Start the appengine-tools gem

lib/appengine-tools/web-xml.rb

+#!/usr/bin/ruby1.8 -w
+#
+# Copyright:: Copyright 2009 Google Inc.
+# Original Author:: Ryan Brown (mailto:ribrdb@google.com)
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+require 'rubygems'
+require 'rack'
+require 'rexml/document'
+
+class WebXmlBuilder < Rack::Builder
+  DUMMY_APP = Proc.new{|env|}
+  
+  def initialize(&block)
+    @path = "/"
+    @paths = Hash.new {|h, k| h[k] = []}
+    instance_eval(&block) if block_given?
+  end
+  
+  def use(middleware, *args, &block)
+    if middleware.respond_to? :to_xml
+      @paths[@path] << [middleware, args, block]
+    else
+      @paths[@path] << [middleware.new(DUMMY_APP, *args, &block)]
+    end
+  end
+  
+  def map(path, &block)
+    if path !~ %r{^https?://}  # we can only natively support path matching
+      saved_path = @path
+      @path = [@path, path].join('/').squeeze('/')
+      begin
+        instance_eval(&block) if block_given?
+      ensure
+        @path = saved_path
+      end
+    end
+  end
+  
+  def run(app)
+    @paths[@path] << [app, [], nil]
+  end
+
+  def to_xml
+    xml = REXML::Document.new.add_element('web-app')

[woodie, 2009/07/03 00:59:21]

It may be more appropriate to use doc

doc = REXML::Document...

+    xml.add_attribute("xmlns", "http://java.sun.com/xml/ns/javaee")
+    xml.add_attribute("version", "2.5")
+    each_path do |path, objects|
+      pattern = path + "*"
+      objects.each do |object, args, block|
+        if object.respond_to? :to_xml
+          object.to_xml(pattern, xml, *args, &block)
+        end
+      end
+    end
+    xml
+  end
+  
+private
+
+  def each_path
+    @paths.sort {|a, b| b[0].length - a[0].length}.each do |path, value|
+      yield path, value
+    end
+  end
+end
+
+class JavaServlet
+  def initialize(klass, name=nil)
+    @klass = klass.to_s
+    @name = (name || klass).to_s
+  end
+  
+  def call(env)
+    raise RuntimeError, "JavaServlet should be dispatched by web.xml"
+  end
+  
+  def to_xml(pattern, xml)
+    servlet = xml.add_element('servlet')
+    servlet.add_element('servlet-name').add_text(@name)
+    servlet.add_element('servlet-class').add_text(@klass)
+    map = xml.add_elemtn('servlet-mapping')
+    map.add_element('servlet-name').add_text(@name)
+    map.add_element('url-pattern').add_text(pattern.to_s)
+  end
+end
+
+class JavaServletFilter
+  def self.to_xml(pattern, xml, klass, name=nil)
+    name ||= klass
+    filter = xml.add_element('filter')
+    filter.add_element('filter-name').add_text(name.to_s)
+    filter.add_element('filter-class').add_text(klass.to_s)
+    map = xml.add_element('filter-mapping')
+    map.add_element('filter-name').add_text(name.to_s)
+    map.add_element('url-pattern').add_text(pattern.to_s)
+  end
+  
+  def self.new(app, *args, &block)
+    app
+  end
+end
+
+class JavaContextListener
+  def self.to_xml(pattern, xml, klass)
+    listener = xml.add_element('listener')
+    listener.add_element('listener-class').add_text(klass.to_s)
+  end
+  
+  def self.new(app, *args, &block)
+    app
+  end
+end
+
+class JavaContextParams
+  def self.to_xml(pattern, xml, params)
+    params.each do |name, value|
+      e = xml.add_element('context-param')
+      e.add_element('param-name').add_text(name.to_s)
+      e.add_element('param-value').add_text(value.to_s)
+    end
+  end
+  
+  def self.new(app, *args, &block)
+    app
+  end
+end