SearchExpressionType

enumeration

描述

Type used to characterize an expression. An expression might have multiple types. For example a Set is also an iterable. A keyword is also considered a string value. SearchExpressionType can be used with SearchExpressionEvaluatorAttribute to describe the parameter list of an evaluator.

[SearchExpressionEvaluator(SearchExpressionType.Iterable | SearchExpressionType.Variadic)]
[SearchExpressionEvaluatorSignatureOverload(SearchExpressionType.Number, SearchExpressionType.Iterable | SearchExpressionType.Variadic)]
[Description("Extract and returns the X first results for each expression.")]
public static IEnumerable<SearchItem> TakeXFirst(SearchExpressionContext c)
{
    var argIndex = 0;
    var takeNumber = 1;
    if (c.args[0].types.HasFlag(SearchExpressionType.Number))
    {
        ++argIndex;
        takeNumber = Math.Max((int)(c.args[0].GetNumberValue(takeNumber)), 0);
    }

    for ( ; argIndex < c.args.Length; ++argIndex)
    {
        var iterable = c.args[argIndex].Execute(c);
        var taken = 0;
        foreach (var item in iterable)
        {
            if (item == null)
                yield return null;
            else
            {
                yield return item;
                ++taken;
                if (taken == takeNumber)
                {
                    c.Break();
                    break;
                }
            }
        }
    }
}

变量

Nil	Denote an invalid Expression.
Optional	Used in SearchExpressionEvaluatorAttribute to specify a aprameter to be Optional.
Variadic	Used in SearchExpressionEvaluatorAttribute to specify that a parameter can be used multiples times. For example count{Iterable1, Iterable2,... IterableN} can be executed with any number of iterables are parameters.
Boolean	Denote a Literal expression of a boolean value.
Number	Denote a Literal expression of a numerical value.
Text	Denote an expression representing a textual (string) value.
Selector	Denote an expression representing a selector. All selector starts with @. For example @size in expression: select{t:material, @size}.
Keyword	Denote an expression yielding a SearchExpressionKeyword.
Set	Denote an iterable expression of a group of generally literal values. For example [1, 2, 3] or [material, shader, texture2d].
Function	Denotes an expression of an evaluator function. For example: count{}.
QueryString	Denote an expression representing a query string. For example: t:shader.
Expandable	Denotes an expression using the ... operator to tell it can be expanded.
Group	Denote an expression of a group of items. Groups are generated by the groupBy{} evaluator.
Literal	Denote an expression built from a literal values: boolean, number, text or keyword. For example in the set expression [1,"hello",true] all set values are literals.
Iterable	Denote an expression that can iterated to yield SearchItem. Set: [1, 2, 3], Query String: t:shader and evaluator: count{} are all example of iterables.
AnyValue	Denote an expression with a value type: either Literal or Iterable.
AnyExpression	Denote any expression of any type (Literal, Iterable or Selector).

脚本 API

SearchExpressionType

描述

变量