Version: 2022.3

SearchExpressionContext

struct in UnityEditor.Search

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描述

This context encapsulate all the datas needed to evaluate a SearchExpression and it allows user to interact with the evaluation runtime of an expression. A SearchExpressionContext is created automatically with a SearchExpressionRuntime anytime SearchExpression.Execute is called.

Here is an example showing ow the SearchExpressionContext is used during evaluation:

[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

argsArguments of passed to the SearchExpression being evaluated.
expression[[]SearchExpression] being evaluated.
items SearchItems yielded by the evaluation of a searchExpression.
runtime SearchExpressionRuntime associated with this context. The runtime stores all runtime data (stack frames, stack of contex and items) necessary for evaluation of a SearchExpression.
searchSearchContex containing the search query that was parsed to create the SearchExpression.
validIs the current context valid or not. If invalid it means the associated SearchExpression is null or the SearchExiressionRuntime is invalid.

公共函数

BreakBreak the evaluation of a SearchExpression meaning items won't be yielded anymore.
ContinueTell SearchExpression evaluation to continue.
IsBreakingHas the current context being flagged to break execution?
IsContinuingHas the current context being flagged to continue execution?
ResetIterationControlRestart evaluation and iteration of SearchExpression.
ResolveAliasTry to resolve an alias value using the SearchExpressionRuntime attached to this context. Each frame if asked to resolve a SearchExpression.alias.
ThrowErrorStop a SearchExpression evaluation by throwing a SearchExceptionEvaluatorException. User writing an evaluator can decide to throw thse exceptions if the parameters passed to evaluation are not valid or if a problem happens during evaluation.
ToStringGet string representation of a context.