`\A` should not be needed.  Also, `_`, `+`, `'`, `:`, `/`, `,`, and `.` do not need to be in here.  They should be passed as single characters without the backslash.  Only `-` and `\s` make sense here, and for hyphen I would also say that the user calling this function should not be the one to put the `\` in front - our code here should do that specifically for hyphen.