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# -*- test-case-name: twisted.web.test.test_util -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
An assortment of web server-related utilities.
"""
from __future__ import division, absolute_import
import linecache
from twisted.python import urlpath
from twisted.python.compat import _PY3, unicode, nativeString, escape
from twisted.python.reflect import fullyQualifiedName
from twisted.web import resource
from twisted.web.template import TagLoader, XMLString, Element, renderer
from twisted.web.template import flattenString
def _PRE(text):
"""
Wraps <pre> tags around some text and HTML-escape it.
This is here since once twisted.web.html was deprecated it was hard to
migrate the html.PRE from current code to twisted.web.template.
For new code consider using twisted.web.template.
@return: Escaped text wrapped in <pre> tags.
@rtype: C{str}
"""
return '<pre>%s</pre>' % (escape(text),)
def redirectTo(URL, request):
"""
Generate a redirect to the given location.
@param URL: A L{bytes} giving the location to which to redirect.
@type URL: L{bytes}
@param request: The request object to use to generate the redirect.
@type request: L{IRequest<twisted.web.iweb.IRequest>} provider
@raise TypeError: If the type of C{URL} a L{unicode} instead of L{bytes}.
@return: A C{bytes} containing HTML which tries to convince the client agent
to visit the new location even if it doesn't respect the I{FOUND}
response code. This is intended to be returned from a render method,
eg::
def render_GET(self, request):
return redirectTo(b"http://example.com/", request)
"""
if isinstance(URL, unicode) :
raise TypeError("Unicode object not allowed as URL")
request.setHeader(b"Content-Type", b"text/html; charset=utf-8")
request.redirect(URL)
content = """
<html>
<head>
<meta http-equiv=\"refresh\" content=\"0;URL=%(url)s\">
</head>
<body bgcolor=\"#FFFFFF\" text=\"#000000\">
<a href=\"%(url)s\">click here</a>
</body>
</html>
""" % {'url': nativeString(URL)}
if _PY3:
content = content.encode("utf8")
return content
class Redirect(resource.Resource):
isLeaf = True
def __init__(self, url):
resource.Resource.__init__(self)
self.url = url
def render(self, request):
return redirectTo(self.url, request)
def getChild(self, name, request):
return self
class ChildRedirector(Redirect):
isLeaf = 0
def __init__(self, url):
# XXX is this enough?
if ((url.find('://') == -1)
and (not url.startswith('..'))
and (not url.startswith('/'))):
raise ValueError("It seems you've given me a redirect (%s) that is a child of myself! That's not good, it'll cause an infinite redirect." % url)
Redirect.__init__(self, url)
def getChild(self, name, request):
newUrl = self.url
if not newUrl.endswith('/'):
newUrl += '/'
newUrl += name
return ChildRedirector(newUrl)
class ParentRedirect(resource.Resource):
"""
I redirect to URLPath.here().
"""
isLeaf = 1
def render(self, request):
return redirectTo(urlpath.URLPath.fromRequest(request).here(), request)
def getChild(self, request):
return self
class DeferredResource(resource.Resource):
"""
I wrap up a Deferred that will eventually result in a Resource
object.
"""
isLeaf = 1
def __init__(self, d):
resource.Resource.__init__(self)
self.d = d
def getChild(self, name, request):
return self
def render(self, request):
self.d.addCallback(self._cbChild, request).addErrback(
self._ebChild,request)
from twisted.web.server import NOT_DONE_YET
return NOT_DONE_YET
def _cbChild(self, child, request):
request.render(resource.getChildForRequest(child, request))
def _ebChild(self, reason, request):
request.processingFailed(reason)
return reason
class _SourceLineElement(Element):
"""
L{_SourceLineElement} is an L{IRenderable} which can render a single line of
source code.
@ivar number: A C{int} giving the line number of the source code to be
rendered.
@ivar source: A C{str} giving the source code to be rendered.
"""
def __init__(self, loader, number, source):
Element.__init__(self, loader)
self.number = number
self.source = source
@renderer
def sourceLine(self, request, tag):
"""
Render the line of source as a child of C{tag}.
"""
return tag(self.source.replace(' ', u' \N{NO-BREAK SPACE}'))
@renderer
def lineNumber(self, request, tag):
"""
Render the line number as a child of C{tag}.
"""
return tag(str(self.number))
class _SourceFragmentElement(Element):
"""
L{_SourceFragmentElement} is an L{IRenderable} which can render several lines
of source code near the line number of a particular frame object.
@ivar frame: A L{Failure<twisted.python.failure.Failure>}-style frame object
for which to load a source line to render. This is really a tuple
holding some information from a frame object. See
L{Failure.frames<twisted.python.failure.Failure>} for specifics.
"""
def __init__(self, loader, frame):
Element.__init__(self, loader)
self.frame = frame
def _getSourceLines(self):
"""
Find the source line references by C{self.frame} and yield, in source
line order, it and the previous and following lines.
@return: A generator which yields two-tuples. Each tuple gives a source
line number and the contents of that source line.
"""
filename = self.frame[1]
lineNumber = self.frame[2]
for snipLineNumber in range(lineNumber - 1, lineNumber + 2):
yield (snipLineNumber,
linecache.getline(filename, snipLineNumber).rstrip())
@renderer
def sourceLines(self, request, tag):
"""
Render the source line indicated by C{self.frame} and several
surrounding lines. The active line will be given a I{class} of
C{"snippetHighlightLine"}. Other lines will be given a I{class} of
C{"snippetLine"}.
"""
for (lineNumber, sourceLine) in self._getSourceLines():
newTag = tag.clone()
if lineNumber == self.frame[2]:
cssClass = "snippetHighlightLine"
else:
cssClass = "snippetLine"
loader = TagLoader(newTag(**{"class": cssClass}))
yield _SourceLineElement(loader, lineNumber, sourceLine)
class _FrameElement(Element):
"""
L{_FrameElement} is an L{IRenderable} which can render details about one
frame from a L{Failure<twisted.python.failure.Failure>}.
@ivar frame: A L{Failure<twisted.python.failure.Failure>}-style frame object
for which to load a source line to render. This is really a tuple
holding some information from a frame object. See
L{Failure.frames<twisted.python.failure.Failure>} for specifics.
"""
def __init__(self, loader, frame):
Element.__init__(self, loader)
self.frame = frame
@renderer
def filename(self, request, tag):
"""
Render the name of the file this frame references as a child of C{tag}.
"""
return tag(self.frame[1])
@renderer
def lineNumber(self, request, tag):
"""
Render the source line number this frame references as a child of
C{tag}.
"""
return tag(str(self.frame[2]))
@renderer
def function(self, request, tag):
"""
Render the function name this frame references as a child of C{tag}.
"""
return tag(self.frame[0])
@renderer
def source(self, request, tag):
"""
Render the source code surrounding the line this frame references,
replacing C{tag}.
"""
return _SourceFragmentElement(TagLoader(tag), self.frame)
class _StackElement(Element):
"""
L{_StackElement} renders an L{IRenderable} which can render a list of frames.
"""
def __init__(self, loader, stackFrames):
Element.__init__(self, loader)
self.stackFrames = stackFrames
@renderer
def frames(self, request, tag):
"""
Render the list of frames in this L{_StackElement}, replacing C{tag}.
"""
return [
_FrameElement(TagLoader(tag.clone()), frame)
for frame
in self.stackFrames]
class FailureElement(Element):
"""
L{FailureElement} is an L{IRenderable} which can render detailed information
about a L{Failure<twisted.python.failure.Failure>}.
@ivar failure: The L{Failure<twisted.python.failure.Failure>} instance which
will be rendered.
@since: 12.1
"""
loader = XMLString("""
<div xmlns:t="http://twistedmatrix.com/ns/twisted.web.template/0.1">
<style type="text/css">
div.error {
color: red;
font-family: Verdana, Arial, helvetica, sans-serif;
font-weight: bold;
}
div {
font-family: Verdana, Arial, helvetica, sans-serif;
}
div.stackTrace {
}
div.frame {
padding: 1em;
background: white;
border-bottom: thin black dashed;
}
div.frame:first-child {
padding: 1em;
background: white;
border-top: thin black dashed;
border-bottom: thin black dashed;
}
div.location {
}
span.function {
font-weight: bold;
font-family: "Courier New", courier, monospace;
}
div.snippet {
margin-bottom: 0.5em;
margin-left: 1em;
background: #FFFFDD;
}
div.snippetHighlightLine {
color: red;
}
span.code {
font-family: "Courier New", courier, monospace;
}
</style>
<div class="error">
<span t:render="type" />: <span t:render="value" />
</div>
<div class="stackTrace" t:render="traceback">
<div class="frame" t:render="frames">
<div class="location">
<span t:render="filename" />:<span t:render="lineNumber" /> in
<span class="function" t:render="function" />
</div>
<div class="snippet" t:render="source">
<div t:render="sourceLines">
<span class="lineno" t:render="lineNumber" />
<code class="code" t:render="sourceLine" />
</div>
</div>
</div>
</div>
<div class="error">
<span t:render="type" />: <span t:render="value" />
</div>
</div>
""")
def __init__(self, failure, loader=None):
Element.__init__(self, loader)
self.failure = failure
@renderer
def type(self, request, tag):
"""
Render the exception type as a child of C{tag}.
"""
return tag(fullyQualifiedName(self.failure.type))
@renderer
def value(self, request, tag):
"""
Render the exception value as a child of C{tag}.
"""
return tag(unicode(self.failure.value).encode('utf8'))
@renderer
def traceback(self, request, tag):
"""
Render all the frames in the wrapped
L{Failure<twisted.python.failure.Failure>}'s traceback stack, replacing
C{tag}.
"""
return _StackElement(TagLoader(tag), self.failure.frames)
def formatFailure(myFailure):
"""
Construct an HTML representation of the given failure.
Consider using L{FailureElement} instead.
@type myFailure: L{Failure<twisted.python.failure.Failure>}
@rtype: C{bytes}
@return: A string containing the HTML representation of the given failure.
"""
result = []
flattenString(None, FailureElement(myFailure)).addBoth(result.append)
if isinstance(result[0], bytes):
# Ensure the result string is all ASCII, for compatibility with the
# default encoding expected by browsers.
return result[0].decode('utf-8').encode('ascii', 'xmlcharrefreplace')
result[0].raiseException()
__all__ = [
"redirectTo", "Redirect", "ChildRedirector", "ParentRedirect",
"DeferredResource", "FailureElement", "formatFailure"]
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