[nongnu] elpa/dart-mode 591b6fe 170/192: Improve handling of strings

[ELPA Syncer]

branch: elpa/dart-mode
commit 591b6fee1fbbe58450ab96c2ad17540d503c4abf
Author: Brady Trainor <mail@bradyt.com>
Commit: Brady Trainor <mail@bradyt.com>

    Improve handling of strings
    
    Previous syntax-propertize-function was copied from python-mode, to
    handle multiline strings. Especially, to avoid treating code as
    strings when following strings like,
    
        '''Don't do this.'''
    
    This commit adds logic to handle trailing backslashes in raw strings,
    like,
    
        r'This is not over\'
    
    The approach is like that taken in csharp-mode, changing syntax of
    backslash from escape to punctuation.
    
    A more complete solution would handle string interpolation, for
    example,
    
        "Hello ${"world"}"
---
 dart-mode.el | 110 +++++++++++++++++++++++++++--------------------------------
 1 file changed, 50 insertions(+), 60 deletions(-)

diff --git a/dart-mode.el b/dart-mode.el
index fddee29..5d63343 100644
--- a/dart-mode.el
+++ b/dart-mode.el
@@ -704,65 +704,55 @@ fontify as declared variables. From ECMA-408,
      (dart--string-interpolation-id-func  (0 font-lock-variable-name-face t))
      (dart--string-interpolation-exp-func (0 font-lock-variable-name-face 
t)))))
 
-(defvar dart-string-delimiter (rx (and
-                                   ;; Match even number of backslashes.
-                                   (or (not (any ?\\ ?\' ?\")) point
-                                       ;; Quotes might be preceded by an 
escaped quote.
-                                       (and (or (not (any ?\\)) point) ?\\
-                                            (* ?\\ ?\\) (any ?\' ?\")))
-                                   (* ?\\ ?\\)
-                                   ;; Match single or triple quotes of any 
kind.
-                                   (group (or  "\"" "\"\"\"" "'" "'''")))))
-
-(defconst dart-syntax-propertize-function
-  (syntax-propertize-rules
-   (dart-string-delimiter
-    (0 (ignore (dart-syntax-stringify))))))
-
-(defsubst dart-syntax-count-quotes (quote-char &optional point limit)
-  "Count number of quotes around point (max is 3).
-QUOTE-CHAR is the quote char to count.  Optional argument POINT is
-the point where scan starts (defaults to current point), and LIMIT
-is used to limit the scan."
-  (let ((i 0))
-    (while (and (< i 3)
-                (or (not limit) (< (+ point i) limit))
-                (eq (char-after (+ point i)) quote-char))
-      (setq i (1+ i)))
-    i))
-
-(defun dart-syntax-stringify ()
-  "Put `syntax-table' property correctly on single/triple quotes."
-  (let* ((num-quotes (length (match-string-no-properties 1)))
-         (ppss (prog2
-                   (backward-char num-quotes)
-                   (syntax-ppss)
-                 (forward-char num-quotes)))
-         (string-start (and (not (nth 4 ppss)) (nth 8 ppss)))
-         (quote-starting-pos (- (point) num-quotes))
-         (quote-ending-pos (point))
-         (num-closing-quotes
-          (and string-start
-               (dart-syntax-count-quotes
-                (char-before) string-start quote-starting-pos))))
-    (cond ((and string-start (= num-closing-quotes 0))
-           ;; This set of quotes doesn't match the string starting
-           ;; kind. Do nothing.
-           nil)
-          ((not string-start)
-           ;; This set of quotes delimit the start of a string.
-           (put-text-property quote-starting-pos (1+ quote-starting-pos)
-                              'syntax-table (string-to-syntax "|")))
-          ((= num-quotes num-closing-quotes)
-           ;; This set of quotes delimit the end of a string.
-           (put-text-property (1- quote-ending-pos) quote-ending-pos
-                              'syntax-table (string-to-syntax "|")))
-          ((> num-quotes num-closing-quotes)
-           ;; This may only happen whenever a triple quote is closing
-           ;; a single quoted string. Add string delimiter syntax to
-           ;; all three quotes.
-           (put-text-property quote-starting-pos quote-ending-pos
-                              'syntax-table (string-to-syntax "|"))))))
+(defun dart-syntax-propertize-function (beg end)
+  "Sets syntax-table text properties for raw and/or multiline strings.
+
+We use fences uniformly for consistency.
+
+In raw strings, we modify backslash characters to have punctuation
+syntax rather than escape syntax.
+
+String interpolation is not handled correctly yet, but the fixes to
+quote characters in multiline strings, and escape characters in raw
+strings, ensures that code outside of strings is not highlighted as
+strings."
+  (goto-char beg)
+  ;; We rely on syntax-propertize-extend-region-functions that `beg`
+  ;; will be at beginning of line, but we ensure here that we are not
+  ;; in a string
+  (while (nth 3 (syntax-ppss))
+    (goto-char (nth 8 (syntax-ppss)))
+    (beginning-of-line))
+  ;; Search for string opening
+  (while (re-search-forward (rx (group (optional ?r))
+                                (group (or (repeat 3 ?\")
+                                           (repeat 3 ?\')
+                                           ?\"
+                                           ?\')))
+                            end t)
+    (let ((bos (match-beginning 2))
+          (rawp (equal (match-string-no-properties 1) "r"))
+          (string-delimiter (match-string-no-properties 2)))
+      ;; Set string fence syntax at beginning of string
+      (put-text-property bos (1+ bos) 'syntax-table (string-to-syntax "|") nil)
+      ;; Look for the end of string delimiter, depending on rawp and
+      ;; string-delimiter
+      (when (or (looking-at string-delimiter)
+                ;; Unless rawp, ensure an even number of backslashes
+                (re-search-forward (concat (if rawp "" (rx (not (any ?\\)) 
(zero-or-more ?\\ ?\\)))
+                                           string-delimiter)
+                                   end t))
+        (let ((eos (match-end 0)))
+          ;; Set end of string fence delimiter
+          (put-text-property (1- eos) eos 'syntax-table (string-to-syntax "|") 
nil)
+          ;; For all strings, remove fence property between fences
+          ;; For raw strings, set all backslashes to punctuation syntax
+          (dolist (pt (number-sequence (1+ bos) (- eos 2)))
+            (when (equal (get-text-property pt 'syntax-table) 
(string-to-syntax "|"))
+              (remove-text-properties pt (1+ pt) 'syntax-table))
+            (when (and rawp (equal (char-after pt) ?\\))
+              (put-text-property pt (1+ pt) 'syntax-table (string-to-syntax 
".") nil)))
+          (goto-char eos))))))
 
 (defun dart-fontify-region (beg end)
   "Use fontify the region between BEG and END as Dart.
@@ -1965,7 +1955,7 @@ Key bindings:
   (setq-local indent-line-function 'dart-indent-line-function)
   (setq indent-tabs-mode nil)
   (setq tab-width 2)
-  (setq-local syntax-propertize-function dart-syntax-propertize-function)
+  (setq-local syntax-propertize-function 'dart-syntax-propertize-function)
   (when dart-enable-analysis-server
     (if (null dart-sdk-path)
         (dart-log