Add defun motions for rust-mode.

Specifically, we can now use:
+ beginning-of-defun
+ end-of-defun
+ mark-defun

where "defun" means a Rust item.

+ Add tests in rust-mode-tests.el
+ Fix indentation in rust-mode-tests.el
+ Add support for trait to Imenu

src/etc/emacs/rust-mode-tests.el

@@ -52,24 +52,24 @@ Also, the result should be the same regardless of whether the code is at the beg
     (loop
      for pad-at-beginning from 0 to 1
      do (loop for pad-at-end from 0 to 1
-           with padding-beginning = (if (= 0 pad-at-beginning) "" padding)
-           with padding-end = (if (= 0 pad-at-end) "" padding)
-           with padding-adjust = (* padding-len pad-at-beginning)
-           with padding-beginning = (if (= 0 pad-at-beginning) "" padding)
-           with padding-end = (if (= 0 pad-at-end) "" padding)
-           ;; If we're adding space to the beginning, and our start position
-           ;; is at the very beginning, we want to test within the added space.
-           ;; Otherwise adjust the start and end for the beginning padding.
-           with start-pos = (if (= 1 start-pos) 1 (+ padding-adjust start-pos))
-           with end-pos = (+ end-pos padding-adjust)
-           do (loop for pos from start-pos to end-pos
-                 do (rust-test-manip-code
-                     (concat padding-beginning unfilled padding-end)
-                     pos
-                     (lambda () 
-                       (let ((fill-column rust-test-fill-column))
-                         (fill-paragraph)))
-                     (concat padding-beginning expected padding-end)))))))
+              with padding-beginning = (if (= 0 pad-at-beginning) "" padding)
+              with padding-end = (if (= 0 pad-at-end) "" padding)
+              with padding-adjust = (* padding-len pad-at-beginning)
+              with padding-beginning = (if (= 0 pad-at-beginning) "" padding)
+              with padding-end = (if (= 0 pad-at-end) "" padding)
+              ;; If we're adding space to the beginning, and our start position
+              ;; is at the very beginning, we want to test within the added space.
+              ;; Otherwise adjust the start and end for the beginning padding.
+              with start-pos = (if (= 1 start-pos) 1 (+ padding-adjust start-pos))
+              with end-pos = (+ end-pos padding-adjust)
+              do (loop for pos from start-pos to end-pos
+                       do (rust-test-manip-code
+                           (concat padding-beginning unfilled padding-end)
+                           pos
+                           (lambda () 
+                             (let ((fill-column rust-test-fill-column))
+                               (fill-paragraph)))
+                           (concat padding-beginning expected padding-end)))))))
 
 (ert-deftest fill-paragraph-top-level-multi-line-style-doc-comment-second-line ()
   (test-fill-paragraph 
@@ -262,14 +262,14 @@ fn bar() { }" 14 67))
 /// "
    103
    "This is the second really really really really really really long paragraph"
-    "/// This is the first really
+   "/// This is the first really
 /// really really really really
 /// really really long paragraph
 ///
 /// This is the second really
 /// really really really really
 /// really long paragraph"
-    ))
+   ))
 
 (ert-deftest auto-fill-multi-line-prefixless ()
   (test-auto-fill
@@ -295,7 +295,7 @@ very very very long string
 
 (ert-deftest indent-struct-fields-aligned ()
   (test-indent
-"
+   "
 struct Foo { bar: int,
              baz: int }
 
@@ -305,7 +305,7 @@ struct Blah {x:int,
 
 (ert-deftest indent-doc-comments ()
   (test-indent
-"
+   "
 /**
  * This is a doc comment
  *
@@ -411,7 +411,7 @@ fn nexted_fns(a: fn(b:int,
     0
 }
 "
-))
+   ))
 
 (ert-deftest indent-multi-line-expr ()
   (test-indent
@@ -423,4 +423,206 @@ fn foo()
         b();
 }
 "
-))
+   ))
+
+(setq rust-test-motion-string
+      "
+fn fn1(arg: int) -> bool {
+    let x = 5;
+    let y = b();
+    true
+}
+
+fn fn2(arg: int) -> bool {
+    let x = 5;
+    let y = b();
+    true
+}
+
+pub fn fn3(arg: int) -> bool {
+    let x = 5;
+    let y = b();
+    true
+}
+
+struct Foo {
+    x: int
+}
+"
+      rust-test-region-string rust-test-motion-string
+      ;; Symbol -> (line column)
+      rust-test-positions-alist '((start-of-fn1 (2 0))
+                                  (start-of-fn1-middle-of-line (2 15))
+                                  (middle-of-fn1 (3 7))
+                                  (end-of-fn1 (6 0))
+                                  (between-fn1-fn2 (7 0))
+                                  (start-of-fn2 (8 0))
+                                  (middle-of-fn2 (10 4))
+                                  (before-start-of-fn1 (1 0))
+                                  (after-end-of-fn2 (13 0))
+                                  (beginning-of-fn3 (14 0))
+                                  (middle-of-fn3 (16 4))
+                                  (middle-of-struct (21 10))
+                                  (before-start-of-struct (19 0))
+                                  (after-end-of-struct (23 0))))
+
+(defun rust-get-buffer-pos (pos-symbol)
+  "Get buffer position from POS-SYMBOL.
+
+POS-SYMBOL is a symbol found in `rust-test-positions-alist'.
+Convert the line-column information from that list into a buffer position value."
+  (interactive "P")
+  (pcase-let ((`(,line ,column) (cadr (assoc pos-symbol rust-test-positions-alist))))
+    (save-excursion
+      (goto-line line)
+      (move-to-column column)
+      (point))))
+
+;;; TODO: Maybe add an ERT explainer function (something that shows the
+;;; surrounding code of the final point, not just the position).
+(defun rust-test-motion (source-code init-pos final-pos manip-func &optional &rest args)
+  "Test that MANIP-FUNC moves point from INIT-POS to FINAL-POS.
+
+If ARGS are provided, send them to MANIP-FUNC.
+
+INIT-POS, FINAL-POS are position symbols found in `rust-test-positions-alist'."
+  (with-temp-buffer
+    (rust-mode)
+    (insert source-code)
+    (goto-char (rust-get-buffer-pos init-pos))
+    (apply manip-func args)
+    (should (equal (point) (rust-get-buffer-pos final-pos)))))
+
+(defun rust-test-region (source-code init-pos reg-beg reg-end manip-func &optional &rest args)
+  "Test that MANIP-FUNC marks region from REG-BEG to REG-END.
+
+INIT-POS is the initial position of point.
+If ARGS are provided, send them to MANIP-FUNC.
+All positions are position symbols found in `rust-test-positions-alist'."
+  (with-temp-buffer
+    (rust-mode)
+    (insert source-code)
+    (goto-char (rust-get-buffer-pos init-pos))
+    (apply manip-func args)
+    (should (equal (list (region-beginning) (region-end))
+                   (list (rust-get-buffer-pos reg-beg)
+                         (rust-get-buffer-pos reg-end))))))
+
+(ert-deftest rust-beginning-of-defun-from-middle-of-fn ()
+  (rust-test-motion 
+   rust-test-motion-string
+   'middle-of-fn1
+   'start-of-fn1
+   #'beginning-of-defun))
+
+(ert-deftest rust-beginning-of-defun-from-end ()
+  (rust-test-motion 
+   rust-test-motion-string
+   'end-of-fn1
+   'start-of-fn1
+   #'beginning-of-defun))
+
+(ert-deftest rust-beginning-of-defun-before-open-brace ()
+  (rust-test-motion 
+   rust-test-motion-string
+   'start-of-fn1-middle-of-line
+   'start-of-fn1
+   #'beginning-of-defun))
+
+(ert-deftest rust-beginning-of-defun-between-fns ()
+  (rust-test-motion 
+   rust-test-motion-string
+   'between-fn1-fn2
+   'start-of-fn1
+   #'beginning-of-defun))
+
+(ert-deftest rust-beginning-of-defun-with-arg ()
+  (rust-test-motion 
+   rust-test-motion-string
+   'middle-of-fn2
+   'start-of-fn1
+   #'beginning-of-defun 2))
+
+(ert-deftest rust-beginning-of-defun-with-negative-arg ()
+  (rust-test-motion 
+   rust-test-motion-string
+   'middle-of-fn1
+   'beginning-of-fn3
+   #'beginning-of-defun -2))
+
+(ert-deftest rust-beginning-of-defun-pub-fn ()
+  (rust-test-motion 
+   rust-test-motion-string
+   'middle-of-fn3
+   'beginning-of-fn3
+   #'beginning-of-defun))
+
+(ert-deftest rust-end-of-defun-from-middle-of-fn ()
+  (rust-test-motion 
+   rust-test-motion-string
+   'middle-of-fn1
+   'between-fn1-fn2
+   #'end-of-defun))
+
+(ert-deftest rust-end-of-defun-from-beg ()
+  (rust-test-motion 
+   rust-test-motion-string
+   'start-of-fn1
+   'between-fn1-fn2
+   #'end-of-defun))
+
+(ert-deftest rust-end-of-defun-before-open-brace ()
+  (rust-test-motion 
+   rust-test-motion-string
+   'start-of-fn1-middle-of-line
+   'between-fn1-fn2
+   #'end-of-defun))
+
+(ert-deftest rust-end-of-defun-between-fns ()
+  (rust-test-motion 
+   rust-test-motion-string
+   'between-fn1-fn2
+   'after-end-of-fn2
+   #'end-of-defun))
+
+(ert-deftest rust-end-of-defun-with-arg ()
+  (rust-test-motion 
+   rust-test-motion-string
+   'middle-of-fn1
+   'after-end-of-fn2
+   #'end-of-defun 2))
+
+(ert-deftest rust-end-of-defun-with-negative-arg ()
+  (rust-test-motion 
+   rust-test-motion-string
+   'middle-of-fn3
+   'between-fn1-fn2
+   #'end-of-defun -2))
+
+(ert-deftest rust-mark-defun-from-middle-of-fn ()
+  (rust-test-region
+   rust-test-region-string
+   'middle-of-fn2
+   'between-fn1-fn2 'after-end-of-fn2
+   #'mark-defun))
+
+(ert-deftest rust-mark-defun-from-end ()
+  (rust-test-region 
+   rust-test-region-string
+   'end-of-fn1
+   'before-start-of-fn1 'between-fn1-fn2
+   #'mark-defun))
+
+(ert-deftest rust-mark-defun-start-of-defun ()
+  (rust-test-region 
+   rust-test-region-string
+   'start-of-fn2
+   'between-fn1-fn2 'after-end-of-fn2
+   #'mark-defun))
+
+(ert-deftest rust-mark-defun-from-middle-of-struct ()
+  (rust-test-region
+   rust-test-region-string
+   'middle-of-struct
+   'before-start-of-struct 'after-end-of-struct
+   #'mark-defun))

src/etc/emacs/rust-mode.el

@@ -324,7 +324,7 @@
 ;;; Imenu support
 (defvar rust-imenu-generic-expression
   (append (loop for item in
-                '("enum" "struct" "type" "mod" "fn")
+                '("enum" "struct" "type" "mod" "fn" "trait")
                 collect `(nil ,(rust-re-item-def item) 1))
           `(("Impl" ,(rust-re-item-def "impl") 1)))
   "Value for `imenu-generic-expression' in Rust mode.
@@ -335,6 +335,46 @@ Imenu will show all the enums, structs, etc. at the same level.
 Implementations will be shown under the `Impl` subheading.
 Use idomenu (imenu with ido-mode) for best mileage.")
 
+;;; Defun Motions
+
+;;; Start of a Rust item
+(setq rust-top-item-beg-re
+      (concat "^\\s-*\\(?:priv\\|pub\\)?\\s-*"
+              (regexp-opt
+               '("enum" "struct" "type" "mod" "use" "fn" "static" "impl"
+                 "extern" "impl" "static" "trait"
+                 ))))
+
+(defun rust-beginning-of-defun (&optional arg)
+  "Move backward to the beginning of the current defun.
+
+With ARG, move backward multiple defuns.  Negative ARG means
+move forward.
+
+This is written mainly to be used as `beginning-of-defun-function' for Rust.
+Don't move to the beginning of the line. `beginning-of-defun',
+which calls this, does that afterwards."
+  (interactive "p")
+  (re-search-backward (concat "^\\(" rust-top-item-beg-re "\\)\\b")
+                      nil 'move (or arg 1)))
+
+(defun rust-end-of-defun ()
+  "Move forward to the next end of defun.
+
+With argument, do it that many times.
+Negative argument -N means move back to Nth preceding end of defun.
+
+Assume that this is called after beginning-of-defun. So point is
+at the beginning of the defun body. 
+
+This is written mainly to be used as `end-of-defun-function' for Rust."
+  (interactive "p")
+  ;; Find the opening brace
+  (re-search-forward "[{]" nil t)
+  (goto-char (match-beginning 0))
+  ;; Go to the closing brace
+  (forward-sexp))
+
 ;; For compatibility with Emacs < 24, derive conditionally
 (defalias 'rust-parent-mode
   (if (fboundp 'prog-mode) 'prog-mode 'fundamental-mode))
@@ -374,6 +414,8 @@ Use idomenu (imenu with ido-mode) for best mileage.")
   (set (make-local-variable 'comment-multi-line) t)
   (set (make-local-variable 'comment-line-break-function) 'rust-comment-indent-new-line)
   (set (make-local-variable 'imenu-generic-expression) rust-imenu-generic-expression)
+  (set (make-local-variable 'beginning-of-defun-function) 'rust-beginning-of-defun)
+  (set (make-local-variable 'end-of-defun-function) 'rust-end-of-defun)
   )