feat(runtime): add timestamp integer and float overloads

Signed-off-by: azjezz <azjezz@protonmail.com>

Author: azjezz

src/Runtime/Extension/DateTime/Function/TimestampFunction.php

@@ -6,12 +6,15 @@
 
 use Cel\Runtime\Exception\TypeConversionException;
 use Cel\Runtime\Function\FunctionInterface;
+use Cel\Runtime\Value\FloatValue;
+use Cel\Runtime\Value\IntegerValue;
 use Cel\Runtime\Value\StringValue;
 use Cel\Runtime\Value\TimestampValue;
 use Cel\Runtime\Value\Value;
 use Cel\Runtime\Value\ValueKind;
 use Cel\Syntax\Member\CallExpression;
 use Override;
+use Psl\DateTime;
 use Psl\DateTime\Exception\RuntimeException;
 use Psl\DateTime\FormatPattern;
 use Psl\DateTime\Timestamp;
@@ -38,6 +41,23 @@ public function isIdempotent(): bool
     #[Override]
     public function getOverloads(): iterable
     {
+        yield [ValueKind::Integer] => static function (CallExpression $expr, array $arguments): TimestampValue {
+            /** @var IntegerValue $seconds */
+            $seconds = $arguments[0];
+
+            return new TimestampValue(Timestamp::fromParts($seconds->value));
+        };
+
+        yield [ValueKind::Float] => static function (CallExpression $expr, array $arguments): TimestampValue {
+            /** @var FloatValue $seconds */
+            $seconds = $arguments[0];
+
+            $wholeSeconds = (int) $seconds->value;
+            $nanoseconds = (int) (($seconds->value - $wholeSeconds) * DateTime\NANOSECONDS_PER_SECOND);
+
+            return new TimestampValue(Timestamp::fromParts($wholeSeconds, $nanoseconds));
+        };
+
         yield [ValueKind::String] =>
             /**
              * @param CallExpression $call      The call expression representing the function call.

tests/Runtime/Extension/DateTimeExtensionTest.php

@@ -243,6 +243,20 @@ public static function provideEvaluationCases(): iterable
             [],
             new EvaluationException('getFullYear: timezone `Mars/Olympus_Mons` is not valid', new Span(0, 71)),
         ];
+
+        /// Timestamp from seconds
+        yield 'DateTime timestamp(): from integer seconds' => [
+            'timestamp(1757766605)',
+            [],
+            new TimestampValue(Timestamp::fromParts(1757766605)),
+        ];
+
+        /// Timestamp from float seconds
+        yield 'DateTime timestamp(): from float seconds' => [
+            'timestamp(1757766605.123456)',
+            [],
+            new TimestampValue(Timestamp::fromParts(1757766605, 123456001)),
+        ];
     }
 
     public function testNowFunctionReturnsCurrentTimestamp(): void