1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/content/xul/templates/src/nsRuleNetwork.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,858 @@
1.4 +/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
1.5 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +/*
1.10 +
1.11 + A rule discrimination network implementation based on ideas from
1.12 + RETE and TREAT.
1.13 +
1.14 + RETE is described in Charles Forgy, "Rete: A Fast Algorithm for the
1.15 + Many Patterns/Many Objects Match Problem", Artificial Intelligence
1.16 + 19(1): pp. 17-37, 1982.
1.17 +
1.18 + TREAT is described in Daniel P. Miranker, "TREAT: A Better Match
1.19 + Algorithm for AI Production System Matching", AAAI 1987: pp. 42-47.
1.20 +
1.21 + --
1.22 +
1.23 + TO DO:
1.24 +
1.25 + . nsAssignmentSet::List objects are allocated by the gallon. We
1.26 + should make it so that these are always allocated from a pool,
1.27 + maybe owned by the nsRuleNetwork?
1.28 +
1.29 + */
1.30 +
1.31 +#ifndef nsRuleNetwork_h__
1.32 +#define nsRuleNetwork_h__
1.33 +
1.34 +#include "mozilla/Attributes.h"
1.35 +#include "nsCOMPtr.h"
1.36 +#include "nsCOMArray.h"
1.37 +#include "nsIAtom.h"
1.38 +#include "nsIDOMNode.h"
1.39 +#include "plhash.h"
1.40 +#include "pldhash.h"
1.41 +#include "nsIRDFNode.h"
1.42 +
1.43 +class nsIRDFResource;
1.44 +class nsXULTemplateResultSetRDF;
1.45 +class nsXULTemplateQueryProcessorRDF;
1.46 +
1.47 +//----------------------------------------------------------------------
1.48 +
1.49 +/**
1.50 + * A memory element that supports an instantiation. A memory element holds a
1.51 + * set of nodes involved in an RDF test such as <member> or <triple> test. A
1.52 + * memory element is created when a specific test matches. The query processor
1.53 + * maintains a map between the memory elements and the results they eventually
1.54 + * matched. When an assertion is removed from the graph, this map is consulted
1.55 + * to determine which results will no longer match.
1.56 + */
1.57 +class MemoryElement {
1.58 +protected:
1.59 + MemoryElement() { MOZ_COUNT_CTOR(MemoryElement); }
1.60 +
1.61 +public:
1.62 + virtual ~MemoryElement() { MOZ_COUNT_DTOR(MemoryElement); }
1.63 +
1.64 + virtual const char* Type() const = 0;
1.65 + virtual PLHashNumber Hash() const = 0;
1.66 + virtual bool Equals(const MemoryElement& aElement) const = 0;
1.67 +
1.68 + bool operator==(const MemoryElement& aMemoryElement) const {
1.69 + return Equals(aMemoryElement);
1.70 + }
1.71 +
1.72 + bool operator!=(const MemoryElement& aMemoryElement) const {
1.73 + return !Equals(aMemoryElement);
1.74 + }
1.75 +};
1.76 +
1.77 +//----------------------------------------------------------------------
1.78 +
1.79 +/**
1.80 + * A collection of memory elements
1.81 + */
1.82 +class MemoryElementSet {
1.83 +public:
1.84 + class ConstIterator;
1.85 + friend class ConstIterator;
1.86 +
1.87 +protected:
1.88 + class List {
1.89 + public:
1.90 + List() { MOZ_COUNT_CTOR(MemoryElementSet::List); }
1.91 +
1.92 + ~List() {
1.93 + MOZ_COUNT_DTOR(MemoryElementSet::List);
1.94 + delete mElement;
1.95 + NS_IF_RELEASE(mNext); }
1.96 +
1.97 + int32_t AddRef() { return ++mRefCnt; }
1.98 +
1.99 + int32_t Release() {
1.100 + int32_t refcnt = --mRefCnt;
1.101 + if (refcnt == 0) delete this;
1.102 + return refcnt; }
1.103 +
1.104 + MemoryElement* mElement;
1.105 + int32_t mRefCnt;
1.106 + List* mNext;
1.107 + };
1.108 +
1.109 + List* mElements;
1.110 +
1.111 +public:
1.112 + MemoryElementSet() : mElements(nullptr) {
1.113 + MOZ_COUNT_CTOR(MemoryElementSet); }
1.114 +
1.115 + MemoryElementSet(const MemoryElementSet& aSet) : mElements(aSet.mElements) {
1.116 + MOZ_COUNT_CTOR(MemoryElementSet);
1.117 + NS_IF_ADDREF(mElements); }
1.118 +
1.119 + MemoryElementSet& operator=(const MemoryElementSet& aSet) {
1.120 + NS_IF_RELEASE(mElements);
1.121 + mElements = aSet.mElements;
1.122 + NS_IF_ADDREF(mElements);
1.123 + return *this; }
1.124 +
1.125 + ~MemoryElementSet() {
1.126 + MOZ_COUNT_DTOR(MemoryElementSet);
1.127 + NS_IF_RELEASE(mElements); }
1.128 +
1.129 +public:
1.130 + class ConstIterator {
1.131 + public:
1.132 + ConstIterator(List* aElementList) : mCurrent(aElementList) {
1.133 + NS_IF_ADDREF(mCurrent); }
1.134 +
1.135 + ConstIterator(const ConstIterator& aConstIterator)
1.136 + : mCurrent(aConstIterator.mCurrent) {
1.137 + NS_IF_ADDREF(mCurrent); }
1.138 +
1.139 + ConstIterator& operator=(const ConstIterator& aConstIterator) {
1.140 + NS_IF_RELEASE(mCurrent);
1.141 + mCurrent = aConstIterator.mCurrent;
1.142 + NS_IF_ADDREF(mCurrent);
1.143 + return *this; }
1.144 +
1.145 + ~ConstIterator() { NS_IF_RELEASE(mCurrent); }
1.146 +
1.147 + ConstIterator& operator++() {
1.148 + List* next = mCurrent->mNext;
1.149 + NS_RELEASE(mCurrent);
1.150 + mCurrent = next;
1.151 + NS_IF_ADDREF(mCurrent);
1.152 + return *this; }
1.153 +
1.154 + ConstIterator operator++(int) {
1.155 + ConstIterator result(*this);
1.156 + List* next = mCurrent->mNext;
1.157 + NS_RELEASE(mCurrent);
1.158 + mCurrent = next;
1.159 + NS_IF_ADDREF(mCurrent);
1.160 + return result; }
1.161 +
1.162 + const MemoryElement& operator*() const {
1.163 + return *mCurrent->mElement; }
1.164 +
1.165 + const MemoryElement* operator->() const {
1.166 + return mCurrent->mElement; }
1.167 +
1.168 + bool operator==(const ConstIterator& aConstIterator) const {
1.169 + return mCurrent == aConstIterator.mCurrent; }
1.170 +
1.171 + bool operator!=(const ConstIterator& aConstIterator) const {
1.172 + return mCurrent != aConstIterator.mCurrent; }
1.173 +
1.174 + protected:
1.175 + List* mCurrent;
1.176 + };
1.177 +
1.178 + ConstIterator First() const { return ConstIterator(mElements); }
1.179 + ConstIterator Last() const { return ConstIterator(nullptr); }
1.180 +
1.181 + // N.B. that the set assumes ownership of the element
1.182 + nsresult Add(MemoryElement* aElement);
1.183 +};
1.184 +
1.185 +//----------------------------------------------------------------------
1.186 +
1.187 +/**
1.188 + * An assignment of a value to a variable
1.189 + */
1.190 +class nsAssignment {
1.191 +public:
1.192 + const nsCOMPtr<nsIAtom> mVariable;
1.193 + nsCOMPtr<nsIRDFNode> mValue;
1.194 +
1.195 + nsAssignment(nsIAtom* aVariable, nsIRDFNode* aValue)
1.196 + : mVariable(aVariable),
1.197 + mValue(aValue)
1.198 + { MOZ_COUNT_CTOR(nsAssignment); }
1.199 +
1.200 + nsAssignment(const nsAssignment& aAssignment)
1.201 + : mVariable(aAssignment.mVariable),
1.202 + mValue(aAssignment.mValue)
1.203 + { MOZ_COUNT_CTOR(nsAssignment); }
1.204 +
1.205 + ~nsAssignment() { MOZ_COUNT_DTOR(nsAssignment); }
1.206 +
1.207 + bool operator==(const nsAssignment& aAssignment) const {
1.208 + return mVariable == aAssignment.mVariable && mValue == aAssignment.mValue; }
1.209 +
1.210 + bool operator!=(const nsAssignment& aAssignment) const {
1.211 + return mVariable != aAssignment.mVariable || mValue != aAssignment.mValue; }
1.212 +
1.213 + PLHashNumber Hash() const {
1.214 + // XXX I have no idea if this hashing function is good or not // XXX change this
1.215 + PLHashNumber temp = PLHashNumber(NS_PTR_TO_INT32(mValue.get())) >> 2; // strip alignment bits
1.216 + return (temp & 0xffff) | NS_PTR_TO_INT32(mVariable.get()); }
1.217 +};
1.218 +
1.219 +
1.220 +//----------------------------------------------------------------------
1.221 +
1.222 +/**
1.223 + * A collection of value-to-variable assignments that minimizes
1.224 + * copying by sharing subsets when possible.
1.225 + */
1.226 +class nsAssignmentSet {
1.227 +public:
1.228 + class ConstIterator;
1.229 + friend class ConstIterator;
1.230 +
1.231 +protected:
1.232 + class List {
1.233 + public:
1.234 + List(const nsAssignment &aAssignment) : mAssignment(aAssignment) {
1.235 + MOZ_COUNT_CTOR(nsAssignmentSet::List); }
1.236 +
1.237 + ~List() {
1.238 + MOZ_COUNT_DTOR(nsAssignmentSet::List);
1.239 + NS_IF_RELEASE(mNext); }
1.240 +
1.241 + int32_t AddRef() { return ++mRefCnt; }
1.242 +
1.243 + int32_t Release() {
1.244 + int32_t refcnt = --mRefCnt;
1.245 + if (refcnt == 0) delete this;
1.246 + return refcnt; }
1.247 +
1.248 + nsAssignment mAssignment;
1.249 + int32_t mRefCnt;
1.250 + List* mNext;
1.251 + };
1.252 +
1.253 + List* mAssignments;
1.254 +
1.255 +public:
1.256 + nsAssignmentSet()
1.257 + : mAssignments(nullptr)
1.258 + { MOZ_COUNT_CTOR(nsAssignmentSet); }
1.259 +
1.260 + nsAssignmentSet(const nsAssignmentSet& aSet)
1.261 + : mAssignments(aSet.mAssignments) {
1.262 + MOZ_COUNT_CTOR(nsAssignmentSet);
1.263 + NS_IF_ADDREF(mAssignments); }
1.264 +
1.265 + nsAssignmentSet& operator=(const nsAssignmentSet& aSet) {
1.266 + NS_IF_RELEASE(mAssignments);
1.267 + mAssignments = aSet.mAssignments;
1.268 + NS_IF_ADDREF(mAssignments);
1.269 + return *this; }
1.270 +
1.271 + ~nsAssignmentSet() {
1.272 + MOZ_COUNT_DTOR(nsAssignmentSet);
1.273 + NS_IF_RELEASE(mAssignments); }
1.274 +
1.275 +public:
1.276 + class ConstIterator {
1.277 + public:
1.278 + ConstIterator(List* aAssignmentList) : mCurrent(aAssignmentList) {
1.279 + NS_IF_ADDREF(mCurrent); }
1.280 +
1.281 + ConstIterator(const ConstIterator& aConstIterator)
1.282 + : mCurrent(aConstIterator.mCurrent) {
1.283 + NS_IF_ADDREF(mCurrent); }
1.284 +
1.285 + ConstIterator& operator=(const ConstIterator& aConstIterator) {
1.286 + NS_IF_RELEASE(mCurrent);
1.287 + mCurrent = aConstIterator.mCurrent;
1.288 + NS_IF_ADDREF(mCurrent);
1.289 + return *this; }
1.290 +
1.291 + ~ConstIterator() { NS_IF_RELEASE(mCurrent); }
1.292 +
1.293 + ConstIterator& operator++() {
1.294 + List* next = mCurrent->mNext;
1.295 + NS_RELEASE(mCurrent);
1.296 + mCurrent = next;
1.297 + NS_IF_ADDREF(mCurrent);
1.298 + return *this; }
1.299 +
1.300 + ConstIterator operator++(int) {
1.301 + ConstIterator result(*this);
1.302 + List* next = mCurrent->mNext;
1.303 + NS_RELEASE(mCurrent);
1.304 + mCurrent = next;
1.305 + NS_IF_ADDREF(mCurrent);
1.306 + return result; }
1.307 +
1.308 + const nsAssignment& operator*() const {
1.309 + return mCurrent->mAssignment; }
1.310 +
1.311 + const nsAssignment* operator->() const {
1.312 + return &mCurrent->mAssignment; }
1.313 +
1.314 + bool operator==(const ConstIterator& aConstIterator) const {
1.315 + return mCurrent == aConstIterator.mCurrent; }
1.316 +
1.317 + bool operator!=(const ConstIterator& aConstIterator) const {
1.318 + return mCurrent != aConstIterator.mCurrent; }
1.319 +
1.320 + protected:
1.321 + List* mCurrent;
1.322 + };
1.323 +
1.324 + ConstIterator First() const { return ConstIterator(mAssignments); }
1.325 + ConstIterator Last() const { return ConstIterator(nullptr); }
1.326 +
1.327 +public:
1.328 + /**
1.329 + * Add an assignment to the set
1.330 + * @param aElement the assigment to add
1.331 + * @return NS_OK if all is well, NS_ERROR_OUT_OF_MEMORY if memory
1.332 + * could not be allocated for the addition.
1.333 + */
1.334 + nsresult Add(const nsAssignment& aElement);
1.335 +
1.336 + /**
1.337 + * Determine if the assignment set contains the specified variable
1.338 + * to value assignment.
1.339 + * @param aVariable the variable for which to lookup the binding
1.340 + * @param aValue the value to query
1.341 + * @return true if aVariable is bound to aValue; false otherwise.
1.342 + */
1.343 + bool HasAssignment(nsIAtom* aVariable, nsIRDFNode* aValue) const;
1.344 +
1.345 + /**
1.346 + * Determine if the assignment set contains the specified assignment
1.347 + * @param aAssignment the assignment to search for
1.348 + * @return true if the set contains the assignment, false otherwise.
1.349 + */
1.350 + bool HasAssignment(const nsAssignment& aAssignment) const {
1.351 + return HasAssignment(aAssignment.mVariable, aAssignment.mValue); }
1.352 +
1.353 + /**
1.354 + * Determine whether the assignment set has an assignment for the
1.355 + * specified variable.
1.356 + * @param aVariable the variable to query
1.357 + * @return true if the assignment set has an assignment for the variable,
1.358 + * false otherwise.
1.359 + */
1.360 + bool HasAssignmentFor(nsIAtom* aVariable) const;
1.361 +
1.362 + /**
1.363 + * Retrieve the assignment for the specified variable
1.364 + * @param aVariable the variable to query
1.365 + * @param aValue an out parameter that will receive the value assigned
1.366 + * to the variable, if any.
1.367 + * @return true if the variable has an assignment, false
1.368 + * if there was no assignment for the variable.
1.369 + */
1.370 + bool GetAssignmentFor(nsIAtom* aVariable, nsIRDFNode** aValue) const;
1.371 +
1.372 + /**
1.373 + * Count the number of assignments in the set
1.374 + * @return the number of assignments in the set
1.375 + */
1.376 + int32_t Count() const;
1.377 +
1.378 + /**
1.379 + * Determine if the set is empty
1.380 + * @return true if the assignment set is empty, false otherwise.
1.381 + */
1.382 + bool IsEmpty() const { return mAssignments == nullptr; }
1.383 +
1.384 + bool Equals(const nsAssignmentSet& aSet) const;
1.385 + bool operator==(const nsAssignmentSet& aSet) const { return Equals(aSet); }
1.386 + bool operator!=(const nsAssignmentSet& aSet) const { return !Equals(aSet); }
1.387 +};
1.388 +
1.389 +
1.390 +//----------------------------------------------------------------------
1.391 +
1.392 +/**
1.393 + * A collection of variable-to-value bindings, with the memory elements
1.394 + * that support those bindings. Essentially, an instantiation is the
1.395 + * collection of variables and values assigned to those variables for a single
1.396 + * result. For each RDF rule in the rule network, each instantiation is
1.397 + * examined and either extended with additional bindings specified by the RDF
1.398 + * rule, or removed if the rule doesn't apply (for instance if a node has no
1.399 + * children). When an instantiation gets to the last node of the rule network,
1.400 + * which is always an nsInstantiationNode, a result is created for it.
1.401 + *
1.402 + * An instantiation object is typically created by "extending" another
1.403 + * instantiation object. That is, using the copy constructor, and
1.404 + * adding bindings and support to the instantiation.
1.405 + */
1.406 +class Instantiation
1.407 +{
1.408 +public:
1.409 + /**
1.410 + * The variable-to-value bindings
1.411 + */
1.412 + nsAssignmentSet mAssignments;
1.413 +
1.414 + /**
1.415 + * The memory elements that support the bindings.
1.416 + */
1.417 + MemoryElementSet mSupport;
1.418 +
1.419 + Instantiation() { MOZ_COUNT_CTOR(Instantiation); }
1.420 +
1.421 + Instantiation(const Instantiation& aInstantiation)
1.422 + : mAssignments(aInstantiation.mAssignments),
1.423 + mSupport(aInstantiation.mSupport) {
1.424 + MOZ_COUNT_CTOR(Instantiation); }
1.425 +
1.426 + Instantiation& operator=(const Instantiation& aInstantiation) {
1.427 + mAssignments = aInstantiation.mAssignments;
1.428 + mSupport = aInstantiation.mSupport;
1.429 + return *this; }
1.430 +
1.431 + ~Instantiation() { MOZ_COUNT_DTOR(Instantiation); }
1.432 +
1.433 + /**
1.434 + * Add the specified variable-to-value assignment to the instantiation's
1.435 + * set of assignments.
1.436 + * @param aVariable the variable to which is being assigned
1.437 + * @param aValue the value that is being assigned
1.438 + * @return NS_OK if no errors, NS_ERROR_OUT_OF_MEMORY if there
1.439 + * is not enough memory to perform the operation
1.440 + */
1.441 + nsresult AddAssignment(nsIAtom* aVariable, nsIRDFNode* aValue) {
1.442 + mAssignments.Add(nsAssignment(aVariable, aValue));
1.443 + return NS_OK; }
1.444 +
1.445 + /**
1.446 + * Add a memory element to the set of memory elements that are
1.447 + * supporting the instantiation
1.448 + * @param aMemoryElement the memory element to add to the
1.449 + * instantiation's set of support
1.450 + * @return NS_OK if no errors occurred, NS_ERROR_OUT_OF_MEMORY
1.451 + * if there is not enough memory to perform the operation.
1.452 + */
1.453 + nsresult AddSupportingElement(MemoryElement* aMemoryElement) {
1.454 + mSupport.Add(aMemoryElement);
1.455 + return NS_OK; }
1.456 +
1.457 + bool Equals(const Instantiation& aInstantiation) const {
1.458 + return mAssignments == aInstantiation.mAssignments; }
1.459 +
1.460 + bool operator==(const Instantiation& aInstantiation) const {
1.461 + return Equals(aInstantiation); }
1.462 +
1.463 + bool operator!=(const Instantiation& aInstantiation) const {
1.464 + return !Equals(aInstantiation); }
1.465 +
1.466 + static PLHashNumber Hash(const void* aKey);
1.467 + static int Compare(const void* aLeft, const void* aRight);
1.468 +};
1.469 +
1.470 +
1.471 +//----------------------------------------------------------------------
1.472 +
1.473 +/**
1.474 + * A collection of intantiations
1.475 + */
1.476 +class InstantiationSet
1.477 +{
1.478 +public:
1.479 + InstantiationSet();
1.480 + InstantiationSet(const InstantiationSet& aInstantiationSet);
1.481 + InstantiationSet& operator=(const InstantiationSet& aInstantiationSet);
1.482 +
1.483 + ~InstantiationSet() {
1.484 + MOZ_COUNT_DTOR(InstantiationSet);
1.485 + Clear(); }
1.486 +
1.487 + class ConstIterator;
1.488 + friend class ConstIterator;
1.489 +
1.490 + class Iterator;
1.491 + friend class Iterator;
1.492 +
1.493 + friend class nsXULTemplateResultSetRDF; // so it can get to the List
1.494 +
1.495 +protected:
1.496 + class List {
1.497 + public:
1.498 + Instantiation mInstantiation;
1.499 + List* mNext;
1.500 + List* mPrev;
1.501 +
1.502 + List() { MOZ_COUNT_CTOR(InstantiationSet::List); }
1.503 + ~List() { MOZ_COUNT_DTOR(InstantiationSet::List); }
1.504 + };
1.505 +
1.506 + List mHead;
1.507 +
1.508 +public:
1.509 + class ConstIterator {
1.510 + protected:
1.511 + friend class Iterator; // XXXwaterson so broken.
1.512 + List* mCurrent;
1.513 +
1.514 + public:
1.515 + ConstIterator(List* aList) : mCurrent(aList) {}
1.516 +
1.517 + ConstIterator(const ConstIterator& aConstIterator)
1.518 + : mCurrent(aConstIterator.mCurrent) {}
1.519 +
1.520 + ConstIterator& operator=(const ConstIterator& aConstIterator) {
1.521 + mCurrent = aConstIterator.mCurrent;
1.522 + return *this; }
1.523 +
1.524 + ConstIterator& operator++() {
1.525 + mCurrent = mCurrent->mNext;
1.526 + return *this; }
1.527 +
1.528 + ConstIterator operator++(int) {
1.529 + ConstIterator result(*this);
1.530 + mCurrent = mCurrent->mNext;
1.531 + return result; }
1.532 +
1.533 + ConstIterator& operator--() {
1.534 + mCurrent = mCurrent->mPrev;
1.535 + return *this; }
1.536 +
1.537 + ConstIterator operator--(int) {
1.538 + ConstIterator result(*this);
1.539 + mCurrent = mCurrent->mPrev;
1.540 + return result; }
1.541 +
1.542 + const Instantiation& operator*() const {
1.543 + return mCurrent->mInstantiation; }
1.544 +
1.545 + const Instantiation* operator->() const {
1.546 + return &mCurrent->mInstantiation; }
1.547 +
1.548 + bool operator==(const ConstIterator& aConstIterator) const {
1.549 + return mCurrent == aConstIterator.mCurrent; }
1.550 +
1.551 + bool operator!=(const ConstIterator& aConstIterator) const {
1.552 + return mCurrent != aConstIterator.mCurrent; }
1.553 + };
1.554 +
1.555 + ConstIterator First() const { return ConstIterator(mHead.mNext); }
1.556 + ConstIterator Last() const { return ConstIterator(const_cast<List*>(&mHead)); }
1.557 +
1.558 + class Iterator : public ConstIterator {
1.559 + public:
1.560 + Iterator(List* aList) : ConstIterator(aList) {}
1.561 +
1.562 + Iterator& operator++() {
1.563 + mCurrent = mCurrent->mNext;
1.564 + return *this; }
1.565 +
1.566 + Iterator operator++(int) {
1.567 + Iterator result(*this);
1.568 + mCurrent = mCurrent->mNext;
1.569 + return result; }
1.570 +
1.571 + Iterator& operator--() {
1.572 + mCurrent = mCurrent->mPrev;
1.573 + return *this; }
1.574 +
1.575 + Iterator operator--(int) {
1.576 + Iterator result(*this);
1.577 + mCurrent = mCurrent->mPrev;
1.578 + return result; }
1.579 +
1.580 + Instantiation& operator*() const {
1.581 + return mCurrent->mInstantiation; }
1.582 +
1.583 + Instantiation* operator->() const {
1.584 + return &mCurrent->mInstantiation; }
1.585 +
1.586 + bool operator==(const ConstIterator& aConstIterator) const {
1.587 + return mCurrent == aConstIterator.mCurrent; }
1.588 +
1.589 + bool operator!=(const ConstIterator& aConstIterator) const {
1.590 + return mCurrent != aConstIterator.mCurrent; }
1.591 +
1.592 + friend class InstantiationSet;
1.593 + };
1.594 +
1.595 + Iterator First() { return Iterator(mHead.mNext); }
1.596 + Iterator Last() { return Iterator(&mHead); }
1.597 +
1.598 + bool Empty() const { return First() == Last(); }
1.599 +
1.600 + Iterator Append(const Instantiation& aInstantiation) {
1.601 + return Insert(Last(), aInstantiation); }
1.602 +
1.603 + Iterator Insert(Iterator aBefore, const Instantiation& aInstantiation);
1.604 +
1.605 + Iterator Erase(Iterator aElement);
1.606 +
1.607 + void Clear();
1.608 +
1.609 + bool HasAssignmentFor(nsIAtom* aVariable) const;
1.610 +};
1.611 +
1.612 +//----------------------------------------------------------------------
1.613 +
1.614 +/**
1.615 + * A abstract base class for all nodes in the rule network
1.616 + */
1.617 +class ReteNode
1.618 +{
1.619 +public:
1.620 + ReteNode() {}
1.621 + virtual ~ReteNode() {}
1.622 +
1.623 + /**
1.624 + * Propagate a set of instantiations "down" through the
1.625 + * network. Each instantiation is a partial set of
1.626 + * variable-to-value assignments, along with the memory elements
1.627 + * that support it.
1.628 + *
1.629 + * The node must evaluate each instantiation, and either 1)
1.630 + * extend it with additional assignments and memory-element
1.631 + * support, or 2) remove it from the set because it is
1.632 + * inconsistent with the constraints that this node applies.
1.633 + *
1.634 + * The node must then pass the resulting instantiation set along
1.635 + * to any of its children in the network. (In other words, the
1.636 + * node must recursively call Propagate() on its children. We
1.637 + * should fix this to make the algorithm interruptable.)
1.638 + *
1.639 + * See TestNode::Propagate for details about instantiation set ownership
1.640 + *
1.641 + * @param aInstantiations the set of instantiations to propagate
1.642 + * down through the network.
1.643 + * @param aIsUpdate true if updating, false for first generation
1.644 + * @param aTakenInstantiations true if the ownership over aInstantiations
1.645 + * has been taken from the caller. If false,
1.646 + * the caller owns it.
1.647 + * @return NS_OK if no errors occurred.
1.648 + */
1.649 + virtual nsresult Propagate(InstantiationSet& aInstantiations,
1.650 + bool aIsUpdate, bool& aTakenInstantiations) = 0;
1.651 +};
1.652 +
1.653 +//----------------------------------------------------------------------
1.654 +
1.655 +/**
1.656 + * A collection of nodes in the rule network
1.657 + */
1.658 +class ReteNodeSet
1.659 +{
1.660 +public:
1.661 + ReteNodeSet();
1.662 + ~ReteNodeSet();
1.663 +
1.664 + nsresult Add(ReteNode* aNode);
1.665 + nsresult Clear();
1.666 +
1.667 + class Iterator;
1.668 +
1.669 + class ConstIterator {
1.670 + public:
1.671 + ConstIterator(ReteNode** aNode) : mCurrent(aNode) {}
1.672 +
1.673 + ConstIterator(const ConstIterator& aConstIterator)
1.674 + : mCurrent(aConstIterator.mCurrent) {}
1.675 +
1.676 + ConstIterator& operator=(const ConstIterator& aConstIterator) {
1.677 + mCurrent = aConstIterator.mCurrent;
1.678 + return *this; }
1.679 +
1.680 + ConstIterator& operator++() {
1.681 + ++mCurrent;
1.682 + return *this; }
1.683 +
1.684 + ConstIterator operator++(int) {
1.685 + ConstIterator result(*this);
1.686 + ++mCurrent;
1.687 + return result; }
1.688 +
1.689 + const ReteNode* operator*() const {
1.690 + return *mCurrent; }
1.691 +
1.692 + const ReteNode* operator->() const {
1.693 + return *mCurrent; }
1.694 +
1.695 + bool operator==(const ConstIterator& aConstIterator) const {
1.696 + return mCurrent == aConstIterator.mCurrent; }
1.697 +
1.698 + bool operator!=(const ConstIterator& aConstIterator) const {
1.699 + return mCurrent != aConstIterator.mCurrent; }
1.700 +
1.701 + protected:
1.702 + friend class Iterator; // XXXwaterson this is so wrong!
1.703 + ReteNode** mCurrent;
1.704 + };
1.705 +
1.706 + ConstIterator First() const { return ConstIterator(mNodes); }
1.707 + ConstIterator Last() const { return ConstIterator(mNodes + mCount); }
1.708 +
1.709 + class Iterator : public ConstIterator {
1.710 + public:
1.711 + Iterator(ReteNode** aNode) : ConstIterator(aNode) {}
1.712 +
1.713 + Iterator& operator++() {
1.714 + ++mCurrent;
1.715 + return *this; }
1.716 +
1.717 + Iterator operator++(int) {
1.718 + Iterator result(*this);
1.719 + ++mCurrent;
1.720 + return result; }
1.721 +
1.722 + ReteNode* operator*() const {
1.723 + return *mCurrent; }
1.724 +
1.725 + ReteNode* operator->() const {
1.726 + return *mCurrent; }
1.727 +
1.728 + bool operator==(const ConstIterator& aConstIterator) const {
1.729 + return mCurrent == aConstIterator.mCurrent; }
1.730 +
1.731 + bool operator!=(const ConstIterator& aConstIterator) const {
1.732 + return mCurrent != aConstIterator.mCurrent; }
1.733 + };
1.734 +
1.735 + Iterator First() { return Iterator(mNodes); }
1.736 + Iterator Last() { return Iterator(mNodes + mCount); }
1.737 +
1.738 + int32_t Count() const { return mCount; }
1.739 +
1.740 +protected:
1.741 + ReteNode** mNodes;
1.742 + int32_t mCount;
1.743 + int32_t mCapacity;
1.744 +};
1.745 +
1.746 +//----------------------------------------------------------------------
1.747 +
1.748 +/**
1.749 + * A node that applies a test condition to a set of instantiations.
1.750 + *
1.751 + * This class provides implementations of Propagate() and Constrain()
1.752 + * in terms of one simple operation, FilterInstantiations(). A node
1.753 + * that is a "simple test node" in a rule network should derive from
1.754 + * this class, and need only implement FilterInstantiations().
1.755 + */
1.756 +class TestNode : public ReteNode
1.757 +{
1.758 +public:
1.759 + TestNode(TestNode* aParent);
1.760 +
1.761 + /**
1.762 + * Retrieve the test node's parent
1.763 + * @return the test node's parent
1.764 + */
1.765 + TestNode* GetParent() const { return mParent; }
1.766 +
1.767 + /**
1.768 + * Calls FilterInstantiations() on the instantiation set, and if
1.769 + * the resulting set isn't empty, propagates the new set down to
1.770 + * each of the test node's children.
1.771 + *
1.772 + * Note that the caller of Propagate is responsible for deleting
1.773 + * aInstantiations if necessary as described below.
1.774 + *
1.775 + * Propagate may be called in update or non-update mode as indicated
1.776 + * by the aIsUpdate argument. Non-update mode is used when initially
1.777 + * generating results, whereas update mode is used when the datasource
1.778 + * changes and new results might be available.
1.779 + *
1.780 + * The last node in a chain of TestNodes is always an nsInstantiationNode.
1.781 + * In non-update mode, this nsInstantiationNode will cache the results
1.782 + * in the query using the SetCachedResults method. The query processor
1.783 + * takes these cached results and creates a nsXULTemplateResultSetRDF
1.784 + * which is the enumeration returned to the template builder. This
1.785 + * nsXULTemplateResultSetRDF owns the instantiations and they will be
1.786 + * deleted when the nsXULTemplateResultSetRDF goes away.
1.787 + *
1.788 + * In update mode, the nsInstantiationNode node will iterate over the
1.789 + * instantiations itself and callback to the builder to update any matches
1.790 + * and generated content. If no instantiations match, then the builder
1.791 + * will never be called.
1.792 + *
1.793 + * Thus, the difference between update and non-update modes is that in
1.794 + * update mode, the results and instantiations have been already handled
1.795 + * whereas in non-update mode they are expected to be returned in an
1.796 + * nsXULTemplateResultSetRDF for further processing by the builder.
1.797 + *
1.798 + * Regardless, aTakenInstantiations will be set to true if the
1.799 + * ownership over aInstantiations has been transferred to a result set.
1.800 + * If set to false, the caller is still responsible for aInstantiations.
1.801 + * aTakenInstantiations will be set properly even if an error occurs.
1.802 + */
1.803 + virtual nsresult Propagate(InstantiationSet& aInstantiations,
1.804 + bool aIsUpdate, bool& aTakenInstantiations) MOZ_OVERRIDE;
1.805 +
1.806 + /**
1.807 + * This is called by a child node on its parent to allow the
1.808 + * parent's constraints to apply to the set of instantiations.
1.809 + *
1.810 + * A node must iterate through the set of instantiations, and for
1.811 + * each instantiation, either 1) extend the instantiation by
1.812 + * adding variable-to-value assignments and memory element support
1.813 + * for those assignments, or 2) remove the instantiation because
1.814 + * it is inconsistent.
1.815 + *
1.816 + * The node must then pass the resulting set of instantiations up
1.817 + * to its parent (by recursive call; we should make this iterative
1.818 + * & interruptable at some point.)
1.819 + *
1.820 + * @param aInstantiations the set of instantiations that must
1.821 + * be constrained
1.822 + * @return NS_OK if no errors occurred
1.823 + */
1.824 + virtual nsresult Constrain(InstantiationSet& aInstantiations);
1.825 +
1.826 + /**
1.827 + * Given a set of instantiations, filter out any that are
1.828 + * inconsistent with the test node's test, and append
1.829 + * variable-to-value assignments and memory element support for
1.830 + * those which do pass the test node's test.
1.831 + *
1.832 + * @param aInstantiations the set of instantiations to be
1.833 + * filtered
1.834 + * @param aCantHandleYet [out] true if the instantiations do not contain
1.835 + * enough information to constrain the data. May be null if this
1.836 + * isn't important to the caller.
1.837 + * @return NS_OK if no errors occurred.
1.838 + */
1.839 + virtual nsresult FilterInstantiations(InstantiationSet& aInstantiations,
1.840 + bool* aCantHandleYet) const = 0;
1.841 + //XXX probably better named "ApplyConstraints" or "Discrminiate" or something
1.842 +
1.843 + /**
1.844 + * Add another node as a child of this node.
1.845 + * @param aNode the node to add.
1.846 + * @return NS_OK if no errors occur.
1.847 + */
1.848 + nsresult AddChild(ReteNode* aNode) { return mKids.Add(aNode); }
1.849 +
1.850 + /**
1.851 + * Remove all the children of this node
1.852 + * @return NS_OK if no errors occur.
1.853 + */
1.854 + nsresult RemoveAllChildren() { return mKids.Clear(); }
1.855 +
1.856 +protected:
1.857 + TestNode* mParent;
1.858 + ReteNodeSet mKids;
1.859 +};
1.860 +
1.861 +#endif // nsRuleNetwork_h__
