Add prettier-js-prettify-region (#92)

* Add prettier-js-prettify-region

* Add test for prettier-js-prettify-region

* Use new function name

* Add menu item to format an active region

* Add guard to ensure the region is active before formatting

Author: jacksonrayhamilton

README.md

@@ -2,7 +2,7 @@
 
 [![MELPA](http://melpa.org/packages/prettier-js-badge.svg)](http://melpa.org/#/prettier-js) [![CI](https://github.com/prettier/prettier-emacs/actions/workflows/test.yml/badge.svg)](https://github.com/prettier/prettier-emacs/actions/workflows/test.yml)
 
-This Emacs package provides a function, `prettier-js`, which formats the current buffer using [Prettier](https://github.com/prettier/prettier). It also exports a minor mode, `prettier-js-mode`, which calls `prettier-js` on save.
+This Emacs package provides a function, `prettier-js-prettify`, which formats the current buffer using [Prettier](https://github.com/prettier/prettier). It also exports a minor mode, `prettier-js-mode`, which calls `prettier-js-prettify` on save.
 
 ## Configuration
 

fixtures/partial-clean.js

@@ -0,0 +1,14 @@
+function messy(a,b)
+{
+    return a+b
+    +100;
+}
+
+const obj = {
+  foo: "bar",
+  baz: 42,
+  qux: [1, 2, 3],
+};
+
+// This is a messy JavaScript file
+if(true){console.log("hello world")}

prettier-js-test.el

@@ -51,7 +51,7 @@
           ;; Visit the temp file
           (with-current-buffer (find-file-noselect temp-file)
             ;; Format the buffer
-            (prettier-js)
+            (prettier-js-prettify)
 
             ;; Get the expected clean content
             (let ((expected-content
@@ -88,7 +88,7 @@
           ;; Visit the messy file
           (with-current-buffer (find-file-noselect temp-src-file)
             ;; Format the buffer using node_modules/.bin/prettier
-            (prettier-js)
+            (prettier-js-prettify)
 
             ;; Get the expected clean content
             (let ((expected-content
@@ -122,7 +122,7 @@
 
             ;; Switch to the indirect buffer and format it
             (with-current-buffer indirect-buffer
-              (prettier-js)
+              (prettier-js-prettify)
 
               ;; Get the expected clean content
               (let ((expected-content
@@ -149,7 +149,7 @@
     (js-mode)
 
     ;; Verify that the appropriate error is signaled with the correct message
-    (let ((err (should-error (prettier-js) :type 'user-error)))
+    (let ((err (should-error (prettier-js-prettify) :type 'user-error)))
       (should (string-match-p "Buffer .* is not visiting a file" (cadr err))))))
 
 (ert-deftest prettier-js-test-executable-not-found ()
@@ -166,7 +166,7 @@
           ;; Visit the temp file
           (with-current-buffer (find-file-noselect temp-file)
             ;; Verify that the appropriate error is signaled with the correct message
-            (let ((err (should-error (prettier-js) :type 'user-error)))
+            (let ((err (should-error (prettier-js-prettify) :type 'user-error)))
               (should (string= "Could not find prettier executable" (cadr err))))
             (kill-buffer)))
 
@@ -189,7 +189,7 @@
           ;; Visit the temp file
           (with-current-buffer (find-file-noselect temp-file)
             ;; Verify that the appropriate error is signaled with the correct message
-            (let ((err (should-error (prettier-js) :type 'user-error)))
+            (let ((err (should-error (prettier-js-prettify) :type 'user-error)))
               (should (string= "Could not find node_modules/.bin/prettier executable" (cadr err))))
             (kill-buffer)))
 
@@ -210,7 +210,7 @@
           ;; Visit the temp file
           (with-current-buffer (find-file-noselect temp-file)
             ;; Verify that the appropriate error is signaled with the correct message
-            (let ((err (should-error (prettier-js) :type 'user-error)))
+            (let ((err (should-error (prettier-js-prettify) :type 'user-error)))
               (should (string= "Could not find diff executable" (cadr err))))
             (kill-buffer)))
 
@@ -238,7 +238,7 @@
             ;; Visit the temp file
             (with-current-buffer (find-file-noselect temp-file)
               ;; Verify that the appropriate error is signaled with the correct message
-              (let ((err (should-error (prettier-js) :type 'user-error)))
+              (let ((err (should-error (prettier-js-prettify) :type 'user-error)))
                 (should (string= "Error calling diff; is GNU diff on your path?" (cadr err))))
               (kill-buffer))))
 
@@ -262,7 +262,7 @@
           ;; Visit the temp file
           (with-current-buffer (find-file-noselect temp-file)
             ;; Run prettier-js which should display the error
-            (prettier-js)
+            (prettier-js-prettify)
 
             ;; Check that the error buffer exists and contains the error message
             (let ((error-buffer (get-buffer "*prettier errors*")))
@@ -295,7 +295,7 @@
           ;; Visit the temp file
           (with-current-buffer (find-file-noselect temp-file)
             ;; Run prettier-js which should display the error
-            (prettier-js)
+            (prettier-js-prettify)
 
             ;; Check that the error buffer exists and contains the error message
             (let ((error-buffer (get-buffer "*prettier errors*")))
@@ -318,5 +318,48 @@
       (when (file-exists-p temp-dir)
         (delete-directory temp-dir t)))))
 
+(ert-deftest prettier-js-test-prettify-region ()
+  "Test that prettier-js-prettify-region correctly formats a region of JavaScript code."
+  (let* ((dirty-file (expand-file-name "fixtures/dirty.js"))
+         (partial-clean-file (expand-file-name "fixtures/partial-clean.js"))
+         (temp-file (make-temp-file "prettier-test-" nil ".js")))
+    (unwind-protect
+        (progn
+          ;; Copy dirty content to temp file
+          (copy-file dirty-file temp-file t)
+
+          ;; Visit the temp file
+          (with-current-buffer (find-file-noselect temp-file)
+            ;; Find the object declaration and format just that region
+            (goto-char (point-min))
+            (search-forward "const obj = {")
+            (beginning-of-line)
+            (let ((start (point))
+                  (end (progn
+                         (search-forward "};")
+                         (point))))
+
+              ;; Set the region and format it
+              (push-mark start)
+              (goto-char end)
+              (activate-mark)
+              (prettier-js-prettify-region)
+
+              ;; Get the expected partial clean content
+              (let ((expected-content
+                     (with-temp-buffer
+                       (insert-file-contents partial-clean-file)
+                       (buffer-string)))
+                    (actual-content (buffer-string)))
+
+                ;; Compare the formatted content with the expected partial clean content
+                (should (string= actual-content expected-content))))
+
+            (kill-buffer)))
+
+      ;; Clean up temp file
+      (when (file-exists-p temp-file)
+        (delete-file temp-file)))))
+
 (provide 'prettier-js-test)
 ;;; prettier-js-test.el ends here

prettier-js.el

@@ -103,7 +103,7 @@ When non-nil, contains the error message to display.")
   (goto-char (point-min))
     (forward-line (1- line)))
 
-(defun prettier-js--apply-rcs-patch (patch-buffer)
+(defun prettier-js--apply-rcs-patch (patch-buffer &optional start)
   "Apply an RCS-formatted diff from PATCH-BUFFER to the current buffer."
   (let ((target-buffer (current-buffer))
         ;; Relative offset between buffer line numbers and line numbers
@@ -116,7 +116,7 @@ When non-nil, contains the error message to display.")
         ;; Appending lines decrements the offset (possibly making it
         ;; negative), deleting lines increments it. This order
         ;; simplifies the forward-line invocations.
-        (line-offset 0))
+        (line-offset (if start (* (- (line-number-at-pos start) 1) -1) 0)))
     (save-excursion
       (with-current-buffer patch-buffer
         (goto-char (point-min))
@@ -249,17 +249,17 @@ Returns the exit code from prettier."
            prettier-cmd bufferfile (list (list :file outputfile) errorfile)
            nil (append prettier-js-args width-args (list "--stdin-filepath" file-path)))))
 
-(defun prettier-js--call-diff (outputfile patchbuf)
+(defun prettier-js--call-diff (outputfile patchbuf &optional start end)
   "Call diff command to generate patch between current buffer and OUTPUTFILE.
 PATCHBUF is the buffer where the diff output will be written."
-  (let ((diff-cmd (prettier-js--get-diff-command)))
-    (call-process-region (point-min) (point-max) diff-cmd nil patchbuf nil
+  (let ((start-point (or start (point-min)))
+        (end-point (or end (point-max)))
+        (diff-cmd (prettier-js--get-diff-command)))
+    (call-process-region start-point end-point diff-cmd nil patchbuf nil
                          "-n" "--strip-trailing-cr" "-" outputfile)))
 
-;;;###autoload
-(defun prettier-js ()
-   "Format the current buffer according to the prettier tool."
-   (interactive)
+(defun prettier-js--prettify (&optional start end)
+   "Format content in the current buffer from START to END."
    (let* ((file-path
            (or (prettier-js--file-path)
                (user-error "Buffer `%s' is not visiting a file" (buffer-name))))
@@ -280,7 +280,7 @@ PATCHBUF is the buffer where the diff output will be written."
      (unwind-protect
          (save-restriction
            (widen)
-           (write-region nil nil bufferfile)
+           (write-region start end bufferfile)
            (if errbuf
                (with-current-buffer errbuf
                  (setq buffer-read-only nil)
@@ -294,9 +294,9 @@ PATCHBUF is the buffer where the diff output will be written."
                  ;; 1 - The files are different (differences found).
                  ;; 2 - Trouble occurred (e.g. invalid options).
                  ;; 0/1 = success, 2 = problem
-                 (if (<= (prettier-js--call-diff outputfile patchbuf) 1)
+                 (if (<= (prettier-js--call-diff outputfile patchbuf start end) 1)
                      (progn
-                       (prettier-js--apply-rcs-patch patchbuf)
+                       (prettier-js--apply-rcs-patch patchbuf start)
                        (message "Applied prettier with args `%s'" prettier-js-args)
                        (if errbuf (prettier-js--kill-error-buffer errbuf)))
                    (setq prettier-js-error-state "Diff command had an issue")
@@ -309,6 +309,22 @@ PATCHBUF is the buffer where the diff output will be written."
        (delete-file bufferfile)
        (delete-file outputfile))))
 
+;;;###autoload
+(defalias 'prettier-js 'prettier-js-prettify)
+
+;;;###autoload
+(defun prettier-js-prettify ()
+  "Format the current buffer according to the prettier tool."
+  (interactive)
+  (prettier-js--prettify))
+
+;;;###autoload
+(defun prettier-js-prettify-region ()
+  "Format the current region according to the prettier tool."
+  (interactive)
+  (when (region-active-p)
+    (prettier-js--prettify (region-beginning) (region-end))))
+
 (defvar prettier-js-mode-menu-map
   (let ((map (make-sparse-keymap "Prettier")))
     map)
@@ -344,7 +360,8 @@ Adds an error item at the top of the menu if there is an error state."
 (easy-menu-define prettier-js-mode-menu prettier-js-mode-menu-map
   "Menu for Prettier mode"
   '("Prettier" :filter prettier-js--menu-filter
-    ["Format buffer" prettier-js t]
+    ["Format buffer" prettier-js-prettify t]
+    ["Format region" prettier-js-prettify-region (region-active-p)]
     "---"
     ["Turn off minor mode" prettier-js-mode :visible prettier-js-mode]
     ["Help for minor mode" (describe-function 'prettier-js-mode) t]))
@@ -356,8 +373,8 @@ Adds an error item at the top of the menu if there is an error state."
   :global nil
   :keymap prettier-js-mode-menu-map
   (if prettier-js-mode
-      (add-hook 'before-save-hook 'prettier-js nil 'local)
-    (remove-hook 'before-save-hook 'prettier-js 'local)))
+      (add-hook 'before-save-hook 'prettier-js-prettify nil 'local)
+    (remove-hook 'before-save-hook 'prettier-js-prettify 'local)))
 
 (provide 'prettier-js)
 ;;; prettier-js.el ends here