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// Copyright 2019 DeepMind Technologies Limited
//
// 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.
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Xml;
using UnityEngine;
namespace Mujoco {
public class MjXmlModifiers {
private XmlDocument _root;
public MjXmlModifiers(XmlDocument root) {
_root = root;
}
public void ApplyModifiersToElement(XmlElement element) {
// Combine all defaults into one. At this stage, we want to overwrite attributes defined by
// the previous defaults.
var aggregateDefaults = _root.CreateElement("aggregate");
// Root default leaf should be processed only once, and handled first (so it's overriden).
var rootDefaultLeaf = _root.SelectSingleNode($"/mujoco/default/{element.Name}") as XmlElement;
if (rootDefaultLeaf != null) {
CopyAttributes(rootDefaultLeaf, aggregateDefaults);
}
// Order matters - reverse class list so that most relevant is last.
var classes = GetApplicableDefaultClasses(element).Reverse();
foreach (var className in classes) {
var defaultClassElement =
_root.SelectSingleNode($"descendant::default[@class='{className}']") as XmlElement;
// Ancestry iterates up in the tree, but we want to apply changes from remote to specific.
var ancestors = GetDefaultAncestry(defaultClassElement, element.Name).Reverse();
foreach (var defaultAncestor in ancestors) {
CopyAttributesOverwriteExisting(defaultAncestor, aggregateDefaults);
}
}
// Add the merged attribiutes to the node, without overwriting the existing values.
CopyAttributes(aggregateDefaults, element);
}
private IEnumerable<XmlElement> GetDefaultAncestry(XmlElement classElement, string nodeType) {
var defaultElement = classElement;
var top = _root.SelectSingleNode("/mujoco/default");
while (defaultElement != top) {
foreach (var element in defaultElement.ChildNodes) {
if (((XmlElement)element).Name == nodeType) {
yield return (XmlElement)element;
}
}
defaultElement = defaultElement.ParentNode as XmlElement;
}
}
// Return a list of names of all the applicable classes. Implemented by climbing up the tree,
// hence results are in order of relevance, from the most specific to most remotely-inherited.
public static IEnumerable<string> GetApplicableDefaultClasses(XmlElement modifiedElement) {
var nodeType = modifiedElement.Name;
// Build the inheritance list for the element that's meant to be modified.
// It will consist of all qualifiers supplied by the element itself and its parents
// using "class" and "childclass" values.
var inheritance = new List<string>();
var element = modifiedElement;
while (element != null) {
var className = element.GetStringAttribute("childclass", string.Empty);
if (element == modifiedElement) {
// "class" attribute does not partcipate in building of the inheritance tree, and so we're
// only considering it if it's defined on the very element we're trying to modify.
className = element.GetStringAttribute("class", className);
}
if (!string.IsNullOrEmpty(className) && !inheritance.Contains(className)) {
inheritance.Add(className);
}
element = element.ParentNode as XmlElement;
}
return inheritance;
}
private static string GetElementClass(XmlElement element) {
var elementClass = element.GetStringAttribute("class", string.Empty);
if (string.IsNullOrEmpty(elementClass)) {
elementClass = element.GetStringAttribute("childclass", string.Empty);
}
return elementClass;
}
public static void CopyAttributes(XmlElement from, XmlElement to) {
foreach (XmlAttribute attribute in from.Attributes) {
if (to.HasAttribute(attribute.Name) == false) {
to.SetAttribute(attribute.Name, attribute.Value);
}
}
}
public static void CopyAttributesOverwriteExisting(XmlElement from, XmlElement to) {
foreach (XmlAttribute attribute in from.Attributes) {
to.SetAttribute(attribute.Name, attribute.Value);
}
}
}
}
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