CLJS-3036: Provide a clojure.edn namespace for Clojure compatibility

Adds the clojure.edn namespace, containing read and read-string.

When writing CLJC libraries intended for use in Clojure and
ClojureScript it is convenient to be able to use clojure.edn/read-string
instead of using reader conditionals to use cljs.reader/read-string in
ClojureScript.

Author: timothypratley

src/main/cljs/clojure/edn.cljs

@@ -0,0 +1,55 @@
+;; Copyright (c) Rich Hickey. All rights reserved.
+;; The use and distribution terms for this software are covered by the
+;; Eclipse Public License 1.0 (http://opensource.org/licenses/eclipse-1.0.php)
+;; which can be found in the file epl-v10.html at the root of this distribution.
+;; By using this software in any fashion, you are agreeing to be bound by
+;; the terms of this license.
+;; You must not remove this notice, or any other, from this software.
+
+(ns clojure.edn
+  "edn reading.
+
+  This namespace provides alias for cljs.reader/read and cljs.reader/read-string.
+  Thus Clojure and ClojureScript source can reference these functions in the same way.
+  In Clojure, read and read-string may cause evaluation,
+  but clojure.edn/read and clojure.edn/read-string will not.
+  In ClojureScript cljs.reader/read and cljs.reader/read-string will not cause evaluation,
+  they only read edn."
+  (:require [cljs.reader :as reader]))
+
+(defn read
+  "Reads the first object from an cljs.tools.reader.reader-types/IPushbackReader.
+   Returns the object read. If EOF, throws if eof-error? is true otherwise returns eof.
+   If no reader is provided, *in* will be used.
+
+   Reads data in the edn format (subset of Clojure data):
+   http://edn-format.org
+
+   cljs.tools.reader.edn/read doesn't depend on dynamic Vars, all configuration
+   is done by passing an opt map.
+
+   opts is a map that can include the following keys:
+   :eof - value to return on end-of-file. When not supplied, eof throws an exception.
+   :readers  - a map of tag symbols to data-reader functions to be considered before default-data-readers.
+              When not supplied, only the default-data-readers will be used.
+   :default - A function of two args, that will, if present and no reader is found for a tag,
+              be called with the tag and the value."
+  ([reader]
+   (reader/read reader))
+  ([opts reader]
+   (reader/read opts reader))
+  ([reader eof-error? eof opts]
+   (reader/read reader eof-error? eof opts)))
+
+(defn read-string
+  "Reads one object from the string s.
+   Returns nil when s is nil or empty.
+
+   Reads data in the edn format (subset of Clojure data):
+   http://edn-format.org
+
+   opts is a map as per cljs.tools.reader.edn/read"
+  ([s]
+   (reader/read-string s))
+  ([opts s]
+   (reader/read-string opts s)))

src/test/cljs/clojure/edn_test.cljs

@@ -0,0 +1,24 @@
+(ns clojure.edn-test
+  (:require [cljs.test :refer-macros [deftest is testing]]
+            [clojure.edn :as edn]
+            [cljs.reader :as reader]
+            [cljs.tools.reader.reader-types :as reader-types]))
+
+(defn- test-reader []
+  (reader-types/string-push-back-reader "[1 2 3]"))
+
+(deftest test-read
+  (testing "Mirrors cljs.reader/read"
+    (is (= (edn/read (test-reader))
+         (reader/read (test-reader))))
+    (is (= (edn/read {} (test-reader))
+           (reader/read {} (test-reader))))
+    (is (= (edn/read (test-reader) false "EOF" {})
+           (reader/read (test-reader) false "EOF" {})))))
+
+(deftest test-read-string
+  (testing "Mirrors cljs.reader/read-string"
+    (is (= (edn/read-string "(+ 1 2)")
+           (reader/read-string "(+ 1 2)")))
+    (is (= (edn/read-string "{:a #{[1]}}")
+           (reader/read-string "{:a #{[1]}}")))))

src/test/cljs/test_runner.cljs

@@ -23,6 +23,7 @@
             [clojure.string-test]
             [clojure.data-test]
             [clojure.datafy-test]
+            [clojure.edn-test]
             [clojure.walk-test]
             [cljs.macro-test]
             [cljs.letfn-test]
@@ -69,6 +70,7 @@
   'clojure.string-test
   'clojure.data-test
   'clojure.datafy-test
+  'clojure.edn-test
   'clojure.walk-test
   'cljs.letfn-test
   'cljs.reducers-test

src/test/self/self_parity/test.cljs

@@ -288,6 +288,7 @@
                  #_[cljs.ns-test]
                  [clojure.string-test]
                  [clojure.data-test]
+                 [clojure.edn]
                  [clojure.walk-test]
                  [cljs.macro-test]
                  [cljs.letfn-test]
@@ -331,6 +332,7 @@
              'cljs.reader-test
              'clojure.string-test
              'clojure.data-test
+             'clojure.edn
              'clojure.walk-test
              'cljs.letfn-test
              'cljs.reducers-test