Add parsing methods where missing.

src/Field/WeekOfYear.php

@@ -18,6 +18,11 @@ final class WeekOfYear
      */
     public const NAME = 'week-of-year';
 
+    /**
+     * The regular expression pattern of the ISO 8601 representation.
+     */
+    public const PATTERN = '[0-9]{2}';
+
     /**
      * @param int      $weekOfYear The week-of-year to check.
      * @param int|null $year       An optional year to check against, validated.

src/Parser/IsoParsers.php

@@ -15,6 +15,7 @@
 use Brick\DateTime\Field\TimeZoneOffsetSecond;
 use Brick\DateTime\Field\TimeZoneOffsetSign;
 use Brick\DateTime\Field\TimeZoneRegion;
+use Brick\DateTime\Field\WeekOfYear;
 use Brick\DateTime\Field\Year;
 
 /**
@@ -165,6 +166,23 @@ public static function yearMonthRange(): PatternParser
             ->toParser();
     }
 
+    /**
+     * Returns a parser for a year such as `2014`.
+     */
+    public static function year(): PatternParser
+    {
+        /** @var PatternParser|null $parser */
+        static $parser;
+
+        if ($parser) {
+            return $parser;
+        }
+
+        return $parser = (new PatternParserBuilder())
+            ->appendCapturePattern(Year::PATTERN, Year::NAME)
+            ->toParser();
+    }
+
     /**
      * Returns a parser for a year-month such as `2014-12`.
      */
@@ -184,6 +202,25 @@ public static function yearMonth(): PatternParser
             ->toParser();
     }
 
+    /**
+     * Returns a parser for a year-week such as `2014-W15`.
+     */
+    public static function yearWeek(): PatternParser
+    {
+        /** @var PatternParser|null $parser */
+        static $parser;
+
+        if ($parser) {
+            return $parser;
+        }
+
+        return $parser = (new PatternParserBuilder())
+            ->appendCapturePattern(Year::PATTERN, Year::NAME)
+            ->appendLiteral('-W')
+            ->appendCapturePattern(WeekOfYear::PATTERN, WeekOfYear::NAME)
+            ->toParser();
+    }
+
     /**
      * Returns a parser for a month-day such as `12-31`.
      */

src/Year.php

@@ -4,6 +4,10 @@
 
 namespace Brick\DateTime;
 
+use Brick\DateTime\Parser\DateTimeParseException;
+use Brick\DateTime\Parser\DateTimeParser;
+use Brick\DateTime\Parser\DateTimeParseResult;
+use Brick\DateTime\Parser\IsoParsers;
 use JsonSerializable;
 
 /**
@@ -37,6 +41,35 @@ public static function of(int $year): Year
         return new Year($year);
     }
 
+    /**
+     * @throws DateTimeException      If the year is not valid.
+     * @throws DateTimeParseException If required fields are missing from the result.
+     */
+    public static function from(DateTimeParseResult $result): Year
+    {
+        $year = (int) $result->getField(Field\Year::NAME);
+
+        return Year::of($year);
+    }
+
+    /**
+     * Obtains an instance of `Year` from a text string.
+     *
+     * @param string              $text   The text to parse, such as `2007`.
+     * @param DateTimeParser|null $parser The parser to use, defaults to the ISO 8601 parser.
+     *
+     * @throws DateTimeException      If the year is not valid.
+     * @throws DateTimeParseException If the text string does not follow the expected format.
+     */
+    public static function parse(string $text, ?DateTimeParser $parser = null): Year
+    {
+        if (! $parser) {
+            $parser = IsoParsers::year();
+        }
+
+        return Year::from($parser->parse($text));
+    }
+
     /**
      * Returns the current year in the given time-zone, according to the given clock.
      *

src/YearWeek.php

@@ -4,6 +4,10 @@
 
 namespace Brick\DateTime;
 
+use Brick\DateTime\Parser\DateTimeParseException;
+use Brick\DateTime\Parser\DateTimeParser;
+use Brick\DateTime\Parser\DateTimeParseResult;
+use Brick\DateTime\Parser\IsoParsers;
 use JsonSerializable;
 
 use function sprintf;
@@ -49,6 +53,36 @@ public static function of(int $year, int $week): YearWeek
         return new YearWeek($year, $week);
     }
 
+    /**
+     * @throws DateTimeException      If the year-week is not valid.
+     * @throws DateTimeParseException If required fields are missing from the result.
+     */
+    public static function from(DateTimeParseResult $result): YearWeek
+    {
+        return YearWeek::of(
+            (int) $result->getField(Field\Year::NAME),
+            (int) $result->getField(Field\WeekOfYear::NAME)
+        );
+    }
+
+    /**
+     * Obtains an instance of `YearWeek` from a text string.
+     *
+     * @param string              $text   The text to parse, such as `2007-W48`.
+     * @param DateTimeParser|null $parser The parser to use, defaults to the ISO 8601 parser.
+     *
+     * @throws DateTimeException      If the year-week is not valid.
+     * @throws DateTimeParseException If the text string does not follow the expected format.
+     */
+    public static function parse(string $text, ?DateTimeParser $parser = null): YearWeek
+    {
+        if (! $parser) {
+            $parser = IsoParsers::yearWeek();
+        }
+
+        return YearWeek::from($parser->parse($text));
+    }
+
     public static function now(TimeZone $timeZone, ?Clock $clock = null): YearWeek
     {
         return LocalDate::now($timeZone, $clock)->getYearWeek();

tests/YearTest.php

@@ -35,6 +35,46 @@ public function testOfInvalidYearThrowsException(int $invalidYear): void
         Year::of($invalidYear);
     }
 
+    /**
+     * @dataProvider providerParse
+     */
+    public function testParse(string $string, int $expectedYear): void
+    {
+        self::assertYearIs($expectedYear, Year::parse($string));
+    }
+
+    public function providerParse(): array
+    {
+        return [
+            ['-2023', -2023],
+            ['-0100', -100],
+            ['1987', 1987],
+            ['121241', 121241],
+        ];
+    }
+
+    /**
+     * @dataProvider providerParseInvalidYearThrowsException
+     */
+    public function testParseInvalidYearThrowsException(string $invalidValue): void
+    {
+        $this->expectException(DateTimeException::class);
+        $this->expectExceptionMessage('Failed to parse "' . $invalidValue . '"');
+
+        Year::parse($invalidValue);
+    }
+
+    public function providerParseInvalidYearThrowsException(): array
+    {
+        return [
+            [''],
+            ['+2000'],
+            ['-100'],
+            ['ABC'],
+            ['9999999999'],
+        ];
+    }
+
     public function providerOfInvalidYearThrowsException(): array
     {
         return [

tests/YearWeekTest.php

@@ -336,6 +336,49 @@ public function testToString(int $year, int $week, string $expected): void
         self::assertSame($expected, (string) $yearWeek);
     }
 
+    /**
+     * @dataProvider providerParse
+     */
+    public function testParse(string $string, int $expectedYear, int $expectedWeek): void
+    {
+        $yearWeek = YearWeek::parse($string);
+        self::assertYearWeekIs($expectedYear, $expectedWeek, $yearWeek);
+    }
+
+    public function providerParse(): array
+    {
+        return [
+            ['-2000-W12', -2000, 12],
+            ['-0100-W01', -100, 1],
+            ['2015-W01', 2015, 1],
+            ['2015-W48', 2015, 48],
+            ['2026-W53', 2026, 53],
+            ['120195-W23', 120195, 23],
+        ];
+    }
+
+    /**
+     * @dataProvider providerParseInvalidYearWeekThrowsException
+     */
+    public function testParseInvalidYearWeekThrowsException(string $invalidValue, ?string $error = null): void
+    {
+        $this->expectException(DateTimeException::class);
+        $this->expectExceptionMessage($error ?? 'Failed to parse "' . $invalidValue . '"');
+
+        YearWeek::parse($invalidValue);
+    }
+
+    public function providerParseInvalidYearWeekThrowsException(): array
+    {
+        return [
+            [''],
+            ['+2000-W01'],
+            ['2000W01'],
+            ['2000-W54', 'Invalid week-of-year: 54 is not in the range 1 to 53.'],
+            ['2025-W53', 'Year 2025 does not have 53 weeks'],
+        ];
+    }
+
     public function testNow(): void
     {
         $now = new FixedClock(Instant::of(2000000000));