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https://github.com/carbon-language/carbon-lang.git
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Jon Ross-Perkins
b76bc875c4
There were some notes about default constructors being required in parse_tree.h, but they don't seem to be. Removing the default constructor forces the explicit `::Invalid` where there's no value immediately being assigned, which works fine for existing code. I think this actually reduces the chance of accidents more than the prior default-construct-as-invalid approach.
87 lines
2.8 KiB
C++
87 lines
2.8 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#ifndef CARBON_TOOLCHAIN_COMMON_INDEX_BASE_H_
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#define CARBON_TOOLCHAIN_COMMON_INDEX_BASE_H_
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#include <type_traits>
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#include "common/ostream.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/iterator.h"
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#include "llvm/Support/Format.h"
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namespace Carbon {
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template <typename DataType>
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class DataIterator;
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// A lightweight handle to an item in a vector.
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//
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// DataIndex is designed to be passed by value, not reference or pointer. They
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// are also designed to be small and efficient to store in data structures.
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struct IndexBase {
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static constexpr int32_t InvalidIndex = -1;
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IndexBase() = delete;
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constexpr explicit IndexBase(int index) : index(index) {}
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auto Print(llvm::raw_ostream& output) const -> void {
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if (is_valid()) {
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output << index;
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} else {
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output << "<invalid>";
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}
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}
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auto is_valid() const -> bool { return index != InvalidIndex; }
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int32_t index;
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};
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// Like IndexBase, but also provides < and > comparison operators.
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struct ComparableIndexBase : public IndexBase {
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using IndexBase::IndexBase;
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};
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// Equality comparison for both IndexBase and ComparableIndexBase.
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template <typename IndexType,
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typename std::enable_if_t<std::is_base_of_v<IndexBase, IndexType>>* =
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nullptr>
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auto operator==(IndexType lhs, IndexType rhs) -> bool {
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return lhs.index == rhs.index;
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}
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template <typename IndexType,
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typename std::enable_if_t<std::is_base_of_v<IndexBase, IndexType>>* =
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nullptr>
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auto operator!=(IndexType lhs, IndexType rhs) -> bool {
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return lhs.index != rhs.index;
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}
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// The < and > comparisons for only ComparableIndexBase.
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template <typename IndexType, typename std::enable_if_t<std::is_base_of_v<
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ComparableIndexBase, IndexType>>* = nullptr>
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auto operator<(IndexType lhs, IndexType rhs) -> bool {
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return lhs.index < rhs.index;
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}
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template <typename IndexType, typename std::enable_if_t<std::is_base_of_v<
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ComparableIndexBase, IndexType>>* = nullptr>
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auto operator<=(IndexType lhs, IndexType rhs) -> bool {
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return lhs.index <= rhs.index;
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}
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template <typename IndexType, typename std::enable_if_t<std::is_base_of_v<
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ComparableIndexBase, IndexType>>* = nullptr>
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auto operator>(IndexType lhs, IndexType rhs) -> bool {
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return lhs.index > rhs.index;
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}
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template <typename IndexType, typename std::enable_if_t<std::is_base_of_v<
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ComparableIndexBase, IndexType>>* = nullptr>
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auto operator>=(IndexType lhs, IndexType rhs) -> bool {
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return lhs.index >= rhs.index;
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}
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} // namespace Carbon
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#endif // CARBON_TOOLCHAIN_COMMON_INDEX_BASE_H_
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