##// END OF EJS Templates
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JSONGrammar.cs
121 lines | 4.8 KiB | text/x-csharp | CSharpLexer
using System.Linq;
using Implab.Automaton.RegularExpressions;
using System;
using Implab.Automaton;
using Implab.Components;
namespace Implab.Formats.JSON {
class JSONGrammar : Grammar<char> {
public enum TokenType {
None,
BeginObject,
EndObject,
BeginArray,
EndArray,
String,
Number,
Literal,
NameSeparator,
ValueSeparator,
Whitespace,
StringBound,
EscapedChar,
UnescapedChar,
EscapedUnicode
}
static LazyAndWeak<JSONGrammar> _instance = new LazyAndWeak<JSONGrammar>(() => new JSONGrammar());
public static JSONGrammar Instance {
get { return _instance.Value; }
}
readonly ScannerContext<TokenType> m_jsonExpression;
readonly ScannerContext<TokenType> m_stringExpression;
readonly CharAlphabet m_defaultAlphabet = new CharAlphabet();
public JSONGrammar() {
DefineAlphabet(Enumerable.Range(0, 0x20).Select(x => (char)x));
var hexDigit = SymbolRangeToken('a','f').Or(SymbolRangeToken('A','F')).Or(SymbolRangeToken('0','9'));
var digit9 = SymbolRangeToken('1', '9');
var zero = SymbolToken('0');
var digit = zero.Or(digit9);
var dot = SymbolToken('.');
var minus = SymbolToken('-');
var sign = SymbolSetToken('-', '+');
var expSign = SymbolSetToken('e', 'E');
var letters = SymbolRangeToken('a', 'z');
var integer = zero.Or(digit9.Cat(digit.EClosure()));
var frac = dot.Cat(digit.Closure());
var exp = expSign.Cat(sign.Optional()).Cat(digit.Closure());
var quote = SymbolToken('"');
var backSlash = SymbolToken('\\');
var specialEscapeChars = SymbolSetToken('\\', '"', '/', 'b', 'f', 't', 'n', 'r');
var unicodeEspace = SymbolToken('u').Cat(hexDigit.Repeat(4));
var whitespace = SymbolSetToken('\n', '\r', '\t', ' ').EClosure();
var beginObject = whitespace.Cat(SymbolToken('{')).Cat(whitespace);
var endObject = whitespace.Cat(SymbolToken('}')).Cat(whitespace);
var beginArray = whitespace.Cat(SymbolToken('[')).Cat(whitespace);
var endArray = whitespace.Cat(SymbolToken(']')).Cat(whitespace);
var nameSep = whitespace.Cat(SymbolToken(':')).Cat(whitespace);
var valueSep = whitespace.Cat(SymbolToken(',')).Cat(whitespace);
var number = minus.Optional().Cat(integer).Cat(frac.Optional()).Cat(exp.Optional());
var literal = letters.Closure();
var unescaped = SymbolTokenExcept(Enumerable.Range(0, 0x20).Union(new int[] { '\\', '"' }).Select(x => (char)x));
var jsonExpression =
number.Tag(TokenType.Number)
.Or(literal.Tag(TokenType.Literal))
.Or(quote.Tag(TokenType.StringBound))
.Or(beginObject.Tag(TokenType.BeginObject))
.Or(endObject.Tag(TokenType.EndObject))
.Or(beginArray.Tag(TokenType.BeginArray))
.Or(endArray.Tag(TokenType.EndArray))
.Or(nameSep.Tag(TokenType.NameSeparator))
.Or(valueSep.Tag(TokenType.ValueSeparator))
.Or(SymbolSetToken('\n', '\r', '\t', ' ').Closure().Tag(TokenType.Whitespace));
var jsonStringExpression =
quote.Tag(TokenType.StringBound)
.Or(backSlash.Cat(specialEscapeChars).Tag(TokenType.EscapedChar))
.Or(backSlash.Cat(unicodeEspace).Tag(TokenType.EscapedUnicode))
.Or(unescaped.Closure().Tag(TokenType.UnescapedChar));
m_jsonExpression = BuildScannerContext<TokenType>(jsonExpression);
m_stringExpression = BuildScannerContext<TokenType>(jsonStringExpression);
}
protected override IAlphabetBuilder<char> AlphabetBuilder {
get {
return m_defaultAlphabet;
}
}
public ScannerContext<TokenType> JsonExpression {
get {
return m_jsonExpression;
}
}
public ScannerContext<TokenType> JsonStringExpression {
get {
return m_stringExpression;
}
}
Token SymbolRangeToken(char start, char stop) {
return SymbolToken(Enumerable.Range(start, stop - start + 1).Select(x => (char)x));
}
protected override IndexedAlphabetBase<char> CreateAlphabet() {
return new CharAlphabet();
}
}
}