80 lines
2.9 KiB
C#
80 lines
2.9 KiB
C#
using System.Dynamic;
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using System.Text.Json;
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using Elsa.Expressions.Models;
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using Elsa.JavaScript.Extensions;
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using Elsa.JavaScript.Notifications;
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using Elsa.JavaScript.Options;
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using Elsa.JavaScript.Services;
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using Elsa.Mediator.Services;
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using Elsa.Workflows.Core;
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using Jint;
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using Microsoft.Extensions.Options;
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namespace Elsa.JavaScript.Implementations
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{
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/// <summary>
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/// Provides a JavaScript evaluator using Jint.
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/// </summary>
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public class JintJavaScriptEvaluator : IJavaScriptEvaluator
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{
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private readonly IEventPublisher _mediator;
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private readonly JintOptions _jintOptions;
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/// <summary>
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/// Constructor.
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/// </summary>
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public JintJavaScriptEvaluator(IEventPublisher mediator, IOptions<JintOptions> scriptOptions)
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{
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_mediator = mediator;
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_jintOptions = scriptOptions.Value;
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}
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/// <inheritdoc />
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public async Task<object?> EvaluateAsync(string expression,
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Type returnType,
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ExpressionExecutionContext context,
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Action<Engine>? configureEngine = default,
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CancellationToken cancellationToken = default)
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{
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var engine = await GetConfiguredEngine(configureEngine, context, cancellationToken);
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var result = ExecuteExpressionAndGetResult(engine, expression);
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return result;
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}
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private async Task<Engine> GetConfiguredEngine(Action<Engine>? configureEngine, ExpressionExecutionContext context, CancellationToken cancellationToken)
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{
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var engine = new Engine(opts =>
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{
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if (_jintOptions.AllowClrAccess)
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opts.AllowClr();
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});
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configureEngine?.Invoke(engine);
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// Add common functions.
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engine.SetValue("setVariable", (Action<string, object>)((name, value) => context.SetVariable(name, value)));
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// ReSharper disable once ConvertClosureToMethodGroup (Jint will not understand).
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engine.SetValue("getVariable", (Func<string, object?>)(name => context.GetVariable(name)));
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engine.SetValue("isNullOrWhiteSpace", (Func<string, bool>)string.IsNullOrWhiteSpace);
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engine.SetValue("isNullOrEmpty", (Func<string, bool>)string.IsNullOrEmpty);
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// Add common .NET types.
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engine.RegisterType<DateTime>();
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engine.RegisterType<TimeSpan>();
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// Allow listeners invoked by the mediator to configure the engine.
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await _mediator.PublishAsync(new EvaluatingJavaScript(engine, context), cancellationToken);
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return engine;
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}
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private static object? ExecuteExpressionAndGetResult(Engine engine, string expression)
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{
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var result = engine.Evaluate(expression);
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return result.ToObject();
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}
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}
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} |