Add a command line interface

Author: jg-rp

jsonpath_rfc9535/__main__.py

@@ -0,0 +1,5 @@
+"""CLI entry point."""
+
+from jsonpath_rfc9535.cli import main
+
+main()

jsonpath_rfc9535/cli.py

@@ -0,0 +1,154 @@
+"""JSONPath, JSON Pointer and JSON Patch command line interface."""
+
+import argparse
+import json
+import sys
+
+import jsonpath_rfc9535 as jsonpath
+from jsonpath_rfc9535.__about__ import __version__
+from jsonpath_rfc9535.exceptions import JSONPathIndexError
+from jsonpath_rfc9535.exceptions import JSONPathSyntaxError
+from jsonpath_rfc9535.exceptions import JSONPathTypeError
+
+INDENT = 2
+
+_EPILOG = """\
+Example usage:
+  Find values in source.json matching a JSONPath query, write them to result.json.
+  $ jsonpath-rfc9535 path -q "$.foo['bar'][?@.baz > 1]" -f source.json -o result.json
+"""
+
+
+class DescriptionHelpFormatter(
+    argparse.RawDescriptionHelpFormatter,
+    argparse.ArgumentDefaultsHelpFormatter,
+):
+    """Raw epilog formatter with defaults."""
+
+
+def setup_parser() -> argparse.ArgumentParser:  # noqa: D103
+    parser = argparse.ArgumentParser(
+        prog="jsonpath-rfc9535",
+        formatter_class=DescriptionHelpFormatter,
+        description=(
+            "Find values in a JSON document given an "
+            "RFC 9535 JSONPath query expression."
+        ),
+        epilog=_EPILOG,
+    )
+
+    parser.add_argument(
+        "-v",
+        "--version",
+        action="version",
+        version=f"jsonpath-rfc9535, version {__version__}",
+        help="Show the version and exit.",
+    )
+
+    parser.add_argument(
+        "--debug",
+        action="store_true",
+        help="Show stack traces.",
+    )
+
+    parser.add_argument(
+        "--pretty",
+        action="store_true",
+        help="Add indents and newlines to output JSON.",
+    )
+
+    parser.set_defaults(func=handle_path_command)
+    group = parser.add_mutually_exclusive_group(required=True)
+
+    group.add_argument(
+        "-q",
+        "--query",
+        help="JSONPath query string.",
+    )
+
+    group.add_argument(
+        "-r",
+        "--path-file",
+        type=argparse.FileType(mode="r"),
+        help="Text file containing a JSONPath query.",
+    )
+
+    parser.add_argument(
+        "-f",
+        "--file",
+        type=argparse.FileType(mode="rb"),
+        default=sys.stdin,
+        help=(
+            "File to read the target JSON document from. "
+            "Defaults to reading from the standard input stream."
+        ),
+    )
+
+    parser.add_argument(
+        "-o",
+        "--output",
+        type=argparse.FileType(mode="w"),
+        default=sys.stdout,
+        help=(
+            "File to write resulting objects to, as a JSON array. "
+            "Defaults to the standard output stream."
+        ),
+    )
+
+    return parser
+
+
+def handle_path_command(args: argparse.Namespace) -> None:  # noqa: PLR0912
+    """Handle the `path` sub command."""
+    # Empty string is OK.
+    if args.query is not None:
+        query = args.query
+    else:
+        query = args.query_file.read().strip()
+
+    try:
+        path = jsonpath.JSONPathEnvironment().compile(query)
+    except JSONPathSyntaxError as err:
+        if args.debug:
+            raise
+        sys.stderr.write(f"json path syntax error: {err}\n")
+        sys.exit(1)
+    except JSONPathTypeError as err:
+        if args.debug:
+            raise
+        sys.stderr.write(f"json path type error: {err}\n")
+        sys.exit(1)
+    except JSONPathIndexError as err:
+        if args.debug:
+            raise
+        sys.stderr.write(f"json path index error: {err}\n")
+        sys.exit(1)
+
+    try:
+        data = json.load(args.file)
+        matches = path.findall(data)
+    except json.JSONDecodeError as err:
+        if args.debug:
+            raise
+        sys.stderr.write(f"target document json decode error: {err}\n")
+        sys.exit(1)
+    except JSONPathTypeError as err:
+        # Type errors are currently only occurring are compile-time.
+        if args.debug:
+            raise
+        sys.stderr.write(f"json path type error: {err}\n")
+        sys.exit(1)
+
+    indent = INDENT if args.pretty else None
+    json.dump(matches, args.output, indent=indent)
+
+
+def main() -> None:
+    """CLI argument parser entry point."""
+    parser = setup_parser()
+    args = parser.parse_args()
+    args.func(args)
+
+
+if __name__ == "__main__":
+    main()

pyproject.toml

@@ -29,6 +29,9 @@ Documentation = "https://jg-rp.github.io/python-jsonpath-rfc9535/"
 Issues = "https://github.com/jg-rp/python-jsonpath-rfc9535/issues"
 Source = "https://github.com/jg-rp/python-jsonpath-rfc9535"
 
+[project.scripts]
+jsonpath-rfc9535 = "jsonpath_rfc9535.cli:main"
+
 [tool.hatch.version]
 path = "jsonpath_rfc9535/__about__.py"