Syntax highlighting that plays well with font-lock

[ubolonton]

This is a continuation of #16.

• Add a minor mode tree-sitter-hl-mode.
• Add mechanism for major modes to customize syntax highlighting: tree-sitter-hl-default-patterns.
• Add default syntax highlighting patterns to the language bundle tree-sitter-langs. This will be left for later, after improving the binary distribution mechanism.
• Face mapping
  • Define faces for most common capture names (scopes) defined in the language repos, e.g. @function.method would map to tree-sitter-hl-face:function.method.
  • Prioritize captures in earlier patterns, when multiple patterns match.
  • Allow end user to add more query patterns: tree-sitter-hl-add-patterns.
  • Map capture names to face names automatically. For example @:font-lock-keyword-face can be mapped to the face font-lock-keyword-face. This will be done later, after discussing with upstream tree-sitter about standardization/conventions.
  • Allow end user to selectively disable certain capture names.
• Respect custom keywords added by user through font-lock-add-keywords. This is too difficult currently, even for font-lock-mode itself (see font-lock-refresh-defaults).
• Support code blocks in org-mode and markdown-mode.
• Support embedded blocks of other languages (injections). This will be left for later.

For now, trying this requires cloning the language repos into the directory repos/ next to tree-sitter-langs.el (regardless of installation method).

I've been using this, and haven't noticed any performance difference from font-lock-mode.
In fact, sometimes it feels faster, in large C buffers.

[dgutov]

Maybe you want to use condition-case instead?

[ubolonton]

This doesn't handle the error. It runs some cleanup code and lets the error propagate.

The closest condition-case equivalent I can think of doesn't preserve the backtrace:

`(condition-case err
    ,body-form
   (error
    ,@error-forms
    (signal (car err) (cdr err))))

[ubolonton]

Extra query patterns can now be added dynamically:

(add-hook 'rust-mode-hook
          (lambda ()
            (tree-sitter-hl-add-patterns
             [(call_expression
               function: (field_expression
                          field: (field_identifier) @function.call))
              (let_declaration (identifier) @variable)
              "?" @keyword
              (self) @keyword])))

Before:

After:

[shackra]

amazing! didn't keep an eye on the project and suddenly, BANG! Syntax highlight is mostly done.