359 lines
10 KiB
C
359 lines
10 KiB
C
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//===- llvm/ADT/TinyPtrVector.h - 'Normally tiny' vectors -------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ADT_TINYPTRVECTOR_H
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#define LLVM_ADT_TINYPTRVECTOR_H
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#include "llvm/ADT/ArrayRef.h"
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#include "llvm/ADT/None.h"
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#include "llvm/ADT/PointerUnion.h"
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#include "llvm/ADT/SmallVector.h"
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#include <cassert>
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#include <cstddef>
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#include <iterator>
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#include <type_traits>
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namespace llvm {
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/// TinyPtrVector - This class is specialized for cases where there are
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/// normally 0 or 1 element in a vector, but is general enough to go beyond that
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/// when required.
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///
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/// NOTE: This container doesn't allow you to store a null pointer into it.
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///
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template <typename EltTy>
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class TinyPtrVector {
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public:
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using VecTy = SmallVector<EltTy, 4>;
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using value_type = typename VecTy::value_type;
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// EltTy must be the first pointer type so that is<EltTy> is true for the
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// default-constructed PtrUnion. This allows an empty TinyPtrVector to
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// naturally vend a begin/end iterator of type EltTy* without an additional
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// check for the empty state.
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using PtrUnion = PointerUnion<EltTy, VecTy *>;
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private:
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PtrUnion Val;
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public:
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TinyPtrVector() = default;
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~TinyPtrVector() {
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if (VecTy *V = Val.template dyn_cast<VecTy*>())
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delete V;
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}
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TinyPtrVector(const TinyPtrVector &RHS) : Val(RHS.Val) {
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if (VecTy *V = Val.template dyn_cast<VecTy*>())
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Val = new VecTy(*V);
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}
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TinyPtrVector &operator=(const TinyPtrVector &RHS) {
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if (this == &RHS)
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return *this;
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if (RHS.empty()) {
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this->clear();
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return *this;
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}
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// Try to squeeze into the single slot. If it won't fit, allocate a copied
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// vector.
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if (Val.template is<EltTy>()) {
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if (RHS.size() == 1)
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Val = RHS.front();
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else
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Val = new VecTy(*RHS.Val.template get<VecTy*>());
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return *this;
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}
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// If we have a full vector allocated, try to re-use it.
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if (RHS.Val.template is<EltTy>()) {
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Val.template get<VecTy*>()->clear();
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Val.template get<VecTy*>()->push_back(RHS.front());
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} else {
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*Val.template get<VecTy*>() = *RHS.Val.template get<VecTy*>();
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}
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return *this;
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}
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TinyPtrVector(TinyPtrVector &&RHS) : Val(RHS.Val) {
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RHS.Val = (EltTy)nullptr;
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}
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TinyPtrVector &operator=(TinyPtrVector &&RHS) {
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if (this == &RHS)
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return *this;
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if (RHS.empty()) {
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this->clear();
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return *this;
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}
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// If this vector has been allocated on the heap, re-use it if cheap. If it
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// would require more copying, just delete it and we'll steal the other
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// side.
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if (VecTy *V = Val.template dyn_cast<VecTy*>()) {
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if (RHS.Val.template is<EltTy>()) {
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V->clear();
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V->push_back(RHS.front());
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RHS.Val = EltTy();
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return *this;
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}
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delete V;
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}
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Val = RHS.Val;
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RHS.Val = EltTy();
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return *this;
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}
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TinyPtrVector(std::initializer_list<EltTy> IL)
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: Val(IL.size() == 0
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? PtrUnion()
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: IL.size() == 1 ? PtrUnion(*IL.begin())
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: PtrUnion(new VecTy(IL.begin(), IL.end()))) {}
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/// Constructor from an ArrayRef.
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///
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/// This also is a constructor for individual array elements due to the single
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/// element constructor for ArrayRef.
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explicit TinyPtrVector(ArrayRef<EltTy> Elts)
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: Val(Elts.empty()
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? PtrUnion()
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: Elts.size() == 1
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? PtrUnion(Elts[0])
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: PtrUnion(new VecTy(Elts.begin(), Elts.end()))) {}
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TinyPtrVector(size_t Count, EltTy Value)
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: Val(Count == 0 ? PtrUnion()
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: Count == 1 ? PtrUnion(Value)
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: PtrUnion(new VecTy(Count, Value))) {}
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// implicit conversion operator to ArrayRef.
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operator ArrayRef<EltTy>() const {
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if (Val.isNull())
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return None;
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if (Val.template is<EltTy>())
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return *Val.getAddrOfPtr1();
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return *Val.template get<VecTy*>();
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}
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// implicit conversion operator to MutableArrayRef.
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operator MutableArrayRef<EltTy>() {
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if (Val.isNull())
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return None;
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if (Val.template is<EltTy>())
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return *Val.getAddrOfPtr1();
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return *Val.template get<VecTy*>();
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}
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// Implicit conversion to ArrayRef<U> if EltTy* implicitly converts to U*.
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template <
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typename U,
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std::enable_if_t<std::is_convertible<ArrayRef<EltTy>, ArrayRef<U>>::value,
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bool> = false>
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operator ArrayRef<U>() const {
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return operator ArrayRef<EltTy>();
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}
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bool empty() const {
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// This vector can be empty if it contains no element, or if it
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// contains a pointer to an empty vector.
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if (Val.isNull()) return true;
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if (VecTy *Vec = Val.template dyn_cast<VecTy*>())
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return Vec->empty();
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return false;
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}
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unsigned size() const {
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if (empty())
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return 0;
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if (Val.template is<EltTy>())
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return 1;
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return Val.template get<VecTy*>()->size();
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}
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using iterator = EltTy *;
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using const_iterator = const EltTy *;
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using reverse_iterator = std::reverse_iterator<iterator>;
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using const_reverse_iterator = std::reverse_iterator<const_iterator>;
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iterator begin() {
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if (Val.template is<EltTy>())
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return Val.getAddrOfPtr1();
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return Val.template get<VecTy *>()->begin();
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}
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iterator end() {
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if (Val.template is<EltTy>())
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return begin() + (Val.isNull() ? 0 : 1);
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return Val.template get<VecTy *>()->end();
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}
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const_iterator begin() const {
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return (const_iterator)const_cast<TinyPtrVector*>(this)->begin();
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}
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const_iterator end() const {
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return (const_iterator)const_cast<TinyPtrVector*>(this)->end();
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}
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reverse_iterator rbegin() { return reverse_iterator(end()); }
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reverse_iterator rend() { return reverse_iterator(begin()); }
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const_reverse_iterator rbegin() const {
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return const_reverse_iterator(end());
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}
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const_reverse_iterator rend() const {
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return const_reverse_iterator(begin());
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}
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EltTy operator[](unsigned i) const {
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assert(!Val.isNull() && "can't index into an empty vector");
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if (Val.template is<EltTy>()) {
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assert(i == 0 && "tinyvector index out of range");
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return Val.template get<EltTy>();
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}
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assert(i < Val.template get<VecTy*>()->size() &&
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"tinyvector index out of range");
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return (*Val.template get<VecTy*>())[i];
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}
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EltTy front() const {
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assert(!empty() && "vector empty");
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if (Val.template is<EltTy>())
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return Val.template get<EltTy>();
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return Val.template get<VecTy*>()->front();
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}
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EltTy back() const {
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assert(!empty() && "vector empty");
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if (Val.template is<EltTy>())
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return Val.template get<EltTy>();
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return Val.template get<VecTy*>()->back();
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}
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void push_back(EltTy NewVal) {
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// If we have nothing, add something.
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if (Val.isNull()) {
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Val = NewVal;
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assert(!Val.isNull() && "Can't add a null value");
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return;
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}
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// If we have a single value, convert to a vector.
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if (Val.template is<EltTy>()) {
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EltTy V = Val.template get<EltTy>();
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Val = new VecTy();
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Val.template get<VecTy*>()->push_back(V);
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}
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// Add the new value, we know we have a vector.
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Val.template get<VecTy*>()->push_back(NewVal);
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}
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void pop_back() {
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// If we have a single value, convert to empty.
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if (Val.template is<EltTy>())
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Val = (EltTy)nullptr;
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else if (VecTy *Vec = Val.template get<VecTy*>())
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Vec->pop_back();
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}
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void clear() {
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// If we have a single value, convert to empty.
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if (Val.template is<EltTy>()) {
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Val = EltTy();
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} else if (VecTy *Vec = Val.template dyn_cast<VecTy*>()) {
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// If we have a vector form, just clear it.
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Vec->clear();
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}
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// Otherwise, we're already empty.
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}
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iterator erase(iterator I) {
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assert(I >= begin() && "Iterator to erase is out of bounds.");
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assert(I < end() && "Erasing at past-the-end iterator.");
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// If we have a single value, convert to empty.
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if (Val.template is<EltTy>()) {
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if (I == begin())
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Val = EltTy();
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} else if (VecTy *Vec = Val.template dyn_cast<VecTy*>()) {
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// multiple items in a vector; just do the erase, there is no
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// benefit to collapsing back to a pointer
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return Vec->erase(I);
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}
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return end();
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}
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iterator erase(iterator S, iterator E) {
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assert(S >= begin() && "Range to erase is out of bounds.");
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assert(S <= E && "Trying to erase invalid range.");
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assert(E <= end() && "Trying to erase past the end.");
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if (Val.template is<EltTy>()) {
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if (S == begin() && S != E)
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Val = EltTy();
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} else if (VecTy *Vec = Val.template dyn_cast<VecTy*>()) {
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return Vec->erase(S, E);
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}
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return end();
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}
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iterator insert(iterator I, const EltTy &Elt) {
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assert(I >= this->begin() && "Insertion iterator is out of bounds.");
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assert(I <= this->end() && "Inserting past the end of the vector.");
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if (I == end()) {
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push_back(Elt);
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return std::prev(end());
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}
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assert(!Val.isNull() && "Null value with non-end insert iterator.");
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if (Val.template is<EltTy>()) {
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EltTy V = Val.template get<EltTy>();
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assert(I == begin());
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Val = Elt;
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push_back(V);
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return begin();
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}
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return Val.template get<VecTy*>()->insert(I, Elt);
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}
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template<typename ItTy>
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iterator insert(iterator I, ItTy From, ItTy To) {
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assert(I >= this->begin() && "Insertion iterator is out of bounds.");
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assert(I <= this->end() && "Inserting past the end of the vector.");
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if (From == To)
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return I;
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// If we have a single value, convert to a vector.
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ptrdiff_t Offset = I - begin();
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if (Val.isNull()) {
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if (std::next(From) == To) {
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Val = *From;
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return begin();
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}
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Val = new VecTy();
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} else if (Val.template is<EltTy>()) {
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EltTy V = Val.template get<EltTy>();
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Val = new VecTy();
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Val.template get<VecTy*>()->push_back(V);
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}
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return Val.template get<VecTy*>()->insert(begin() + Offset, From, To);
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}
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};
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} // end namespace llvm
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#endif // LLVM_ADT_TINYPTRVECTOR_H
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