Panic when compiling a regular expression

Question

I am writing a regular expression for password validation with the following code:

func IsPasswordValid(value string) bool {
    pattern := regexp.MustCompile(`^.*(?=.{7,})(?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[^a-zA-Z0-9]).*$`)
    return pattern.MatchString(value)
}

When I execute the application, it panics:

Line 45: - regexp: Compile(`^.*(?=.{7,})(?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[^a-zA-Z0-9]).*$`): error parsing regexp: invalid or unsupported Perl syntax: `(?=` 

This regular expression works in Javascript and Ruby but not in Go. What I am do wrong here?

Answer 1

From the docs:

The syntax of the regular expressions accepted is the same general syntax used by Perl, Python, and other languages. More precisely, it is the syntax accepted by RE2 and described at http://code.google.com/p/re2/wiki/Syntax, except for \C.

The RE2 wiki clearly states:

(?=re) before text matching re (NOT SUPPORTED)

See also:

• http://golang.org/pkg/regexp/
• https://code.google.com/p/re2/wiki/Syntax

EDIT: if you really need PCRE features, you can use a binding package, e.g. https://github.com/tuxychandru/golang-pkg-pcre/. Otherwise, try to rethink your regexp and what it should match.