[perl5] Add lsp support

layers/+lang/perl5/README.org

@@ -8,8 +8,11 @@
 - [[#description][Description]]
   - [[#features][Features:]]
 - [[#install][Install]]
-  - [[#layer][Layer]]
-  - [[#auto-completion-plsense][Auto-completion: PlSense]]
+- [[#configuration][Configuration]]
+  - [[#choosing-a-backend][Choosing a backend]]
+    - [[#company-plsense][Company-plsense]]
+      - [[#auto-completion-plsense][Auto-completion: PlSense]]
+    - [[#lsp][LSP]]
 - [[#key-bindings][Key bindings]]
   - [[#perldoc][Perldoc]]
   - [[#pod-and-here-doc][POD and HERE doc]]
@@ -21,20 +24,66 @@ This layer adds support for the Perl5 language.
 
 ** Features:
 - Syntactic and semantic checking using [[https://github.com/flycheck/flycheck][flycheck]]
-- Auto-completion using [[https://github.com/CeleritasCelery/company-plsense][company-plsense]]
+- Auto-completion
 - Format code with =perltidy=
 - Jump to symbol definition
 - Interactive debug via [[https://github.com/realgud/realgud][realgud]] with [[http://search.cpan.org/~rocky/Devel-Trepan-0.73/lib/Devel/Trepan.pm][trepan.pl]]
+- LSP and DAP support
 
 * Install
-** Layer
 To use this configuration layer, add it to your =~/.spacemacs=. You will need to
 add =perl5= to the existing =dotspacemacs-configuration-layers= list in this
 file.
 
-** Auto-completion: PlSense
+* Configuration
+All layer configurations can be done by setting layer variables in your dotfile.
+No custom user config lines are necessary
+
+** Choosing a backend
+This layer provides two alternative backends to choose from.
+
+*** Company-plsense
+This is the default choice if nothing is set and no lsp layer
+is loaded in your dotfile. This mode only provides very
+limited IDE capabilities. Used best if only small files
+are edited. To set explicitly set the following in your
+dotfile:
+
+#+BEGIN_SRC emacs-lisp
+  (perl5 :variables perl5-backend 'company-plsense)
+#+END_SRC
+
+**** Auto-completion: PlSense
 =company-plsense= requires installation of the =plsense= server from [[https://github.com/aki2o/plsense#install][here]].
 
+*** LSP
+For proper IDE support this backend should be used. It is
+based on an external server which will be started automatically
+by emacs, once a perl5 file is opened. The key bindings are
+the same for all lsp modes so if you are already familiar with
+one you should be able to work the same in all modes.
+
+To set explicitly do the following in your dotfile:
+
+#+BEGIN_SRC emacs-lisp
+  (perl5 :variables
+         perl5-backend 'lsp)
+#+END_SRC
+
+For this to work you will also need to obtain
+the latest version of the lsp server from [[https://github.com/richterger/Perl-LanguageServer][here]].
+
+Alternatively the server can be installed with:
+
+#+BEGIN_SRC sh
+  cpan Perl::LanguageServer
+#+END_SRC
+
+NOTE: Key bindings for LSP are defined in the
+LSP layer. Also it is advisable to have a look
+at the autocomplete layer for an optimal
+intellisense config for LSP.
+
 * Key bindings
 ** Perldoc
 Browse formatted perldocs.

layers/+lang/perl5/config.el

@@ -16,3 +16,8 @@
 
 (defvar perl5-perltidy-options '()
   "Command line options to pass to perltidy")
+
+(defvar perl5-backend nil
+  "The backend to use for IDE features.
+Possible values are `lsp' and `company-plsense'.
+If `nil' then 'company-plsense` is the default backend unless `lsp' layer is used")

layers/+lang/perl5/funcs.el

@@ -9,6 +9,36 @@
 ;;
 ;;; License: GPLv3
 
+(defun spacemacs//perl5-backend ()
+  "Return selected backend."
+  (if perl5-backend
+      perl5-backend
+    (cond
+     ((configuration-layer/layer-used-p 'lsp) 'lsp)
+     (t 'company-plsense))))
+
+(defun spacemacs//perl5-setup-company ()
+  "Conditionally setup company based on backend."
+  (pcase (spacemacs//perl5-backend)
+    ;; Activate lsp company explicitly to activate
+    ;; standard backends as well
+    (`lsp (spacemacs|add-company-backends
+            :backends company-capf
+            :modes cperl-mode))
+    (`company-plsense (spacemacs|add-company-backends)
+                      :backends company-plsense
+                      :modes cperl-mode)))
+
+(defun spacemacs//perl5-setup-backend ()
+  "Conditionally setup perl5 backend."
+  (pcase (spacemacs//perl5-backend)
+    (`lsp (lsp))))
+
+(defun spacemacs//perl5-setup-dap ()
+  "Conditionally setup perl5 DAP integration."
+  ;; currently DAP is only available using LSP
+  (pcase (spacemacs//perl5-backend)
+    (`lsp (add-hook 'cperl-mode-hook #'dap-mode))))
 
 (defun spacemacs//perl5-smartparens-enable ()
   (define-key cperl-mode-map "{" nil))

layers/+lang/perl5/layers.el

@@ -0,0 +1,14 @@
+;;; layers.el --- Perl5 Layer layers File for Spacemacs
+;;
+;; Copyright (c) 2012-2020 Sylvain Benner & Contributors
+;;
+;; Author: Maximilian Wolff <smile13241324@gmail.com>
+;; URL: https://github.com/syl20bnr/spacemacs
+;;
+;; This file is not part of GNU Emacs.
+;;
+;;; License: GPLv3
+
+(when (and (boundp 'perl5-backend)
+           (eq perl5-backend 'lsp))
+  (configuration-layer/declare-layer-dependencies '(lsp)))

layers/+lang/perl5/packages.el

@@ -9,23 +9,27 @@
 ;;
 ;;; License: GPLv3
 
-(setq perl5-packages
-      '(
-        (company-plsense :requires company)
-        (cperl-mode :location built-in)
-        flycheck
-        org
-        realgud
-        smartparens
-        ))
+(defconst perl5-packages
+  '(
+    (company-plsense :requires company)
+    (cperl-mode :location built-in)
+    flycheck
+    org
+    dap-mode
+    realgud
+    smartparens))
+
+(defun perl5/pre-init-dap-mode ()
+  (pcase (spacemacs//perl5-backend)
+    (`lsp (add-to-list 'spacemacs--dap-supported-modes 'cperl-mode)
+          (add-hook 'cperl-mode-hook #'dap-mode))))
+
+(defun perl5/post-init-company ()
+  (spacemacs//perl5-setup-company))
 
 (defun perl5/init-company-plsense ()
   (use-package company-plsense
-    :defer t
-    :init
-    (spacemacs|add-company-backends
-     :backends company-plsense
-     :modes cperl-mode)))
+    :defer t))
 
 (defun perl5/init-cperl-mode ()
   (use-package cperl-mode
@@ -33,7 +37,6 @@
     :mode "\\.\\(p[lm]x?\\|P[LM]X?\\)\\'"
     :interpreter "perl"
     :interpreter "perl5"
-
     :init
     (progn
       (setq
@@ -42,8 +45,8 @@
        cperl-indent-level 4        ; 4 spaces is the standard indentation
        cperl-close-paren-offset -4 ; indent the closing paren back four spaces
        cperl-continued-statement-offset 4 ; if a statement continues indent it to four spaces
-       cperl-indent-parens-as-block t)) ; parentheses are indented with the block and not with scope
-
+       cperl-indent-parens-as-block t) ; parentheses are indented with the block and not with scope
+      (add-hook 'cperl-mode-hook #'spacemacs//perl5-setup-backend))
     :config
     (progn
       ;; Don't highlight arrays and hashes in comments
@@ -106,19 +109,20 @@
       (add-hook 'cperl-mode-hook
                 (lambda () (local-set-key (kbd "<tab>") 'indent-for-tab-command)))
 
-      (spacemacs/declare-prefix-for-mode 'cperl-mode "m=" "format")
-      (spacemacs/declare-prefix-for-mode 'cperl-mode "mg" "find-symbol")
-      (spacemacs/declare-prefix-for-mode 'cperl-mode "mh" "perldoc")
+      (unless (eq (spacemacs//perl5-backend) 'lsp)
+        (spacemacs/declare-prefix-for-mode 'cperl-mode "m=" "format")
+        (spacemacs/declare-prefix-for-mode 'cperl-mode "mg" "find-symbol")
+        (spacemacs/declare-prefix-for-mode 'cperl-mode "mh" "perldoc"))
       (spacemacs/set-leader-keys-for-major-mode 'cperl-mode
+        "hh" 'cperl-perldoc-at-point
         "==" 'spacemacs/perltidy-format
         "=b" 'spacemacs/perltidy-format-buffer
         "=f" 'spacemacs/perltidy-format-function
-        "hh" 'cperl-perldoc-at-point
         "hd" 'cperl-perldoc
         "v" 'cperl-select-this-pod-or-here-doc)
 
       (font-lock-add-keywords 'cperl-mode
-                      '(("\\_<say\\_>" . cperl-nonoverridable-face))))))
+                              '(("\\_<say\\_>" . cperl-nonoverridable-face))))))
 
 (defun perl5/post-init-flycheck ()
   (spacemacs/enable-flycheck 'cperl-mode))