Underscores not working in named segments

[basicdays]

Hey all,

Just tried to have a named segment with an underscore, and found that it wasn't working as expected. I have a sample script and output to have as an example:

#!/usr/bin/env node
const UrlPattern = require('url-pattern');
const pattern = new UrlPattern('/test/:value_here');

console.dir(pattern);
console.log(pattern.match('/test/stuff'));
console.log(pattern.match('/test/stuff_here'));

UrlPattern {
  isRegex: false,
  ast:
   [ { tag: 'static', value: '/test/' },
     { tag: 'named', value: 'value' },
     { tag: 'static', value: '_here' } ],
  regex: /^\/test\/([a-zA-Z0-9-_~ %]+)_here$/,
  names: [ 'value' ] }
null
{ value: 'stuff' }

It seems to be parsing the underscore in the named segment as a static separator by accident.

[snd]

it's working as intended.

https://github.com/snd/url-pattern#named-segments states that:

the name must be at least one character in the regex character set a-zA-Z0-9.

note that this doesn't include _.

you can make it work as you expect:

> const UrlPattern = require('url-pattern');
> const pattern = new UrlPattern('/test/:value_here', {segmentNameCharset: 'a-zA-Z0-9_-'});

> console.dir(pattern);
{ isRegex: false,
  ast: 
   [ { tag: 'static', value: '/test/' },
     { tag: 'named', value: 'value_here' } ],
  regex: /^\/test\/([a-zA-Z0-9-_~ %]+)$/,
  names: [ 'value_here' ] }
> console.log(pattern.match('/test/stuff'));
{ value_here: 'stuff' }
> console.log(pattern.match('/test/stuff_here'));
{ value_here: 'stuff_here' }

for all options see: https://github.com/snd/url-pattern#customize-the-pattern-syntax

i see that this default can be confusing and i consider changing it in the future. see #33