CLJS-1299: Add support for more literals in reader

Adds support for rich character literals like `\space`, `\return` and
unicode literals like `\u1234`. The implementation is a port of the JVM's
`CharacterReader`.

See http://dev.clojure.org/jira/browse/CLJS-1299

Author: rymndhng

src/main/cljs/cljs/reader.cljs

@@ -334,6 +334,21 @@ nil if the end of stream has been reached")
                 (.-length token)))
       (special-symbols token (symbol token)))))
 
+(defn read-literal
+  [rdr ch]
+  (let [token (read-token rdr ch)
+        chars (subs token 1)]
+    (cond (identical? (.-length chars) 1) chars
+          (identical? chars "tab")       "\t"
+          (identical? chars "return")    "\r"
+          (identical? chars "newline")   "\n"
+          (identical? chars "space")     " "
+          (identical? chars "backspace") "\b"
+          (identical? chars "formfeed")  "\f"
+          (identical? (.charAt chars 0) "u") (make-unicode-char (subs chars 1))
+          (identical? (.charAt chars 0) "o") (not-implemented rdr token)
+          :else (reader-error rdr "Unknown character literal: " token))))
+
 (defn read-keyword
   [reader initch]
   (let [token (read-token reader (read-char reader))
@@ -407,7 +422,7 @@ nil if the end of stream has been reached")
    (identical? c \]) read-unmatched-delimiter
    (identical? c \{) read-map
    (identical? c \}) read-unmatched-delimiter
-   (identical? c \\) read-char
+   (identical? c \\) read-literal
    (identical? c \#) read-dispatch
    :else nil))
 

src/test/cljs/cljs/reader_test.cljs

@@ -94,6 +94,10 @@
     (reader/register-default-tag-parser! (fn [tag val] val))
     (is (= [1 2] (reader/read-string "#a.b/c [1 2]"))))
 
+  (testing "Character Literals"
+    (is (= [\tab \return \newline \space \backspace \formfeed \u1234]
+          (reader/read-string "[\\tab \\return \\newline \\space \\backspace \\formfeed \\u1234]"))))
+
   ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   ;; Unicode Tests