forked from jasder/antlr
Improved support for enums
This commit is contained in:
Sam Harwell
parent
45ab2eb70a
commit
0572a1cd9d
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@ -70,6 +70,7 @@
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<Compile Include="Atn\PredicateTransition.cs" />
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<Compile Include="Atn\PredictionContext.cs" />
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<Compile Include="Atn\PredictionContextCache.cs" />
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<Compile Include="Atn\PredictionMode.cs" />
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<Compile Include="Atn\RangeTransition.cs" />
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<Compile Include="Atn\RuleStartState.cs" />
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<Compile Include="Atn\RuleStopState.cs" />
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@ -0,0 +1,911 @@
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/*
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* [The "BSD license"]
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* Copyright (c) 2013 Terence Parr
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* Copyright (c) 2013 Sam Harwell
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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using System.Collections;
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using System.Collections.Generic;
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using Antlr4.Runtime.Atn;
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using Antlr4.Runtime.Misc;
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using Sharpen;
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namespace Antlr4.Runtime.Atn
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{
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[System.Serializable]
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public sealed class PredictionMode
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{
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/// <summary>
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/// Do only local context prediction (SLL style) and using
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/// heuristic which almost always works but is much faster
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/// than precise answer.
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/// </summary>
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/// <remarks>
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/// Do only local context prediction (SLL style) and using
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/// heuristic which almost always works but is much faster
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/// than precise answer.
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/// </remarks>
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internal static readonly PredictionMode Sll = new PredictionMode();
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/// <summary>Full LL(*) that always gets right answer.</summary>
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/// <remarks>
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/// Full LL(*) that always gets right answer. For speed
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/// reasons, we terminate the prediction process when we know for
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/// sure which alt to predict. We don't always know what
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/// the ambiguity is in this mode.
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/// </remarks>
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internal static readonly PredictionMode Ll = new PredictionMode();
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/// <summary>
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/// Tell the full LL prediction algorithm to pursue lookahead until
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/// it has uniquely predicted an alternative without conflict or it's
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/// certain that it's found an ambiguous input sequence.
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/// </summary>
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/// <remarks>
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/// Tell the full LL prediction algorithm to pursue lookahead until
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/// it has uniquely predicted an alternative without conflict or it's
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/// certain that it's found an ambiguous input sequence. when this
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/// variable is false. When true, the prediction process will
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/// continue looking for the exact ambiguous sequence even if
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/// it has already figured out which alternative to predict.
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/// </remarks>
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internal static readonly PredictionMode LlExactAmbigDetection = new PredictionMode
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();
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/// <summary>A Map that uses just the state and the stack context as the key.</summary>
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/// <remarks>A Map that uses just the state and the stack context as the key.</remarks>
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internal class AltAndContextMap : FlexibleHashMap<ATNConfig, BitArray>
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{
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public AltAndContextMap() : base(PredictionMode.AltAndContextConfigEqualityComparator
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.Instance)
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{
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}
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}
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private sealed class AltAndContextConfigEqualityComparator : AbstractEqualityComparator
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<ATNConfig>
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{
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public static readonly PredictionMode.AltAndContextConfigEqualityComparator Instance
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= new PredictionMode.AltAndContextConfigEqualityComparator();
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public AltAndContextConfigEqualityComparator()
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{
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}
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/// <summary>Code is function of (s, _, ctx, _)</summary>
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public override int HashCode(ATNConfig o)
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{
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int hashCode = 7;
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hashCode = 31 * hashCode + o.GetState().stateNumber;
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hashCode = 31 * hashCode + o.GetContext().GetHashCode();
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return hashCode;
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}
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public override bool Equals(ATNConfig a, ATNConfig b)
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{
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if (a == b)
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{
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return true;
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}
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if (a == null || b == null)
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{
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return false;
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}
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if (HashCode(a) != HashCode(b))
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{
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return false;
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}
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return a.GetState().stateNumber == b.GetState().stateNumber && a.GetContext().Equals
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(b.GetContext());
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}
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}
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/// <summary>Computes the SLL prediction termination condition.</summary>
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/// <remarks>
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/// Computes the SLL prediction termination condition.
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/// <p/>
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/// This method computes the SLL prediction termination condition for both of
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/// the following cases.
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/// <ul>
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/// <li>The usual SLL+LL fallback upon SLL conflict</li>
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/// <li>Pure SLL without LL fallback</li>
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/// </ul>
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/// <p/>
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/// <strong>COMBINED SLL+LL PARSING</strong>
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/// <p/>
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/// When LL-fallback is enabled upon SLL conflict, correct predictions are
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/// ensured regardless of how the termination condition is computed by this
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/// method. Due to the substantially higher cost of LL prediction, the
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/// prediction should only fall back to LL when the additional lookahead
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/// cannot lead to a unique SLL prediction.
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/// <p/>
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/// Assuming combined SLL+LL parsing, an SLL configuration set with only
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/// conflicting subsets should fall back to full LL, even if the
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/// configuration sets don't resolve to the same alternative (e.g.
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/// <code></code>
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///
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/// 1,2}} and
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/// <code></code>
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///
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/// 3,4}}. If there is at least one non-conflicting
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/// configuration, SLL could continue with the hopes that more lookahead will
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/// resolve via one of those non-conflicting configurations.
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/// <p/>
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/// Here's the prediction termination rule them: SLL (for SLL+LL parsing)
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/// stops when it sees only conflicting configuration subsets. In contrast,
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/// full LL keeps going when there is uncertainty.
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/// <p/>
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/// <strong>HEURISTIC</strong>
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/// <p/>
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/// As a heuristic, we stop prediction when we see any conflicting subset
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/// unless we see a state that only has one alternative associated with it.
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/// The single-alt-state thing lets prediction continue upon rules like
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/// (otherwise, it would admit defeat too soon):
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/// <p/>
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/// <code>[12|1|[], 6|2|[], 12|2|[]]. s : (ID | ID ID?) ';' ;</code>
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/// <p/>
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/// When the ATN simulation reaches the state before
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/// <code>';'</code>
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/// , it has a
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/// DFA state that looks like:
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/// <code>[12|1|[], 6|2|[], 12|2|[]]</code>
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/// . Naturally
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/// <code>12|1|[]</code>
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/// and
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/// <code>12|2|[]</code>
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/// conflict, but we cannot stop
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/// processing this node because alternative to has another way to continue,
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/// via
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/// <code>[6|2|[]]</code>
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/// .
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/// <p/>
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/// It also let's us continue for this rule:
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/// <p/>
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/// <code>[1|1|[], 1|2|[], 8|3|[]] a : A | A | A B ;</code>
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/// <p/>
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/// After matching input A, we reach the stop state for rule A, state 1.
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/// State 8 is the state right before B. Clearly alternatives 1 and 2
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/// conflict and no amount of further lookahead will separate the two.
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/// However, alternative 3 will be able to continue and so we do not stop
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/// working on this state. In the previous example, we're concerned with
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/// states associated with the conflicting alternatives. Here alt 3 is not
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/// associated with the conflicting configs, but since we can continue
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/// looking for input reasonably, don't declare the state done.
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/// <p/>
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/// <strong>PURE SLL PARSING</strong>
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/// <p/>
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/// To handle pure SLL parsing, all we have to do is make sure that we
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/// combine stack contexts for configurations that differ only by semantic
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/// predicate. From there, we can do the usual SLL termination heuristic.
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/// <p/>
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/// <strong>PREDICATES IN SLL+LL PARSING</strong>
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/// <p/>
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/// SLL decisions don't evaluate predicates until after they reach DFA stop
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/// states because they need to create the DFA cache that works in all
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/// semantic situations. In contrast, full LL evaluates predicates collected
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/// during start state computation so it can ignore predicates thereafter.
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/// This means that SLL termination detection can totally ignore semantic
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/// predicates.
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/// <p/>
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/// Implementation-wise,
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/// <see cref="ATNConfigSet">ATNConfigSet</see>
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/// combines stack contexts but not
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/// semantic predicate contexts so we might see two configurations like the
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/// following.
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/// <p/>
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/// <code></code>
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/// (s, 1, x,
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/// ), (s, 1, x', {p})}
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/// <p/>
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/// Before testing these configurations against others, we have to merge
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/// <code>x</code>
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/// and
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/// <code>x'</code>
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/// (without modifying the existing configurations).
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/// For example, we test
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/// <code>(x+x')==x''</code>
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/// when looking for conflicts in
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/// the following configurations.
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/// <p/>
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/// <code></code>
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/// (s, 1, x,
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/// ), (s, 1, x', {p}), (s, 2, x'', {})}
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/// <p/>
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/// If the configuration set has predicates (as indicated by
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/// <see cref="ATNConfigSet.HasSemanticContext()">ATNConfigSet.HasSemanticContext()</see>
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/// ), this algorithm makes a copy of
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/// the configurations to strip out all of the predicates so that a standard
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/// <see cref="ATNConfigSet">ATNConfigSet</see>
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/// will merge everything ignoring predicates.
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/// </remarks>
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public static bool HasSLLConflictTerminatingPrediction(PredictionMode mode, ATNConfigSet
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configs)
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{
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if (AllConfigsInRuleStopStates(configs))
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{
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return true;
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}
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// pure SLL mode parsing
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if (mode == PredictionMode.Sll)
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{
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// Don't bother with combining configs from different semantic
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// contexts if we can fail over to full LL; costs more time
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// since we'll often fail over anyway.
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if (configs.HasSemanticContext())
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{
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// dup configs, tossing out semantic predicates
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ATNConfigSet dup = new ATNConfigSet();
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foreach (ATNConfig c in configs)
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{
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c = c.Transform(c.GetState(), SemanticContext.None);
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dup.AddItem(c);
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}
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configs = dup;
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}
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}
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// now we have combined contexts for configs with dissimilar preds
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// pure SLL or combined SLL+LL mode parsing
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ICollection<BitArray> altsets = GetConflictingAltSubsets(configs);
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bool heuristic = HasConflictingAltSet(altsets) && !HasStateAssociatedWithOneAlt(configs
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);
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return heuristic;
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}
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/// <summary>
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/// Checks if any configuration in
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/// <code>configs</code>
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/// is in a
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/// <see cref="RuleStopState">RuleStopState</see>
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/// . Configurations meeting this condition have reached
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/// the end of the decision rule (local context) or end of start rule (full
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/// context).
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/// </summary>
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/// <param name="configs">the configuration set to test</param>
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/// <returns>
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///
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/// <code>true</code>
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/// if any configuration in
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/// <code>configs</code>
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/// is in a
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/// <see cref="RuleStopState">RuleStopState</see>
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/// , otherwise
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/// <code>false</code>
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/// </returns>
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public static bool HasConfigInRuleStopState(ATNConfigSet configs)
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{
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foreach (ATNConfig c in configs)
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{
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if (c.GetState() is RuleStopState)
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{
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return true;
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}
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}
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return false;
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}
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/// <summary>
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/// Checks if all configurations in
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/// <code>configs</code>
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/// are in a
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/// <see cref="RuleStopState">RuleStopState</see>
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/// . Configurations meeting this condition have reached
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/// the end of the decision rule (local context) or end of start rule (full
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/// context).
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/// </summary>
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/// <param name="configs">the configuration set to test</param>
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/// <returns>
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///
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/// <code>true</code>
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/// if all configurations in
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/// <code>configs</code>
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/// are in a
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/// <see cref="RuleStopState">RuleStopState</see>
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/// , otherwise
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/// <code>false</code>
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/// </returns>
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public static bool AllConfigsInRuleStopStates(ATNConfigSet configs)
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{
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foreach (ATNConfig config in configs)
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{
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if (!(config.GetState() is RuleStopState))
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{
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return false;
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}
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}
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return true;
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}
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/// <summary>Full LL prediction termination.</summary>
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/// <remarks>
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/// Full LL prediction termination.
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/// <p/>
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/// Can we stop looking ahead during ATN simulation or is there some
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/// uncertainty as to which alternative we will ultimately pick, after
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/// consuming more input? Even if there are partial conflicts, we might know
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/// that everything is going to resolve to the same minimum alternative. That
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/// means we can stop since no more lookahead will change that fact. On the
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/// other hand, there might be multiple conflicts that resolve to different
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/// minimums. That means we need more look ahead to decide which of those
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/// alternatives we should predict.
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/// <p/>
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/// The basic idea is to split the set of configurations
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/// <code>C</code>
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/// , into
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/// conflicting subsets
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/// <code>(s, _, ctx, _)</code>
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/// and singleton subsets with
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/// non-conflicting configurations. Two configurations conflict if they have
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/// identical
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/// <see cref="ATNConfig#state">ATNConfig#state</see>
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/// and
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/// <see cref="ATNConfig#context">ATNConfig#context</see>
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/// values
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/// but different
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/// <see cref="ATNConfig.GetAlt()">ATNConfig.GetAlt()</see>
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/// value, e.g.
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/// <code>(s, i, ctx, _)</code>
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/// and
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/// <code>(s, j, ctx, _)</code>
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/// for
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/// <code>i!=j</code>
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/// .
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/// <p/>
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/// Reduce these configuration subsets to the set of possible alternatives.
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/// You can compute the alternative subsets in one pass as follows:
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/// <p/>
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/// <code></code>
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/// A_s,ctx =
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/// i | (s, i, ctx, _)}} for each configuration in
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/// <code>C</code>
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/// holding
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/// <code>s</code>
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/// and
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/// <code>ctx</code>
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/// fixed.
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/// <p/>
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/// Or in pseudo-code, for each configuration
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/// <code>c</code>
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/// in
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/// <code>C</code>
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/// :
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/// <pre>
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/// map[c] U= c.
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/// <see cref="ATNConfig.GetAlt()">getAlt()</see>
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/// # map hash/equals uses s and x, not
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/// alt and not pred
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/// </pre>
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/// <p/>
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/// The values in
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/// <code>map</code>
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/// are the set of
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/// <code>A_s,ctx</code>
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/// sets.
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/// <p/>
|
||||
/// If
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/// <code>|A_s,ctx|=1</code>
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/// then there is no conflict associated with
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/// <code>s</code>
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/// and
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/// <code>ctx</code>
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/// .
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/// <p/>
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/// Reduce the subsets to singletons by choosing a minimum of each subset. If
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/// the union of these alternative subsets is a singleton, then no amount of
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/// more lookahead will help us. We will always pick that alternative. If,
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/// however, there is more than one alternative, then we are uncertain which
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/// alternative to predict and must continue looking for resolution. We may
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/// or may not discover an ambiguity in the future, even if there are no
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/// conflicting subsets this round.
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/// <p/>
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/// The biggest sin is to terminate early because it means we've made a
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/// decision but were uncertain as to the eventual outcome. We haven't used
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/// enough lookahead. On the other hand, announcing a conflict too late is no
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/// big deal; you will still have the conflict. It's just inefficient. It
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/// might even look until the end of file.
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/// <p/>
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/// No special consideration for semantic predicates is required because
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/// predicates are evaluated on-the-fly for full LL prediction, ensuring that
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||||
/// no configuration contains a semantic context during the termination
|
||||
/// check.
|
||||
/// <p/>
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/// <strong>CONFLICTING CONFIGS</strong>
|
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/// <p/>
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/// Two configurations
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/// <code>(s, i, x)</code>
|
||||
/// and
|
||||
/// <code>(s, j, x')</code>
|
||||
/// , conflict
|
||||
/// when
|
||||
/// <code>i!=j</code>
|
||||
/// but
|
||||
/// <code>x=x'</code>
|
||||
/// . Because we merge all
|
||||
/// <code>(s, i, _)</code>
|
||||
/// configurations together, that means that there are at
|
||||
/// most
|
||||
/// <code>n</code>
|
||||
/// configurations associated with state
|
||||
/// <code>s</code>
|
||||
/// for
|
||||
/// <code>n</code>
|
||||
/// possible alternatives in the decision. The merged stacks
|
||||
/// complicate the comparison of configuration contexts
|
||||
/// <code>x</code>
|
||||
/// and
|
||||
/// <code>x'</code>
|
||||
/// . Sam checks to see if one is a subset of the other by calling
|
||||
/// merge and checking to see if the merged result is either
|
||||
/// <code>x</code>
|
||||
/// or
|
||||
/// <code>x'</code>
|
||||
/// . If the
|
||||
/// <code>x</code>
|
||||
/// associated with lowest alternative
|
||||
/// <code>i</code>
|
||||
/// is the superset, then
|
||||
/// <code>i</code>
|
||||
/// is the only possible prediction since the
|
||||
/// others resolve to
|
||||
/// <code>min(i)</code>
|
||||
/// as well. However, if
|
||||
/// <code>x</code>
|
||||
/// is
|
||||
/// associated with
|
||||
/// <code>j>i</code>
|
||||
/// then at least one stack configuration for
|
||||
/// <code>j</code>
|
||||
/// is not in conflict with alternative
|
||||
/// <code>i</code>
|
||||
/// . The algorithm
|
||||
/// should keep going, looking for more lookahead due to the uncertainty.
|
||||
/// <p/>
|
||||
/// For simplicity, I'm doing a equality check between
|
||||
/// <code>x</code>
|
||||
/// and
|
||||
/// <code>x'</code>
|
||||
/// that lets the algorithm continue to consume lookahead longer
|
||||
/// than necessary. The reason I like the equality is of course the
|
||||
/// simplicity but also because that is the test you need to detect the
|
||||
/// alternatives that are actually in conflict.
|
||||
/// <p/>
|
||||
/// <strong>CONTINUE/STOP RULE</strong>
|
||||
/// <p/>
|
||||
/// Continue if union of resolved alternative sets from non-conflicting and
|
||||
/// conflicting alternative subsets has more than one alternative. We are
|
||||
/// uncertain about which alternative to predict.
|
||||
/// <p/>
|
||||
/// The complete set of alternatives,
|
||||
/// <code>[i for (_,i,_)]</code>
|
||||
/// , tells us which
|
||||
/// alternatives are still in the running for the amount of input we've
|
||||
/// consumed at this point. The conflicting sets let us to strip away
|
||||
/// configurations that won't lead to more states because we resolve
|
||||
/// conflicts to the configuration with a minimum alternate for the
|
||||
/// conflicting set.
|
||||
/// <p/>
|
||||
/// <strong>CASES</strong>
|
||||
/// <ul>
|
||||
/// <li>no conflicts and more than 1 alternative in set => continue</li>
|
||||
/// <li>
|
||||
/// <code>(s, 1, x)</code>
|
||||
/// ,
|
||||
/// <code>(s, 2, x)</code>
|
||||
/// ,
|
||||
/// <code>(s, 3, z)</code>
|
||||
/// ,
|
||||
/// <code>(s', 1, y)</code>
|
||||
/// ,
|
||||
/// <code>(s', 2, y)</code>
|
||||
/// yields non-conflicting set
|
||||
/// <code></code>
|
||||
///
|
||||
/// 3}} U conflicting sets
|
||||
/// <code></code>
|
||||
/// min(
|
||||
/// 1,2})} U
|
||||
/// <code></code>
|
||||
/// min(
|
||||
/// 1,2})} =
|
||||
/// <code></code>
|
||||
///
|
||||
/// 1,3}} => continue
|
||||
/// </li>
|
||||
/// <li>
|
||||
/// <code>(s, 1, x)</code>
|
||||
/// ,
|
||||
/// <code>(s, 2, x)</code>
|
||||
/// ,
|
||||
/// <code>(s', 1, y)</code>
|
||||
/// ,
|
||||
/// <code>(s', 2, y)</code>
|
||||
/// ,
|
||||
/// <code>(s'', 1, z)</code>
|
||||
/// yields non-conflicting set
|
||||
/// <code></code>
|
||||
///
|
||||
/// 1}} U conflicting sets
|
||||
/// <code></code>
|
||||
/// min(
|
||||
/// 1,2})} U
|
||||
/// <code></code>
|
||||
/// min(
|
||||
/// 1,2})} =
|
||||
/// <code></code>
|
||||
///
|
||||
/// 1}} => stop and predict 1</li>
|
||||
/// <li>
|
||||
/// <code>(s, 1, x)</code>
|
||||
/// ,
|
||||
/// <code>(s, 2, x)</code>
|
||||
/// ,
|
||||
/// <code>(s', 1, y)</code>
|
||||
/// ,
|
||||
/// <code>(s', 2, y)</code>
|
||||
/// yields conflicting, reduced sets
|
||||
/// <code></code>
|
||||
///
|
||||
/// 1}} U
|
||||
/// <code></code>
|
||||
///
|
||||
/// 1}} =
|
||||
/// <code></code>
|
||||
///
|
||||
/// 1}} => stop and predict 1, can announce
|
||||
/// ambiguity
|
||||
/// <code></code>
|
||||
///
|
||||
/// 1,2}}</li>
|
||||
/// <li>
|
||||
/// <code>(s, 1, x)</code>
|
||||
/// ,
|
||||
/// <code>(s, 2, x)</code>
|
||||
/// ,
|
||||
/// <code>(s', 2, y)</code>
|
||||
/// ,
|
||||
/// <code>(s', 3, y)</code>
|
||||
/// yields conflicting, reduced sets
|
||||
/// <code></code>
|
||||
///
|
||||
/// 1}} U
|
||||
/// <code></code>
|
||||
///
|
||||
/// 2}} =
|
||||
/// <code></code>
|
||||
///
|
||||
/// 1,2}} => continue</li>
|
||||
/// <li>
|
||||
/// <code>(s, 1, x)</code>
|
||||
/// ,
|
||||
/// <code>(s, 2, x)</code>
|
||||
/// ,
|
||||
/// <code>(s', 3, y)</code>
|
||||
/// ,
|
||||
/// <code>(s', 4, y)</code>
|
||||
/// yields conflicting, reduced sets
|
||||
/// <code></code>
|
||||
///
|
||||
/// 1}} U
|
||||
/// <code></code>
|
||||
///
|
||||
/// 3}} =
|
||||
/// <code></code>
|
||||
///
|
||||
/// 1,3}} => continue</li>
|
||||
/// </ul>
|
||||
/// <strong>EXACT AMBIGUITY DETECTION</strong>
|
||||
/// <p/>
|
||||
/// If all states report the same conflicting set of alternatives, then we
|
||||
/// know we have the exact ambiguity set.
|
||||
/// <p/>
|
||||
/// <code>|A_<em>i</em>|>1</code> and
|
||||
/// <code>A_<em>i</em> = A_<em>j</em></code> for all <em>i</em>, <em>j</em>.
|
||||
/// <p/>
|
||||
/// In other words, we continue examining lookahead until all
|
||||
/// <code>A_i</code>
|
||||
/// have more than one alternative and all
|
||||
/// <code>A_i</code>
|
||||
/// are the same. If
|
||||
/// <code></code>
|
||||
/// A=
|
||||
/// {1,2}, {1,3}}}, then regular LL prediction would terminate
|
||||
/// because the resolved set is
|
||||
/// <code></code>
|
||||
///
|
||||
/// 1}}. To determine what the real
|
||||
/// ambiguity is, we have to know whether the ambiguity is between one and
|
||||
/// two or one and three so we keep going. We can only stop prediction when
|
||||
/// we need exact ambiguity detection when the sets look like
|
||||
/// <code></code>
|
||||
/// A=
|
||||
/// {1,2}}} or
|
||||
/// <code></code>
|
||||
///
|
||||
/// {1,2},{1,2}}}, etc...
|
||||
/// </remarks>
|
||||
public static int ResolvesToJustOneViableAlt(ICollection<BitArray> altsets)
|
||||
{
|
||||
return GetSingleViableAlt(altsets);
|
||||
}
|
||||
|
||||
/// <summary>
|
||||
/// Determines if every alternative subset in
|
||||
/// <code>altsets</code>
|
||||
/// contains more
|
||||
/// than one alternative.
|
||||
/// </summary>
|
||||
/// <param name="altsets">a collection of alternative subsets</param>
|
||||
/// <returns>
|
||||
///
|
||||
/// <code>true</code>
|
||||
/// if every
|
||||
/// <see cref="System.Collections.BitArray">System.Collections.BitArray</see>
|
||||
/// in
|
||||
/// <code>altsets</code>
|
||||
/// has
|
||||
/// <see cref="System.Collections.BitArray.Cardinality()">cardinality</see>
|
||||
/// > 1, otherwise
|
||||
/// <code>false</code>
|
||||
/// </returns>
|
||||
public static bool AllSubsetsConflict(ICollection<BitArray> altsets)
|
||||
{
|
||||
return !HasNonConflictingAltSet(altsets);
|
||||
}
|
||||
|
||||
/// <summary>
|
||||
/// Determines if any single alternative subset in
|
||||
/// <code>altsets</code>
|
||||
/// contains
|
||||
/// exactly one alternative.
|
||||
/// </summary>
|
||||
/// <param name="altsets">a collection of alternative subsets</param>
|
||||
/// <returns>
|
||||
///
|
||||
/// <code>true</code>
|
||||
/// if
|
||||
/// <code>altsets</code>
|
||||
/// contains a
|
||||
/// <see cref="System.Collections.BitArray">System.Collections.BitArray</see>
|
||||
/// with
|
||||
/// <see cref="System.Collections.BitArray.Cardinality()">cardinality</see>
|
||||
/// 1, otherwise
|
||||
/// <code>false</code>
|
||||
/// </returns>
|
||||
public static bool HasNonConflictingAltSet(ICollection<BitArray> altsets)
|
||||
{
|
||||
foreach (BitArray alts in altsets)
|
||||
{
|
||||
if (alts.Cardinality() == 1)
|
||||
{
|
||||
return true;
|
||||
}
|
||||
}
|
||||
return false;
|
||||
}
|
||||
|
||||
/// <summary>
|
||||
/// Determines if any single alternative subset in
|
||||
/// <code>altsets</code>
|
||||
/// contains
|
||||
/// more than one alternative.
|
||||
/// </summary>
|
||||
/// <param name="altsets">a collection of alternative subsets</param>
|
||||
/// <returns>
|
||||
///
|
||||
/// <code>true</code>
|
||||
/// if
|
||||
/// <code>altsets</code>
|
||||
/// contains a
|
||||
/// <see cref="System.Collections.BitArray">System.Collections.BitArray</see>
|
||||
/// with
|
||||
/// <see cref="System.Collections.BitArray.Cardinality()">cardinality</see>
|
||||
/// > 1, otherwise
|
||||
/// <code>false</code>
|
||||
/// </returns>
|
||||
public static bool HasConflictingAltSet(ICollection<BitArray> altsets)
|
||||
{
|
||||
foreach (BitArray alts in altsets)
|
||||
{
|
||||
if (alts.Cardinality() > 1)
|
||||
{
|
||||
return true;
|
||||
}
|
||||
}
|
||||
return false;
|
||||
}
|
||||
|
||||
/// <summary>
|
||||
/// Determines if every alternative subset in
|
||||
/// <code>altsets</code>
|
||||
/// is equivalent.
|
||||
/// </summary>
|
||||
/// <param name="altsets">a collection of alternative subsets</param>
|
||||
/// <returns>
|
||||
///
|
||||
/// <code>true</code>
|
||||
/// if every member of
|
||||
/// <code>altsets</code>
|
||||
/// is equal to the
|
||||
/// others, otherwise
|
||||
/// <code>false</code>
|
||||
/// </returns>
|
||||
public static bool AllSubsetsEqual(ICollection<BitArray> altsets)
|
||||
{
|
||||
IEnumerator<BitArray> it = altsets.GetEnumerator();
|
||||
BitArray first = it.Next();
|
||||
while (it.HasNext())
|
||||
{
|
||||
BitArray next = it.Next();
|
||||
if (!next.Equals(first))
|
||||
{
|
||||
return false;
|
||||
}
|
||||
}
|
||||
return true;
|
||||
}
|
||||
|
||||
/// <summary>
|
||||
/// Returns the unique alternative predicted by all alternative subsets in
|
||||
/// <code>altsets</code>
|
||||
/// . If no such alternative exists, this method returns
|
||||
/// <see cref="ATN.InvalidAltNumber">ATN.InvalidAltNumber</see>
|
||||
/// .
|
||||
/// </summary>
|
||||
/// <param name="altsets">a collection of alternative subsets</param>
|
||||
public static int GetUniqueAlt(ICollection<BitArray> altsets)
|
||||
{
|
||||
BitArray all = GetAlts(altsets);
|
||||
if (all.Cardinality() == 1)
|
||||
{
|
||||
return all.NextSetBit(0);
|
||||
}
|
||||
return ATN.InvalidAltNumber;
|
||||
}
|
||||
|
||||
/// <summary>
|
||||
/// Gets the complete set of represented alternatives for a collection of
|
||||
/// alternative subsets.
|
||||
/// </summary>
|
||||
/// <remarks>
|
||||
/// Gets the complete set of represented alternatives for a collection of
|
||||
/// alternative subsets. This method returns the union of each
|
||||
/// <see cref="System.Collections.BitArray">System.Collections.BitArray</see>
|
||||
/// in
|
||||
/// <code>altsets</code>
|
||||
/// .
|
||||
/// </remarks>
|
||||
/// <param name="altsets">a collection of alternative subsets</param>
|
||||
/// <returns>
|
||||
/// the set of represented alternatives in
|
||||
/// <code>altsets</code>
|
||||
/// </returns>
|
||||
public static BitArray GetAlts(ICollection<BitArray> altsets)
|
||||
{
|
||||
BitArray all = new BitArray();
|
||||
foreach (BitArray alts in altsets)
|
||||
{
|
||||
all.Or(alts);
|
||||
}
|
||||
return all;
|
||||
}
|
||||
|
||||
/// <summary>This function gets the conflicting alt subsets from a configuration set.
|
||||
/// </summary>
|
||||
/// <remarks>
|
||||
/// This function gets the conflicting alt subsets from a configuration set.
|
||||
/// For each configuration
|
||||
/// <code>c</code>
|
||||
/// in
|
||||
/// <code>configs</code>
|
||||
/// :
|
||||
/// <pre>
|
||||
/// map[c] U= c.
|
||||
/// <see cref="ATNConfig.GetAlt()">getAlt()</see>
|
||||
/// # map hash/equals uses s and x, not
|
||||
/// alt and not pred
|
||||
/// </pre>
|
||||
/// </remarks>
|
||||
[NotNull]
|
||||
public static ICollection<BitArray> GetConflictingAltSubsets(ATNConfigSet configs
|
||||
)
|
||||
{
|
||||
PredictionMode.AltAndContextMap configToAlts = new PredictionMode.AltAndContextMap
|
||||
();
|
||||
foreach (ATNConfig c in configs)
|
||||
{
|
||||
BitArray alts = configToAlts.Get(c);
|
||||
if (alts == null)
|
||||
{
|
||||
alts = new BitArray();
|
||||
configToAlts.Put(c, alts);
|
||||
}
|
||||
alts.Set(c.GetAlt());
|
||||
}
|
||||
return configToAlts.Values;
|
||||
}
|
||||
|
||||
/// <summary>Get a map from state to alt subset from a configuration set.</summary>
|
||||
/// <remarks>
|
||||
/// Get a map from state to alt subset from a configuration set. For each
|
||||
/// configuration
|
||||
/// <code>c</code>
|
||||
/// in
|
||||
/// <code>configs</code>
|
||||
/// :
|
||||
/// <pre>
|
||||
/// map[c.
|
||||
/// <see cref="ATNConfig#state">state</see>
|
||||
/// ] U= c.
|
||||
/// <see cref="ATNConfig.GetAlt()">getAlt()</see>
|
||||
/// </pre>
|
||||
/// </remarks>
|
||||
[NotNull]
|
||||
public static IDictionary<ATNState, BitArray> GetStateToAltMap(ATNConfigSet configs
|
||||
)
|
||||
{
|
||||
IDictionary<ATNState, BitArray> m = new Dictionary<ATNState, BitArray>();
|
||||
foreach (ATNConfig c in configs)
|
||||
{
|
||||
BitArray alts = m.Get(c.GetState());
|
||||
if (alts == null)
|
||||
{
|
||||
alts = new BitArray();
|
||||
m.Put(c.GetState(), alts);
|
||||
}
|
||||
alts.Set(c.GetAlt());
|
||||
}
|
||||
return m;
|
||||
}
|
||||
|
||||
public static bool HasStateAssociatedWithOneAlt(ATNConfigSet configs)
|
||||
{
|
||||
IDictionary<ATNState, BitArray> x = GetStateToAltMap(configs);
|
||||
foreach (BitArray alts in x.Values)
|
||||
{
|
||||
if (alts.Cardinality() == 1)
|
||||
{
|
||||
return true;
|
||||
}
|
||||
}
|
||||
return false;
|
||||
}
|
||||
|
||||
public static int GetSingleViableAlt(ICollection<BitArray> altsets)
|
||||
{
|
||||
BitArray viableAlts = new BitArray();
|
||||
foreach (BitArray alts in altsets)
|
||||
{
|
||||
int minAlt = alts.NextSetBit(0);
|
||||
viableAlts.Set(minAlt);
|
||||
if (viableAlts.Cardinality() > 1)
|
||||
{
|
||||
// more than 1 viable alt
|
||||
return ATN.InvalidAltNumber;
|
||||
}
|
||||
}
|
||||
return viableAlts.NextSetBit(0);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
|
@ -1 +1 @@
|
|||
Subproject commit f14a6feaed23300e61e95b09756cd2295c1e2636
|
||||
Subproject commit 60b41b32982f35792e379f71364e61a0db4db658
|
||||
Loading…
Reference in New Issue