Add jsonmodify tool

This tool is used to modify apex_manifest.json when building apex
module.

Here's the usage:

usage: jsonmodify [-h] [-o output] [-v path value] [-s path value]
                     [-r path] [-a path [value ...]]
                     [input]

positional arguments:
  input                 JSON file

optional arguments:
  -h, --help            show this help message and exit
  -o output, --out output
                        write result to a file. If omitted, print to stdout
  -v path value, --value path value
                        set value of the key specified by path. If path
                        doesn't exist, creates new one.
  -s path value, --replace path value
                        replace value of the key specified by path. If path
                        doesn't exist, no op.
  -r path, --remove path
                        remove the key specified by path. If path doesn't
                        exist, no op.
  -a path [value ...], --append_list path [value ...]
                        append values to the list specified by path. If path
                        doesn't exist, creates new list for it.

Bug: 138695532
Test: m jsonmodify
Test: echo {} | jsonmodify -v name hello -a list.nested a b c
{
  "name": "hello",
  "list": {
    "nested": [
      "a",
      "b",
      "c"
    ]
  }
}

Change-Id: I2cd043c614b3ad2306a0c27ccee302633c6d2525

scripts/Android.bp

@@ -69,3 +69,19 @@ python_test_host {
     },
     test_suites: ["general-tests"],
 }
+
+python_binary_host {
+    name: "jsonmodify",
+    main: "jsonmodify.py",
+    srcs: [
+        "jsonmodify.py",
+    ],
+    version: {
+        py2: {
+            enabled: true,
+        },
+        py3: {
+            enabled: false,
+        },
+    }
+}

scripts/jsonmodify.py

@@ -0,0 +1,121 @@
+#!/usr/bin/env python
+#
+# Copyright (C) 2019 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+import argparse
+import collections
+import json
+import sys
+
+def follow_path(obj, path):
+  cur = obj
+  last_key = None
+  for key in path.split('.'):
+    if last_key:
+      if last_key not in cur:
+        return None,None
+      cur = cur[last_key]
+    last_key = key
+  if last_key not in cur:
+    return None,None
+  return cur, last_key
+
+
+def ensure_path(obj, path):
+  cur = obj
+  last_key = None
+  for key in path.split('.'):
+    if last_key:
+      if last_key not in cur:
+        cur[last_key] = dict()
+      cur = cur[last_key]
+    last_key = key
+  return cur, last_key
+
+
+class SetValue(str):
+  def apply(self, obj, val):
+    cur, key = ensure_path(obj, self)
+    cur[key] = val
+
+
+class Replace(str):
+  def apply(self, obj, val):
+    cur, key = follow_path(obj, self)
+    if cur:
+      cur[key] = val
+
+
+class Remove(str):
+  def apply(self, obj):
+    cur, key = follow_path(obj, self)
+    if cur:
+      del cur[key]
+
+
+class AppendList(str):
+  def apply(self, obj, *args):
+    cur, key = ensure_path(obj, self)
+    if key not in cur:
+      cur[key] = list()
+    if not isinstance(cur[key], list):
+      raise ValueError(self + " should be a array.")
+    cur[key].extend(args)
+
+
+def main():
+  parser = argparse.ArgumentParser()
+  parser.add_argument('-o', '--out',
+                      help='write result to a file. If omitted, print to stdout',
+                      metavar='output',
+                      action='store')
+  parser.add_argument('input', nargs='?', help='JSON file')
+  parser.add_argument("-v", "--value", type=SetValue,
+                      help='set value of the key specified by path. If path doesn\'t exist, creates new one.',
+                      metavar=('path', 'value'),
+                      nargs=2, dest='patch', default=[], action='append')
+  parser.add_argument("-s", "--replace", type=Replace,
+                      help='replace value of the key specified by path. If path doesn\'t exist, no op.',
+                      metavar=('path', 'value'),
+                      nargs=2, dest='patch', action='append')
+  parser.add_argument("-r", "--remove", type=Remove,
+                      help='remove the key specified by path. If path doesn\'t exist, no op.',
+                      metavar='path',
+                      nargs=1, dest='patch', action='append')
+  parser.add_argument("-a", "--append_list", type=AppendList,
+                      help='append values to the list specified by path. If path doesn\'t exist, creates new list for it.',
+                      metavar=('path', 'value'),
+                      nargs='+', dest='patch', default=[], action='append')
+  args = parser.parse_args()
+
+  if args.input:
+    with open(args.input) as f:
+      obj = json.load(f, object_pairs_hook=collections.OrderedDict)
+  else:
+    obj = json.load(sys.stdin, object_pairs_hook=collections.OrderedDict)
+
+  for p in args.patch:
+    p[0].apply(obj, *p[1:])
+
+  if args.out:
+    with open(args.out, "w") as f:
+      json.dump(obj, f, indent=2)
+  else:
+    print(json.dumps(obj, indent=2))
+
+
+if __name__ == '__main__':
+  main()