Add indentation information segment

mood-line.el

@@ -169,6 +169,123 @@
 ;; Variable definitions
 ;; ---------------------------------- ;;
 
+(defcustom mood-line-show-indentation-information nil
+  "When non-nil, show the indentation information of the current buffer."
+  :group 'mood-line
+  :type 'boolean)
+
+;; Based on `editorconfig-indentation-alist' and `doom-modeline-indent-alist'.
+;; See <https://github.com/editorconfig/editorconfig-emacs/blob/master/editorconfig.el#L175>.
+;; See <https://github.com/seagle0128/doom-modeline/blob/master/doom-modeline-core.el#L282>.
+(defcustom mood-line-indent-alist
+  '((apache-mode apache-indent-level)
+    (awk-mode c-basic-offset)
+    (bpftrace-mode c-basic-offset)
+    (c++-mode c-basic-offset)
+    (c-mode c-basic-offset)
+    (cmake-mode cmake-tab-width)
+    (coffee-mode coffee-tab-width)
+    (cperl-mode cperl-indent-level)
+    (crystal-mode crystal-indent-level)
+    (csharp-mode c-basic-offset)
+    (css-mode css-indent-offset)
+    (d-mode c-basic-offset)
+    (emacs-lisp-mode lisp-indent-offset)
+    (enh-ruby-mode enh-ruby-indent-level)
+    (erlang-mode erlang-indent-level)
+    (ess-mode ess-indent-offset)
+    (f90-mode f90-associate-indent
+              f90-continuation-indent
+              f90-critical-indent
+              f90-do-indent
+              f90-if-indent
+              f90-program-indent
+              f90-type-indent)
+    (feature-mode feature-indent-offset
+                  feature-indent-level)
+    (fsharp-mode fsharp-continuation-offset
+                 fsharp-indent-level
+                 fsharp-indent-offset)
+    (groovy-mode groovy-indent-offset)
+    (haskell-mode haskell-indent-spaces
+                  haskell-indent-offset
+                  haskell-indentation-layout-offset
+                  haskell-indentation-left-offset
+                  haskell-indentation-starter-offset
+                  haskell-indentation-where-post-offset
+                  haskell-indentation-where-pre-offset
+                  shm-indent-spaces)
+    (haxor-mode haxor-tab-width)
+    (idl-mode c-basic-offset)
+    (jade-mode jade-tab-width)
+    (java-mode c-basic-offset)
+    (js-mode js-indent-level)
+    (js-jsx-mode js-indent-level sgml-basic-offset)
+    (js2-mode js2-basic-offset)
+    (js2-jsx-mode js2-basic-offset sgml-basic-offset)
+    (js3-mode js3-indent-level)
+    (json-mode js-indent-level)
+    (json-ts-mode json-ts-mode-indent-offset)
+    (julia-mode julia-indent-offset)
+    (kotlin-mode kotlin-tab-width)
+    (latex-mode tex-indent-basic)
+    (lisp-mode lisp-indent-offset)
+    (livescript-mode livescript-tab-width)
+    (lua-mode lua-indent-level)
+    (matlab-mode matlab-indent-level)
+    (meson-mode meson-indent-basic)
+    (mips-mode mips-tab-width)
+    (mustache-mode mustache-basic-offset)
+    (nasm-mode nasm-basic-offset)
+    (nginx-mode nginx-indent-level)
+    (nxml-mode nxml-child-indent)
+    (objc-mode c-basic-offset)
+    (octave-mode octave-block-offset)
+    (perl-mode perl-indent-level)
+    (php-mode c-basic-offset)
+    (pike-mode c-basic-offset)
+    (ps-mode ps-mode-tab)
+    (pug-mode pug-tab-width)
+    (puppet-mode puppet-indent-level)
+    (python-mode python-indent-offset)
+    (rjsx-mode js-indent-level sgml-basic-offset)
+    (ruby-mode ruby-indent-level)
+    (rust-mode rust-indent-offset)
+    (rustic-mode rustic-indent-offset)
+    (scala-mode scala-indent:step)
+    (scss-mode css-indent-offset)
+    (sgml-mode sgml-basic-offset)
+    (sh-mode sh-basic-offset sh-indentation)
+    (slim-mode slim-indent-offset)
+    (sml-mode sml-indent-level)
+    (tcl-mode tcl-indent-level
+              tcl-continued-indent-level)
+    (terra-mode terra-indent-level)
+    (typescript-mode typescript-indent-level)
+    (typescript-ts-base-mode typescript-ts-mode-indent-offset)
+    (verilog-mode verilog-indent-level
+                  verilog-indent-level-behavioral
+                  verilog-indent-level-declaration
+                  verilog-indent-level-module
+                  verilog-cexp-indent
+                  verilog-case-indent)
+    (web-mode web-mode-attr-indent-offset
+              web-mode-attr-value-indent-offset
+              web-mode-code-indent-offset
+              web-mode-css-indent-offset
+              web-mode-markup-indent-offset
+              web-mode-sql-indent-offset
+              web-mode-block-padding
+              web-mode-script-padding
+              web-mode-style-padding)
+    (yaml-mode yaml-indent-offset))
+  "Indentation retrieving variables matched to major modes.
+Which is used when `mood-line-show-indentation-information' is non-nil.
+When multiple variables are specified for a mode, they will be tried resolved
+in the given order."
+  :group 'mood-line
+  :type '(alist :key-type symbol :value-type sexp))
+
 (defcustom mood-line-show-eol-style nil
   "When non-nil, show the EOL style of the current buffer."
   :group 'mood-line
@@ -736,6 +853,30 @@ Checkers checked, in order: `flycheck', `flymake'."
           (propertize " %p%%  "
                       'face 'mood-line-unimportant)))
 
+;; ---------------------------------- ;;
+;; Indentation segment
+;; ---------------------------------- ;;
+
+(defun mood-line-segment-indent ()
+  "Display the indentation information of the current buffer."
+  (when mood-line-show-indentation-information
+    (format "%s %s %d  "
+            (if indent-tabs-mode "TAB" "SPC")
+            (let ((lookup-var
+                   (seq-find (lambda (var) (and var (boundp var)))
+                             (cdr (assoc major-mode mood-line-indent-alist))
+                             nil)))
+              ;; If we don't know the indent offset variable of this major mode,
+              ;; display a "-".
+              (if lookup-var
+                  ;; Some major modes, for example lisp-mode, works better when
+                  ;; lisp-indent-offset is nil, we use "-" for nil, too.
+                  (if (not (null (symbol-value lookup-var)))
+                      (format "%d" (symbol-value lookup-var))
+                    "-")
+                "-"))
+            tab-width)))
+
 ;; ---------------------------------- ;;
 ;; EOL segment
 ;; ---------------------------------- ;;
@@ -858,7 +999,8 @@ Checkers checked, in order: `flycheck', `flymake'."
 
                     ;; Right
                     (format-mode-line
-                     '((:eval (mood-line-segment-eol))
+                     '((:eval (mood-line-segment-indent))
+                       (:eval (mood-line-segment-eol))
                        (:eval (mood-line-segment-encoding))
                        (:eval (mood-line-segment-vc))
                        (:eval (mood-line-segment-major-mode))