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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 "support/BitSet.h"
#include "atn/PredictionContext.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;
/** 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;
bool dipsIntoOuterContext;
/// 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;
ATNConfigSet(bool fullCtx = true);
ATNConfigSet(const Ref<ATNConfigSet> &old);
virtual ~ATNConfigSet();
virtual 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>
virtual bool add(const Ref<ATNConfig> &config, PredictionContextMergeCache *mergeCache);
virtual std::vector<ATNState *> getStates();
/**
* 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();
virtual std::vector<Ref<SemanticContext>> getPredicates();
virtual Ref<ATNConfig> get(size_t i) const;
virtual void optimizeConfigs(ATNSimulator *interpreter);
bool addAll(const Ref<ATNConfigSet> &other);
bool operator == (const ATNConfigSet &other);
virtual size_t hashCode();
virtual size_t size();
virtual bool isEmpty();
virtual void clear();
virtual bool isReadonly();
virtual void setReadonly(bool readonly);
virtual std::string toString();
protected:
/// 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;
virtual size_t getHash(ATNConfig *c); // Hash differs depending on set type.
private:
size_t _cachedHashCode;
/// All configs but hashed by (s, i, _, pi) not including context. Wiped out
/// when we go readonly as this set becomes a DFA state.
std::unordered_map<size_t, ATNConfig *> _configLookup;
void InitializeInstanceFields();
};
} // namespace atn
} // namespace antlr4
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