[nongnu] elpa/rust-mode 55080f6 100/486: Fix syntax and highlighting for char literals

[ELPA Syncer]

branch: elpa/rust-mode
commit 55080f6744fc11b92016c3babcf4d35c2e4995a6
Author: Micah Chalmer <micah@micahchalmer.net>
Commit: Micah Chalmer <micah@micahchalmer.net>

    Fix syntax and highlighting for char literals
    
    This uses syntax properties to make it so that emacs recognizes the
    single quote, rather than the double quote, as the string delimiter
    within character literals, while leaving the syntax unchanged elsewhere.
---
 rust-mode-tests.el |  6 ++++++
 rust-mode.el       | 61 +++++++++++++++++++++++++++++++++++++++++-------------
 2 files changed, 53 insertions(+), 14 deletions(-)

diff --git a/rust-mode-tests.el b/rust-mode-tests.el
index 54b4524..0df9060 100644
--- a/rust-mode-tests.el
+++ b/rust-mode-tests.el
@@ -893,3 +893,9 @@ list of substrings of `STR' each followed by its face."
    "/* #[foo] */"
    '("/* " font-lock-comment-delimiter-face
      "#[foo] */" font-lock-comment-face)))
+
+(ert-deftest font-lock-double-quote-character-literal ()
+  (rust-test-font-lock
+   "'\"'; let"
+   '("'\"'" font-lock-string-face
+     "let" font-lock-keyword-face)))
diff --git a/rust-mode.el b/rust-mode.el
index dae685f..70b49fe 100644
--- a/rust-mode.el
+++ b/rust-mode.el
@@ -44,6 +44,13 @@
 
     table))
 
+(defvar rust-mode-character-literal-syntax-table
+  (let ((table (make-syntax-table rust-mode-syntax-table)))
+    (modify-syntax-entry ?' "\"" table)
+    (modify-syntax-entry ?\" "_" table)
+
+    table))
+
 (defgroup rust-mode nil
   "Support for Rust code."
   :link '(url-link "http://www.rust-lang.org/";)
@@ -259,14 +266,6 @@
      ;; Lifetimes like `'foo`
      (,(concat "'" (rust-re-grab rust-re-ident) "[^']") 1 
font-lock-variable-name-face)
 
-     ;; Character constants, since they're not treated as strings
-     ;; in order to have sufficient leeway to parse 'lifetime above.
-     (,(rust-re-grab "'[^']'") 1 font-lock-string-face)
-     (,(rust-re-grab "'\\\\[nrt]'") 1 font-lock-string-face)
-     (,(rust-re-grab "'\\\\x[[:xdigit:]]\\{2\\}'") 1 font-lock-string-face)
-     (,(rust-re-grab "'\\\\u[[:xdigit:]]\\{4\\}'") 1 font-lock-string-face)
-     (,(rust-re-grab "'\\\\U[[:xdigit:]]\\{8\\}'") 1 font-lock-string-face)
-
      ;; CamelCase Means Type Or Constructor
      (,(rust-re-grabword rust-re-CamelCase) 1 font-lock-type-face)
      )
@@ -439,12 +438,19 @@ 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")
+  (interactive)
   ;; Find the opening brace
-  (re-search-forward "[{]" nil t)
-  (goto-char (match-beginning 0))
-  ;; Go to the closing brace
-  (forward-sexp))
+  (if (re-search-forward "[{]" nil t)
+      (progn
+        (goto-char (match-beginning 0))
+        ;; Go to the closing brace
+        (condition-case err
+            (forward-sexp)
+          (scan-error
+           ;; The parentheses are unbalanced; instead of being unable to 
fontify, just jump to the end of the buffer
+           (goto-char (point-max)))))
+    ;; There is no opening brace, so consider the whole buffer to be one 
"defun"
+    (goto-char (point-max))))
 
 ;; For compatibility with Emacs < 24, derive conditionally
 (defalias 'rust-parent-mode
@@ -481,7 +487,34 @@ This is written mainly to be used as 
`end-of-defun-function' for Rust."
   (setq-local comment-line-break-function 'rust-comment-indent-new-line)
   (setq-local imenu-generic-expression rust-imenu-generic-expression)
   (setq-local beginning-of-defun-function 'rust-beginning-of-defun)
-  (setq-local end-of-defun-function 'rust-end-of-defun))
+  (setq-local end-of-defun-function 'rust-end-of-defun)
+  (setq-local parse-sexp-lookup-properties t)
+  (add-hook 'syntax-propertize-extend-region-functions 
'rust-syntax-propertize-extend-region)
+  (setq-local syntax-propertize-function 'rust-syntax-propertize))
+
+(defun rust-syntax-propertize-extend-region (start end)
+  (save-excursion
+    (goto-char start)
+    (beginning-of-defun)
+    (cons
+     (point)
+     (progn
+       (goto-char end)
+       (end-of-defun)
+       (point)))))
+
+(defun rust-syntax-propertize (start end)
+  ;; Find character literals and make the syntax table recognize the single 
quote as the string delimiter
+  (dolist (char-lit-re
+           '("'[^']'"
+             "'\\\\['nrt]'"
+             "'\\\\x[[:xdigit:]]\\{2\\}'"
+             "'\\\\u[[:xdigit:]]\\{4\\}'"
+             "'\\\\U[[:xdigit:]]\\{8\\}'"))
+    (save-excursion
+      (goto-char start)
+      (while (re-search-forward char-lit-re end t)
+        (put-text-property (match-beginning 0) (match-end 0) 'syntax-table 
rust-mode-character-literal-syntax-table)))))
 
 ;;;###autoload
 (add-to-list 'auto-mode-alist '("\\.rs\\'" . rust-mode))