private static IQueryPart CreateQueryPart(
IIndexedFieldLookup fieldLookup,
QueryParserState state,
QueryToken token,
ITokenizer wordTokenizer,
IQueryPart?currentQuery)
{
switch (token.TokenType)
{
case QueryTokenType.Text:
return(ComposePart(currentQuery, CreateWordPart(token, wordTokenizer)));
case QueryTokenType.FieldFilter:
var(fieldId, tokenizer) = fieldLookup.GetFieldInfo(token.TokenText);
var filteredPart = CreateQueryPart(fieldLookup, state, state.GetNextToken(), tokenizer, null);
return(ComposePart(
currentQuery,
new FieldFilterQueryOperator(token.TokenText, fieldId, filteredPart)));
case QueryTokenType.OrOperator:
case QueryTokenType.AndOperator:
case QueryTokenType.NearOperator:
case QueryTokenType.PrecedingNearOperator:
case QueryTokenType.PrecedingOperator:
var rightPart = CreateQueryPart(fieldLookup, state, state.GetNextToken(), wordTokenizer, null);
return(CombineParts(currentQuery, rightPart, token.TokenType, token.Tolerance));
case QueryTokenType.OpenBracket:
var bracketedPart = state.GetTokensUntil(QueryTokenType.CloseBracket)
.Aggregate((IQueryPart?)null, (current, next) => CreateQueryPart(fieldLookup, state, next, wordTokenizer, current));
if (bracketedPart == null)
{
throw new QueryParserException(ExceptionMessages.EmptyBracketedExpressionsAreNotSupported);
}
return(ComposePart(currentQuery, new BracketedQueryPart(bracketedPart)));
case QueryTokenType.BeginAdjacentTextOperator:
var words = state.GetTokensUntil(QueryTokenType.EndAdjacentTextOperator)
.SelectMany(t => CreateWordParts(t, wordTokenizer))
.ToList();
if (words.Count == 0)
{
throw new QueryParserException(ExceptionMessages.EmptyAdjacentTextPartsAreNotSupported);
}
return(ComposePart(currentQuery, new AdjacentWordsQueryOperator(words)));
default:
throw new QueryParserException(ExceptionMessages.UnexpectedTokenEncountered, token.TokenType);
}
}
public IQuery Parse(IIndexedFieldLookup fieldLookup, string queryText, ITokenizer wordTokenizer)
{
if (fieldLookup is null)
{
throw new ArgumentNullException(nameof(fieldLookup));
}
IQueryPart?rootPart = null;
var state = new QueryParserState(queryText);
while (state.TryGetNextToken(out var token))
{
rootPart = CreateQueryPart(fieldLookup, state, token, wordTokenizer, rootPart);
}
return(new Query(rootPart ?? EmptyQueryPart.Instance));
}
private static IQueryPart CreateQueryPart(
IIndexedFieldLookup fieldLookup,
QueryParserState state,
QueryToken token,
ITokenizer wordTokenizer,
IQueryPart rootPart)
{
switch (token.TokenType)
{
case QueryTokenType.Text:
return(ComposePart(rootPart, CreateWordPart(token, wordTokenizer)));
case QueryTokenType.FieldFilter:
var filteredPart = CreateQueryPart(fieldLookup, state, state.GetNextToken(), wordTokenizer, null);
if (fieldLookup.TryGetIdForField(token.TokenText, out var fieldId))
{
return(ComposePart(
rootPart,
new FieldFilterQueryOperator(token.TokenText, fieldId, filteredPart)));
}
throw new QueryParserException(ExceptionMessages.UnknownFieldReference, token.TokenText);
case QueryTokenType.OrOperator:
case QueryTokenType.AndOperator:
case QueryTokenType.NearOperator:
case QueryTokenType.PrecedingNearOperator:
case QueryTokenType.PrecedingOperator:
var rightPart = CreateQueryPart(fieldLookup, state, state.GetNextToken(), wordTokenizer, null);
return(CombineParts(rootPart, rightPart, token.TokenType, token.Tolerance));
case QueryTokenType.OpenBracket:
var bracketedPart = state.GetTokensUntil(QueryTokenType.CloseBracket)
.Aggregate((IQueryPart)null, (current, next) => CreateQueryPart(fieldLookup, state, next, wordTokenizer, current));
return(bracketedPart == null
? rootPart
: ComposePart(rootPart, new BracketedQueryPart(bracketedPart)));
default:
throw new QueryParserException(ExceptionMessages.UnexpectedTokenEncountered, token.TokenType);
}
}
