import re

_SEMVER_RE = re.compile(
    r'^(?P<major>0|[1-9]\d*)\.(?P<minor>0|[1-9]\d*)\.(?P<patch>0|[1-9]\d*)'
    r'(?:-(?P<prerelease>(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*)'
    r'(?:\.(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*))*))?'
    r'(?:\+(?P<build>[0-9a-zA-Z-]+(?:\.[0-9a-zA-Z-]+)*))?$'
)


def parse_semver(s):
    if not isinstance(s, str):
        return None
    m = _SEMVER_RE.match(s)
    if m is None:
        return None
    return {
        "major": int(m.group("major")),
        "minor": int(m.group("minor")),
        "patch": int(m.group("patch")),
        "prerelease": m.group("prerelease"),
        "build": m.group("build"),
    }