Merge pull request #469 from jmglov/json-writer

Add pixie.data.json for reading and writing JSON

Author: thomasmulvaney

pixie/data/json.pxi

@@ -0,0 +1,41 @@
+(ns pixie.data.json
+  (:require [pixie.parser.json]
+            [pixie.string :as string]))
+
+(def read-string pixie.parser.json/read-string)
+
+(defprotocol IToJSON
+  (write-string [this]))
+
+(defn- write-map [m]
+  (str "{"
+       (->> m
+            (transduce (comp (map (fn [[k v]] (string/interp "$(write-string k)$: $(write-string v)$")))
+                             (interpose ", "))
+                       string-builder))
+       "}"))
+
+(defn- write-sequential [xs]
+  (str "["
+       (->> xs
+            (transduce (comp (map write-string)
+                             (interpose ", "))
+                       string-builder))
+       "]"))
+
+(defn- write-str [s]
+  (string/interp "\"$s$\""))
+
+(extend-protocol IToJSON
+  Character (write-string [this] (write-str this))
+  Cons (write-string [this] (write-sequential this))
+  EmptyList (write-string [this] (write-sequential this))
+  Nil (write-string [_] "null")
+  Number (write-string [this] (str this))
+  Keyword (write-string [this] (write-str (name this)))
+  LazySeq (write-string [this] (write-sequential this))
+  IMap (write-string [this] (write-map this))
+  IVector (write-string [this] (write-sequential this))
+  PersistentList (write-string [this] (write-sequential this))
+  Ratio (write-string [this] (str (float this)))
+  String (write-string [this] (write-str this)))

tests/pixie/tests/data/test-json.pxi

@@ -0,0 +1,76 @@
+(ns pixie.tests.data.test-json
+  (:require [pixie.test :refer :all]
+            [pixie.data.json :as json]))
+
+
+
+;; This test just ensures that we can use read-string; more thorough testing is
+;; done in pixie.tests.parser.test-json
+(deftest test-read-string
+  (assert= (json/read-string "{\"foo\": 42, \"bar\": [\"baz\"]}")
+           {"foo" 42, "bar" ["baz"]}))
+
+(deftest test-strings
+  (assert-table [x y] (assert= (json/write-string x) y)
+                \a "\"a\""
+                "foo" "\"foo\""
+                :bar "\"bar\""
+                "" "\"\""))
+
+(deftest test-numbers
+  (assert-table [x y] (assert= (json/write-string x) y)
+                1 "1"
+                1.0 "1.000000"
+                0.1 "0.100000"
+                1.1 "1.100000"
+                1234.5678 "1234.567800"
+                -1 "-1"
+                -0.1 "-0.100000"
+                -1.1 "-1.100000"
+                -1234.5678 "-1234.567800"
+                1e1 "10.000000"
+                3/1 "3"))
+
+(deftest test-vectors
+  (assert-table [x y] (assert= (json/write-string x) y)
+                [] "[]"
+                [nil] "[null]"
+                [1 2] "[1, 2]"
+                [1 1.0 nil] "[1, 1.000000, null]"
+                ["foo" 42] "[\"foo\", 42]"))
+
+(deftest test-seqs
+  (assert-table [x y] (assert= (json/write-string x) y)
+                (take 0 (range)) "[]"
+                (take 1 (repeat nil)) "[null]"
+                (map identity [1 2]) "[1, 2]"
+                (reduce + [1 2 3]) "6"))
+
+(deftest test-lists
+  (assert-table [x y] (assert= (json/write-string x) y)
+                '() "[]"
+                '(nil) "[null]"
+                '(1 2) "[1, 2]"
+                '(1 1.0 nil) "[1, 1.000000, null]"
+                '("foo" 42) "[\"foo\", 42]"
+                (list) "[]"
+                (list nil) "[null]"
+                (list 1 2) "[1, 2]"
+                (list 1 1.0 nil) "[1, 1.000000, null]"
+                (list "foo" 42) "[\"foo\", 42]"))
+
+(deftest test-maps
+  (assert-table [x y] (assert= (json/write-string x) y)
+                {} "{}"
+                {:foo 42} "{\"foo\": 42}"
+                {"foo" 42} "{\"foo\": 42}"
+                {"foo" 42, "bar" nil} "{\"foo\": 42, \"bar\": null}"))
+
+(deftest test-round-trip
+  (let [data {"foo" 1, "bar" [2 3]}]  ; won't work with keywords because the parser doesn't keywordise them (yet)
+    (assert= (-> data json/write-string json/read-string)
+             data))
+
+  (let [string "{\"foo\": [1, 2, 3]}"]
+    (assert= (-> string json/read-string json/write-string)
+             string)))