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using System.Linq;
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using Implab.Automaton.RegularExpressions;
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using System;
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using Implab.Automaton;
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namespace Implab.Formats.JSON {
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class JSONGrammar : Grammar<char,JSONGrammar.TokenType> {
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public enum TokenType {
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None,
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BeginObject,
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EndObject,
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BeginArray,
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EndArray,
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String,
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Number,
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Literal,
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NameSeparator,
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ValueSeparator,
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StringBound,
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EscapedChar,
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UnescapedChar,
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EscapedUnicode
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}
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static Lazy<JSONGrammar> _instance = new Lazy<JSONGrammar>();
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public static JSONGrammar Instance {
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get { return _instance.Value; }
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}
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readonly ScannerContext<TokenType> m_jsonDFA;
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readonly ScannerContext<TokenType> m_stringDFA;
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public JSONGrammar() {
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DefineAlphabet(Enumerable.Range(0, 0x20).Select(x => (char)x));
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var hexDigit = SymbolRangeToken('a','f').Or(SymbolRangeToken('A','F')).Or(SymbolRangeToken('0','9'));
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var digit9 = SymbolRangeToken('1', '9');
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var zero = SymbolToken('0');
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var digit = zero.Or(digit9);
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var dot = SymbolToken('.');
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var minus = SymbolToken('-');
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var sign = SymbolSetToken('-', '+');
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var expSign = SymbolSetToken('e', 'E');
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var letters = SymbolRangeToken('a', 'z');
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var integer = zero.Or(digit9.Cat(digit.EClosure()));
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var frac = dot.Cat(digit.Closure());
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var exp = expSign.Cat(sign.Optional()).Cat(digit.Closure());
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var quote = SymbolToken('"');
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var backSlash = SymbolToken('\\');
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var specialEscapeChars = SymbolSetToken('\\', '"', '/', 'b', 'f', 't', 'n', 'r');
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var unicodeEspace = SymbolToken('u').Cat(hexDigit.Repeat(4));
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var whitespace = SymbolSetToken('\n', '\r', '\t', ' ').EClosure();
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var beginObject = whitespace.Cat(SymbolToken('{')).Cat(whitespace);
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var endObject = whitespace.Cat(SymbolToken('}')).Cat(whitespace);
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var beginArray = whitespace.Cat(SymbolToken('[')).Cat(whitespace);
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var endArray = whitespace.Cat(SymbolToken(']')).Cat(whitespace);
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var nameSep = whitespace.Cat(SymbolToken(':')).Cat(whitespace);
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var valueSep = whitespace.Cat(SymbolToken(',')).Cat(whitespace);
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var number = minus.Optional().Cat(integer).Cat(frac.Optional()).Cat(exp.Optional());
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var literal = letters.Closure();
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var unescaped = SymbolTokenExcept(Enumerable.Range(0, 0x20).Union(new int[] { '\\', '"' }).Select(x => (char)x));
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var jsonExpression =
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number.Tag(TokenType.Number)
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.Or(literal.Tag(TokenType.Literal))
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.Or(quote.Tag(TokenType.StringBound))
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.Or(beginObject.Tag(TokenType.BeginObject))
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.Or(endObject.Tag(TokenType.EndObject))
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.Or(beginArray.Tag(TokenType.BeginArray))
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.Or(endArray.Tag(TokenType.EndArray))
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.Or(nameSep.Tag(TokenType.NameSeparator))
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.Or(valueSep.Tag(TokenType.ValueSeparator));
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var jsonStringExpression =
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quote.Tag(TokenType.StringBound)
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.Or(backSlash.Cat(specialEscapeChars).Tag(TokenType.EscapedChar))
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.Or(backSlash.Cat(unicodeEspace).Tag(TokenType.EscapedUnicode))
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.Or(unescaped.Closure().Tag(TokenType.UnescapedChar));
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m_jsonDFA = BuildScannerContext(jsonExpression);
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m_stringDFA = BuildScannerContext(jsonStringExpression);
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}
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public ScannerContext<TokenType> JsonDFA {
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get {
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return m_jsonDFA;
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}
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}
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public ScannerContext<TokenType> JsonStringDFA {
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get {
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return m_stringDFA;
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}
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}
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Token<TokenType> SymbolRangeToken(char start, char stop) {
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return SymbolToken(Enumerable.Range(start,stop - start).Cast<char>());
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}
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protected override IAlphabetBuilder<char> CreateAlphabet() {
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return new CharAlphabet();
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}
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}
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}
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