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using Implab;
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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Threading.Tasks;
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namespace Implab.Parsing {
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/// <summary>
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/// Базовый абстрактный класс. Грамматика, позволяет формулировать выражения над алфавитом типа <c>char</c>.
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/// </summary>
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/// <typeparam name="TGrammar"></typeparam>
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public abstract class Grammar<TGrammar> where TGrammar: Grammar<TGrammar>, new() {
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Alphabet m_alphabet = new Alphabet();
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static TGrammar _instance;
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public static TGrammar Instance{
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get {
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if (_instance == null)
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_instance = new TGrammar();
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return _instance;
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}
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}
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public SymbolToken UnclassifiedToken() {
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return new SymbolToken(Alphabet.UNCLASSIFIED);
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}
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public void DefineAlphabet(IEnumerable<char> alphabet) {
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Safe.ArgumentNotNull(alphabet, "alphabet");
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foreach (var ch in alphabet)
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m_alphabet.DefineSymbol(ch);
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}
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public Token SymbolRangeToken(char start, char end) {
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return SymbolToken(Enumerable.Range(start, end - start + 1).Select(x => (char)x));
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}
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public Token SymbolToken(char symbol) {
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return Token.New(TranslateOrAdd(symbol));
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}
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public Token SymbolToken(IEnumerable<char> symbols) {
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Safe.ArgumentNotNull(symbols, "symbols");
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return Token.New(TranslateOrAdd(symbols).ToArray());
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}
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public Token SymbolSetToken(params char[] set) {
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return SymbolToken(set);
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}
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int TranslateOrAdd(char ch) {
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var t = m_alphabet.Translate(ch);
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if (t == Alphabet.UNCLASSIFIED)
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t = m_alphabet.DefineSymbol(ch);
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return t;
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}
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IEnumerable<int> TranslateOrAdd(IEnumerable<char> symbols) {
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return symbols.Distinct().Select(TranslateOrAdd);
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}
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int TranslateOrDie(char ch) {
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var t = m_alphabet.Translate(ch);
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if (t == Alphabet.UNCLASSIFIED)
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throw new ApplicationException(String.Format("Symbol '{0}' is UNCLASSIFIED", ch));
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return t;
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}
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IEnumerable<int> TranslateOrDie(IEnumerable<char> symbols) {
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return symbols.Distinct().Select(TranslateOrDie);
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}
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public Token SymbolTokenExcept(IEnumerable<char> symbols) {
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Safe.ArgumentNotNull(symbols, "symbols");
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return Token.New( Enumerable.Range(0, m_alphabet.Count).Except(TranslateOrDie(symbols)).ToArray());
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}
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protected CDFADefinition BuildDFA(Token lang) {
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Safe.ArgumentNotNull(lang, "lang");
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var dfa = new CDFADefinition(m_alphabet);
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var builder = new DFABuilder();
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lang.Accept( builder );
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builder.BuildDFA(dfa);
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if (dfa.InitialStateIsFinal)
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throw new ApplicationException("The specified language contains empty token");
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return dfa.Optimize();
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}
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//protected abstract TGrammar CreateInstance();
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}
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}
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