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The open source OpenXR runtime
scripts: Add json merging script
Part-of: <https://gitlab.freedesktop.org/monado/monado/-/merge_requests/2635>
authored by
Jakob Bornecrantz
and committed by
Marge Bot
0a639c04
7218ff54
+1
CMakeLists.txt
+1
CMakeLists.txt
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cmake/MergeJSON.cmake
+77
cmake/MergeJSON.cmake
···
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# Copyright 2025, NVIDIA CORPORATION.
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# SPDX-License-Identifier: BSL-1.0
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# JSON merge function: merges multiple JSON files into one output file
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#
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# To use this function in your CMakeLists.txt:
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# include(${CMAKE_SOURCE_DIR}/scripts/CMakeLists.txt)
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#
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# Usage:
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# merge_json_files(
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# OUTPUT <output_file>
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# SOURCES <json_file1> <json_file2> ...
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# [ALLOW_OVERWRITE]
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# [IGNORE_SCHEMA]
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# )
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#
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# Arguments:
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# OUTPUT - Output file path (required)
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# SOURCES - List of JSON files to merge (required)
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# ALLOW_OVERWRITE - Optional flag to allow duplicate keys
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# IGNORE_SCHEMA - Optional flag to ignore "$schema" field in output
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#
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# The function automatically:
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# - Sorts input files alphabetically for consistent results
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# - Tracks dependencies so output is regenerated when inputs change
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# - Errors on duplicate keys unless ALLOW_OVERWRITE is specified
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#
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# Example:
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# merge_json_files(
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# OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/merged.json"
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# SOURCES file1.json file2.json file3.json
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# IGNORE_SCHEMA
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# )
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function(merge_json_files)
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set(options ALLOW_OVERWRITE IGNORE_SCHEMA)
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set(oneValueArgs OUTPUT)
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set(multiValueArgs SOURCES)
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cmake_parse_arguments(
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MERGE_JSON "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN}
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)
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if(NOT MERGE_JSON_OUTPUT)
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message(FATAL_ERROR "merge_json_files: OUTPUT argument is required")
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endif()
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if(NOT MERGE_JSON_SOURCES)
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message(FATAL_ERROR "merge_json_files: SOURCES argument is required")
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endif()
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# Build command arguments
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set(MERGE_COMMAND ${PYTHON_EXECUTABLE}
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${CMAKE_CURRENT_FUNCTION_LIST_DIR}/merge_json.py -o
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"${MERGE_JSON_OUTPUT}"
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)
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if(MERGE_JSON_ALLOW_OVERWRITE)
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list(APPEND MERGE_COMMAND --allow-overwrite)
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endif()
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if(MERGE_JSON_IGNORE_SCHEMA)
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list(APPEND MERGE_COMMAND --ignore-schema)
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endif()
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list(APPEND MERGE_COMMAND ${MERGE_JSON_SOURCES})
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# Create custom command with proper dependencies
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add_custom_command(
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OUTPUT "${MERGE_JSON_OUTPUT}"
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COMMAND ${MERGE_COMMAND}
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VERBATIM
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DEPENDS ${CMAKE_CURRENT_FUNCTION_LIST_DIR}/merge_json.py
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${MERGE_JSON_SOURCES}
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COMMENT "Merging JSON files into ${MERGE_JSON_OUTPUT}"
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)
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endfunction()
+139
cmake/merge_json.py
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cmake/merge_json.py
···
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#!/usr/bin/env python3
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# Copyright 2025, NVIDIA CORPORATION.
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# SPDX-License-Identifier: BSL-1.0
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"""
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Helper script to merge multiple JSON files into one.
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This script merges the root JSON objects from multiple input files
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while preserving field ordering. Files are processed in sorted order
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to ensure consistent results. Fields are merged in the order they
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appear across the input files.
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"""
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import argparse
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import json
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import sys
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from pathlib import Path
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def merge_json_files(json_files, output_file, allow_overwrite=False,
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ignore_schema=False):
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"""
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Merge multiple JSON files into a single output file.
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Args:
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json_files: List of paths to JSON files to merge
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output_file: Path to the output file
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allow_overwrite: If True, allow later files to overwrite keys
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from earlier files
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ignore_schema: If True, ignore the "$schema" field in input files
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"""
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merged = {}
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# Sort files to ensure consistent ordering
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sorted_files = sorted(json_files)
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for json_file in sorted_files:
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try:
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with open(json_file, 'r', encoding='utf-8') as f:
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data = json.load(f)
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if not isinstance(data, dict):
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print(f"Error: {json_file} does not contain a JSON "
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f"object at root level",
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file=sys.stderr)
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sys.exit(1)
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# Merge while preserving order - check for duplicates
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for key, value in data.items():
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if key == "$schema" and ignore_schema:
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continue
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if key in merged:
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if allow_overwrite:
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print(f"Warning: Key '{key}' from {json_file} "
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f"overwrites previous definition",
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file=sys.stderr)
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else:
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print(f"Error: Duplicate key '{key}' found in "
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f"{json_file}. Use --allow-overwrite to "
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f"permit overwriting.",
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file=sys.stderr)
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sys.exit(1)
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merged[key] = value
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except FileNotFoundError:
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print(f"Error: File not found: {json_file}", file=sys.stderr)
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sys.exit(1)
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except json.JSONDecodeError as e:
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print(f"Error: Failed to parse JSON from {json_file}: {e}",
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file=sys.stderr)
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sys.exit(1)
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except Exception as e:
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print(f"Error: Failed to read {json_file}: {e}",
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file=sys.stderr)
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sys.exit(1)
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# Write merged JSON to output file
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try:
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with open(output_file, 'w', encoding='utf-8') as f:
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json.dump(merged, f, indent='\t', ensure_ascii=False)
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f.write('\n') # Add trailing newline
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# Printing, left in if we want it in the future.
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if False:
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print(f"Successfully merged {len(json_files)} file(s) into "
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f"{output_file}")
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except Exception as e:
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print(f"Error: Failed to write to {output_file}: {e}",
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file=sys.stderr)
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sys.exit(1)
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def main():
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parser = argparse.ArgumentParser(
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description='Merge multiple JSON files into one, preserving '
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'field ordering.',
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formatter_class=argparse.RawDescriptionHelpFormatter,
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epilog="""
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Examples:
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%(prog)s -o merged.json file1.json file2.json file3.json
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%(prog)s -o output.json base.json overrides.json
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%(prog)s -o output.json --allow-overwrite base.json overrides.json
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%(prog)s -o output.json --ignore-schema schema.json data.json
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"""
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)
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parser.add_argument('-o', '--output',
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required=True,
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metavar='OUTPUT',
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help='Output file path for the merged JSON')
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parser.add_argument('--allow-overwrite',
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action='store_true',
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help='Allow later files to overwrite duplicate '
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'keys from earlier files')
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parser.add_argument('--ignore-schema',
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action='store_true',
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help='Ignore the "$schema" field in input files')
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parser.add_argument('json_files',
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nargs='+',
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metavar='JSON_FILE',
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help='JSON files (will be sorted alphabetically)')
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args = parser.parse_args()
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# Validate that we have at least one input file
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if not args.json_files:
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print("Error: At least one JSON file must be provided",
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file=sys.stderr)
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sys.exit(1)
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merge_json_files(args.json_files, args.output, args.allow_overwrite,
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args.ignore_schema)
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if __name__ == '__main__':
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main()