private static Lex LexBoost(QueryLexer lexer)
{
lexer.Ignore();
lexer.AcceptDigitRun();
lexer.Emit(LexemeType.Boost);
return(LexText);
}
private static Lex LexEditDistance(QueryLexer lexer)
{
lexer.Ignore();
lexer.AcceptDigitRun();
lexer.Emit(LexemeType.EditDistance);
return(LexText);
}
private static Lex LexField(QueryLexer lexer)
{
lexer.Backup();
lexer.Emit(LexemeType.Field);
lexer.Ignore();
return(LexText);
}
private static Lex LexEOS(QueryLexer lexer)
{
if (lexer.Width > 0)
{
lexer.Emit(LexemeType.Term);
}
return(LexPastEOS);
}
private static Lex LexTerm(QueryLexer lexer)
{
if (lexer.Width > 1)
{
lexer.Backup();
lexer.Emit(LexemeType.Term);
}
lexer.Ignore();
if (lexer.HasMore)
{
return(LexText);
}
return(LexPastEOS);
}
public QueryParser(string str, Query query, CultureInfo?culture = null)
{
_lexer = new QueryLexer(str);
Query = query;
Culture = culture ?? CultureInfo.CurrentCulture;
}
private static Lex LexText(QueryLexer lexer)
{
while (true)
{
(bool EOS, char ch) = lexer.Next();
if (EOS)
{
return(LexEOS);
}
// Escape character is '\'
if (ch == '\\')
{
lexer.EscapeCharacter();
continue;
}
if (ch == ':')
{
return(LexField);
}
if (ch == '~')
{
lexer.Backup();
if (lexer.Width > 0)
{
lexer.Emit(LexemeType.Term);
}
return(LexEditDistance);
}
if (ch == '^')
{
lexer.Backup();
if (lexer.Width > 0)
{
lexer.Emit(LexemeType.Term);
}
return(LexBoost);
}
// "+" indicates term presence is required
// checking for length to ensure that only
// leading "+" are considered
if (ch == '+' && lexer.Width == 1)
{
lexer.Emit(LexemeType.Presence);
return(LexText);
}
// "-" indicates term presence is prohibited
// checking for length to ensure that only
// leading "-" are considered
if (ch == '-' && lexer.Width == 1)
{
lexer.Emit(LexemeType.Presence);
return(LexText);
}
if (ch.IsLunrSeparator())
{
return(LexTerm);
}
}
}
private static Lex LexPastEOS(QueryLexer lexer) => throw new InvalidOperationException("End of string should never be called");
