[Fix #3] Add parse stream and generate stream (#20)

  Following #3,
  we followed the inline implementation of
  https://github.com/metosin/muuntaja/pull/94/files
  to add the suggested feature.

Co-authored-by: David Pham <davidpham87@gmail.com>

project.clj

@@ -1,4 +1,4 @@
-(defproject clj-commons/clj-yaml (or (System/getenv "PROJECT_VERSION") "0.7.2")
+(defproject clj-commons/clj-yaml (or (System/getenv "PROJECT_VERSION") "0.7.3")
   :description "YAML encoding and decoding for Clojure using SnakeYAML"
   :url "https://github.com/clj-commons/clj-yaml"
   :license {:name "Eclipse Public License - v 1.0"

src/clojure/clj_yaml/core.clj

@@ -157,3 +157,14 @@
                             :allow-recursive-keys allow-recursive-keys
                             :allow-duplicate-keys allow-duplicate-keys)
                  string) keywords))
+
+;; From https://github.com/metosin/muuntaja/pull/94/files
+(defn generate-stream
+  "Dump the content of data as yaml into writer."
+  [writer data & opts]
+  (.dump ^Yaml (apply make-yaml opts) (encode data) writer))
+
+(defn parse-stream
+  [^java.io.Reader reader & {:keys [keywords] :or {keywords true} :as opts}]
+  (decode (.load ^Yaml (apply make-yaml (into [] cat opts))
+                 reader) keywords))

test/clj_yaml/core_test.clj

@@ -1,8 +1,12 @@
 (ns clj-yaml.core-test
   (:require [clojure.test :refer (deftest testing is)]
             [clojure.string :as string]
-            [clj-yaml.core :refer [parse-string unmark generate-string]])
+            [clojure.java.io :as io]
+            [clj-yaml.core :refer [parse-string unmark generate-string
+                                   parse-stream generate-stream]])
   (:import [java.util Date]
+           (java.io ByteArrayOutputStream OutputStreamWriter ByteArrayInputStream)
+           java.nio.charset.StandardCharsets
            (org.yaml.snakeyaml.error YAMLException)
            (org.yaml.snakeyaml.constructor DuplicateKeyException)))
 
@@ -241,3 +245,34 @@ foo/bar: 42
                              parse-string
                              generate-string
                              parse-string)))))
+
+(defn to-bytes
+  "Converts a string to a byte array."
+  [data]
+  (.getBytes ^String data StandardCharsets/UTF_8))
+
+(defn roundtrip
+  "Testing roundtrip of string and stream parser, and checking their equivalence."
+  [data-as-string]
+  (let [data (parse-string data-as-string)
+        data-stream (parse-stream (io/reader (ByteArrayInputStream. (to-bytes data-as-string))))
+        output-stream (ByteArrayOutputStream.)
+        writer (OutputStreamWriter. output-stream)
+        _ (generate-stream writer data)
+        reader (ByteArrayInputStream. (.toByteArray output-stream))]
+    (= data ;; string -> edn
+       (parse-string (generate-string data)) ;; edn -> string -> edn
+       (parse-stream (io/reader reader)) ;; edn -> stream -> edn
+       ;; stream -> edn
+       data-stream)))
+
+(deftest roundtrip-test
+  (testing "Roundtrip test"
+    (is (roundtrip duplicate-keys-yaml))
+    (is (roundtrip hashes-of-lists-yaml))
+    (is (roundtrip inline-hash-yaml))
+    (is (roundtrip inline-list-yaml))
+    (is (roundtrip list-of-hashes-yaml))
+    (is (roundtrip list-yaml))
+    (is (roundtrip nested-hash-yaml))))
+