result += "\n %s" % (self.content,) 

return result 

 

 

def getCallStack(skip=0): 

"""Retrieve the call stack for the caller. 

 

Parameters 

---------- 

skip : `int`, non-negative 

Number of stack frames above caller to skip. 

 

Returns 

------- 

output : `list` of `StackFrame` 

The call stack. The `list` is ordered with the most recent frame to 

last. 

 

Notes 

----- 

This function is excluded from the call stack. 

""" 

frame = getCallerFrame(skip + 1) 

stack = [] 

while frame: 

stack.append(StackFrame.fromFrame(frame)) 

frame = frame.f_back 

return list(reversed(stack))