/// <summary>
/// build specification from rsql query
/// </summary>
/// <param name="queryCollection"></param>
/// <returns></returns>
private Expression <Func <T, bool> > Build(IQueryCollection queryCollection)
{
var result = QueryExpressionHelper.True <T>();
if (queryCollection.TryGetValue(_autumnSettings.QueryField, out var query))
{
result = GetOrRegistryQuery(query, _autumnSettings);
}
return(result);
}
/// <summary>
/// visit a comparison expression
/// </summary>
/// <param name="context"></param>
/// <returns></returns>
public override Expression <Func <T, bool> > VisitComparison(QueryParser.ComparisonContext context)
{
var comparator = context.comparator().GetText().ToLowerInvariant();
switch (comparator)
{
case "=is-null=":
case "=nil=":
return(QueryExpressionHelper.GetIsNullExpression <T>(_parameter, context, _namingStrategy));
case "==":
case "=eq=":
return(QueryExpressionHelper.GetEqExpression <T>(_parameter, context, _namingStrategy));
case "!=":
case "=neq=":
return(QueryExpressionHelper.GetNeqExpression <T>(_parameter, context, _namingStrategy));
case "<":
case "=lt=":
return(QueryExpressionHelper.GetLtExpression <T>(_parameter, context, _namingStrategy));
case "<=":
case "=le=":
return(QueryExpressionHelper.GetLeExpression <T>(_parameter, context, _namingStrategy));
case ">":
case "=gt=":
return(QueryExpressionHelper.GetGtExpression <T>(_parameter, context, _namingStrategy));
case ">=":
case "=ge=":
return(QueryExpressionHelper.GetGeExpression <T>(_parameter, context, _namingStrategy));
case "=in=":
return(QueryExpressionHelper.GetInExpression <T>(_parameter, context, _namingStrategy));
case "=out=":
case "=nin=":
return(QueryExpressionHelper.GetOutExpression <T>(_parameter, context, _namingStrategy));
default:
throw new QueryComparisonUnknownComparatorException(context);
}
}
private static Expression <Func <T, bool> > GetOrRegistryQuery(string query, AutumnSettings autumnSettings)
{
lock (QueryExpressionHelper.QueriesCache)
{
if (string.IsNullOrWhiteSpace(query))
{
return(QueryExpressionHelper.True <T>());
}
var hash = Hash($"{typeof(T).FullName}?{query}");
if (QueryExpressionHelper.QueriesCache.TryGetValue(hash, out Expression <Func <T, bool> > result))
{
return(result);
}
var antlrInputStream = new AntlrInputStream(query);
var lexer = new QueryLexer(antlrInputStream);
var commonTokenStream = new CommonTokenStream(lexer);
var parser = new QueryParser(commonTokenStream);
var eval = parser.or();
var visitor = new DefaultQueryVisitor <T>(autumnSettings.NamingStrategy);
result = visitor.VisitOr(eval);
QueryExpressionHelper.QueriesCache.Set(hash, result);
return(result);
}
}
/// <summary>
/// visit a and expression
/// </summary>
/// <param name="context"></param>
/// <returns></returns>
public override Expression <Func <T, bool> > VisitAnd(QueryParser.AndContext context)
{
return(QueryExpressionHelper.GetAndExpression(this, context));
}
