add: Grammar builder test with a simple gramma.
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@ -5,7 +5,7 @@ public class GrammarBuilder
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/// <summary>
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/// 指定文法的生成式
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/// </summary>
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public Dictionary<NonTerminator, List<List<TerminatorBase>>> Generators { get; } = [];
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public Dictionary<NonTerminator, List<List<TerminatorBase>>> Generators { get; init; } = [];
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/// <summary>
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/// 文法的起始符
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@ -108,6 +108,7 @@ public class GrammarBuilder
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{
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// 指定表达式开头是终结符
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Terminator terminator = (Terminator)expressionHead;
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result.Add(terminator);
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}
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else
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@ -139,8 +140,18 @@ public class GrammarBuilder
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{
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changed = false;
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// 不能在foreach过程中修改集合
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// 因此需要在遍历完成之后添加
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List<Expression> addedExpressions = [];
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foreach (Expression e in closure)
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{
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if (e.Pos >= e.Right.Count)
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{
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// 已经移进到达句型的末尾
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continue;
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}
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TerminatorBase next = e.Right[e.Pos];
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if (next.IsTerminated)
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@ -169,14 +180,22 @@ public class GrammarBuilder
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Left = nonTerminator, Right = nextExpression, LookAhead = lookAhead
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};
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if (closure.Add(newExpression))
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if (!closure.Contains(newExpression))
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{
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addedExpressions.Add(newExpression);
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}
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}
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}
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}
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foreach (Expression addedExpression in addedExpressions)
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{
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if (closure.Add(addedExpression))
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{
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changed = true;
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}
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}
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}
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}
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}
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return closure;
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}
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@ -197,7 +216,8 @@ public class GrammarBuilder
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bool added = true;
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while (added)
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{
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added = false;
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// 同样不能在foreach期间修改集合
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HashSet<LrState> addedStates = [];
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foreach (LrState state in Automation)
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{
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@ -206,20 +226,19 @@ public class GrammarBuilder
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foreach (Expression e in state.Expressions)
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{
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if (e.Pos >= e.Right.Count)
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{
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// 已经移进到达末尾
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continue;
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}
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TerminatorBase next = e.Right[e.Pos];
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Expression nextExpression = new()
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{
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Left = e.Left, Right = e.Right, LookAhead = e.LookAhead, Pos = e.Pos
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};
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if (nextExpression.Pos >= nextExpression.Right.Count)
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{
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// 移进符号已经到达句型的末尾
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continue;
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}
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nextExpression.Pos += 1;
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TerminatorBase next = nextExpression.Right[nextExpression.Pos];
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if (!nextExpressions.TryAdd(next, [nextExpression]))
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{
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nextExpressions[next].Add(nextExpression);
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@ -241,18 +260,27 @@ public class GrammarBuilder
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if (Automation.TryGetValue(newState, out LrState? oldState))
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{
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// 存在这个项目集闭包
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state.Transformer.Add(pair.Key, oldState);
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state.AddTransform(pair.Key, oldState);
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}
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else
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{
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// 不存在这个项目集闭包
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Automation.Add(newState);
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state.Transformer.Add(pair.Key, newState);
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// 但是需要考虑该状态在addedStates集合中的情况
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if (addedStates.TryGetValue(newState, out LrState? addedState))
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{
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state.AddTransform(pair.Key, addedState);
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}
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else
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{
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state.AddTransform(pair.Key, newState);
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addedStates.Add(newState);
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}
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}
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}
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}
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added = true;
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}
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}
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}
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added = addedStates.Count != 0;
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Automation.UnionWith(addedStates);
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}
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return new Grammar { Begin = Begin, BeginState = beginState };
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@ -16,6 +16,28 @@ public class LrState : IEquatable<LrState>
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/// </summary>
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public Dictionary<TerminatorBase, LrState> Transformer { get; } = [];
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/// <summary>
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/// 向状态中添加一个迁移规则
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/// </summary>
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/// <param name="terminator">迁移的条件</param>
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/// <param name="next">迁移到达的状态</param>
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/// <exception cref="InvalidOperationException">如果在状态中已经存在该迁移规则且迁移到的状态和欲设置的状态不同
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/// 抛出无效操作异常</exception>
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public void AddTransform(TerminatorBase terminator, LrState next)
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{
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if (Transformer.TryGetValue(terminator, out LrState? state))
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{
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if (state != next)
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{
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throw new InvalidOperationException("A terminator transform to two different states");
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}
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}
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else
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{
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Transformer.Add(terminator, next);
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}
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}
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public bool Equals(LrState? other)
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{
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if (other is null)
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110
Canon.Tests/GrammarParserTests/SimpleGrammarTests.cs
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110
Canon.Tests/GrammarParserTests/SimpleGrammarTests.cs
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@ -0,0 +1,110 @@
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using Canon.Core.Enums;
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using Canon.Core.GrammarParser;
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namespace Canon.Tests.GrammarParserTests;
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public class SimpleGrammarTests
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{
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/// <summary>
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/// 用于测试的简单语法
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/// S -> E
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/// E -> E+T | E-T | T
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/// T -> T*F | T/F | F
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/// F -> (E) | n
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/// 为了方便测试指定
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/// E ProgramStruct
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/// T ProgramBody
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/// F StatementList
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/// n Identifier
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/// </summary>
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private static readonly Dictionary<NonTerminator, List<List<TerminatorBase>>> s_simpleGrammar = new()
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{
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{
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new NonTerminator(NonTerminatorType.StartNonTerminator), [
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[new NonTerminator(NonTerminatorType.ProgramStruct)]
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]
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},
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{
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new NonTerminator(NonTerminatorType.ProgramStruct), [
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[
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new NonTerminator(NonTerminatorType.ProgramStruct), new Terminator(OperatorType.Plus),
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new NonTerminator(NonTerminatorType.ProgramBody)
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],
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[
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new NonTerminator(NonTerminatorType.ProgramStruct), new Terminator(OperatorType.Minus),
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new NonTerminator(NonTerminatorType.ProgramBody)
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],
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[new NonTerminator(NonTerminatorType.ProgramBody)]
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]
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},
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{
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new NonTerminator(NonTerminatorType.ProgramBody), [
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[
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new NonTerminator(NonTerminatorType.ProgramBody), new Terminator(OperatorType.Multiply),
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new NonTerminator(NonTerminatorType.StatementList)
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],
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[
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new NonTerminator(NonTerminatorType.ProgramBody), new Terminator(OperatorType.Divide),
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new NonTerminator(NonTerminatorType.StatementList)
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],
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[new NonTerminator(NonTerminatorType.StatementList)]
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]
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},
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{
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new NonTerminator(NonTerminatorType.StatementList), [
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[
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new Terminator(DelimiterType.LeftParenthesis), new NonTerminator(NonTerminatorType.ProgramStruct),
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new Terminator(DelimiterType.RightParenthesis)
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],
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[Terminator.IdentifierTerminator]
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]
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}
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};
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[Fact]
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public void FirstSetTest()
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{
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GrammarBuilder builder = new()
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{
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Generators = s_simpleGrammar, Begin = new NonTerminator(NonTerminatorType.StartNonTerminator)
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};
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builder.Build();
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Assert.Contains(builder.FirstSet, pair =>
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pair.Key == new NonTerminator(NonTerminatorType.StartNonTerminator));
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Assert.Contains(builder.FirstSet, pair =>
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pair.Key == new NonTerminator(NonTerminatorType.ProgramStruct));
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Assert.Contains(builder.FirstSet, pair =>
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pair.Key == new NonTerminator(NonTerminatorType.ProgramBody));
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Assert.Contains(builder.FirstSet, pair =>
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pair.Key == new NonTerminator(NonTerminatorType.StatementList));
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foreach (HashSet<Terminator> terminators in builder.FirstSet.Values)
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{
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Assert.Contains(Terminator.IdentifierTerminator, terminators);
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Assert.Contains(new Terminator(DelimiterType.LeftParenthesis), terminators);
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}
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}
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[Fact]
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public void StatsTest()
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{
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GrammarBuilder builder = new()
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{
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Generators = s_simpleGrammar, Begin = new NonTerminator(NonTerminatorType.StartNonTerminator)
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};
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Grammar grammar = builder.Build();
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Assert.Equal(30, builder.Automation.Count);
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// 来自Ichirinko不辞辛劳的手算
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Assert.Contains(new NonTerminator(NonTerminatorType.ProgramStruct), grammar.BeginState.Transformer.Keys);
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Assert.Contains(new NonTerminator(NonTerminatorType.ProgramBody), grammar.BeginState.Transformer.Keys);
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Assert.Contains(new NonTerminator(NonTerminatorType.StatementList),
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grammar.BeginState.Transformer.Keys);
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Assert.Contains(new Terminator(DelimiterType.LeftParenthesis), grammar.BeginState.Transformer.Keys);
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Assert.Contains(Terminator.IdentifierTerminator, grammar.BeginState.Transformer.Keys);
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}
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}
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