[nongnu] elpa/scala-mode a0b73b2 177/217: add string interpolation (#116)

[ELPA Syncer]

branch: elpa/scala-mode
commit a0b73b25377f5aedf50abe198d6b6111310735be
Author: Brian Malehorn <bmalehorn@users.noreply.github.com>
Commit: Sam Halliday <sam.halliday@gmail.com>

    add string interpolation (#116)
    
    Before, scala-mode wouldn't highlight formatter variables, making them a
    bit difficult to pick out:
    
         val s = s"foo $bar"
    
    Now, they're given a different color (`font-lock-variable-name-face`)
    than the surrounding string.
    
    Text inside `${}` will be highlighted homogenously (rather than
    recursively highlighted as constants, keywords, etc.). This is what
    `ruby-mode` does and it's definitely good enough.
    
    Closes #60.
---
 scala-mode-fontlock.el |  2 ++
 scala-mode-syntax.el   | 23 +++++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/scala-mode-fontlock.el b/scala-mode-fontlock.el
index 7c0aa7d..e919353 100644
--- a/scala-mode-fontlock.el
+++ b/scala-mode-fontlock.el
@@ -487,6 +487,8 @@ Does not continue past limit.
     (scala-font-lock:mark-floatingPointLiteral . font-lock-constant-face)
     (scala-font-lock:mark-integerLiteral . font-lock-constant-face)
 
+    (scala-syntax:interpolation-matcher 0 font-lock-variable-name-face t)
+
     ))
 
 (defun scala-font-lock:syntactic-face-function (state)
diff --git a/scala-mode-syntax.el b/scala-mode-syntax.el
index 6eb9312..c0b6277 100644
--- a/scala-mode-syntax.el
+++ b/scala-mode-syntax.el
@@ -155,6 +155,29 @@
           "\\|" scala-syntax:symbolLiteral-re
           "\\|" "null" "\\)"))
 
+(defconst scala-syntax:interpolation-re
+  (concat "\\(" "\\$"  scala-syntax:id-re "\\|" "\\${[^}\n\\\\]*}" "\\)"))
+
+(defun scala-syntax:interpolation-matcher (end)
+  (let* ((pos nil)
+         (syntax nil)
+         (str-start nil)
+         (char-before-str nil))
+    (while (and
+            (setq pos (re-search-forward scala-syntax:interpolation-re end t))
+            (setq syntax (syntax-ppss pos))
+            (if (nth 3 syntax) ;; "is string"
+                (progn
+                  (setq str-start (nth 8 syntax))
+                  ;; s"foo"
+                  ;; ^-- `char-before-str', must be identifier
+                  (setq char-before-str (char-after (1- str-start)))
+                  ;; break if match
+                  (null (string-match-p
+                         scala-syntax:id-re (string char-before-str))))
+              t))) ;; keep going
+    pos))
+
 ;; Paths (Chapter 3.1)
 ;; emacs has a problem with these regex, don't use them
 ;; (defconst scala-syntax:classQualifier-re (concat "[[]" scala-syntax:id-re 
"[]]"))