Added "Bind to grammar/schema" to command palette

[AlexXuChen]

Added new command, "Bind to grammar/schema", to command palette menu.

Closes #514

Signed-off-by: Alexander Chen alchen@redhat.com

[datho7561]

Something that I ran into is that this will fail if the document has no root element. The code for the CodeLens assumes that there is a root element, since the CodeLens is placed right above the root element.

eg. try binding the following file to a grammar:

<?xml version="1.0" encoding="UTF-8"?>

This will involve adding a check in LemMinX to see if there is a root element when trying to build the edit to add the grammar association.

[AlexXuChen]

FOR REFERENCE:

this fix won't solve if the user manually deletes the schema binding, this can be added with an onDidChangeTextDocument listener:

 async function onDidChangeTextDocument(document: TextDocument) {
    if (typeof timeout !== 'undefined') {
      clearTimeout(timeout);
    }

    await checkCanBindGrammar(document);
  }
  return Disposable.from(...disposables);

and called as:

workspace.onDidChangeTextDocument(event => onDidChangeTextDocument(event.document), null, disposables);

[angelozerr]

this fix won't solve if the user manually deletes the schema binding, this can be added with an onDidChangeTextDocument listener:

AssociateGrammarCommand should throw an error when XML document is already bound to a XSD/DTD. See my comments at https://github.com/eclipse/lemminx/pull/1084/files#r672637564

I agree with you, without onDidChangeTextDocument, the menu to bind a grammar will appear if user write teh binding with the editor, but if it applies the binding, AssociateGrammarCommand will throw an error.

[angelozerr]

After playing with this PR, I think hide command with setContext is not a good idea because:

• we need to track the binding declaration inside XML file and I find code is complex just to hide a menu.
• I have in my mind a new feature to give the capability to rebind a XML with an another XSD/DTD file for instance. In this case the command should be visible every time. But it's out the scope of the PR.

In other words, I think should remove the canBindGrammar from package.json and all code which update setContext. When user will try to bind the XML with a grammar and this XML i salready bound, we should just display an error message like I suggested in https://github.com/redhat-developer/vscode-xml/pull/544/files#r673821683

We could improve that in future release by rebind teh XMLwith a new XSD/DTD by improving AssociateGrammarCommand.

[angelozerr]

Code is now perfect and I play with the lemMinx / vscode-xml PR and it works great. There is some usecase that we must improve but we can do that in an another PR (ex : try to bind with XML which have no root tag element, bind a xml-model, etc.).

I will create an issue for that as soon as this PR are merged. Once LemMinx PR will be merged (see my comments), I'm OK to merge this PR.