Findnlohmann_json.cmake

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# Copyright (C) 2026 The Qt Company Ltd.

# SPDX-License-Identifier: BSD-3-Clause

# Findnlohmann_json.cmake - Find the nlohmann/json library

# This module defines:

#   nlohmann_json_FOUND - System has nlohmann/json

#   nlohmann_json_INCLUDE_DIR - The nlohmann/json include directory (single)

#   nlohmann_json_INCLUDE_DIRS - The nlohmann/json include directories (list)

#   nlohmann_json::nlohmann_json - Imported target for nlohmann/json

# The module first tries pkg-config, then falls back to direct path search.

# Try pkg-config first

find_package(PkgConfig QUIET)

if(PkgConfig_FOUND)

    pkg_check_modules(PC_nlohmann_json QUIET nlohmann_json nlohmann-json)

endif()

# Use pkg-config results if available, otherwise search directly

if(PC_nlohmann_json_FOUND)

    # pkg-config found it - extract include dirs

    set(nlohmann_json_INCLUDE_DIRS ${PC_nlohmann_json_INCLUDE_DIRS})

    # FPHSA expects a single directory, so extract the first one (if any)

    if(nlohmann_json_INCLUDE_DIRS)

        list(GET nlohmann_json_INCLUDE_DIRS 0 nlohmann_json_INCLUDE_DIR)

    endif()

else()

    find_path(nlohmann_json_INCLUDE_DIR

        NAMES nlohmann/json.hpp

        HINTS

            # Homebrew (Apple Silicon)

            /opt/homebrew/opt/nlohmann-json

            # Homebrew (Intel)

            /usr/local/opt/nlohmann-json

            # Environment variable override

            ENV NLOHMANN_JSON_ROOT

        PATH_SUFFIXES include

        DOC "nlohmann/json include directory"

    # Set INCLUDE_DIRS from the single directory for consistency

    if(nlohmann_json_INCLUDE_DIR)

        set(nlohmann_json_INCLUDE_DIRS ${nlohmann_json_INCLUDE_DIR})

    endif()

endif()

include(FindPackageHandleStandardArgs)

find_package_handle_standard_args(nlohmann_json

    REQUIRED_VARS nlohmann_json_INCLUDE_DIR

    FAIL_MESSAGE "nlohmann/json not found. Install via:

    Homebrew: brew install nlohmann-json

    APT:      sudo apt install nlohmann-json3-dev

    Conan:    conan install nlohmann_json/3.11.3

    vcpkg:    vcpkg install nlohmann-json"

if(nlohmann_json_FOUND AND NOT TARGET nlohmann_json::nlohmann_json)

    add_library(nlohmann_json::nlohmann_json INTERFACE IMPORTED)

    set_property(TARGET nlohmann_json::nlohmann_json PROPERTY

        INTERFACE_INCLUDE_DIRECTORIES ${nlohmann_json_INCLUDE_DIRS}

endif()

mark_as_advanced(nlohmann_json_INCLUDE_DIR nlohmann_json_INCLUDE_DIRS)