Don't rewrite ~ @foo to ~@foo

The problem is ~ @foo is being reformatted to ~@foo, a different
expression. We fix this by not treating spaces between ~ and @
as "surrounding spaces".

cljfmt/src/cljfmt/core.cljc

@@ -33,10 +33,6 @@
 (defn- transform [form zf & args]
   (z/root (apply zf (z/of-node form) args)))
 
-(defn- surrounding? [zloc p?]
-  (and (p? zloc) (or (nil? (z/left* zloc))
-                     (nil? (z/skip z/right* p? zloc)))))
-
 (defn root? [zloc]
   (nil? (z/up* zloc)))
 
@@ -49,9 +45,23 @@
 (defn- clojure-whitespace? [zloc]
   (z/whitespace? zloc))
 
+(defn- unquote? [zloc]
+  (and zloc (= (n/tag (z/node zloc)) :unquote)))
+
+(defn- deref? [zloc]
+  (and zloc (= (n/tag (z/node zloc)) :deref)))
+
+(defn- unquote-deref? [zloc]
+  (and (deref? zloc)
+       (unquote? (z/up* zloc))))
+
 (defn- surrounding-whitespace? [zloc]
   (and (not (top? zloc))
-       (surrounding? zloc clojure-whitespace?)))
+       (clojure-whitespace? zloc)
+       (or (and (nil? (z/left* zloc))
+                ;; don't convert ~ @ to ~@
+                (not (unquote-deref? (z/right* zloc))))
+           (nil? (z/skip z/right* clojure-whitespace? zloc)))))
 
 (defn remove-surrounding-whitespace [form]
   (transform form edit-all surrounding-whitespace? z/remove*))

cljfmt/test/cljfmt/core_test.cljc

@@ -692,7 +692,34 @@
          ["#:clj {:a :b"
           ":c :d}"]
          ["#:clj {:a :b"
-          "       :c :d}"]))))
+          "       :c :d}"])))
+  (testing "~ @ is not ~@"
+    (is (reformats-to?
+         ["~ @foo"]
+         ["~ @foo"]))
+    (is (reformats-to?
+         ["~(deref foo)"]
+         ["~(deref foo)"]))
+    (is (reformats-to?
+         ["~(clojure.core/deref foo)"]
+         ["~(clojure.core/deref foo)"]))
+    (is (reformats-to?
+         ["~ @foo"]
+         ["~ @foo"]))
+    (is (reformats-to?
+         ["~     @foo"]
+         ["~     @foo"]))
+    (is (reformats-to?
+         ["~\n@foo"]
+         ["~"
+          " @foo"]))
+    (is (reformats-to?
+         ["~;;comment\n@foo"]
+         ["~;;comment"
+          " @foo"]))
+    (is (reformats-to?
+         ["~#_a@foo"]
+         ["~#_a @foo"]))))
 
 (deftest test-remove-multiple-non-indenting-spaces
   (let [opts {:remove-multiple-non-indenting-spaces? true}]
@@ -1568,7 +1595,9 @@
                "(~@foo"
                "bar)"
                "(#:foo{:bar 1}"
-               "baz)"]]
+               "baz)"
+               "(~ @foo"
+               "bar)"]]
     (testing ":cursive style uses 2 spaces unless starting with a collection"
       (is (reformats-to?
            input
@@ -1627,7 +1656,9 @@
             "(~@foo"
             "  bar)"
             "(#:foo{:bar 1}"
-            "  baz)"]
+            "  baz)"
+            "(~ @foo"
+            "  bar)"]
            {:function-arguments-indentation :cursive})))
     (testing ":zprint uses 2 spaces if starting with a symbol, keyword, or list"
       (is (reformats-to?
@@ -1687,5 +1718,7 @@
             "(~@foo"
             " bar)"
             "(#:foo{:bar 1}"
-            " baz)"]
+            " baz)"
+            "(~ @foo"
+            " bar)"]
            {:function-arguments-indentation :zprint})))))