Implement native JSON support using Jansson

* configure.ac: New option --with-json.

* src/json.c (Fjson_serialize, Fjson_insert, Fjson_parse_string)
(Fjson_parse_buffer): New defuns.
(json_out_of_memory, json_parse_error, json_release_object)
(check_string_without_embedded_nulls, json_check, lisp_to_json)
(json_insert, json_insert_callback, json_to_lisp)
(json_read_buffer_callback, Fjson_parse_buffer, define_error): New
helper function.
(syms_of_json): New file.

* src/lisp.h: Declaration for syms_of_json.

* src/emacs.c (main): Enable JSON functions.

* src/Makefile.in (JSON_LIBS, JSON_CFLAGS, JSON_OBJ, EMACS_CFLAGS)
(base_obj, LIBES): Compile json.c if --with-json is enabled.

* test/src/json-tests.el (json-serialize/roundtrip)
(json-serialize/object, json-parse-string/object): New unit tests.

1 files changed, 61 insertions, 0 deletions

diff --git a/test/src/json-tests.el b/test/src/json-tests.el
new file mode 100644
index 00000000000..1d8f9a490ba
--- /dev/null
+++ b/test/src/json-tests.el
@@ -0,0 +1,61 @@
+;;; json-tests.el --- unit tests for json.c          -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2017 Free Software Foundation, Inc.
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; Unit tests for src/json.c.
+
+;;; Code:
+
+(require 'cl-lib)
+(require 'map)
+
+(ert-deftest json-serialize/roundtrip ()
+  (let ((lisp [nil :json-false t 0 123 -456 3.75 "foo"])
+        (json "[null,false,true,0,123,-456,3.75,\"foo\"]"))
+    (should (equal (json-serialize lisp) json))
+    (with-temp-buffer
+      (json-insert lisp)
+      (should (equal (buffer-string) json))
+      (should (eobp)))
+    (should (equal (json-parse-string json) lisp))
+    (with-temp-buffer
+      (insert json)
+      (goto-char 1)
+      (should (equal (json-parse-buffer) lisp))
+      (should (eobp)))))
+
+(ert-deftest json-serialize/object ()
+  (let ((table (make-hash-table :test #'equal)))
+    (puthash "abc" [1 2 t] table)
+    (puthash "def" nil table)
+    (should (equal (json-serialize table)
+                   "{\"abc\":[1,2,true],\"def\":null}"))))
+
+(ert-deftest json-parse-string/object ()
+  (let ((actual
+         (json-parse-string
+          "{ \"abc\" : [1, 2, true], \"def\" : null, \"abc\" : [9, false] }\n")))
+    (should (hash-table-p actual))
+    (should (equal (hash-table-count actual) 2))
+    (should (equal (cl-sort (map-pairs actual) #'string< :key #'car)
+                   '(("abc" . [9 :json-false]) ("def"))))))
+
+(provide 'json-tests)
+;;; json-tests.el ends here