inject language based on file extension & shebang (#3970)

* inject language based on file extension

Nodes can now be captured with "injection.filename". If this capture
contains a valid file extension known to Helix, then the content will
be highlighted as that language.

* inject language by shebang

Nodes can now be captured with "injection.shebang". If this capture
contains a valid shebang line known to Helix, then the content will
be highlighted as the language the shebang calls for.

* add documentation for language injection

* nix: fix highlights

The `@` is now highlighted properly on either side of the function arg.

Also, extending the phases with `buildPhase = prev.buildPhase + ''''`
is now highlighted properly.

Fix highlighting of `''$` style escapes (requires tree-sitter-nix bump)

Fix `inherit` highlighting.

* simplify injection_for_match

Split out injection pair logic into its own method to make the overall
flow easier to follow.

Also transform the top-level function into a method on a
HighlightConfiguration.

* markdown: add shebang injection query

3 files changed, 23 insertions, 4 deletions

diff --git a/runtime/queries/markdown/injections.scm b/runtime/queries/markdown/injections.scm
index e8839351..80977459 100644
--- a/runtime/queries/markdown/injections.scm
+++ b/runtime/queries/markdown/injections.scm
@@ -1,6 +1,10 @@
 ; From nvim-treesitter/nvim-treesitter
 
 (fenced_code_block
+  (code_fence_content) @injection.shebang @injection.content
+  (#set! injection.include-unnamed-children))
+
+(fenced_code_block
   (info_string
     (language) @injection.language)
   (code_fence_content) @injection.content (#set! injection.include-unnamed-children))
diff --git a/runtime/queries/nix/highlights.scm b/runtime/queries/nix/highlights.scm
index a998aa64..4633e178 100644
--- a/runtime/queries/nix/highlights.scm
+++ b/runtime/queries/nix/highlights.scm
@@ -47,8 +47,10 @@
 (float_expression) @constant.numeric.float
 
 (escape_sequence) @constant.character.escape
+(dollar_escape) @constant.character.escape
 
 (function_expression
+  "@"? @punctuation.delimiter
   universal: (identifier) @variable.parameter
   "@"? @punctuation.delimiter
 )
@@ -82,7 +84,8 @@
 (binding
   attrpath: (attrpath attr: (identifier)) @variable.other.member)
 
-(inherit_from attrs: (inherited_attrs attr: (identifier) @variable))
+(inherit_from attrs: (inherited_attrs attr: (identifier) @variable.other.member))
+(inherited_attrs attr: (identifier) @variable)
 
 (has_attr_expression
   expression: (_)
diff --git a/runtime/queries/nix/injections.scm b/runtime/queries/nix/injections.scm
index 62b48233..1da63ce0 100644
--- a/runtime/queries/nix/injections.scm
+++ b/runtime/queries/nix/injections.scm
@@ -10,9 +10,11 @@
 ; such as those of stdenv.mkDerivation.
 ((binding
    attrpath: (attrpath (identifier) @_path)
-   expression: (indented_string_expression
-     (string_fragment) @injection.content))
- (#match? @_path "(^\\w*Phase|(pre|post)\\w*|(.*\\.)?\\w*([sS]cript|[hH]ook)|(.*\\.)?startup)$")
+   expression: [
+     (indented_string_expression (string_fragment) @injection.content)
+     (binary_expression (indented_string_expression (string_fragment) @injection.content))
+   ])
+ (#match? @_path "(^\\w*Phase|command|(pre|post)\\w*|(.*\\.)?\\w*([sS]cript|[hH]ook)|(.*\\.)?startup)$")
  (#set! injection.language "bash")
  (#set! injection.combined))
 
@@ -150,3 +152,13 @@
 ;  (#match? @_func "(^|\\.)writeFSharp(Bin)?$")
 ;  (#set! injection.language "f-sharp")
 ;  (#set! injection.combined))
+
+((apply_expression
+   function: (apply_expression function: (_) @_func
+     argument: (string_expression (string_fragment) @injection.filename))
+   argument: (indented_string_expression (string_fragment) @injection.content))
+ (#match? @_func "(^|\\.)write(Text|Script(Bin)?)$")
+ (#set! injection.combined))
+
+((indented_string_expression (string_fragment) @injection.shebang @injection.content)
+  (#set! injection.combined))
\ No newline at end of file