WIP: font-lock-variable-face on assignment

julia-mode-tests.el

@@ -433,6 +433,8 @@ function( i=1:2 )
     end
 end")
 
+;;; font-lock tests
+
 (ert-deftest julia--test-symbol-font-locking-at-bol ()
   "Symbols get font-locked at beginning or line."
   (julia--should-font-lock
@@ -513,6 +515,43 @@ end")
     (julia--should-font-lock string 74 font-lock-type-face) ; B
     ))
 
+(ert-deftest julia--test-variable-font-lock ()
+  (julia--should-font-lock "x = 5" 1 font-lock-variable-name-face)
+  (julia--should-font-lock "  x = 5" 3 font-lock-variable-name-face)
+  (julia--should-font-lock "x[] = 5" 1 font-lock-variable-name-face)
+  (julia--should-font-lock "x[3][2] = 5" 1 font-lock-variable-name-face)
+  (julia--should-font-lock "x[3,2] = 5" 1 font-lock-variable-name-face)
+  (julia--should-font-lock "x[1:2] = 5" 1 font-lock-variable-name-face)
+  (julia--should-font-lock "x += 5" 1 font-lock-variable-name-face)
+  (julia--should-font-lock "x .= 5" 1 font-lock-variable-name-face)
+  (julia--should-font-lock "x .+= 5" 1 font-lock-variable-name-face)
+  (let ((str "foo.bar = 5" ))
+    (julia--should-font-lock str 1 font-lock-variable-name-face)
+    (julia--should-font-lock str 4 font-lock-variable-name-face)
+    (julia--should-font-lock str 5 font-lock-variable-name-face)
+    (julia--should-font-lock str 7 font-lock-variable-name-face))
+  (let ((str "foo.baz._bar = 5" ))
+    (julia--should-font-lock str 1 font-lock-variable-name-face)
+    (julia--should-font-lock str 4 font-lock-variable-name-face)
+    (julia--should-font-lock str 5 font-lock-variable-name-face)
+    (julia--should-font-lock str 8 font-lock-variable-name-face)
+    (julia--should-font-lock str 9 font-lock-variable-name-face)
+    (julia--should-font-lock str 12 font-lock-variable-name-face)))
+
+(ert-deftest julia--test-variable-font-lock-named-tuple ()
+  "Test named tuples aren't font-locked as variable declarations."
+  :expected-result :failed
+  (julia--should-font-lock "(x=1, y=2)" 2 nil)
+  (julia--should-font-lock "(x=1, y=2)" 7 nil))
+
+(ert-deftest julia--test-variable-font-lock-kwarg ()
+  "Test function keyword arguments aren't font-locked as variable declarations."
+  :expected-result :failed
+  (julia--should-font-lock "f(x=1, y=2)" 3 nil)
+  (julia--should-font-lock "f(x=1, y=2)" 8 nil)
+  (julia--should-font-lock "f(; x=1, y=2)" 5 nil)
+  (julia--should-font-lock "f(; x=1, y=2)" 10 nil))
+
 ;;; Movement
 (ert-deftest julia--test-beginning-of-defun-assn-1 ()
   "Point moves to beginning of single-line assignment function."

julia-mode.el

@@ -269,6 +269,33 @@ a LaTeX string with a unicode symbol."
   (rx (or bol whitespace "(" "[" "," "=")
       (group ":" (or letter (syntax symbol)) (0+ (or word (syntax symbol))))))
 
+;; TODO: multiple assignment "a, b, c = x"
+;; TODO: this highlights named tuple symbols (e.g. "a" in "(a=1,
+;; b=2)") and keyword args after a semi-colon
+(defconst julia--variable-assignment-regex
+  (rx
+   ;; assignment can only happen in certain contexts
+   (or bol ?\;
+       ;; don't count f(a=5) as assignment
+       (and (or buffer-start (not (any word ?_))) ?\()
+       (and (or "begin" "let") (0+ blank)))
+   (0+ blank)
+   (group
+    ;; Namespace qualifier e.g. "Base" in "Base.Threads"
+    (optional (any word ?_) (0+ (any word ?_ ?.)) ?.)
+    ;; actual variable name
+    (1+ (any word ?_)))
+   ;; setindex! expression
+   (* ?\[ (* (not (any ?\]))) ?\])
+   (0+ blank)
+   ;; assignment can be broadcasted
+   (optional ?.)
+   ;; modify and set via e.g. +=
+   (optional (any ?+ ?- ?* ?/ "//" ?\\ ?^ ?÷ ?% "<<" ">>" ">>>" ?| ?& ?⊻))
+   ;; make sure assignment expression isn't some other operator that
+   ;; starts with =
+   ?= (not (any ?> ?=))))
+
 (defconst julia-font-lock-keywords
   ;; font-lock-builtin-face intentionally unused since any name from
   ;; names(Base) can be aliased in a baremodule.
@@ -283,6 +310,7 @@ a LaTeX string with a unicode symbol."
      '("true" "false" "C_NULL" "Inf" "NaN" "Inf32" "NaN32" "nothing" "undef" "missing")
      'symbols)
     'font-lock-constant-face)
+   (list julia--variable-assignment-regex 1 'font-lock-variable-name-face)
    (list julia-unquote-regex 2 'font-lock-constant-face)
    (list julia-forloop-in-regex 1 'font-lock-keyword-face)
    (list julia--forloop-=-regex 1 'font-lock-keyword-face)