view roundup/cgi/TAL/TALParser.py @ 5630:07abc8d36940

Add etag support to rest interface to prevent multiple users from overwriting other users changes. All GET requests for an object (issue, user, keyword etc.) or a property of an object (e.g the title of an issue) return the etag for the object in the ETag header as well as the @etag field in the returned object. All requests that change existing objects (DELETE, PUT or PATCH) require: 1 A request include an ETag header with the etag value retrieved for the object. 2 A submits a form that includes the field @etag that must have the value retrieved for the object. If an etag is not supplied by one of these methods, or any supplied etag does not match the etag calculated at the time the DELETE, PUT or PATCH request is made, HTTP error 412 (Precondition Failed) is returned and no change is made. At that time the client code should retrieve the object again, reconcile the changes and can try to send a new update. The etag is the md5 hash of the representation (repr()) of the object retrieved from the database.
author John Rouillard <rouilj@ieee.org>
date Fri, 01 Mar 2019 22:57:07 -0500
parents 23b8e6067f7c
children
line wrap: on
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##############################################################################
#
# Copyright (c) 2001, 2002 Zope Corporation and Contributors.
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.0 (ZPL).  A copy of the ZPL should accompany this distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE.
#
##############################################################################
"""
Parse XML and compile to TALInterpreter intermediate code.
"""

from .XMLParser import XMLParser
from .TALDefs import XML_NS, ZOPE_I18N_NS, ZOPE_METAL_NS, ZOPE_TAL_NS
from .TALGenerator import TALGenerator

class TALParser(XMLParser):

    ordered_attributes = 1

    def __init__(self, gen=None): # Override
        XMLParser.__init__(self)
        if gen is None:
            gen = TALGenerator()
        self.gen = gen
        self.nsStack = []
        self.nsDict = {XML_NS: 'xml'}
        self.nsNew = []

    def getCode(self):
        return self.gen.getCode()

    def getWarnings(self):
        return ()

    def StartNamespaceDeclHandler(self, prefix, uri):
        self.nsStack.append(self.nsDict.copy())
        self.nsDict[uri] = prefix
        self.nsNew.append((prefix, uri))

    def EndNamespaceDeclHandler(self, prefix):
        self.nsDict = self.nsStack.pop()

    def StartElementHandler(self, name, attrs):
        if self.ordered_attributes:
            # attrs is a list of alternating names and values
            attrlist = []
            for i in range(0, len(attrs), 2):
                key = attrs[i]
                value = attrs[i+1]
                attrlist.append((key, value))
        else:
            # attrs is a dict of {name: value}
            attrlist = sorted(attrs.items()) # Sorted for definiteness
        name, attrlist, taldict, metaldict, i18ndict \
              = self.process_ns(name, attrlist)
        attrlist = self.xmlnsattrs() + attrlist
        self.gen.emitStartElement(name, attrlist, taldict, metaldict, i18ndict)

    def process_ns(self, name, attrlist):
        taldict = {}
        metaldict = {}
        i18ndict = {}
        fixedattrlist = []
        name, namebase, namens = self.fixname(name)
        for key, value in attrlist:
            key, keybase, keyns = self.fixname(key)
            ns = keyns or namens # default to tag namespace
            item = key, value
            if ns == 'metal':
                metaldict[keybase] = value
                item = item + ("metal",)
            elif ns == 'tal':
                taldict[keybase] = value
                item = item + ("tal",)
            elif ns == 'i18n':
                assert 0, "dealing with i18n: " + repr((keybase, value))
                i18ndict[keybase] = value
                item = item + ('i18n',)
            fixedattrlist.append(item)
        if namens in ('metal', 'tal', 'i18n'):
            taldict['tal tag'] = namens
        return name, fixedattrlist, taldict, metaldict, i18ndict

    def xmlnsattrs(self):
        newlist = []
        for prefix, uri in self.nsNew:
            if prefix:
                key = "xmlns:" + prefix
            else:
                key = "xmlns"
            if uri in (ZOPE_METAL_NS, ZOPE_TAL_NS, ZOPE_I18N_NS):
                item = (key, uri, "xmlns")
            else:
                item = (key, uri)
            newlist.append(item)
        self.nsNew = []
        return newlist

    def fixname(self, name):
        if ' ' in name:
            uri, name = name.split(' ')
            prefix = self.nsDict[uri]
            prefixed = name
            if prefix:
                prefixed = "%s:%s" % (prefix, name)
            ns = 'x'
            if uri == ZOPE_TAL_NS:
                ns = 'tal'
            elif uri == ZOPE_METAL_NS:
                ns = 'metal'
            elif uri == ZOPE_I18N_NS:
                ns = 'i18n'
            return (prefixed, name, ns)
        return (name, name, None)

    def EndElementHandler(self, name):
        name = self.fixname(name)[0]
        self.gen.emitEndElement(name)

    def DefaultHandler(self, text):
        self.gen.emitRawText(text)

def test():
    import sys
    p = TALParser()
    file = "tests/input/test01.xml"
    if sys.argv[1:]:
        file = sys.argv[1]
    p.parseFile(file)
    program, macros = p.getCode()
    from .TALInterpreter import TALInterpreter
    from .DummyEngine import DummyEngine
    engine = DummyEngine(macros)
    TALInterpreter(program, macros, engine, sys.stdout, wrap=0)()

if __name__ == "__main__":
    test()

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