[TxMt] Re: Ordering in language grammar

[Allan Odgaard]

On 25 Mar 2015, at 22:12, Jacob Carlborg wrote:

> I'm trying to match the following code in the D language grammar:
>
> static if (true) {}
>
> void foo ()
> {
>  static if (true) {}
> }
>
> The first static-if is correctly recognized as 
> "keyword.control.conditional.d". But the static-if inside "foo" is 
> recognized as a method "meta.definition.method.d". I managed to get 
> the top level static-if correctly recognized by moving the pattern for 
> the static-if before the pattern for a method. But I don't understand 
> why that doesn't work inside "foo".

This is because of the indent. The rule for 
‘meta.definition.method.d’ will match from the start of the line 
(eating leading whitespace), so while the static keyword rule has 
precedence, this rule cannot match at the beginning of the line (where 
there is just whitespace), so TextMate will instead pick the rule that 
can match.

You could prefix the keyword.control.conditional.d pattern with (^\s+) 
so that this rule will also be a candidate when at the beginning of the 
line, though in general having rules match leading whitespace makes the 
grammar more difficult to work with (as you’ll get these unexpected 
issues).

> Another thing I noticed is the "static if" on the top level seems to 
> be recognized as a single word. When I use the hot keys for moving the 
> cursor a word it jumps from the start of "static" to the end of "if", 
> instead of to the end of "static".

This is because the whitespace between the two keywords are scoped as a 
keyword, so TextMate consider the entire thing a single unit for 
character movement (and word selection, etc.).

One way to fix this is by using captures for the non-whitespace and only 
assigning a scope name to the captures, e.g.:

	{	match = '\b(?:(?<keyword>static)\s+)?(?<keyword>if|else|switch)\b';
		captures = {
			keyword = { name = 'keyword.control.conditional.d'; };
		};
	},

For more info about character classes (which is used for word movement) 
see this blog post: http://blog.macromates.com/2012/clever-completion/