$v = "1.5.8-alpha+20200305";

// functional API
if (semver_valid($v)) {
    echo "Version {$v} is valid";
}
if (semver_valid($v) && semver_compare($v, "1.0.0") > 0) {
    echo "Version {$v} is greather than 1.0.0";
}
if (semver_satisfies($v, "1.2", ">=")) {
    echo "Version {$v} satisfies >=1.2.0 constraint";
}
// bumping versions
echo semver_bump_patch(semver_bump_minor(semver_bump("0.0.0"))); // 1.1.1

// OOP API
$version = SemverVersion::createFromString($v);
echo $version->major; // 1
echo $version->minor; // 5
echo $version->patch; // 8
echo $version->prerelease; // alpha
echo $version->metadata; // 20200305

$newVersion = new SemverVersion(1, 5, 8, "beta", date("Ymd"));

/**
 * Validates given string if is a valid semver compliant version string
 *
 * @param string $version version string to verify
 * @return true in case of semver compliant version string, false otherwise
 */
function semver_valid(string $version): bool {}

/**
 * Converts given string into int (usefull for ordering)
 *
 * @param string $version version string to convert
 * @return int computed numerical version representation
 * @throws InvalidArgumentException in case of invalid semver non-compliant version string
 */
function semver_numeric(string $version): int {}

/**
 * Compares two semver compliant version strings (usefull for sorting)
 * 
 * @param string $x valid semver version string to compare
 * @param string $y valid semver version string to compare against
 * @return int returns -1 if $x is less than $y, 0 if $x and $y are equal of 1 if $x is greather than $y
 * @throws InvalidArgumentException in case of invalid semver non-compliant version string arguments
 */
function semver_compare(string $x, string $y): int {}

/**
 * Compares if two semver compliant version strings fullfils one of the operators:
 * - `=`  - Equality
 * - `>=` - Higher or equal to
 * - `<=` - Lower or equal to
 * - `<`  - Lower than
 * - `>`  - Higher than
 * - `~`  - Tilde comparison (see https://getcomposer.org/doc/articles/versions.md#tilde-version-range-)
 * - `^`  - Caret comparison (see https://getcomposer.org/doc/articles/versions.md#caret-version-range-)
 *
 * @param string $x valid semver version string to compare
 * @param string $y valid semver version string to compare against
 * @param string $op comparator operator
 * @return int returns -1 if $x is less than $y, 0 if $x and $y are equal of 1 if $x is greather than $y
 * @throws InvalidArgumentException in case of invalid semver non-compliant version string arguments
 */
function semver_satisfies(string $x, string $y, string $op): bool {}

/**
 * Bumps major semver version string
 * 
 * @param string $version valid semver version string
 * @return string returns semver version string with bumped major version
 * @throws InvalidArgumentException in case of invalid semver non-compliant version string argument
 */
function semver_bump(string $version): stirng {}

/**
 * Bumps minor semver version string
 * 
 * @param string $version valid semver version string
 * @return string returns semver version string with bumped minor version
 * @throws InvalidArgumentException in case of invalid semver non-compliant version string argument
 */
function semver_bump_minor(string $version): stirng {}

/**
 * Bumps patch semver version string
 * 
 * @param string $version valid semver version string
 * @return string returns semver version string with bumped patch version
 * @throws InvalidArgumentException in case of invalid semver non-compliant version string argument
 */
function semver_bump_patch(string $version): stirng {}

class SemverVersion
{
    public readonly int $major = 0;
    public readonly int $minor = 0;
    public readonly int $patch = 0;
    public readonly ?string $prerelease = null;
    public readonly ?string $metadata = null;

    /**
     * Parses semver compliant version string and create SemverVersion object
     * 
     * @param string $version valid semver version string
     * @return SemverVersion returns semver version object
     * @throws InvalidArgumentException in case of invalid semver non-compliant version string argument
     */
    public static function createFromString(string $version): self {}

    /**
     * Create SemverVersion object
     * 
     * @param int $major non-negative major version number
     * @param int $minor non-negative minor version number
     * @param int $patch non-negative patch version number
     * @param string|null $prerelease valid semver prerelease string
     * @param string|null $metadata valid semver metadata string
     * @throws InvalidArgumentException in case of invalid semver non-compliant version arguments
     */
    public function __construct(int $major, int $minor, int $patch, ?string $prerelease = null, ?string $metadata = null) {}

    /**
     * Renders SemverVersion object into semver version string
     * 
     * @return string returns rendered semver version string
     */
    public function __toString(): string {}
}