René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"completions of [validateset] parameters fails to escape special characters","articleBody":"# Steps to reproduce\r\n\r\n```powershell\r\nfunction test ([validateset('$test', 'test$', 'test test', '#', '# hello', '#requires more', '\u003c# hello #\u003e')]$test) {echo $test}\r\n\r\ntest \u003cALT-SPACE\u003e   # value `$test` will not be escaped or quoted due to `$`, nor will the completions that start with `#`, except `#requires more` gets quoted\r\n# also, `\u003c# hello #\u003e` fails to be quoted\r\ntest \"\u003cALT-SPAC\u003e\"  # values `$test` and `test$` will not have the `$` escaped\r\n```\r\n\r\n# Expected behavior\r\n\r\nAll special characters (those affecting tokenizing the argument correct intentions) would force quoting or escaping.  \r\n\r\n# Actual behavior\r\n\r\nSome characters do, some do not.  \r\n\r\nThis is due to a reliance of using the parser (via CompletionRequiresQuotes() method) to determine if there is more than 1 token, or if the parser has an error parsing the tokens contained in the completion.  In the case of `$test` the parser sees exactly the one successful token and no more.  I've also determined the same is happening for `#`\r\n\r\nI understand why the parser is being used, but I think the idea is flawed because the parser doesn't know the full context of the completion, and can be swayed, as I have done here with the `$test` argument value.\r\n\r\n# Environment data\r\n\r\nPowerShell 7.0.0-preview.2\r\n\r\n# Considerations\r\n\r\nThis is partially related to other completion bugs I have been reporting.  I'd like to consider writing a more specific helper function/method for handling argument completions that can correctly determine if an argument needs quoted, and/or (if already quoted) properly escaped, and would not rely directly on the parser.  I have covered this idea in #9881, and I am working on converting the PowerShell code example to C#.  Using this helper, all argument type completions will be funneled through a single method for proper quoting and escaping.  This does mean that making tweaks to the parser that might affect how a completion needs to be quoted/escaped would require tweaking this helper as well.\r\n","author":{"url":"https://github.com/msftrncs","@type":"Person","name":"msftrncs"},"datePublished":"2019-07-24T01:31:20.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":5},"url":"https://github.com/10218/PowerShell/issues/10218"}