import re

_SEMVER_RE = re.compile(
    r'^(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)'
    r'(?:-((?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*)(?:\.(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*))*))?'
    r'(?:\+([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 not m:
        return None
    major, minor, patch, prerelease, build = m.groups()
    return {
        'major': int(major),
        'minor': int(minor),
        'patch': int(patch),
        'prerelease': prerelease,
        'build': build,
    }