The Tor Browser: js/src/frontend/ParseMaps.h@6474c204b198 (annotated)

js/src/frontend/ParseMaps.h@6474c204b198 (annotated)

js/src/frontend/ParseMaps.h

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #ifndef frontend_ParseMaps_h
 #define frontend_ParseMaps_h
 #include "mozilla/Attributes.h"
 #include "mozilla/TypeTraits.h"
 #include "ds/InlineMap.h"
 #include "gc/Barrier.h"
 #include "js/Vector.h"
 class JSAtom;
 typedef uintptr_t jsatomid;
 namespace js {
 class LifoAlloc;
 namespace frontend {
 class DefinitionSingle;
 class DefinitionList;
 typedef InlineMap<JSAtom *, jsatomid, 24> AtomIndexMap;
 typedef InlineMap<JSAtom *, DefinitionSingle, 24> AtomDefnMap;
 typedef InlineMap<JSAtom *, DefinitionList, 24> AtomDefnListMap;
 /*
  * For all unmapped atoms recorded in al, add a mapping from the atom's index
  * to its address. map->length must already be set to the number of atoms in
  * the list and map->vector must point to pre-allocated memory.
  */
 void
 InitAtomMap(AtomIndexMap *indices, HeapPtr<JSAtom> *atoms);
 /*
  * A pool that permits the reuse of the backing storage for the defn, index, or
  * defn-or-header (multi) maps.
  *
  * The pool owns all the maps that are given out, and is responsible for
  * relinquishing all resources when |purgeAll| is triggered.
  */
 class ParseMapPool
 {
     typedef Vector<void *, 32, SystemAllocPolicy> RecyclableMaps;
     RecyclableMaps      all;
     RecyclableMaps      recyclable;
     void checkInvariants();
     void recycle(void *map) {
         JS_ASSERT(map);
 #ifdef DEBUG
         bool ok = false;
         /* Make sure the map is in |all| but not already in |recyclable|. */
         for (void **it = all.begin(), **end = all.end(); it != end; ++it) {
             if (*it == map) {
                 ok = true;
                 break;
             }
         }
         JS_ASSERT(ok);
         for (void **it = recyclable.begin(), **end = recyclable.end(); it != end; ++it)
             JS_ASSERT(*it != map);
 #endif
         JS_ASSERT(recyclable.length() < all.length());
         recyclable.infallibleAppend(map); /* Reserved in allocateFresh. */
     }
     void *allocateFresh();
     void *allocate() {
         if (recyclable.empty())
             return allocateFresh();
         void *map = recyclable.popCopy();
         asAtomMap(map)->clear();
         return map;
     }
     /* Arbitrary atom map type, that has keys and values of the same kind. */
     typedef AtomIndexMap AtomMapT;
     static AtomMapT *asAtomMap(void *ptr) {
         return reinterpret_cast<AtomMapT *>(ptr);
     }
   public:
     ~ParseMapPool() {
         purgeAll();
     }
     void purgeAll();
     bool empty() const {
         return all.empty();
     }
     /* Fallibly aquire one of the supported map types from the pool. */
     template <typename T>
     T *acquire() {
         return reinterpret_cast<T *>(allocate());
     }
     /* Release one of the supported map types back to the pool. */
     void release(AtomIndexMap *map) {
         recycle((void *) map);
     }
     void release(AtomDefnMap *map) {
         recycle((void *) map);
     }
     void release(AtomDefnListMap *map) {
         recycle((void *) map);
     }
 }; /* ParseMapPool */
 /*
  * N.B. This is a POD-type so that it can be included in the ParseNode union.
  * If possible, use the corresponding |OwnedAtomThingMapPtr| variant.
  */
 template <class Map>
 struct AtomThingMapPtr
 {
     Map *map_;
     void init() { clearMap(); }
     bool ensureMap(ExclusiveContext *cx);
     void releaseMap(ExclusiveContext *cx);
     bool hasMap() const { return map_; }
     Map *getMap() { return map_; }
     void setMap(Map *newMap) { JS_ASSERT(!map_); map_ = newMap; }
     void clearMap() { map_ = nullptr; }
     Map *operator->() { return map_; }
     const Map *operator->() const { return map_; }
     Map &operator*() const { return *map_; }
 };
 typedef AtomThingMapPtr<AtomIndexMap> AtomIndexMapPtr;
 /*
  * Wrapper around an AtomThingMapPtr (or its derivatives) that automatically
  * releases a map on destruction, if one has been acquired.
  */
 template <typename AtomThingMapPtrT>
 class OwnedAtomThingMapPtr : public AtomThingMapPtrT
 {
     ExclusiveContext *cx;
   public:
     explicit OwnedAtomThingMapPtr(ExclusiveContext *cx) : cx(cx) {
         AtomThingMapPtrT::init();
     }
     ~OwnedAtomThingMapPtr() {
         AtomThingMapPtrT::releaseMap(cx);
     }
 };
 typedef OwnedAtomThingMapPtr<AtomIndexMapPtr> OwnedAtomIndexMapPtr;
 /*
  * DefinitionSingle and DefinitionList represent either a single definition
  * or a list of them. The representation of definitions varies between
  * parse handlers, being either a Definition* (FullParseHandler) or a
  * Definition::Kind (SyntaxParseHandler). Methods on the below classes are
  * templated to distinguish the kind of value wrapped by the class.
  */
 /* Wrapper for a single definition. */
 class DefinitionSingle
 {
     uintptr_t bits;
   public:
     template <typename ParseHandler>
     static DefinitionSingle new_(typename ParseHandler::DefinitionNode defn)
     {
         DefinitionSingle res;
         res.bits = ParseHandler::definitionToBits(defn);
         return res;
     }
     template <typename ParseHandler>
     typename ParseHandler::DefinitionNode get() {
         return ParseHandler::definitionFromBits(bits);
     }
 };
 struct AtomDefnMapPtr : public AtomThingMapPtr<AtomDefnMap>
 {
     template <typename ParseHandler>
     MOZ_ALWAYS_INLINE
     typename ParseHandler::DefinitionNode lookupDefn(JSAtom *atom) {
         AtomDefnMap::Ptr p = map_->lookup(atom);
         return p ? p.value().get<ParseHandler>() : ParseHandler::nullDefinition();
     }
 };
 typedef OwnedAtomThingMapPtr<AtomDefnMapPtr> OwnedAtomDefnMapPtr;
 /*
  * A nonempty list containing one or more pointers to Definitions.
  *
  * By far the most common case is that the list contains exactly one
  * Definition, so the implementation is optimized for that case.
  *
  * Nodes for the linked list (if any) are allocated from the tempPool of a
  * context the caller passes into pushFront and pushBack. This means the
  * DefinitionList does not own the memory for the nodes: the JSContext does.
  * As a result, DefinitionList is a POD type; it can be safely and cheaply
  * copied.
  */
 class DefinitionList
 {
   public:
     class Range;
   private:
     friend class Range;
     /* A node in a linked list of Definitions. */
     struct Node
     {
         uintptr_t bits;
         Node *next;
         Node(uintptr_t bits, Node *next) : bits(bits), next(next) {}
     };
     union {
         uintptr_t bits;
         Node *head;
     } u;
     Node *firstNode() const {
         JS_ASSERT(isMultiple());
         return (Node *) (u.bits & ~0x1);
     }
     static Node *
     allocNode(ExclusiveContext *cx, LifoAlloc &alloc, uintptr_t bits, Node *tail);
   public:
     class Range
     {
         friend class DefinitionList;
         Node *node;
         uintptr_t bits;
         explicit Range(const DefinitionList &list) {
             if (list.isMultiple()) {
                 node = list.firstNode();
                 bits = node->bits;
             } else {
                 node = nullptr;
                 bits = list.u.bits;
             }
         }
       public:
         /* An empty Range. */
         Range() : node(nullptr), bits(0) {}
         void popFront() {
             JS_ASSERT(!empty());
             if (!node) {
                 bits = 0;
                 return;
             }
             node = node->next;
             bits = node ? node->bits : 0;
         }
         template <typename ParseHandler>
         typename ParseHandler::DefinitionNode front() {
             JS_ASSERT(!empty());
             return ParseHandler::definitionFromBits(bits);
         }
         bool empty() const {
             JS_ASSERT_IF(!bits, !node);
             return !bits;
         }
     };
     DefinitionList() {
         u.bits = 0;
     }
     explicit DefinitionList(uintptr_t bits) {
         u.bits = bits;
         JS_ASSERT(!isMultiple());
     }
     explicit DefinitionList(Node *node) {
         u.head = node;
         u.bits |= 0x1;
         JS_ASSERT(isMultiple());
     }
     bool isMultiple() const { return (u.bits & 0x1) != 0; }
     template <typename ParseHandler>
     typename ParseHandler::DefinitionNode front() {
         return ParseHandler::definitionFromBits(isMultiple() ? firstNode()->bits : u.bits);
     }
     /*
      * If there are multiple Definitions in this list, remove the first and
      * return true. Otherwise there is exactly one Definition in the list; do
      * nothing and return false.
      */
     bool popFront() {
         if (!isMultiple())
             return false;
         Node *node = firstNode();
         Node *next = node->next;
         if (next->next)
             *this = DefinitionList(next);
         else
             *this = DefinitionList(next->bits);
         return true;
     }
     /*
      * Add a definition to the front of this list.
      *
      * Return true on success. On OOM, report on cx and return false.
      */
     template <typename ParseHandler>
     bool pushFront(ExclusiveContext *cx, LifoAlloc &alloc,
                    typename ParseHandler::DefinitionNode defn) {
         Node *tail;
         if (isMultiple()) {
             tail = firstNode();
         } else {
             tail = allocNode(cx, alloc, u.bits, nullptr);
             if (!tail)
                 return false;
         }
         Node *node = allocNode(cx, alloc, ParseHandler::definitionToBits(defn), tail);
         if (!node)
             return false;
         *this = DefinitionList(node);
         return true;
     }
     /* Overwrite the first Definition in the list. */
     template <typename ParseHandler>
         void setFront(typename ParseHandler::DefinitionNode defn) {
         if (isMultiple())
             firstNode()->bits = ParseHandler::definitionToBits(defn);
         else
             *this = DefinitionList(ParseHandler::definitionToBits(defn));
     }
     Range all() const { return Range(*this); }
 #ifdef DEBUG
     void dump();
 #endif
 };
 typedef AtomDefnMap::Range      AtomDefnRange;
 typedef AtomDefnMap::AddPtr     AtomDefnAddPtr;
 typedef AtomDefnMap::Ptr        AtomDefnPtr;
 typedef AtomIndexMap::AddPtr    AtomIndexAddPtr;
 typedef AtomIndexMap::Ptr       AtomIndexPtr;
 typedef AtomDefnListMap::Ptr    AtomDefnListPtr;
 typedef AtomDefnListMap::AddPtr AtomDefnListAddPtr;
 typedef AtomDefnListMap::Range  AtomDefnListRange;
 /*
  * AtomDecls is a map of atoms to (sequences of) Definitions. It is used by
  * ParseContext to store declarations. A declaration associates a name with a
  * Definition.
  *
  * Declarations with function scope (such as const, var, and function) are
  * unique in the sense that they override any previous declarations with the
  * same name. For such declarations, we only need to store a single Definition,
  * using the method addUnique.
  *
  * Declarations with block scope (such as let) are slightly more complex. They
  * override any previous declarations with the same name, but only do so for
  * the block they are associated with. This is known as shadowing. For such
  * definitions, we need to store a sequence of Definitions, including those
  * introduced by previous declarations (and which are now shadowed), using the
  * method addShadow. When we leave the block associated with the let, the method
  * remove is used to unshadow the declaration immediately preceding it.
  */
 template <typename ParseHandler>
 class AtomDecls
 {
     typedef typename ParseHandler::DefinitionNode DefinitionNode;
     /* AtomDeclsIter needs to get at the DefnListMap directly. */
     friend class AtomDeclsIter;
     ExclusiveContext *cx;
     LifoAlloc &alloc;
     AtomDefnListMap  *map;
     AtomDecls(const AtomDecls &other) MOZ_DELETE;
     void operator=(const AtomDecls &other) MOZ_DELETE;
   public:
     explicit AtomDecls(ExclusiveContext *cx, LifoAlloc &alloc) : cx(cx),
                                                                  alloc(alloc),
                                                                  map(nullptr) {}
     ~AtomDecls();
     bool init();
     void clear() {
         map->clear();
     }
     /* Return the definition at the head of the chain for |atom|. */
     DefinitionNode lookupFirst(JSAtom *atom) const {
         JS_ASSERT(map);
         AtomDefnListPtr p = map->lookup(atom);
         if (!p)
             return ParseHandler::nullDefinition();
         return p.value().front<ParseHandler>();
     }
     /* Perform a lookup that can iterate over the definitions associated with |atom|. */
     DefinitionList::Range lookupMulti(JSAtom *atom) const {
         JS_ASSERT(map);
         if (AtomDefnListPtr p = map->lookup(atom))
             return p.value().all();
         return DefinitionList::Range();
     }
     /* Add-or-update a known-unique definition for |atom|. */
     bool addUnique(JSAtom *atom, DefinitionNode defn) {
         JS_ASSERT(map);
         AtomDefnListAddPtr p = map->lookupForAdd(atom);
         if (!p)
             return map->add(p, atom, DefinitionList(ParseHandler::definitionToBits(defn)));
         JS_ASSERT(!p.value().isMultiple());
         p.value() = DefinitionList(ParseHandler::definitionToBits(defn));
         return true;
     }
     bool addShadow(JSAtom *atom, DefinitionNode defn);
     /* Updating the definition for an entry that is known to exist is infallible. */
     void updateFirst(JSAtom *atom, DefinitionNode defn) {
         JS_ASSERT(map);
         AtomDefnListMap::Ptr p = map->lookup(atom);
         JS_ASSERT(p);
         p.value().setFront<ParseHandler>(defn);
     }
     /* Remove the node at the head of the chain for |atom|. */
     void remove(JSAtom *atom) {
         JS_ASSERT(map);
         AtomDefnListMap::Ptr p = map->lookup(atom);
         if (!p)
             return;
         DefinitionList &list = p.value();
         if (!list.popFront()) {
             map->remove(p);
             return;
         }
     }
     AtomDefnListMap::Range all() const {
         JS_ASSERT(map);
         return map->all();
     }
 #ifdef DEBUG
     void dump();
 #endif
 };
 } /* namespace frontend */
 } /* namespace js */
 namespace mozilla {
 template <>
 struct IsPod<js::frontend::DefinitionSingle> : TrueType {};
 template <>
 struct IsPod<js::frontend::DefinitionList> : TrueType {};
 } /* namespace mozilla */
 #endif /* frontend_ParseMaps_h */

The Tor Browser / annotate

js/src/frontend/ParseMaps.h@6474c204b198 (annotated)

js/src/frontend/ParseMaps.h