Add support for get documentation

ocaml-eglot-req.el

@@ -84,6 +84,14 @@ included and the documentation output can be set using MARKUP-KIND."
           `(:with_doc, with-doc)
           `(:doc_dormat, markup-kind)))
 
+(defun ocaml-eglot-req--GetDocumentationParam (identifier markup-kind)
+  "Compute the `GetDocumentationParam'.
+A potential IDENTIFIER can be given and MARKUP-KIND can be parametrized."
+  (let ((params (append (ocaml-eglot-req--TextDocumentPositionParams)
+                        `(:contentFormat, markup-kind))))
+    (if identifier (append params `(:identifier, identifier))
+      params)))
+
 ;;; Concrete requests
 
 (defun ocaml-eglot-req--jump (target)
@@ -121,5 +129,14 @@ The markup used to format documentation can be set using MARKUP-KIND."
   (let ((params (make-vector 1 uri)))
     (ocaml-eglot-req--send :ocamllsp/inferIntf params)))
 
+(defun ocaml-eglot-req--get-documentation (identifier markup-kind)
+  "Execute the `ocamllsp/getDocumentation'.
+If IDENTIFIER is non-nil, it documents it, otherwise, it use the identifier
+under the cursor.  The MARKUP-KIND can also be configured."
+  (let ((params (ocaml-eglot-req--GetDocumentationParam
+                 identifier
+                 markup-kind)))
+    (ocaml-eglot-req--send :ocamllsp/getDocumentation params)))
+
 (provide 'ocaml-eglot-req)
 ;;; ocaml-eglot-req.el ends here

ocaml-eglot-util.el

@@ -89,6 +89,10 @@
   (when (not (ocaml-eglot-util--on-interface))
     (eglot--error "Function is only available for interfaces")))
 
+(defun ocaml-eglot-util--format-markup (markup)
+  "Format MARKUP according to LSP's spec."
+  (eglot--format-markup markup))
+
 ;; Jump features
 
 (defun ocaml-eglot-util--extract-jump-position (jump-result)

ocaml-eglot.el

@@ -63,7 +63,7 @@ Otherwise, `merlin-construct' only includes constructors."
   :group 'ocaml-eglot
   :type 'boolean)
 
-(defcustom ocaml-eglot-preferred-markupkind "plaintext"
+(defcustom ocaml-eglot-preferred-markupkind "markdown"
   "Preferred markup format."
   :group 'ocaml-eglot
   :type 'string)
@@ -274,9 +274,10 @@ of result (LIMIT)."
   (let* ((start (eglot--pos-to-lsp-position))
          (limit (or(if (> limit 1) limit nil)
                    ocaml-eglot-type-search-limit 25))
-         (markup-kind ocaml-eglot-preferred-markupkind)
          (with-doc (or ocaml-eglot-type-search-include-doc :json-false))
-         (entries (ocaml-eglot-req--search query limit with-doc markup-kind))
+         ;; We use plaintext because the result of the documentation may
+         ;; be truncated
+         (entries (ocaml-eglot-req--search query limit with-doc "plaintext"))
          (choices (ocaml-eglot--search-to-completion entries))
          (chosen  (ocaml-eglot--search-completion
                    choices
@@ -323,6 +324,26 @@ It use the ARG to use local values or not."
           (insert-construct-choice choice))))))
 
 
+;; Get Documentation
+
+(defun ocaml-eglot--document-aux (identifier)
+  "Displays the OCaml documentation for the IDENTIFIER under the cursor."
+  (when-let* ((result (ocaml-eglot-req--get-documentation
+                       identifier ocaml-eglot-preferred-markupkind))
+              (doc-value (cl-getf result :doc))
+              (formated-value (ocaml-eglot-util--format-markup doc-value)))
+    (message "%s" formated-value)))
+
+(defun ocaml-eglot-document ()
+  "Displays the OCaml documentation for the identifier under the cursor."
+  (interactive)
+  (ocaml-eglot--document-aux nil))
+
+(defun ocaml-eglot-document-identifier (identifier)
+  "Displays the OCaml documentation for a given IDENTIFIER."
+  (interactive "sIdentifier: ")
+  (ocaml-eglot--document-aux identifier))
+
 ;;; Mode
 
 (defvar ocaml-eglot-map
@@ -331,6 +352,7 @@ It use the ARG to use local values or not."
     (define-key ocaml-eglot-keymap (kbd "C-c C-c") #'ocaml-eglot-error-prev)
     (define-key ocaml-eglot-keymap (kbd "C-c C-l") #'ocaml-eglot-locate)
     (define-key ocaml-eglot-keymap (kbd "C-c C-a") #'ocaml-eglot-alternate-file)
+    (define-key ocaml-eglot-keymap (kbd "C-c C-d") #'ocaml-eglot-document)
     ocaml-eglot-keymap)
   "Keymap for OCaml-eglot minor mode.")