bpo-31553: add --json-lines option to json.tool (#10051)

* add jsonlines option to json.tool

* code review

* fix:avoid read infile after it close

* improve doc in whatsnew 3.8

1 files changed, 11 insertions, 5 deletions

diff --git a/Lib/json/tool.py b/Lib/json/tool.py
index 5932f4e..1d82bc8 100644
--- a/Lib/json/tool.py
+++ b/Lib/json/tool.py
@@ -26,19 +26,25 @@ def main():
                         help='write the output of infile to outfile')
     parser.add_argument('--sort-keys', action='store_true', default=False,
                         help='sort the output of dictionaries alphabetically by key')
+    parser.add_argument('--json-lines', action='store_true', default=False,
+                        help='parse input using the jsonlines format')
     options = parser.parse_args()
 
     infile = options.infile or sys.stdin
     outfile = options.outfile or sys.stdout
     sort_keys = options.sort_keys
-    with infile:
+    json_lines = options.json_lines
+    with infile, outfile:
         try:
-            obj = json.load(infile)
+            if json_lines:
+                objs = (json.loads(line) for line in infile)
+            else:
+                objs = (json.load(infile), )
+            for obj in objs:
+                json.dump(obj, outfile, sort_keys=sort_keys, indent=4)
+                outfile.write('\n')
         except ValueError as e:
             raise SystemExit(e)
-    with outfile:
-        json.dump(obj, outfile, sort_keys=sort_keys, indent=4)
-        outfile.write('\n')
 
 
 if __name__ == '__main__':