Python Package Version (PEP 440) Regex for Go

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching python package version (pep 440), ported and verified for Go. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. The snippet below is ready to drop into your Go project — whether you're validating in a Gin handler, a gRPC service, or a command-line tool.

Go Implementation

// Python Package Version (PEP 440)
// ReDoS-safe | RegexVault — Dev & Systems > SemVer

package validation

import "regexp"

var pythonPackageVersionPep440Re = regexp.MustCompile(`^(?:([0-9]+)!)?([0-9]+(?:\.[0-9]+)*)(?:[-_.]?(?:a|alpha|b|beta|c|rc|preview)[-_.]?([0-9]+))?(?:[-_.]?post[-_.]?([0-9]+))?(?:[-_.]?dev[-_.]?([0-9]+))?(?:\+([a-zA-Z0-9]+(?:[-_.][a-zA-Z0-9]+)*))?$`)

func ValidatePythonPackageVersionPep440(s string) bool {
    return pythonPackageVersionPep440Re.MatchString(s)
}

// Example
// fmt.Println(ValidatePythonPackageVersionPep440("1.0")) // true

Test Cases

When to use this pattern

This pattern is drawn from the Dev & Systems > SemVer category and carries a ReDoS-safe certification. That matters for Go developers because Go's RE2 engine is inherently safe from catastrophic backtracking, but this pattern has been additionally verified for correctness. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

PEP 440 allows epoch (1!), pre-release suffixes (a/alpha/b/beta/rc), post-releases (.post1), dev releases (.dev1), and local version labels (+local). Use packaging.version.Version() in Python for canonical parsing.