args.h

// SPDX-License-Identifier: MIT
/**
 * @page args.h
 * @author Jakov Dragičević (github:jakovdev)
 * @copyright MIT License.
 * @brief Decentralized CLI argument framework.
 * @details
 * This library lets each translation unit declare and register arguments near
 * the code that owns them, instead of maintaining a single global argument
 * table. Registration is constructor-driven and therefore complete before
 * calling @ref args_parse.
 *
 * Correctness depends on constructor attribute support (GCC/Clang) or 
 * .CRT$XCU sections (MSVC) executing registration hooks before @c main.
 *
 * @attention WIP, only supports options.
 * @note Partial C++ support due to struct field declaration order.
 * Most macros will break because they don't take this into account.
 * You can manually initialize fields which should make it work like in C.
 *
 * @see @subpage args_intro "Decentralized CLI Argument Framework"
 *
 * Source code:
 * @include args.h
 */
 
/**
 * @page args_intro Decentralized CLI Argument Framework
 *
 * # Overview
 * @ref args.h "args.h" provides a header-only argument manager intended for
 * modular C codebases. Arguments are declared with @ref ARGUMENT in any source
 * file, registered automatically, then processed in three explicit stages:
 * parsing, validation, and actions.
 *
 * # Feature Highlights
 * - Distributed argument declarations with constructor-based registration.
 * - Automatic help generation.
 * - Dependency/conflict/subset relationships between arguments.
 * - Automatic validation of required arguments and relation rules.
 * - Typed parsing helpers via @ref ARG_PARSER family.
 * - Validation and general callbacks with flexible execution policies.
 * - Deterministic cross-file ordering for help, validate, and action stages.
 *
 * # Quick Start
 * @code{.c}
 * #define ARGS_IMPLEMENTATION
 * #include "args.h"
 *
 * // Simple flag argument example
 *
 * static bool my_flag;
 *
 * static void print_my_flag(void)
 * {
 *     printf("Hello from my_flag\n");
 * }
 *
 * ARGUMENT(my_flag) = {
 *     .set = &my_flag,
 *     .action_callback = print_my_flag,
 *     .action_phase = ARG_CALLBACK_IF_SET,
 *     .help = "Enable my flag",
 *     .lopt = "my-flag",
 *     .opt = 'f',
 * };
 *
 * int main(int argc, char **argv) {
 *     if (!args_parse(argc, argv) || !args_validate())
 *         return 1;
 *     args_actions();
 *     printf("My flag is %s\n", my_flag ? "enabled!" : "disabled!");
 *     return 0;
 * }
 *
 * // Possible outputs:
 * // 
 * // $ ./my_program
 * // My flag is disabled!
 * // 
 * // $ ./my_program -f
 * // Hello from my_flag!
 * // My flag is enabled!
 * // 
 * // $ ./my_program -h
 * // Usage: ./my_program [ARGUMENTS]
 * // 
 * // Optional arguments:
 * //   -f, --my-flag    Enable my flag
 * //   -h, --help       Display this help message
 * @endcode
 *
 * # Docs Navigation
 * - @ref args_core "Core API"
 * - @ref args_parsers "Parser Helpers"
 * - @ref args_callbacks "Callback Phases"
 * - @ref args_relations "Relationships"
 * - @ref args_customizable "Customization Points"
 * @if ARGS_INTERNALS
 * - @ref args_internals "Internals"
 * @endif
 */
 
#ifndef ARGS_H_
#define ARGS_H_
 
#include <errno.h>
#include <stdbool.h>
#include <stddef.h>
 
/** @defgroup args_core args.h: Core API */
/** @defgroup args_parsers args.h: Parser Helpers */
/** @defgroup args_callbacks args.h: Callback Phases */
/** @defgroup args_relations args.h: Relationships */
/** @defgroup args_customizable args.h: Customization Points */
/** @cond ARGS_INTERNALS */
/** @defgroup args_internals args.h: Internals */
/** @endcond */
 
/** @addtogroup args_core
 * @brief Argument creation and registration macros.
 * @details
 * Use @ref ARGUMENT to declare and register new arguments.
 * Each argument is an instance of @ref argument, which has fields for storage,
 * callbacks, schema rules, and ordering controls that you can initialize.
 */
 
/** @name Creating New Arguments */
/** @{ */
 
#ifndef __cplusplus
/** @ingroup args_core
 * @brief Creates and registers a new argument object.
 * @hideinitializer
 * @details
 * Use this macro at file scope. It declares @ref argument @c _arg_<name>,
 * wires constructor-based registration, then leaves a second
 * declaration target for designated initialization.
 * @param name Unique argument identifier used in generated symbol names.
 * @pre The identifier is unique within the link unit.
 * @post The argument is linked into internal processing lists before @c main.
 * @see ARG
 * @see ARG_DECLARE
 * @see ARG_EXTERN
 */
#define ARGUMENT(name)                          \
    ARG_DECLARE(name);                      \
    _ARGS_CONSTRUCTOR(_arg_register_##name) \
    {                                       \
        _args_register(ARG(name));      \
    }                                       \
    ARG_DECLARE(name)
#else
#define ARGUMENT(name)                          \
    ARG_EXTERN(name);                       \
    _ARGS_CONSTRUCTOR(_arg_register_##name) \
    {                                       \
        _args_register(ARG(name));      \
    }                                       \
    ARG_DECLARE(name)
#endif
 
/** @} */
/** @name Requirement And Visibility */
/** @{ */
 
/** @ingroup args_core
 * @brief Requirement policy for @ref argument::arg_req.
 */
enum arg_requirement {
    ARG_OPTIONAL, /**< User does not need to provide the argument. */
    ARG_REQUIRED, /**< Argument must be present unless conflicted out. */
    ARG_HIDDEN, /**< Optional and omitted from generated help output. */
    ARG_SOMETIME, /**< Conditionally required, enforce via relations/callbacks. */
};
 
/** @} */
/** @name Parameter Modes */
/** @{ */
 
/** @ingroup args_core
 * @brief Parameter requirement for @ref argument::param_req.
 * @remark Semantics intentionally match common @c getopt usage.
 */
enum arg_parameter {
    ARG_PARAM_NONE, /**< Argument is a flag, does not take a parameter. */
    ARG_PARAM_REQUIRED, /**< @ref argument::parse_callback receives non-NULL @p str. */
    ARG_PARAM_OPTIONAL, /**< @ref argument::parse_callback may receive NULL @p str. */
};
 
/** @} */
 
/** @addtogroup args_parsers
 * @brief Parser callback generation and built-in parser helpers.
 * @par Built-in parser wrappers
 * @ref ARG_PARSE_L, @ref ARG_PARSE_LL, @ref ARG_PARSE_UL,
 * @ref ARG_PARSE_ULL, @ref ARG_PARSE_F, and @ref ARG_PARSE_D are convenience
 * wrappers around @ref ARG_PARSER.
 */
 
/** @name Parser Generation */
/** @{ */
 
/** @ingroup args_parsers
 * @brief Generates a typed parser callback with common conversion checks.
 * @hideinitializer
 * @details
 * The generated function is named @c parse_<name> and matches @ref argument::parse_callback.
 * It parses @p str, rejects malformed input, range errors, and custom condition failures,
 * then writes to @p dest.
 * @param name Suffix used for generated function name.
 * @param strto Conversion routine, e.g. @c strtol or @c strtod.
 * @param ARG_BASE Macro, leave out macro for no base, or e.g. ARG_BASE(10) to pass to strto.
 * @param strto_t Return type of @p strto.
 * @param dest_t Destination pointee type.
 * @param CAST Optional cast expression when narrowing/widening.
 * @param cond Rejection predicate evaluated against local variable @c val.
 * @param err Error text, falls back to @ref ARG_ERR when empty.
 * @retval ARG_VALID Input accepted and stored in @p dest.
 * @retval ARG_INVALID Input rejected with diagnostic message.
 */
#define ARG_PARSER(name, strto, ARG_BASE, strto_t, dest_t, CAST, cond, err)    \
    static struct arg_callback parse_##name(const char *str, void *dest)   \
    {                                                                      \
        errno = 0;                                                     \
        char *end = NULL;                                              \
        strto_t val = strto(str, &end ARG_BASE);                       \
        if (end == str || *end != '\0' || errno == ERANGE || (cond))   \
            return ARG_INVALID((err) && *(err) ? (err) : ARG_ERR); \
        *(dest_t *)dest = CAST val;                                    \
        return ARG_VALID();                                            \
    }
 
/** @ingroup args_parsers
 * @brief Helper for the @p ARG_BASE parameter in @ref ARG_PARSER.
 * @note If the conversion function doesn't take a base parameter,
 * omit the macro like in the @ref ARG_PARSE_F macro definition.
 * @param N Numeric base to pass to conversion functions, e.g. 10 for decimal or 16 for hex.
 * @hideinitializer
 */
#define ARG_BASE(N) , N
 
#ifndef ARG_ERR
/** @ingroup args_parsers
 * @brief Default parser error message if @p err is empty in @ref ARG_PARSER.
 * @remark Overridable before including @ref args.h.
 */
#define ARG_ERR "Invalid value"
#endif
 
/** @} */
/** @name Built-in Parser Wrappers */
/** @{ */
 
/** @ingroup args_parsers
 * @brief Convenience wrapper of @ref ARG_PARSER using @c strtol.
 * @hideinitializer
 */
#define ARG_PARSE_L(name, base, dest_t, CAST, cond, err) \
    ARG_PARSER(name, strtol, ARG_BASE(base), long, dest_t, CAST, cond, err)
 
/** @ingroup args_parsers
 * @brief Convenience wrapper of @ref ARG_PARSER using @c strtoll.
 * @hideinitializer
 */
#define ARG_PARSE_LL(name, base, dest_t, CAST, cond, err)                  \
    ARG_PARSER(name, strtoll, ARG_BASE(base), long long, dest_t, CAST, \
           cond, err)
 
/** @ingroup args_parsers
 * @brief Convenience wrapper of @ref ARG_PARSER using @c strtoul.
 * @hideinitializer
 */
#define ARG_PARSE_UL(name, base, dest_t, CAST, cond, err)                      \
    ARG_PARSER(name, strtoul, ARG_BASE(base), unsigned long, dest_t, CAST, \
           cond, err)
 
/** @ingroup args_parsers
 * @brief Convenience wrapper of @ref ARG_PARSER using @c strtoull.
 * @hideinitializer
 */
#define ARG_PARSE_ULL(name, base, dest_t, CAST, cond, err)                     \
    ARG_PARSER(name, strtoull, ARG_BASE(base), unsigned long long, dest_t, \
           CAST, cond, err)
 
/** @ingroup args_parsers
 * @brief Convenience wrapper of @ref ARG_PARSER using @c strtof.
 * @hideinitializer
 */
#define ARG_PARSE_F(name, dest_t, CAST, cond, err) \
    ARG_PARSER(name, strtof, , float, dest_t, CAST, cond, err)
 
/** @ingroup args_parsers
 * @brief Convenience wrapper of @ref ARG_PARSER using @c strtod.
 * @hideinitializer
 */
#define ARG_PARSE_D(name, dest_t, CAST, cond, err) \
    ARG_PARSER(name, strtod, , double, dest_t, CAST, cond, err)
 
/** @} */
 
/** @addtogroup args_parsers
 * @par Custom parser contract
 * Custom parser callbacks return @ref ARG_INVALID or @ref ARG_VALID and
 * use signature @c (const char *str, void *dest).
 */
 
/** @name Parser Generation */
/** @{ */
 
/** @ingroup args_callbacks
 * @brief Result object returned by parser/validator callbacks.
 * @invariant @ref arg_callback::error is @c NULL when the callback succeeds.
 */
struct arg_callback {
    /**
     * @brief Diagnostic user-facing message for failures, NULL on success.
     */
    const char *error;
};
 
/** @ingroup args_callbacks
 * @brief Creates a failing @ref arg_callback value.
 * @param msg Diagnostic message to show the user, e.g. "Must be a positive integer".
 * @hideinitializer
 */
#define ARG_INVALID(msg) ((struct arg_callback){ .error = msg })
 
/** @ingroup args_callbacks
 * @brief Creates a successful @ref arg_callback value.
 * @hideinitializer
 */
#define ARG_VALID() ((struct arg_callback){ .error = NULL })
 
/** @} */
 
/** @ingroup args_parsers
 * @brief Copy of the raw process argument vector.
 * @details Exposed for use cases such as rendering usage with executable name.
 */
struct args_raw {
    int c; /**< Argument count. */
    char **v; /**< Argument vector. */
};
 
#ifdef ARGS_EXTERN_ARGR
/** @ingroup args_customizable
 * @brief Global storage of raw @c argc/@c argv values.
 * @note Available when @c ARGS_EXTERN_ARGR is defined before including @ref args.h.
 */
extern struct args_raw argr;
#endif
 
/** @ingroup args_customizable
 * @brief Prints generated CLI help output.
 * @details
 * Create your own help parse callback and call this function from it so you
 * can provide custom @p usage, @p hint, @p req, and @p opt strings.
 *
 * Example:
 * @code{.c}
 * #define ARGS_EXTERN_ARGR
 * #include "args.h"
 *
 * static struct arg_callback parse_help(const char *str, void *dest)
 * {
 *     // help is a flag argument, safe to ignore both
 *     (void)str;
 *     (void)dest;
 *     args_help_print("Usage: ",
 *                     argr.v[0],
 *                     " [OPTIONS]\n",
 *                     "\nRequired options:\n",
 *                     "\nOptional options:\n");
 *     exit(EXIT_SUCCESS);
 * }
 *
 * ARGUMENT(help) = {
 *     .parse_callback = parse_help,
 *     .help = "Display this help message",
 *     .lopt = "help",
 *     .opt = 'h',
 * };
 * @endcode
 *
 * Outputs: @c "{usage}{bin}{hint}{req}<required args>\n{opt}<optional args>\n"
 */
void args_help_print(const char *usage, const char *bin, const char *hint,
             const char *req, const char *opt);
 
/** @name Callback Stages */
/** @{ */
 
/** @ingroup args_core
 * @brief Parses command line arguments and runs parse-phase relations.
 * @details
 * For each user-provided option, the parser resolves the matching @ref argument
 * and calls @ref argument::parse_callback when available.
 * Parse-time dependency/conflict relations are enforced immediately.
 * Duplicate-argument detection applies only when @ref argument::set is non-NULL,
 * though keep in mind it is implicitly allocated for most features.
 *
 * @par Execution order
 * For each user-provided argument:
 * -# If argument takes a parameter and is already set, error for repeated argument
 * -# Run @ref argument::parse_callback if it exists
 * -# Check dependency/conflict relations if @ref arg_relation_phase is @ref arg_relation_phase::ARG_RELATION_PARSE
 * -# Set @ref argument::set to true (implicit allocation if needed)
 *
 * @pre Every argument was declared via @ref ARGUMENT and linked in.
 * @post All successfully processed arguments with non-NULL @ref argument::set
 * have @c *set == true.
 * @retval true Parse succeeded for all encountered options.
 * @retval false At least one user-facing parse error occurred.
 * @see args_validate
 */
bool args_parse(int argc, char *argv[]);
 
/** @} */
 
/** @addtogroup args_callbacks
 * @brief Callback execution policies.
 * @details
 * @par Lifecycle
 * Execution proceeds through parse, validate, and action stages. Internal
 * schema checks happen inside library logic. Project-specific checks belong in
 * your callbacks.
 */
 
/** @name Callback Phases */
/** @{ */
 
/** @ingroup args_callbacks
 * @brief Execution policy for @ref argument::validate_phase and @ref argument::action_phase.
 */
enum arg_callback_phase {
    ARG_CALLBACK_ALWAYS, /**< Run regardless of user input state. */
    ARG_CALLBACK_IF_SET, /**< Run only when the argument was provided. */
    ARG_CALLBACK_IF_UNSET, /**< Run only when the argument was not provided. */
};
 
/** @} */
/** @name Callback Stages */
/** @{ */
 
/** @ingroup args_core
 * @brief Validates argument schema rules and user-provided combinations.
 * @details
 * This stage enforces required-argument rules, non-parse relation phases, and
 * executes @ref argument::validate_callback according to @ref argument::validate_phase.
 *
 * @par Validation checks
 * For each registered argument:
 * -# If @ref arg_requirement::ARG_REQUIRED, check it was provided (unless conflicted out)
 * -# Check dependency/conflict relations if @ref arg_relation_phase is not @ref arg_relation_phase::ARG_RELATION_PARSE
 * -# Run @ref argument::validate_callback if it exists using @ref argument::validate_phase
 *
 * @pre @ref args_parse was called.
 * @post All validation callbacks due in this pass have executed.
 * @retval true All checks passed.
 * @retval false One or more constraints failed.
 */
bool args_validate(void);
 
/** @ingroup args_core
 * @brief Executes action callbacks for arguments matching action phase rules.
 * @pre @ref args_validate returned @c true.
 * @post All eligible @ref argument::action_callback functions have run.
 */
void args_actions(void);
 
/** @} */
 
/** @addtogroup args_relations
 * @brief Dependencies, conflicts, and subset propagation.
 * @details
 * Relations model command schemas declaratively:
 * - dependency: argument requires others to be set
 * - conflict: argument requires others to be unset, overriding ARG_REQUIRED
 * - subset: setting an argument that lists subset arguments triggers them
 */
 
/** @name Referencing Arguments */
/** @{ */
 
/** @ingroup args_relations
 * @brief Returns the address of @ref argument object @p name.
 * @param name Argument identifier used in @ref ARGUMENT.
 * @hideinitializer
 */
#define ARG(name) &_arg_##name
 
/** @ingroup args_relations
 * @brief Forward declares an argument for same-file forward references.
 * @hideinitializer
 * @details
 * Example:
 * @code{.c}
 * ARG_DECLARE(foo);
 * ARGUMENT(bar) = {
 *     ...
 *     ARG_DEPENDS(ARG_RELATION_PARSE, ARG(foo)),
 *     ...
 * };
 * ARGUMENT(foo) = { ... };
 * @endcode
 * @param name Argument identifier used in @ref ARGUMENT.
 */
#define ARG_DECLARE(name) struct argument _arg_##name
 
/** @ingroup args_relations
 * @brief Extern declaration for an argument defined in another file.
 * @hideinitializer
 * @details
 * Example:
 *
 * foo.c
 * @code{.c}
 * ARGUMENT(foo) = { ... };
 * @endcode
 *
 * bar.c
 * @code{.c}
 * ARG_EXTERN(foo);
 * ARGUMENT(bar) = {
 *     ...
 *     ARG_DEPENDS(ARG_RELATION_PARSE, ARG(foo)),
 *     ...
 * };
 * @endcode
 * @param name Argument identifier used in @ref ARGUMENT.
 */
#define ARG_EXTERN(name) extern struct argument _arg_##name
 
/** @} */
/** @name Relation Declarations */
/** @{ */
 
/** @ingroup args_relations
 * @brief Declares dependency relations for an argument.
 * @hideinitializer
 * @details
 * When setting this argument, all dependencies must already be set.
 * Use inside an @ref ARGUMENT definition.
 *
 * Example:
 * @code{.c}
 * ARGUMENT(foo) = { ... };
 * ARGUMENT(bar) = { ... };
 * ARGUMENT(baz) = {
 *     ...
 *     ARG_DEPENDS(ARG_RELATION_PARSE, ARG(foo), ARG(bar)),
 *     ...
 * };
 * @endcode
 * @param relation_phase When to check dependencies, see @ref arg_relation_phase.
 * @param ... A list of @ref ARG macros with @ref ARGUMENT names.
 */
#define ARG_DEPENDS(relation_phase, ...)                           \
    ._.deps_phase = relation_phase,                            \
    ._.deps = (struct argument *[]){ __VA_ARGS__, NULL },      \
    ._.deps_n = sizeof((struct argument *[]){ __VA_ARGS__ }) / \
            sizeof(struct argument *)
 
/** @ingroup args_relations
 * @brief Declares conflict relations for an argument.
 * @hideinitializer
 * @details
 * If a conflict argument is set, this one must not be set, overriding
 * ARG_REQUIRED. Use inside an @ref ARGUMENT definition.
 *
 * Example:
 * @code{.c}
 * ARGUMENT(foo) = { ... };
 * ARGUMENT(bar) = { ... };
 * ARGUMENT(baz) = {
 *     ...
 *     ARG_CONFLICTS(ARG_RELATION_PARSE, ARG(foo), ARG(bar)),
 *     ...
 * };
 * @endcode
 * @param relation_phase When to check conflicts, see @ref arg_relation_phase.
 * @param ... A list of @ref ARG macros with @ref ARGUMENT names.
 */
#define ARG_CONFLICTS(relation_phase, ...)                         \
    ._.cons_phase = relation_phase,                            \
    ._.cons = (struct argument *[]){ __VA_ARGS__, NULL },      \
    ._.cons_n = sizeof((struct argument *[]){ __VA_ARGS__ }) / \
            sizeof(struct argument *)
 
/** @ingroup args_relations
 * @brief Declares subset arguments triggered by a parent argument.
 * @hideinitializer
 * @details
 * When this argument is set, all subsets are also processed. Parent string
 * is passed to subset parsers unless customized with @ref ARG_SUBSTRINGS.
 * Use inside an @ref ARGUMENT definition.
 *
 * Example:
 * @code{.c}
 * ARGUMENT(foo) = { ... };
 * ARGUMENT(bar) = { ... };
 * ARGUMENT(baz) = {
 *     ...
 *     ARG_SUBSETS(ARG(foo), ARG(bar)),
 *     ARG_SUBSTRINGS("out.txt", ARG_SUBPASS),
 *     ...
 * };
 * @endcode
 * @param ... A list of @ref ARG macros with @ref ARGUMENT names.
 */
#define ARG_SUBSETS(...)                                           \
    ._.subs = (struct argument *[]){ __VA_ARGS__, NULL },      \
    ._.subs_n = sizeof((struct argument *[]){ __VA_ARGS__ }) / \
            sizeof(struct argument *)
 
/** @ingroup args_relations
 * @brief Supplies index-aligned custom strings for subset processing.
 * @hideinitializer
 * @details
 * Use @ref ARG_SUBPASS to pass parent string, omit entirely if not needed.
 * @param ... A list of strings or @ref ARG_SUBPASS.
 */
#define ARG_SUBSTRINGS(...) \
    ._.subs_strs = ((const char *[]){ __VA_ARGS__, NULL })
 
/** @ingroup args_relations
 * @brief Special marker meaning "forward parent string to subset parser".
 * @hideinitializer
 * @details
 * Use in @ref ARG_SUBSTRINGS to indicate that the parent argument's string
 * should be passed to the subset parser instead of a custom string.
 */
#define ARG_SUBPASS ((const char *)-1)
 
/** @} */
/** @name Relation Evaluation Phases */
/** @{ */
 
/** @ingroup args_relations
 * @brief Relation evaluation phase used by @ref ARG_DEPENDS and @ref ARG_CONFLICTS.
 */
enum arg_relation_phase {
    ARG_RELATION_PARSE, /**< Parse-time checks, effectively no-op when unset. */
    ARG_RELATION_VALIDATE_ALWAYS, /**< Validate-time checks regardless of argument state. */
    ARG_RELATION_VALIDATE_SET, /**< Validate-time checks only when the argument is set. */
    ARG_RELATION_VALIDATE_UNSET, /**< Validate-time checks only when the argument is not set. */
};
 
/** @} */
 
/** @addtogroup args_relations
 * @name Cross-File Execution Ordering
 * @brief Deterministic ordering controls for help/validate/action lists.
 * @{ */
 
/** @ingroup args_relations
 * @brief Place argument first in the selected ordered list.
 * @hideinitializer
 * @details
 * Value for @ref argument::validate_order, @ref argument::action_order, or @ref argument::help_order.
 */
#define ARG_ORDER_FIRST ((struct argument *)-1)
 
/** @ingroup args_relations
 * @brief Place argument immediately after another argument.
 * @hideinitializer
 * @details
 * Value for @ref argument::validate_order, @ref argument::action_order, or @ref argument::help_order.
 * Use @ref ARG_DECLARE or @ref ARG_EXTERN to forward-declare the referenced argument.
 *
 * Example:
 * @code{.c}
 * ARG_DECLARE(foo);
 * ARGUMENT(bar) = {
 *     ...
 *     .validate_order = ARG_ORDER_AFTER(ARG(foo)),
 *     ...
 * };
 * @endcode
 * @param arg Argument supplied using the @ref ARG macro.
 */
#define ARG_ORDER_AFTER(arg) (arg)
 
/** @} */
/** @cond ARGS_INTERNALS */
 
/** @addtogroup args_internals
 * @brief Internal structures and definitions not intended for public use.
 * @details
 * These are implementation details and may change without warning.
 * Don't rely on them outside of the library itself.
 */
 
/** @ingroup args_internals
 * @brief Internal runtime/link-list and relation metadata.
 */
struct _args_internal {
    struct argument *next_args;
    struct argument *next_help;
    struct argument *next_validate;
    struct argument *next_action;
    struct argument **deps;
    size_t deps_n;
    struct argument **cons;
    size_t cons_n;
    struct argument **subs;
    const char **subs_strs;
    size_t subs_n;
    size_t help_len;
    enum arg_relation_phase deps_phase;
    enum arg_relation_phase cons_phase;
    bool valid;
};
 
/** @endcond */
/** @name Creating New Arguments */
/** @{ */
 
/** @ingroup args_core
 * @brief Declarative schema object for one CLI argument.
 * @details
 * Initialize this type through @ref ARGUMENT.
 * C designated initializers let you specify only the fields you need.
 * @invariant At least one of @ref argument::opt or @ref argument::lopt is set.
 */
struct argument {
    /** @name Storage */
    /** @{ */
 
    /**
     * @brief Tracks whether the user supplied this argument.
     * @details
     * If NULL, it is allocated implicitly when needed by schema features.
     */
    bool *set;
 
    /**
     * @brief Destination pointer passed as @p dest to parser callbacks.
     */
    void *dest;
 
    /** @} */
    /** @name Callbacks */
    /** @{ */
 
    /**
     * @brief Function invoked during @ref args_parse.
     * @details
     * Use @ref ARG_PARSER helpers for numeric parsing, or provide custom logic.
     * Callbacks aren't limited to parsing e.g. --help exiting immediately.
     * @warning @p str is NULL when @ref argument::param_req is @ref arg_parameter::ARG_PARAM_NONE.
     * @warning @p dest ( @ref argument::dest ) is NULL if you didn't initialize it.
     *
     * Example:
     * @code{.c}
     * static double mydouble;
     * ARG_PARSE_D(mydoubles, double, , val < 5.0,
     *             "Must be >= 5.0\n");
     * ARGUMENT(myarg) = {
     *     ...
     *     .dest = &mydouble,
     *     .parse_callback = parse_mydoubles,
     *     ...
     * };
     * @endcode
     *
     * You can also write custom parsers:
     * @code{.c}
     * enum Color { COLOR_INVALID = -1, RED, GREEN, BLUE };
     * static enum Color color = COLOR_INVALID;
     * static struct arg_callback parse_color(const char *str, void *dest) {
     *     // Using 'color' directly is also possible in this example
     *     enum Color col = COLOR_INVALID;
     *     if (strcmp(str, "red") == 0)
     *         col = RED;
     *     else if (strcmp(str, "green") == 0)
     *         col = GREEN;
     *     else if (strcmp(str, "blue") == 0)
     *         col = BLUE;
     *     else
     *         return ARG_INVALID("Invalid color\n");
     *     *(enum Color *)dest = col;
     *     return ARG_VALID();
     * }
     * ARGUMENT(color) = {
     *     ...
     *     .dest = &color,
     *     .parse_callback = parse_color,
     *     ...
     * };
     * @endcode
     * @param str User-provided value string.
     * @param dest Alias of @ref argument::dest, potentially NULL.
     * @retval ARG_VALID Callback accepted input.
     * @retval ARG_INVALID Callback rejected input.
     */
    struct arg_callback (*parse_callback)(const char *str, void *dest);
 
    /**
     * @brief Function invoked during @ref args_validate.
     * @details
     * Use for project-specific constraints after the parse stage.
     *
     * Example:
     * @code{.c}
     * enum Color { RED, GREEN, BLUE };
     * static enum Color color;
     * static bool other_option;
     * static struct arg_callback validate_color(void) {
     *     if (color == RED && other_option)
     *         return ARG_INVALID("Red color cannot be used.\n");
     *     return ARG_VALID();
     * }
     * ARGUMENT(color) = {
     *     ...
     *     .dest = &color,
     *     .validate_callback = validate_color,
     *     ...
     * };
     * @endcode
     *
     * @retval ARG_VALID Validation succeeded.
     * @retval ARG_INVALID Validation failed.
     */
    struct arg_callback (*validate_callback)(void);
 
    /**
     * @brief Function invoked during @ref args_actions.
     * @details
     * Intended for side effects such as applying runtime configuration.
     *
     * Example:
     * @code{.c}
     * static bool verbose;
     * static void print_verbose(void) {
     *     printf("Verbose mode is on\n");
     * }
     * ARGUMENT(verbose) = {
     *     ...
     *     .set = &verbose,
     *     .action_callback = print_verbose,
     *     .action_phase = ARG_CALLBACK_IF_SET,
     *     ...
     * };
     * @endcode
     */
    void (*action_callback)(void);
 
    /** @} */
    /** @name Schema */
    /** @{ */
 
    /**
     * @brief Specifies whether this argument is required, optional, or hidden.
     * @see arg_requirement
     */
    enum arg_requirement arg_req;
 
    /**
     * @brief Specifies whether this argument takes a parameter and if it's required.
     * @see arg_parameter
     */
    enum arg_parameter param_req;
 
    /**
     * @brief Controls when @ref argument::validate_callback runs.
     * @see arg_callback_phase
     */
    enum arg_callback_phase validate_phase;
 
    /**
     * @brief Controls when @ref argument::action_callback runs.
     * @see arg_callback_phase
     */
    enum arg_callback_phase action_phase;
 
    /** @} */
    /** @name Ordering */
    /** @{ */
 
    /**
     * @brief Ordering for validation.
     * @details
     * Use @ref ARG_ORDER_FIRST or @ref ARG_ORDER_AFTER, NULL means append at the end.
     */
    struct argument *validate_order;
 
    /**
     * @brief Ordering for action execution.
     * @details
     * Use @ref ARG_ORDER_FIRST or @ref ARG_ORDER_AFTER, NULL means append at the end.
     */
    struct argument *action_order;
 
    /**
     * @brief Ordering for help display.
     * @details
     * Use @ref ARG_ORDER_FIRST or @ref ARG_ORDER_AFTER, NULL means append at the end.
     */
    struct argument *help_order;
 
    /** @} */
    /** @name Help Presentation */
    /** @{ */
 
    /**
     * @brief Help description for this argument.
     * @details
     * Multiline strings are supported (e.g. @c "Line1\nLine2").
     * @see ARGS_STR_PREPAD
     * @see ARGS_PARAM_OFFSET
     * @see ARGS_HELP_OFFSET
     */
    const char *help;
 
    /**
     * @brief Parameter name for help display (e.g., "N" for a number).
     * @invariant Required when @ref argument::param_req is not @ref arg_parameter::ARG_PARAM_NONE.
     */
    const char *param;
 
    /**
     * @brief Long option name (e.g. @c "output" -> @c --output).
     */
    const char *lopt;
 
    /**
     * @brief Short option character (e.g. @c 'o' -> @c -o).
     */
    char opt;
 
    /** @} */
    /** @cond ARGS_INTERNALS */
 
    /**
     * @brief Internal runtime metadata populated by registration.
     */
    struct _args_internal _;
 
    /** @endcond */
};
 
/** @} */
/** @cond ARGS_INTERNALS */
 
/** @ingroup args_internals
 * @brief Internal registration entry point used by @ref ARGUMENT.
 * @warning Prefer @ref ARGUMENT for all public usage.
 */
void _args_register(struct argument *);
 
#ifdef __cplusplus
#define _ARGS_CONSTRUCTOR(f) \
    static void f(void); \
    struct f##_t_ {      \
        f##_t_(void) \
        {            \
            f(); \
        }            \
    };                   \
    static f##_t_ f##_;  \
    static void f(void)
#elif defined(_MSC_VER) && !defined(__clang__)
#pragma section(".CRT$XCU", read)
#define _ARGS_CONSTRUCTOR2_(f, p)                                \
    static void f(void);                                     \
    __declspec(allocate(".CRT$XCU")) void (*f##_)(void) = f; \
    __pragma(comment(linker, "/include:" p #f "_")) static void f(void)
#ifdef _WIN64
#define _ARGS_CONSTRUCTOR(f) _ARGS_CONSTRUCTOR2_(f, "")
#else /* _WIN32 */
#define _ARGS_CONSTRUCTOR(f) _ARGS_CONSTRUCTOR2_(f, "_")
#endif
#else /* GCC, Clang */
/** @ingroup args_internals
 * @brief Constructor abstraction for GCC/Clang/MSVC registration hooks.
 * @hideinitializer
 * @see https://stackoverflow.com/questions/1113409/attribute-constructor-equivalent-in-vc
 */
#define _ARGS_CONSTRUCTOR(f)                              \
    static void f(void) __attribute__((constructor)); \
    static void f(void)
#endif
 
/** @endcond */
 
#endif /* ARGS_H_ */
#if defined(ARGS_IMPLEMENTATION) && !defined(_ARGS_IMPLEMENTED)
#define _ARGS_IMPLEMENTED
 
/** @addtogroup args_customizable
 * @brief Customization points for overriding default behaviors.
 * @details
 * Define the following macros before including @ref args.h to override default
 * implementations. You can also use these in your own code for consistency.
 */
 
/** @name Help Formatting */
/** @{ */
 
#ifndef ARGS_STR_PREPAD
/** @ingroup args_customizable
 * @brief Pre-padding for help text.
 * @remark Overridable before including @ref args.h.
 */
#define ARGS_STR_PREPAD (2)
#elif ARGS_STR_PREPAD < 0
#error ARGS_STR_PREPAD cannot be negative
#endif
 
#ifndef ARGS_PARAM_OFFSET
/** @ingroup args_customizable
 * @brief Offset between argument and parameter in help text.
 * @remark Overridable before including @ref args.h.
 */
#define ARGS_PARAM_OFFSET (1)
#elif ARGS_PARAM_OFFSET < 1
#error ARGS_PARAM_OFFSET must be at least 1 for proper formatting
#endif
 
#ifndef ARGS_HELP_OFFSET
/** @ingroup args_customizable
 * @brief Offset from longest argument for help text.
 * @remark Overridable before including @ref args.h.
 */
#define ARGS_HELP_OFFSET (4)
#elif ARGS_HELP_OFFSET < 1
#error ARGS_HELP_OFFSET must be at least 1 for proper formatting
#endif
 
#ifndef ARGS_PRINT_H
/** @ingroup args_customizable
 * @brief Allow using print.h functions for args_pe, args_pd, args_pi and args_abort.
 * @remark Define @ref ARGS_PRINT_H and include @ref print.h before including @ref args.h.
 * @attention Temporarily disabled
 * @hideinitializer
 */
#define ARGS_PRINT_H 0
#else
#ifndef PRINT_H_
#error "Include print.h before including args.h"
#endif /* PRINT_H_ */
#undef ARGS_PRINT_H
#define ARGS_PRINT_H 0 /* 1 */
#endif /* ARGS_PRINT_H */
 
#ifndef args_po
/* Disabled for now 
#if ARGS_PRINT_H
#define args_po print
#else Default */
/** @ingroup args_customizable
 * @brief Normal print.
 * @remark Overridable before including @ref args.h.
 */
#define args_po(...) printf(__VA_ARGS__)
/* #endif ARGS_PRINT_H */
#endif /* args_po */
 
/** @} */
/** @name Error Handling */
/** @{ */
 
#ifndef args_pe
#if ARGS_PRINT_H
#define args_pe perr
#else /* Default */
/** @ingroup args_customizable
 * @brief Error print.
 * @remark Overridable before including @ref args.h.
 */
#define args_pe(...) fprintf(stderr, __VA_ARGS__)
#endif /* ARGS_PRINT_H */
#endif /* args_pe */
 
#ifndef NDEBUG /* DEBUG */
#ifndef args_pd
#if ARGS_PRINT_H
#define args_pd pdev
#else /* Default */
/** @ingroup args_customizable
 * @brief Developer-only debug print.
 * @note Only available when NDEBUG is not defined
 * @remark Overridable before including @ref args.h.
 */
#define args_pd(...) fprintf(stderr, __VA_ARGS__)
#endif /* ARGS_PRINT_H */
#endif /* args_pd */
#else /* RELEASE */
#undef args_pd
#define args_pd(...)
#endif /* NDEBUG */
 
#ifndef args_pi
#if ARGS_PRINT_H
#define args_pi(arg) perr("Internal error for %s\n", arg_str(arg))
#else /* Default */
/** @ingroup args_customizable
 * @brief Internal error print, user-facing dev print.
 * @remark Overridable before including @ref args.h.
 */
#define args_pi(arg) args_pe("Internal error for %s\n", arg_str(arg))
#endif /* ARGS_PRINT_H */
#endif /* args_pi */
 
#ifndef args_abort
#if ARGS_PRINT_H
#define args_abort pabort
#else /* Default */
/** @ingroup args_customizable
 * @brief Abort function.
 * @remark Overridable before including @ref args.h.
 */
#define args_abort() abort()
#endif /* ARGS_PRINT_H */
#endif /* args_abort */
 
#ifndef ARGS_IMPLICIT_SETS
/** @ingroup args_customizable
 * @brief Maximum implicit allocations of @ref argument::set booleans.
 * @remark Overridable before including @ref args.h.
 */
#define ARGS_IMPLICIT_SETS (64)
#elif ARGS_IMPLICIT_SETS < 1
#error ARGS_IMPLICIT_SETS must be at least 1 for defined behavior
#endif
 
/** @} */
/** @cond ARGS_INTERNALS */
/** @addtogroup args_internals
 * @{
 */
 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
struct args_raw argr = { 0 };
 
/* Lists */
static struct argument *args;
static struct argument *help;
static struct argument *validate;
static struct argument *action;
 
#define for_each_arg(a, list) \
    for (struct argument *a = (list); a; a = (a)->_.next_##list)
 
#define for_each_rel(a, rel, var)                                  \
    for (size_t var##i = 0; var##i < (a)->_.rel##_n; var##i++) \
        for (struct argument *var = (a)->_.rel[var##i]; var; var = NULL)
 
static size_t args_num;
static size_t longest;
 
#ifndef ARG_STR_MAX_CALLS
#define ARG_STR_MAX_CALLS (2)
#endif
 
#ifndef ARG_STR_BUF_SIZE
#define ARG_STR_BUF_SIZE (BUFSIZ)
#endif
 
static const char *arg_str(const struct argument *a)
{
    if (!a)
        return "<null-arg>";
 
    static char buf[ARG_STR_MAX_CALLS][ARG_STR_BUF_SIZE];
    static size_t i = 0;
 
    if (a->opt && a->lopt)
        snprintf(buf[i], sizeof(buf[i]), "-%c, --%s", a->opt, a->lopt);
    else if (a->opt) /* TODO: Handle case where every arg has no lopt */
        snprintf(buf[i], sizeof(buf[i]), "-%c     ", a->opt);
    else if (a->lopt)
        snprintf(buf[i], sizeof(buf[i]), "    --%s", a->lopt);
    else
        return "<invalid-arg>";
 
    i = 1 - i;
    return buf[1 - i];
}
 
static void arg_set_new(struct argument *a)
{
    static bool sets[ARGS_IMPLICIT_SETS] = { 0 };
    static size_t sets_n = 0;
 
    if (sets_n >= ARGS_IMPLICIT_SETS) {
        args_pd("ARGS_IMPLICIT_SETS exceeded, try increasing it\n");
        args_pi(a);
        args_abort();
    }
 
    a->set = &sets[sets_n++];
}
 
void _args_register(struct argument *a)
{
    if (!a) {
        args_pd("Cannot register %s\n", arg_str(a));
        args_pi(a);
        args_abort();
    }
 
    if (!a->opt && !a->lopt) {
        args_pd("%s must have an option\n", arg_str(a));
        args_pi(a);
        args_abort();
    }
 
    if (a->_.valid) {
        args_pd("%s has internals pre-set\n", arg_str(a));
        args_pi(a);
        args_abort();
    }
 
    if (a->param_req != ARG_PARAM_NONE && !a->param) {
        args_pd("%s requires parameter but has no .param\n",
            arg_str(a));
        args_pi(a);
        args_abort();
    }
 
    if (a->param_req != ARG_PARAM_NONE && !a->parse_callback) {
        args_pd("%s has .param but has no .parse_callback\n",
            arg_str(a));
        args_pi(a);
        args_abort();
    }
 
    if (a->validate_phase != ARG_CALLBACK_ALWAYS && !a->validate_callback) {
        args_pd("%s has .validate_phase but has no .validate_callback\n",
            arg_str(a));
        args_pi(a);
        args_abort();
    }
 
    if (a->action_phase != ARG_CALLBACK_ALWAYS && !a->action_callback) {
        args_pd("%s has .action_phase but has no .action_callback\n",
            arg_str(a));
        args_pi(a);
        args_abort();
    }
 
    if (a->arg_req == ARG_SOMETIME && !a->_.deps && !a->_.cons &&
        !a->validate_callback) {
        args_pd("%s has no dependencies, conflicts, or validator\n",
            arg_str(a));
        args_pi(a);
        args_abort();
    }
 
    if (!a->set) {
        bool needs_set = false;
        if (a->param_req != ARG_PARAM_NONE)
            needs_set = true;
        if (a->arg_req != ARG_OPTIONAL && a->arg_req != ARG_HIDDEN)
            needs_set = true;
        if (a->validate_phase != ARG_CALLBACK_ALWAYS ||
            a->action_phase != ARG_CALLBACK_ALWAYS)
            needs_set = true;
        if (a->_.deps || a->_.cons || a->_.subs)
            needs_set = true;
        if (needs_set)
            arg_set_new(a);
    }
 
    size_t ndeps = 0;
    size_t ncons = 0;
    size_t nsubs = 0;
 
    if (!a->_.deps) {
        if (a->_.deps_n > 0) {
            args_pd("%s has deps_n=%zu but deps=NULL\n", arg_str(a),
                a->_.deps_n);
            args_pd("Add dependencies using ARG_DEPENDS()\n");
            args_pi(a);
            args_abort();
        }
 
        if (a->_.deps_phase != ARG_RELATION_PARSE) {
            args_pd("%s has relation phase but no dependencies\n",
                arg_str(a));
            args_pi(a);
            args_abort();
        }
 
        goto arg_no_deps;
    }
 
    while (a->_.deps[ndeps])
        ndeps++;
 
    if (ndeps != a->_.deps_n) {
        args_pd("%s deps_n=%zu but actual is %zu\n", arg_str(a),
            a->_.deps_n, ndeps);
        args_pd("Add dependencies using ARG_DEPENDS()\n");
        args_pi(a);
        args_abort();
    }
 
    for_each_rel(a, deps, dep) {
        if (!dep) {
            args_pd("%s NULL deps[%zu]\n", arg_str(a), depi);
            args_pi(a);
            args_abort();
        }
 
        if (dep == a) {
            args_pd("%s depends on itself\n", arg_str(a));
            args_pi(a);
            args_abort();
        }
 
        if (!dep->set)
            arg_set_new(dep);
    }
 
arg_no_deps:
    if (!a->_.cons) {
        if (a->_.cons_n > 0) {
            args_pd("%s cons_n=%zu but cons=NULL\n", arg_str(a),
                a->_.cons_n);
            args_pd("Add conflicts using ARG_CONFLICTS()\n");
            args_pi(a);
            args_abort();
        }
 
        if (a->_.cons_phase != ARG_RELATION_PARSE) {
            args_pd("%s has relation phase but no conflicts\n",
                arg_str(a));
            args_pi(a);
            args_abort();
        }
 
        goto arg_no_cons;
    }
 
    while (a->_.cons[ncons])
        ncons++;
 
    if (ncons != a->_.cons_n) {
        args_pd("%s cons_n=%zu but actual is %zu\n", arg_str(a),
            a->_.cons_n, ncons);
        args_pd("Add conflicts using ARG_CONFLICTS()\n");
        args_pi(a);
        args_abort();
    }
 
    for_each_rel(a, cons, con) {
        if (!con) {
            args_pd("%s NULL cons[%zu]\n", arg_str(a), coni);
            args_pi(a);
            args_abort();
        }
 
        if (con == a) {
            args_pd("%s conflicts itself\n", arg_str(a));
            args_pi(a);
            args_abort();
        }
 
        if (!con->set)
            arg_set_new(con);
 
        for_each_rel(a, deps, dep) {
            if (dep != con)
                continue;
 
            args_pd("%s both depends and conflicts %s\n",
                arg_str(a), arg_str(con));
            args_pi(a);
            args_abort();
        }
    }
 
arg_no_cons:
    if (!a->_.subs) {
        if (a->_.subs_n > 0) {
            args_pd("%s subs_n=%zu but subs=NULL\n", arg_str(a),
                a->_.subs_n);
            args_pd("Specify subsets using ARG_SUBSETS()\n");
            args_pi(a);
            args_abort();
        }
 
        if (a->_.subs_strs) {
            args_pd("%s has subs_strs but no subsets\n",
                arg_str(a));
            args_pi(a);
            args_abort();
        }
 
        goto arg_no_subs;
    }
 
    while (a->_.subs[nsubs])
        nsubs++;
 
    if (nsubs != a->_.subs_n) {
        args_pd("%s subs_n=%zu but actual is %zu\n", arg_str(a),
            a->_.subs_n, nsubs);
        args_pd("Specify subset args using ARG_SUBSETS()\n");
        args_pi(a);
        args_abort();
    }
 
    if (a->_.subs_strs) {
        size_t nsstrs = 0;
        while (a->_.subs_strs[nsstrs])
            nsstrs++;
 
        if (nsstrs != a->_.subs_n) {
            args_pd("%s subs_n=%zu but subs_strs has %zu entries\n",
                arg_str(a), a->_.subs_n, nsstrs);
            args_pd("Both lists must be the same size\n");
            args_pi(a);
            args_abort();
        }
    }
 
    for_each_rel(a, subs, sub) {
        if (sub == a) {
            args_pd("%s subsets itself\n", arg_str(a));
            args_pi(a);
            args_abort();
        }
 
        if (!sub->set)
            arg_set_new(sub);
 
        if (a->param_req != ARG_PARAM_REQUIRED &&
            sub->param_req == ARG_PARAM_REQUIRED &&
            (!a->_.subs_strs || a->_.subs_strs[subi] == ARG_SUBPASS)) {
            args_pd("%s requires param but superset %s might not and has no custom string\n",
                arg_str(sub), arg_str(a));
            args_pi(a);
            args_abort();
        }
 
        if (!a->set)
            arg_set_new(a);
 
        for_each_rel(a, cons, con) {
            if (con == sub) {
                args_pd("%s both supersets and conflicts %s\n",
                    arg_str(a), arg_str(sub));
                args_pi(a);
                args_abort();
            }
        }
 
        for_each_rel(sub, deps, dep) {
            if (dep == a) {
                args_pd("%s supersets %s but also depends on it\n",
                    arg_str(a), arg_str(sub));
                args_pi(a);
                args_abort();
            }
        }
    }
 
arg_no_subs:
    for_each_arg(c, args) {
        if ((a->opt && c->opt && a->opt == c->opt) ||
            (a->lopt && c->lopt && strcmp(a->lopt, c->lopt) == 0)) {
            args_pd("%s same opts as %s\n", arg_str(a), arg_str(c));
            args_pi(a);
            args_abort();
        }
    }
 
#define args_insert(list)                \
    do {                             \
        a->_.next_##list = list; \
        list = a;                \
    } while (0);
 
    args_insert(args);
    args_insert(help);
    args_insert(validate);
    args_insert(action);
#undef args_insert
 
    size_t len = ARGS_STR_PREPAD + strlen(arg_str(a));
    if (a->param)
        len += ARGS_PARAM_OFFSET + strlen(a->param);
    size_t check = len;
    if (a->help)
        check += ARGS_HELP_OFFSET + strlen(a->help);
    if (check >= ARG_STR_BUF_SIZE) {
        args_pd("%s combined opt, lopt, help string too long: %zu chars\n",
            arg_str(a), check);
        args_pi(a);
        args_abort();
    }
    a->_.help_len = len;
    if (len > longest)
        longest = len;
 
    a->_.valid = true;
    args_num++;
}
 
static bool arg_process(struct argument *a, const char *str)
{
    if (!a->_.valid) {
        args_pd("%s has internals pre-set\n", arg_str(a));
        args_pd("Please register arguments using ARGUMENT()\n");
        args_pi(a);
        args_abort();
    }
 
    if (a->set && *a->set) {
        args_pe("Argument %s specified multiple times\n", arg_str(a));
        return false;
    }
 
    if (a->parse_callback) {
        struct arg_callback ret = a->parse_callback(str, a->dest);
        if (ret.error) {
            args_pe("%s: %s\n", arg_str(a), ret.error);
            return false;
        }
    }
 
    if (a->_.deps_phase == ARG_RELATION_PARSE) {
        for_each_rel(a, deps, dep) {
            if (!*dep->set) {
                args_pe("%s requires %s to be set first\n",
                    arg_str(a), arg_str(dep));
                return false;
            }
        }
    }
 
    if (a->_.cons_phase == ARG_RELATION_PARSE) {
        for_each_rel(a, cons, con) {
            if (*con->set) {
                args_pe("%s conflicts with %s\n", arg_str(a),
                    arg_str(con));
                return false;
            }
        }
    }
 
    if (a->set)
        *a->set = true;
 
    for_each_rel(a, subs, sub) {
        if (*sub->set)
            continue;
 
        const char *sub_str = str;
        if (a->_.subs_strs && a->_.subs_strs[subi] &&
            a->_.subs_strs[subi] != ARG_SUBPASS)
            sub_str = a->_.subs_strs[subi];
 
        if (!arg_process(sub, sub_str))
            return false;
    }
 
    return true;
}
 
static bool arg_option(const char *token)
{
    if (!token || token[0] != '-' || token[1] == '\0')
        return false;
 
    if (strcmp(token, "--") == 0)
        return true;
 
    if (token[1] == '-') {
        const char *name = token + 2;
        const char *eq = strchr(name, '=');
        size_t name_len = eq ? (size_t)(eq - name) : strlen(name);
        for_each_arg(c, args) {
            if (c->lopt && strncmp(c->lopt, name, name_len) == 0 &&
                c->lopt[name_len] == '\0')
                return true;
        }
 
        return false;
    }
 
    for_each_arg(c, args) {
        if (c->opt && c->opt == token[1])
            return true;
    }
 
    return false;
}
 
static bool arg_parse_lopt(int *i)
{
    char *arg = argr.v[*i];
    char *name = arg + 2;
    char *value = strchr(name, '=');
    size_t name_len = value ? (size_t)(value - name) : strlen(name);
    if (value)
        value++;
 
    struct argument *a = NULL;
    for_each_arg(c, args) {
        if (c->lopt && strncmp(c->lopt, name, name_len) == 0 &&
            c->lopt[name_len] == '\0') {
            a = c;
            break;
        }
    }
 
    if (!a) {
        args_pe("Unknown: --%.*s\n", (int)name_len, name);
        return false;
    }
 
    const char *str = NULL;
    if (a->param_req == ARG_PARAM_REQUIRED) {
        if (value) {
            str = value;
        } else if (*i + 1 < argr.c) {
            str = argr.v[++(*i)];
        } else {
            args_pe("--%s requires a parameter\n", a->lopt);
            return false;
        }
    } else if (a->param_req == ARG_PARAM_OPTIONAL) {
        if (value)
            str = value;
        else if (*i + 1 < argr.c && !arg_option(argr.v[*i + 1]))
            str = argr.v[++(*i)];
    } else {
        if (value) {
            args_pe("--%s does not take a parameter\n", a->lopt);
            return false;
        }
    }
 
    return arg_process(a, str);
}
 
static bool arg_parse_opt(int *i)
{
    char *arg = argr.v[*i];
    for (size_t j = 1; arg[j]; j++) {
        char opt = arg[j];
 
        struct argument *a = NULL;
        for_each_arg(c, args) {
            if (c->opt == opt) {
                a = c;
                break;
            }
        }
 
        if (!a) {
            args_pe("Unknown: -%c\n", opt);
            return false;
        }
 
        const char *str = NULL;
        if (a->param_req == ARG_PARAM_REQUIRED) {
            if (arg[j + 1]) {
                str = arg + j + 1;
                j = strlen(arg);
            } else if (*i + 1 < argr.c) {
                str = argr.v[++(*i)];
            } else {
                args_pe("-%c requires a parameter\n", opt);
                return false;
            }
        } else if (a->param_req == ARG_PARAM_OPTIONAL) {
            if (arg[j + 1]) {
                str = arg + j + 1;
                j = strlen(arg);
            }
        }
 
        if (!arg_process(a, str))
            return false;
    }
    return true;
}
 
#define args_vaorder(list)                                                   \
    do {                                                                 \
        for_each_arg(a, list) {                                      \
            struct argument *order = a->list##_order;            \
            if (order == NULL || order == (struct argument *)-1) \
                continue;                                    \
                                                                             \
            bool found = false;                                  \
            for_each_arg(check, list) {                          \
                if (check == order) {                        \
                    found = true;                        \
                    break;                               \
                }                                            \
            }                                                    \
                                                                             \
            if (!found) {                                        \
                args_pd("%s has invalid argument in " #list  \
                    "_order\n",                          \
                    arg_str(a));                         \
                args_pi(a);                                  \
                args_abort();                                \
            }                                                    \
        }                                                            \
    } while (0)
 
#define args_reorder(list)                                                             \
    do {                                                                           \
        struct argument *ordered = NULL;                                       \
        struct argument *unordered = list;                                     \
        list = NULL;                                                           \
                                                                                       \
        struct argument **pp = &unordered;                                     \
        while (*pp) {                                                          \
            struct argument *a = *pp;                                      \
            if (a->list##_order == (struct argument *)-1) {                \
                *pp = a->_.next_##list;                                \
                a->_.next_##list = ordered;                            \
                ordered = a;                                           \
            } else {                                                       \
                pp = &(*pp)->_.next_##list;                            \
            }                                                              \
        }                                                                      \
                                                                                       \
        bool changed = true;                                                   \
        while (unordered && changed) {                                         \
            changed = false;                                               \
            pp = &unordered;                                               \
            while (*pp) {                                                  \
                struct argument *a = *pp;                              \
                struct argument *ord = a->list##_order;                \
                bool can_place = false;                                \
                struct argument **insert_pos = NULL;                   \
                                                                                       \
                if (ord == NULL) {                                     \
                    can_place = true;                              \
                    if (!ordered) {                                \
                        insert_pos = &ordered;                 \
                    } else {                                       \
                        struct argument *cur =                 \
                            ordered;                       \
                        while (cur->_.next_##list)             \
                            cur = cur->_.next_##list;      \
                        insert_pos =                           \
                            &cur->_.next_##list;           \
                    }                                              \
                } else {                                               \
                    struct argument **pord = &ordered;             \
                    while (*pord) {                                \
                        if (*pord == ord) {                    \
                            can_place = true;              \
                            insert_pos =                   \
                                &(*pord)->_            \
                                     .next_##list; \
                            break;                         \
                        }                                      \
                        pord = &(*pord)->_.next_##list;        \
                    }                                              \
                }                                                      \
                                                                                       \
                if (can_place && insert_pos) {                         \
                    *pp = a->_.next_##list;                        \
                    a->_.next_##list = *insert_pos;                \
                    *insert_pos = a;                               \
                    changed = true;                                \
                } else {                                               \
                    pp = &(*pp)->_.next_##list;                    \
                }                                                      \
            }                                                              \
        }                                                                      \
                                                                                       \
        if (unordered) {                                                       \
            if (!ordered) {                                                \
                ordered = unordered;                                   \
            } else {                                                       \
                struct argument *cur = ordered;                        \
                while (cur->_.next_##list)                             \
                    cur = cur->_.next_##list;                      \
                cur->_.next_##list = unordered;                        \
            }                                                              \
        }                                                                      \
                                                                                       \
        list = ordered;                                                        \
    } while (0)
 
bool args_parse(int argc, char *argv[])
{
    argr.c = argc;
    argr.v = argv;
 
    args_vaorder(help);
    args_vaorder(validate);
    args_vaorder(action);
#undef args_vaorder
 
    args_reorder(help);
    args_reorder(validate);
    args_reorder(action);
#undef args_reorder
 
    bool success = true;
 
    for (int i = 1; i < argr.c; i++) {
        char *arg = argr.v[i];
 
        if (strcmp(arg, "--") == 0)
            break;
 
        if (arg[0] != '-')
            continue;
 
        if (arg[1] == '\0')
            continue;
 
        if (arg[1] == '-') {
            if (!arg_parse_lopt(&i))
                success = false;
        } else {
            if (!arg_parse_opt(&i))
                success = false;
        }
    }
 
    return success;
}
 
bool args_validate(void)
{
    bool any_invalid = false;
 
    for_each_arg(a, validate) {
        if (!a->_.valid) {
            args_pd("%s has internals pre-set\n", arg_str(a));
            args_pd("Please register arguments using ARGUMENT()\n");
            args_pi(a);
            args_abort();
        }
 
        if (a->arg_req == ARG_REQUIRED && !*a->set) {
            bool any_conflict_set = false;
            for_each_rel(a, cons, con) {
                if (*con->set) {
                    any_conflict_set = true;
                    break;
                }
            }
            if (!any_conflict_set) {
                args_pe("Missing required argument: %s\n",
                    arg_str(a));
                a->_.valid = false;
                any_invalid = true;
            }
        }
 
        bool should_check_deps = false;
        switch (a->_.deps_phase) {
        case ARG_RELATION_PARSE:
            break;
        case ARG_RELATION_VALIDATE_ALWAYS:
            should_check_deps = true;
            break;
        case ARG_RELATION_VALIDATE_SET:
            should_check_deps = *a->set;
            break;
        case ARG_RELATION_VALIDATE_UNSET:
            should_check_deps = !*a->set;
            break;
        default:
            args_pd("Unknown dependency relation phase in %s\n",
                arg_str(a));
            args_pi(a);
            break;
        }
 
        if (should_check_deps) {
            for_each_rel(a, deps, dep) {
                if (*dep->set)
                    continue;
                args_pe("%s requires %s to be set\n",
                    arg_str(a), arg_str(dep));
                any_invalid = true;
            }
        }
 
        bool should_check_cons = false;
        switch (a->_.cons_phase) {
        case ARG_RELATION_PARSE:
            break;
        case ARG_RELATION_VALIDATE_ALWAYS:
            should_check_cons = true;
            break;
        case ARG_RELATION_VALIDATE_SET:
            should_check_cons = *a->set;
            break;
        case ARG_RELATION_VALIDATE_UNSET:
            should_check_cons = !*a->set;
            break;
        default:
            args_pd("Unknown conflict relation phase in %s\n",
                arg_str(a));
            args_pi(a);
            break;
        }
 
        if (should_check_cons) {
            for_each_rel(a, cons, con) {
                if (!*con->set)
                    continue;
                args_pe("%s conflicts with %s\n", arg_str(a),
                    arg_str(con));
                any_invalid = true;
            }
        }
 
        if (!a->validate_callback)
            continue;
 
        bool should_validate = false;
        switch (a->validate_phase) {
        case ARG_CALLBACK_ALWAYS:
            should_validate = true;
            break;
        case ARG_CALLBACK_IF_SET:
            should_validate = *a->set;
            break;
        case ARG_CALLBACK_IF_UNSET:
            should_validate = !*a->set;
            break;
        default:
            args_pd("Unknown .validate_phase in %s\n", arg_str(a));
            args_pi(a);
            args_abort();
        }
 
        if (should_validate) {
            struct arg_callback ret = a->validate_callback();
            if (ret.error) {
                args_pe("%s: %s\n", arg_str(a), ret.error);
                any_invalid = true;
                a->_.valid = false;
            }
        }
    }
 
    return !any_invalid;
}
 
void args_actions(void)
{
    for_each_arg(a, action) {
        if (!a->action_callback)
            continue;
 
        bool should_act = false;
        switch (a->action_phase) {
        case ARG_CALLBACK_ALWAYS:
            should_act = true;
            break;
        case ARG_CALLBACK_IF_SET:
            should_act = *a->set;
            break;
        case ARG_CALLBACK_IF_UNSET:
            should_act = !*a->set;
            break;
        default:
            args_pd("Unknown .action_phase in %s\n", arg_str(a));
            args_pi(a);
            args_abort();
        }
 
        if (should_act)
            a->action_callback();
    }
}
 
static void arg_help_print(const struct argument *a)
{
    args_po("%*s%s", ARGS_STR_PREPAD, "", arg_str(a));
    if (a->param)
        args_po("%*s%s", ARGS_PARAM_OFFSET, "", a->param);
 
    if (!a->help) {
        args_po("\n");
        return;
    }
 
    size_t off = longest + ARGS_HELP_OFFSET;
    size_t pad = off > a->_.help_len ? off - a->_.help_len : 1;
 
    bool first = true;
    const char *phelp = a->help;
    while (*phelp) {
        const char *nl = strchr(phelp, '\n');
        size_t line = nl ? (size_t)(nl - phelp) : strlen(phelp);
 
        if (first) {
            args_po("%*s%.*s", (int)pad, "", (int)line, phelp);
            first = false;
        } else {
            args_po("\n%*s%.*s", (int)off, "", (int)line, phelp);
        }
 
        if (!nl)
            break;
        phelp = nl + 1;
    }
 
    args_po("\n");
}
 
void args_help_print(const char *usage, const char *bin, const char *hint,
             const char *req, const char *opt)
{
    args_po("%s%s%s", usage, bin, hint);
 
    bool first = true;
    for_each_arg(a, help) {
        if (a->arg_req == ARG_OPTIONAL || a->arg_req == ARG_HIDDEN)
            continue;
        if (first) {
            args_po("%s", req);
            first = false;
        }
        arg_help_print(a);
    }
 
    first = true;
    for_each_arg(a, help) {
        if (a->arg_req != ARG_OPTIONAL)
            continue;
        if (first) {
            args_po("%s", opt);
            first = false;
        }
        arg_help_print(a);
    }
}
 
#undef for_each_arg
#undef for_each_rel
 
/** @} */
/** @endcond */
#endif /* ARGS_IMPLEMENTATION */
 
/*
args.h
https://github.com/jakovdev/clix/
Copyright (c) 2026 Jakov Dragičević
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/