lsp-erlang: Add semantic token support for erlang-language-platform (#…

…4166)

Supporting
"bound"               default :underline, bound variable in pattern
"exported_function"   default :underline
"deprecated_function" default :strike-through

CHANGELOG.org

@@ -1,5 +1,6 @@
 * Changelog
 ** Unreleased 8.0.1
+  * Add semantic token support for [[https://github.com/WhatsApp/erlang-language-platform][erlang-language-platform]] in lsp-erlang client.
   * Update [[https://github.com/WhatsApp/erlang-language-platform][erlang-language-platform]] download file names to match new upstream names.
   * Add [[https://github.com/WhatsApp/erlang-language-platform][erlang-language-platform]] support in lsp-erlang client.
   * Add [[https://github.com/elixir-tools/credo-language-server][credo-language-server]]

clients/lsp-erlang.el

@@ -25,6 +25,7 @@
 ;;; Code:
 
 (require 'lsp-mode)
+(require 'lsp-semantic-tokens)
 
 (defgroup lsp-erlang nil
   "LSP support for the Erlang programming language.
@@ -41,6 +42,12 @@ It can use erlang-ls or erlang-language-platform (ELP)."
   :group 'lsp-mode
   :link '(url-link "https://github.com/WhatsApp/erlang-language-platform"))
 
+(defgroup lsp-erlang-elp-semantic-tokens nil
+  "LSP semantic tokens support for ELP."
+  :group 'lsp-erlang-elp
+  :link '(url-link "https://github.com/WhatsApp/erlang-language-platform")
+  :package-version '(lsp-mode . "8.0.1"))
+
 (defcustom lsp-erlang-server 'erlang-ls
   "Choose LSP server."
   :type '(choice (const :tag "erlang-ls" erlang-ls)
@@ -119,6 +126,59 @@ It can use erlang-ls or erlang-language-platform (ELP)."
              :set-executable? t)
  '(:system "elp"))
 
+;; Semantic tokens
+
+;; Modifier faces
+
+(defface lsp-erlang-elp-bound-modifier-face
+  '((t :underline t))
+  "The face modification to use for bound variables in patterns."
+  :group 'lsp-erlang-elp-semantic-tokens)
+
+(defface lsp-erlang-elp-exported-function-modifier-face
+  '((t :underline t))
+  "The face modification to use for exported functions."
+  :group 'lsp-erlang-elp-semantic-tokens)
+
+(defface lsp-erlang-elp-deprecated-function-modifier-face
+  '((t :strike-through t))
+  "The face modification to use for deprecated functions."
+  :group 'lsp-erlang-elp-semantic-tokens)
+
+
+;; ---------------------------------------------------------------------
+;; Semantic token modifier face customization
+
+(defcustom lsp-erlang-elp-bound-modifier 'lsp-erlang-elp-bound-modifier-face
+  "Face for semantic token modifier for `bound' attribute."
+  :type 'face
+  :group 'lsp-erlang-elp-semantic-tokens
+  :package-version '(lsp-mode . "8.0.1"))
+
+(defcustom lsp-erlang-elp-exported-function-modifier 'lsp-erlang-elp-exported-function-modifier-face
+  "Face for semantic token modifier for `exported_function' attribute."
+  :type 'face
+  :group 'lsp-erlang-elp-semantic-tokens
+  :package-version '(lsp-mode . "8.0.1"))
+
+(defcustom lsp-erlang-elp-deprecated-function-modifier 'lsp-erlang-elp-deprecated-function-modifier-face
+  "Face for semantic token modifier for `deprecated_function' attribute."
+  :type 'face
+  :group 'lsp-erlang-elp-semantic-tokens
+  :package-version '(lsp-mode . "8.0.1"))
+
+;; ---------------------------------------------------------------------
+
+(defun lsp-erlang-elp--semantic-modifiers ()
+  "Mapping between rust-analyzer keywords and fonts to apply.
+The keywords are sent in the initialize response, in the semantic
+tokens legend."
+  `(
+    ("bound" . ,lsp-erlang-elp-bound-modifier)
+    ("exported_function" . ,lsp-erlang-elp-exported-function-modifier)
+    ("deprecated_function" . ,lsp-erlang-elp-deprecated-function-modifier)))
+
+;; ---------------------------------------------------------------------
 ;; Client
 
 (lsp-register-client
@@ -132,6 +192,9 @@ It can use erlang-ls or erlang-language-platform (ELP)."
                        ,@(cl-rest lsp-erlang-elp-server-command))))
   :activation-fn (lsp-activate-on "erlang")
   :priority (if (eq lsp-erlang-server 'erlang-language-platform) 1 -2)
+  :semantic-tokens-faces-overrides `(:discard-default-modifiers t
+                                                                :modifiers
+                                                                ,(lsp-erlang-elp--semantic-modifiers))
   :server-id 'elp
   :custom-capabilities `((experimental . ((snippetTextEdit . ,(and lsp-enable-snippet (featurep 'yasnippet))))))
   :download-server-fn (lambda (_client callback error-callback _update?)