add function info for YEAR

src/Database/FunctionInfo/FunctionInfoRegistryFactory.php

@@ -35,6 +35,7 @@ public function createDefaultFunctionInfos(): array
 			new Sum(),
 			new Trim(),
 			new Value(),
+			new Year(),
 		];
 	}
 }

src/Database/FunctionInfo/Year.php

@@ -0,0 +1,80 @@
+<?php
+
+declare(strict_types=1);
+
+namespace MariaStan\Database\FunctionInfo;
+
+use MariaStan\Analyser\AnalyserConditionTypeEnum;
+use MariaStan\Analyser\ExprTypeResult;
+use MariaStan\Ast\Expr\FunctionCall\FunctionCall;
+use MariaStan\Parser\Exception\ParserException;
+use MariaStan\Schema\DbType\DbTypeEnum;
+use MariaStan\Schema\DbType\IntType;
+use MariaStan\Schema\DbType\NullType;
+
+use function count;
+use function in_array;
+
+final class Year implements FunctionInfo
+{
+	/** @inheritDoc */
+	public function getSupportedFunctionNames(): array
+	{
+		return ['YEAR'];
+	}
+
+	public function getFunctionType(): FunctionTypeEnum
+	{
+		return FunctionTypeEnum::SIMPLE;
+	}
+
+	public function checkSyntaxErrors(FunctionCall $functionCall): void
+	{
+		$args = $functionCall->getArguments();
+		$argCount = count($args);
+
+		if ($argCount !== 1) {
+			throw new ParserException(
+				FunctionInfoHelper::createArgumentCountErrorMessageFixed(
+					$functionCall->getFunctionName(),
+					1,
+					$argCount,
+				),
+			);
+		}
+	}
+
+	/** @inheritDoc */
+	public function getInnerConditions(?AnalyserConditionTypeEnum $condition, array $arguments): array
+	{
+		// TRUTHY(YEAR(A)) => NOT_NULL(A)
+		// FALSY(YEAR(A)) => NOT_NULL(A)
+		// NOT_NULL(YEAR(A)) => NOT_NULL(A)
+		// NULL(YEAR(A)) => []
+		$innerCondition = match ($condition) {
+			null, AnalyserConditionTypeEnum::NULL => null,
+			default => AnalyserConditionTypeEnum::NOT_NULL,
+		};
+
+		return [$innerCondition];
+	}
+
+	/**
+	 * @inheritDoc
+	 * @phpcsSuppress SlevomatCodingStandard.Functions.UnusedParameter
+	 */
+	public function getReturnType(
+		FunctionCall $functionCall,
+		array $argumentTypes,
+		?AnalyserConditionTypeEnum $condition,
+		bool $isNonEmptyAggResultSet,
+	): ExprTypeResult {
+		$date = $argumentTypes[0];
+		$isNullable = $date->isNullable || $date->type::getTypeEnum() !== DbTypeEnum::DATETIME;
+		$type = in_array($date->type::getTypeEnum(), [DbTypeEnum::DATETIME, DbTypeEnum::VARCHAR], true)
+			? new IntType()
+			: new NullType();
+
+		return new ExprTypeResult($type, $isNullable, null, $date->knowledgeBase);
+	}
+}

tests/Analyser/AnalyserTest.php

@@ -836,6 +836,7 @@ private static function provideValidFunctionCallTestData(): iterable
 			$selects["DATE_FORMAT({$label}, Y-m, null)"] = "SELECT DATE_FORMAT({$value}, '%Y-%m', null)";
 			$selects["DATE_FORMAT({$label}, Y-m, en_US)"] = "SELECT DATE_FORMAT({$value}, '%Y-%m', 'en_US')";
 			$selects["DATE({$label})"] = "SELECT DATE({$value})";
+			$selects["YEAR({$label})"] = "SELECT YEAR({$value})";
 			$selects["DATE_ADD({$label}, INTERVAL)"] = "SELECT DATE_ADD({$value}, INTERVAL 1 SECOND)";
 
 			// TODO: handle this later when we have better type system.
@@ -1604,6 +1605,8 @@ private static function provideValidNullabilityOperatorTestData(): iterable
 			'NOT LCASE(col_vchar)',
 			'UPPER(col_vchar) IS NULL',
 			'UCASE(col_vchar) IS NOT NULL',
+			'YEAR(col_vchar) IS NOT NULL',
+			'YEAR(col_vchar) IS NULL',
 		];
 
 		foreach (['COALESCE', 'IFNULL', 'NVL'] as $coalesceFn) {