Creating the KQL fulltext function.

Author: afoucret

docs/reference/esql/functions/description/kql.asciidoc

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+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+package org.elasticsearch.xpack.esql.expression.function.fulltext;
+
+import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
+import org.elasticsearch.common.io.stream.StreamInput;
+import org.elasticsearch.common.io.stream.StreamOutput;
+import org.elasticsearch.xpack.esql.core.expression.Expression;
+import org.elasticsearch.xpack.esql.core.querydsl.query.KqlQuery;
+import org.elasticsearch.xpack.esql.core.tree.NodeInfo;
+import org.elasticsearch.xpack.esql.core.tree.Source;
+import org.elasticsearch.xpack.esql.expression.function.FunctionInfo;
+import org.elasticsearch.xpack.esql.expression.function.Param;
+import org.elasticsearch.xpack.esql.io.stream.PlanStreamInput;
+
+import java.io.IOException;
+import java.util.List;
+
+/**
+ * Full text function that performs a {@link KqlQuery} .
+ */
+public class Kql extends FullTextFunction {
+    public static final NamedWriteableRegistry.Entry ENTRY = new NamedWriteableRegistry.Entry(Expression.class, "Kql", Kql::new);
+
+    @FunctionInfo(
+        returnType = "boolean",
+        preview = true,
+        description = "Performs a KQL query. Returns true if the provided KQL query string matches the row.",
+        examples = {}
+    )
+    public Kql(
+        Source source,
+        @Param(name = "query", type = { "keyword", "text" }, description = "Query string in KQL string format.") Expression queryString
+    ) {
+        super(source, queryString, List.of(queryString));
+    }
+
+    private Kql(StreamInput in) throws IOException {
+        this(Source.readFrom((PlanStreamInput) in), in.readNamedWriteable(Expression.class));
+    }
+
+    @Override
+    public void writeTo(StreamOutput out) throws IOException {
+        source().writeTo(out);
+        out.writeNamedWriteable(query());
+    }
+
+    @Override
+    public String getWriteableName() {
+        return ENTRY.name;
+    }
+
+    @Override
+    public String functionName() {
+        return "KQL";
+    }
+
+    @Override
+    public Expression replaceChildren(List<Expression> newChildren) {
+        return new Kql(source(), newChildren.get(0));
+    }
+
+    @Override
+    protected NodeInfo<? extends Expression> info() {
+        return NodeInfo.create(this, Kql::new, query());
+    }
+
+}

docs/reference/esql/functions/kibana/definition/kql.json

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+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+package org.elasticsearch.xpack.esql.expression.function.fulltext;
+
+import com.carrotsearch.randomizedtesting.annotations.Name;
+import com.carrotsearch.randomizedtesting.annotations.ParametersFactory;
+
+import org.apache.lucene.util.BytesRef;
+import org.elasticsearch.xpack.esql.core.expression.Expression;
+import org.elasticsearch.xpack.esql.core.tree.Source;
+import org.elasticsearch.xpack.esql.core.type.DataType;
+import org.elasticsearch.xpack.esql.expression.function.AbstractFunctionTestCase;
+import org.elasticsearch.xpack.esql.expression.function.FunctionName;
+import org.elasticsearch.xpack.esql.expression.function.TestCaseSupplier;
+import org.hamcrest.Matcher;
+
+import java.util.LinkedList;
+import java.util.List;
+import java.util.function.Supplier;
+
+import static org.hamcrest.Matchers.equalTo;
+
+@FunctionName("kql")
+public class KqlTests extends AbstractFunctionTestCase {
+
+    public KqlTests(@Name("TestCase") Supplier<TestCaseSupplier.TestCase> testCaseSupplier) {
+        this.testCase = testCaseSupplier.get();
+    }
+
+    @ParametersFactory
+    public static Iterable<Object[]> parameters() {
+        List<TestCaseSupplier> suppliers = new LinkedList<>();
+        for (DataType strType : DataType.stringTypes()) {
+            suppliers.add(
+                new TestCaseSupplier(
+                    "<" + strType + ">",
+                    List.of(strType),
+                    () -> testCase(strType, randomAlphaOfLengthBetween(1, 10), equalTo(true))
+                )
+            );
+        }
+        List<TestCaseSupplier> errorsSuppliers = errorsForCasesWithoutExamples(suppliers, (v, p) -> "string");
+        // Don't test null, as it is not allowed but the expected message is not a type error - so we check it separately in VerifierTests
+        return parameterSuppliersFromTypedData(errorsSuppliers.stream().filter(s -> s.types().contains(DataType.NULL) == false).toList());
+    }
+
+    public final void testFold() {
+        Expression expression = buildLiteralExpression(testCase);
+        if (testCase.getExpectedTypeError() != null) {
+            assertTypeResolutionFailure(expression);
+            return;
+        }
+        assertFalse("expected resolved", expression.typeResolved().unresolved());
+    }
+
+    private static TestCaseSupplier.TestCase testCase(DataType strType, String str, Matcher<Boolean> matcher) {
+        return new TestCaseSupplier.TestCase(
+            List.of(new TestCaseSupplier.TypedData(new BytesRef(str), strType, "query")),
+            "EndsWithEvaluator[str=Attribute[channel=0], suffix=Attribute[channel=1]]",
+            DataType.BOOLEAN,
+            matcher
+        );
+    }
+
+    @Override
+    protected Expression build(Source source, List<Expression> args) {
+        return new Kql(source, args.get(0));
+    }
+}