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/* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
* Use of this file is governed by the BSD 3-clause license that
* can be found in the LICENSE.txt file in the project root.
*/
#pragma once
#include <cassert>
#include "support/BitSet.h"
#include "atn/PredictionContext.h"
#include "atn/ATNConfig.h"
#include "FlatHashSet.h"
namespace antlr4 {
namespace atn {
/// Specialized set that can track info about the set, with support for combining similar configurations using a
/// graph-structured stack.
class ANTLR4CPP_PUBLIC ATNConfigSet {
public:
/// Track the elements as they are added to the set; supports get(i)
std::vector<Ref<ATNConfig>> configs;
// TODO: these fields make me pretty uncomfortable but nice to pack up info together, saves recomputation
// TODO: can we track conflicts as they are added to save scanning configs later?
size_t uniqueAlt = 0;
/** Currently this is only used when we detect SLL conflict; this does
* not necessarily represent the ambiguous alternatives. In fact,
* I should also point out that this seems to include predicated alternatives
* that have predicates that evaluate to false. Computed in computeTargetState().
*/
antlrcpp::BitSet conflictingAlts;
// Used in parser and lexer. In lexer, it indicates we hit a pred
// while computing a closure operation. Don't make a DFA state from this.
bool hasSemanticContext = false;
bool dipsIntoOuterContext = false;
/// Indicates that this configuration set is part of a full context
/// LL prediction. It will be used to determine how to merge $. With SLL
/// it's a wildcard whereas it is not for LL context merge.
const bool fullCtx = true;
ATNConfigSet();
ATNConfigSet(const ATNConfigSet &other);
ATNConfigSet(ATNConfigSet&&) = delete;
explicit ATNConfigSet(bool fullCtx);
virtual ~ATNConfigSet() = default;
bool add(const Ref<ATNConfig> &config);
/// <summary>
/// Adding a new config means merging contexts with existing configs for
/// {@code (s, i, pi, _)}, where {@code s} is the
/// <seealso cref="ATNConfig#state"/>, {@code i} is the <seealso cref="ATNConfig#alt"/>, and
/// {@code pi} is the <seealso cref="ATNConfig#semanticContext"/>. We use
/// {@code (s,i,pi)} as key.
/// <p/>
/// This method updates <seealso cref="#dipsIntoOuterContext"/> and
/// <seealso cref="#hasSemanticContext"/> when necessary.
/// </summary>
bool add(const Ref<ATNConfig> &config, PredictionContextMergeCache *mergeCache);
bool addAll(const ATNConfigSet &other);
std::vector<ATNState*> getStates() const;
/**
* Gets the complete set of represented alternatives for the configuration
* set.
*
* @return the set of represented alternatives in this configuration set
*
* @since 4.3
*/
antlrcpp::BitSet getAlts() const;
std::vector<Ref<const SemanticContext>> getPredicates() const;
const Ref<ATNConfig>& get(size_t i) const;
void optimizeConfigs(ATNSimulator *interpreter);
size_t size() const;
bool isEmpty() const;
void clear();
bool isReadonly() const;
void setReadonly(bool readonly);
virtual size_t hashCode() const;
virtual bool equals(const ATNConfigSet &other) const;
virtual std::string toString() const;
private:
struct ATNConfigHasher final {
const ATNConfigSet* atnConfigSet;
size_t operator()(const ATNConfig *other) const {
assert(other != nullptr);
return atnConfigSet->hashCode(*other);
}
};
struct ATNConfigComparer final {
const ATNConfigSet* atnConfigSet;
bool operator()(const ATNConfig *lhs, const ATNConfig *rhs) const {
assert(lhs != nullptr);
assert(rhs != nullptr);
return atnConfigSet->equals(*lhs, *rhs);
}
};
mutable std::atomic<size_t> _cachedHashCode = 0;
/// Indicates that the set of configurations is read-only. Do not
/// allow any code to manipulate the set; DFA states will point at
/// the sets and they must not change. This does not protect the other
/// fields; in particular, conflictingAlts is set after
/// we've made this readonly.
bool _readonly = false;
virtual size_t hashCode(const ATNConfig &atnConfig) const;
virtual bool equals(const ATNConfig &lhs, const ATNConfig &rhs) const;
using LookupContainer = FlatHashSet<ATNConfig*, ATNConfigHasher, ATNConfigComparer>;
/// All configs but hashed by (s, i, _, pi) not including context. Wiped out
/// when we go readonly as this set becomes a DFA state.
LookupContainer _configLookup;
};
inline bool operator==(const ATNConfigSet &lhs, const ATNConfigSet &rhs) { return lhs.equals(rhs); }
inline bool operator!=(const ATNConfigSet &lhs, const ATNConfigSet &rhs) { return !operator==(lhs, rhs); }
} // namespace atn
} // namespace antlr4
namespace std {
template <>
struct hash<::antlr4::atn::ATNConfigSet> {
size_t operator()(const ::antlr4::atn::ATNConfigSet &atnConfigSet) const {
return atnConfigSet.hashCode();
}
};
} // namespace std
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