XPCOM Collections¶
nsTArray
and AutoTArray
¶
nsTArray<T>
is a typesafe array for holding various objects, similar to std::vector<T>
. (note that
nsTArray<T>
is dynamically-sized, unlike std::array<T>
) Here’s an
incomplete list of mappings between the two:
std::vector<T> |
nsTArray<T> |
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Rust Bindings¶
When the thin_vec
crate is built in Gecko, thin_vec::ThinVec<T>
is
guaranteed to have the same memory layout and allocation strategy as
nsTArray
, meaning that the two types may be used interchangeably across
FFI boundaries. The type is not safe to pass by-value over FFI
boundaries, due to Rust and C++ differing in when they run destructors.
The element type T
must be memory-compatible with both Rust and C++ code
to use over FFI.
nsTHashMap
and nsTHashSet
¶
These types are the recommended interface for writing new XPCOM hashmaps and hashsets in XPCOM code.
Supported Hash Keys¶
The following types are supported as the key parameter to nsTHashMap
and
nsTHashSet
.
Type |
Hash Key |
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Any key not in this list must inherit from the PLDHashEntryHdr
class to
implement manual hashing behaviour.
Class Reference¶
Note
The nsTHashMap
and nsTHashSet
types are not declared exactly like
this in code. This is intended largely as a practical reference.
-
template<K, V>
class nsTHashMap<K, V>¶ The
nsTHashMap<K, V>
class is currently defined as a thin type alias aroundnsBaseHashtable
. See the methods defined on that class for more detailed documentation.https://searchfox.org/mozilla-central/source/xpcom/ds/nsBaseHashtable.h
-
uint32_t Count() const¶
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bool IsEmpty() const¶
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bool Get(KeyType aKey, V *aData) const¶
Get the value, returning a flag indicating the presence of the entry in the table.
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V Get(KeyType aKey) const¶
Get the value, returning a default-initialized object if the entry is not present in the table.
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Maybe<V> MaybeGet(KeyType aKey) const¶
Get the value, returning Nothing if the entry is not present in the table.
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V &LookupOrInsert(KeyType aKey, Args&&... aArgs) const¶
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V &LookupOrInsertWith(KeyType aKey, F &&aFunc) const¶
-
uint32_t Count() const¶
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template<K>
class nsTHashSet<K>¶ The
nsTHashSet<K>
class is currently defined as a thin type alias aroundnsTBaseHashSet
. See the methods defined on that class for more detailed documentation.https://searchfox.org/mozilla-central/source/xpcom/ds/nsTHashSet.h