gh-131952: Add color to the json CLI

Lib/json/tool.py

@@ -5,7 +5,9 @@
 """
 import argparse
 import json
+import re
 import sys
+from _colorize import ANSIColors, can_colorize
 
 
 def main():
@@ -48,6 +50,8 @@ def main():
         dump_args['indent'] = None
         dump_args['separators'] = ',', ':'
 
+    with_colors = can_colorize()
+
     try:
         if options.infile == '-':
             infile = sys.stdin
@@ -68,12 +72,42 @@ def main():
             outfile = open(options.outfile, 'w', encoding='utf-8')
         with outfile:
             for obj in objs:
-                json.dump(obj, outfile, **dump_args)
+                if with_colors:
+                    json_str = json.dumps(obj, **dump_args)
+                    outfile.write(colorize_json(json_str))
+                else:
+                    json.dump(obj, outfile, **dump_args)
                 outfile.write('\n')
     except ValueError as e:
         raise SystemExit(e)
 
 
+color_pattern = re.compile(r'''
+    (?P<string>"(\\.|[^"\\])*?") |   # String
+    (?P<number>[\d\-+.Ee]+)      |   # Number
+    (?P<boolean>true|false)      |   # Boolean
+    (?P<null>null)                   # Null
+''', re.VERBOSE)
+
+
+def colorize_json(json_str):
+    colors = {
+        'string': ANSIColors.GREEN,
+        'number': ANSIColors.YELLOW,
+        'boolean': ANSIColors.CYAN,
+        'null': ANSIColors.CYAN,
+    }
+
+    def replace(match):
+        for key in colors:
+            if match.group(key):
+                color = colors[key]
+                return f"{color}{match.group(key)}{ANSIColors.RESET}"
+        return match.group()
+
+    return re.sub(color_pattern, replace, json_str)
+
+
 if __name__ == '__main__':
     try:
         main()

Lib/test/test_json/test_tool.py

@@ -10,6 +10,14 @@
 from test.support.script_helper import assert_python_ok
 
 
+def no_color(func):
+    def inner(*args, **kwargs):
+        with os_helper.EnvironmentVarGuard() as env:
+            env['PYTHON_COLORS'] = '0'
+            return func(*args, **kwargs)
+    return inner
+
+
 @support.requires_subprocess()
 class TestMain(unittest.TestCase):
     data = """
@@ -87,6 +95,7 @@ class TestMain(unittest.TestCase):
     }
     """)
 
+    @no_color
     def test_stdin_stdout(self):
         args = sys.executable, '-m', self.module
         process = subprocess.run(args, input=self.data, capture_output=True, text=True, check=True)
@@ -102,7 +111,8 @@ def _create_infile(self, data=None):
 
     def test_infile_stdout(self):
         infile = self._create_infile()
-        rc, out, err = assert_python_ok('-m', self.module, infile)
+        rc, out, err = assert_python_ok('-m', self.module, infile,
+                                        PYTHON_COLORS='0')
         self.assertEqual(rc, 0)
         self.assertEqual(out.splitlines(), self.expect.encode().splitlines())
         self.assertEqual(err, b'')
@@ -116,7 +126,8 @@ def test_non_ascii_infile(self):
         ''').encode()
 
         infile = self._create_infile(data)
-        rc, out, err = assert_python_ok('-m', self.module, infile)
+        rc, out, err = assert_python_ok('-m', self.module, infile,
+                                        PYTHON_COLORS='0')
 
         self.assertEqual(rc, 0)
         self.assertEqual(out.splitlines(), expect.splitlines())
@@ -125,7 +136,8 @@ def test_non_ascii_infile(self):
     def test_infile_outfile(self):
         infile = self._create_infile()
         outfile = os_helper.TESTFN + '.out'
-        rc, out, err = assert_python_ok('-m', self.module, infile, outfile)
+        rc, out, err = assert_python_ok('-m', self.module, infile, outfile,
+                                        PYTHON_COLORS='0')
         self.addCleanup(os.remove, outfile)
         with open(outfile, "r", encoding="utf-8") as fp:
             self.assertEqual(fp.read(), self.expect)
@@ -135,33 +147,38 @@ def test_infile_outfile(self):
 
     def test_writing_in_place(self):
         infile = self._create_infile()
-        rc, out, err = assert_python_ok('-m', self.module, infile, infile)
+        rc, out, err = assert_python_ok('-m', self.module, infile, infile,
+                                        PYTHON_COLORS='0')
         with open(infile, "r", encoding="utf-8") as fp:
             self.assertEqual(fp.read(), self.expect)
         self.assertEqual(rc, 0)
         self.assertEqual(out, b'')
         self.assertEqual(err, b'')
 
+    @no_color
     def test_jsonlines(self):
         args = sys.executable, '-m', self.module, '--json-lines'
         process = subprocess.run(args, input=self.jsonlines_raw, capture_output=True, text=True, check=True)
         self.assertEqual(process.stdout, self.jsonlines_expect)
         self.assertEqual(process.stderr, '')
 
     def test_help_flag(self):
-        rc, out, err = assert_python_ok('-m', self.module, '-h')
+        rc, out, err = assert_python_ok('-m', self.module, '-h',
+                                        PYTHON_COLORS='0')
         self.assertEqual(rc, 0)
         self.assertTrue(out.startswith(b'usage: '))
         self.assertEqual(err, b'')
 
     def test_sort_keys_flag(self):
         infile = self._create_infile()
-        rc, out, err = assert_python_ok('-m', self.module, '--sort-keys', infile)
+        rc, out, err = assert_python_ok('-m', self.module, '--sort-keys', infile,
+                                        PYTHON_COLORS='0')
         self.assertEqual(rc, 0)
         self.assertEqual(out.splitlines(),
                          self.expect_without_sort_keys.encode().splitlines())
         self.assertEqual(err, b'')
 
+    @no_color
     def test_indent(self):
         input_ = '[1, 2]'
         expect = textwrap.dedent('''\
@@ -175,6 +192,7 @@ def test_indent(self):
         self.assertEqual(process.stdout, expect)
         self.assertEqual(process.stderr, '')
 
+    @no_color
     def test_no_indent(self):
         input_ = '[1,\n2]'
         expect = '[1, 2]\n'
@@ -183,6 +201,7 @@ def test_no_indent(self):
         self.assertEqual(process.stdout, expect)
         self.assertEqual(process.stderr, '')
 
+    @no_color
     def test_tab(self):
         input_ = '[1, 2]'
         expect = '[\n\t1,\n\t2\n]\n'
@@ -191,6 +210,7 @@ def test_tab(self):
         self.assertEqual(process.stdout, expect)
         self.assertEqual(process.stderr, '')
 
+    @no_color
     def test_compact(self):
         input_ = '[ 1 ,\n 2]'
         expect = '[1,2]\n'
@@ -203,7 +223,8 @@ def test_no_ensure_ascii_flag(self):
         infile = self._create_infile('{"key":"💩"}')
         outfile = os_helper.TESTFN + '.out'
         self.addCleanup(os.remove, outfile)
-        assert_python_ok('-m', self.module, '--no-ensure-ascii', infile, outfile)
+        assert_python_ok('-m', self.module, '--no-ensure-ascii', infile,
+                         outfile, PYTHON_COLORS='0')
         with open(outfile, "rb") as f:
             lines = f.read().splitlines()
         # asserting utf-8 encoded output file
@@ -214,14 +235,15 @@ def test_ensure_ascii_default(self):
         infile = self._create_infile('{"key":"💩"}')
         outfile = os_helper.TESTFN + '.out'
         self.addCleanup(os.remove, outfile)
-        assert_python_ok('-m', self.module, infile, outfile)
+        assert_python_ok('-m', self.module, infile, outfile, PYTHON_COLORS='0')
         with open(outfile, "rb") as f:
             lines = f.read().splitlines()
         # asserting an ascii encoded output file
         expected = [b'{', rb'    "key": "\ud83d\udca9"', b"}"]
         self.assertEqual(lines, expected)
 
     @unittest.skipIf(sys.platform =="win32", "The test is failed with ValueError on Windows")
+    @no_color
     def test_broken_pipe_error(self):
         cmd = [sys.executable, '-m', self.module]
         proc = subprocess.Popen(cmd,
@@ -232,6 +254,53 @@ def test_broken_pipe_error(self):
         proc.communicate(b'"{}"')
         self.assertEqual(proc.returncode, errno.EPIPE)
 
+    def test_colors(self):
+        infile = os_helper.TESTFN
+        self.addCleanup(os.remove, infile)
+
+        cases = (
+            ('{}', b'{}'),
+            ('[]', b'[]'),
+            ('null', b'\x1b[36mnull\x1b[0m'),
+            ('true', b'\x1b[36mtrue\x1b[0m'),
+            ('false', b'\x1b[36mfalse\x1b[0m'),
+            ('"foo"', b'\x1b[32m"foo"\x1b[0m'),
+            (r'" \"foo\" "', b'\x1b[32m" \\"foo\\" "\x1b[0m'),
+            ('123', b'\x1b[33m123\x1b[0m'),
+            ('-1.2345e+23', b'\x1b[33m-1.2345e+23\x1b[0m'),
+            (r'{"\\": ""}',
+             b'''\
+{
+    \x1b[32m"\\\\"\x1b[0m: \x1b[32m""\x1b[0m
+}'''),
+            (r'{"\\\\": ""}',
+             b'''\
+{
+    \x1b[32m"\\\\\\\\"\x1b[0m: \x1b[32m""\x1b[0m
+}'''),
+            ('{"foo": "bar", "baz": 1234, "qux": [true, false, null]}',
+             b'''\
+{
+    \x1b[32m"foo"\x1b[0m: \x1b[32m"bar"\x1b[0m,
+    \x1b[32m"baz"\x1b[0m: \x1b[33m1234\x1b[0m,
+    \x1b[32m"qux"\x1b[0m: [
+        \x1b[36mtrue\x1b[0m,
+        \x1b[36mfalse\x1b[0m,
+        \x1b[36mnull\x1b[0m
+    ]
+}'''),
+        )
+
+        for input_, expected in cases:
+            with self.subTest(input=input_):
+                with open(infile, "w", encoding="utf-8") as fp:
+                    fp.write(input_)
+                _, stdout, _ = assert_python_ok('-m', self.module, infile,
+                                                PYTHON_COLORS='1')
+                stdout = stdout.replace(b'\r\n', b'\n')  # normalize line endings
+                stdout = stdout.strip()
+                self.assertEqual(stdout, expected)
+
 
 @support.requires_subprocess()
 class TestTool(TestMain):

Misc/NEWS.d/next/Library/2025-04-05-16-05-34.gh-issue-131952.HX6gCX.rst

@@ -0,0 +1 @@
+Add color output to the :program:`json.tool` CLI.