QueryEngine<T0>

Description

A QueryEngine defines how to build a query from an input string. It can be customized to support custom filters and operators.

<TData>: The filtered data type.

using System.Collections.Generic;
using System.Linq;
using UnityEditor;
using UnityEditor.Search;
using UnityEngine;

static class Example_QueryEngine
{
    static List<MyObjectType> s_Data;

    static QueryEngine<MyObjectType> SetupQueryEngine()
    {
        // Set up the query engine
        var queryEngine = new QueryEngine<MyObjectType>();

        // Add a filter for MyObjectType.id that supports all operators
        queryEngine.AddFilter("id", myObj => myObj.id);
        // Add a filter for MyObjectType.name that supports only contains (:), equal (=) and not equal (!=)
        queryEngine.AddFilter("n", myObj => myObj.name, new[] { ":", "=", "!=" });
        // Add a filter for MyObjectType.active that supports only equal and not equal
        queryEngine.AddFilter("a", myObj => myObj.active, new[] { "=", "!=" });
        // Add a filter for the computed property magnitude that supports equal, not equal, lesser, greater, lesser or equal and greater or equal.
        queryEngine.AddFilter("m", myObj => myObj.position.magnitude, new[] { "=", "!=", "<", ">", "<=", ">=" });

        // Set up what data from objects of type MyObjectType will be matched against search words
        queryEngine.SetSearchDataCallback(myObj => new[] { myObj.id.ToString(), myObj.name });

        return queryEngine;
    }

    [MenuItem("Examples/QueryEngine/Class")]
    public static void RunExample()
    {
        s_Data = GenerateExampleData();
        var queryEngine = SetupQueryEngine();
        TestFiltering(queryEngine, s_Data);
    }

    static void TestFiltering(QueryEngine<MyObjectType> queryEngine, IEnumerable<MyObjectType> inputData)
    {
        // Find objects that have an id > 2 and are active
        var filteredData = FilterData("id>2 a=true", queryEngine, inputData);
        ValidateData(filteredData, s_Data.Where(myObj => myObj.id > 2 && myObj.active));

        // Find objects that are not active and have a name that contains Test
        filteredData = FilterData("a=false n:Test", queryEngine, inputData);
        ValidateData(filteredData, s_Data.Where(myObj => myObj.name.Contains("Test") && !myObj.active));

        // Find objects that have a magnitude higher than 1 or the id 0.
        filteredData = FilterData("m>1 or id=0", queryEngine, inputData);
        ValidateData(filteredData, s_Data.Where(myObj => myObj.position.magnitude > 1f || myObj.id == 0));
    }

    static IEnumerable<MyObjectType> FilterData(string inputQuery, QueryEngine<MyObjectType> queryEngine, IEnumerable<MyObjectType> inputData)
    {
        // Parse the query string into a query operation
        var query = queryEngine.Parse(inputQuery);

        // If the query is not valid, print all errors and return an empty data set
        if (!query.valid)
        {
            foreach (var queryError in query.errors)
            {
                Debug.LogFormat(LogType.Error, LogOption.NoStacktrace, null, $"Error parsing input at {queryError.index}: {queryError.reason}");
            }

            return new List<MyObjectType>();
        }

        // Apply the query on a data set and get the filtered result.
        var filteredData = query.Apply(inputData);
        return filteredData;
    }

    static void ValidateData(IEnumerable<MyObjectType> filteredData, IEnumerable<MyObjectType> expectedData)
    {
        var filteredDataArray = filteredData.ToArray();
        var expectedDataArray = expectedData.ToArray();
        Debug.Assert(filteredDataArray.Length == expectedDataArray.Length, $"Filtered data should have {expectedDataArray.Length} elements.");
        if (filteredDataArray.Length != expectedDataArray.Length)
            return;

        for (var i = 0; i < expectedDataArray.Length; i++)
        {
            Debug.Assert(filteredDataArray[i] == expectedDataArray[i], $"{filteredDataArray[i]} should be equal to {expectedDataArray[i]}");
        }
    }

    static List<MyObjectType> GenerateExampleData()
    {
        var data = new List<MyObjectType>()
        {
            new MyObjectType { id = 0, name = "Test 1", position = new Vector2(0, 0), active = false },
            new MyObjectType { id = 1, name = "Test 2", position = new Vector2(0, 1), active = true },
            new MyObjectType { id = 2, name = "Test 3", position = new Vector2(1, 0), active = false },
            new MyObjectType { id = 3, name = "Test 4", position = new Vector2(1, 1), active = true },
            new MyObjectType { id = 4, name = "Test 5", position = new Vector2(2, 0), active = false },
            new MyObjectType { id = 5, name = "Test 6", position = new Vector2(0, 2), active = true }
        };

        return data;
    }

    /// <summary>
    /// Custom type. This is the type of objects that will be searched by the QueryEngine.
    /// </summary>
    class MyObjectType
    {
        public int id { get; set; }
        public string name { get; set; }
        public Vector2 position { get; set; }
        public bool active { get; set; }

        public MyObjectType()
        {
            id = 0;
            name = "";
            position = Vector2.zero;
            active = false;
        }

        public override string ToString()
        {
            return $"({id}, {name}, ({position.x}, {position.y}), {active})";
        }
    }
}

Properties

Constructors

Public Methods