/*
 * For MIT-open-group:
 * Copyright 1985, 1987, 1990, 1998  The Open Group
 * Copyright 2008  Dan Nicholson
 *
 * For HPND:
 * Copyright (c) 1993 by Silicon Graphics Computer Systems, Inc.
 * SPDX-License-Identifier: HPND
 *
 * For MIT:
 * Copyright © 2009-2012 Daniel Stone
 * Copyright © 2012 Intel Corporation
 * Copyright © 2012 Ran Benita
 *
 * SPDX-License-Identifier: MIT-open-group AND HPND AND MIT
 *
 * Author: Daniel Stone <daniel@fooishbar.org>
 */

#ifndef _XKBCOMMON_H_
#define _XKBCOMMON_H_

#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdarg.h>

#include <xkbcommon/xkbcommon-names.h>
#include <xkbcommon/xkbcommon-keysyms.h>

#ifdef __cplusplus
extern "C" {
#endif

#if defined(__GNUC__) && !defined(__CYGWIN__)
# define XKB_EXPORT      __attribute__((visibility("default")))
#elif defined(_WIN32)
# define XKB_EXPORT      __declspec(dllexport)
#else
# define XKB_EXPORT
#endif

/**
 * @file
 * Main libxkbcommon API.
 */

/**
 * @struct xkb_context
 * Opaque top level library context object.
 *
 * The context contains various general library data and state, like
 * logging level and include paths.
 *
 * Objects are created in a specific context, and multiple contexts may
 * coexist simultaneously.  Objects from different contexts are completely
 * separated and do not share any memory or state.
 */
struct xkb_context;

/**
 * @struct xkb_keymap
 * Opaque compiled keymap object.
 *
 * The keymap object holds all of the static keyboard information obtained
 * from compiling XKB files.
 *
 * A keymap is immutable after it is created (besides reference counts, etc.);
 * if you need to change it, you must create a new one.
 */
struct xkb_keymap;

/**
 * @struct xkb_state
 * Opaque keyboard state object.
 *
 * State objects contain the active state of a keyboard (or keyboards), such
 * as the currently effective layout and the active modifiers.  It acts as a
 * simple state machine, wherein key presses and releases are the input, and
 * key symbols (keysyms) are the output.
 */
struct xkb_state;

/**
 * A number used to represent a physical key on a keyboard.
 *
 * A standard PC-compatible keyboard might have 102 keys.  An appropriate
 * keymap would assign each of them a keycode, by which the user should
 * refer to the key throughout the library.
 *
 * Historically, the X11 protocol, and consequentially the XKB protocol,
 * assign only 8 bits for keycodes.  This limits the number of different
 * keys that can be used simultaneously in a single keymap to 256
 * (disregarding other limitations).  This library does not share this limit;
 * keycodes beyond 255 (*extended* keycodes) are not treated specially.
 * Keymaps and applications which are compatible with X11 should not use
 * these keycodes.
 *
 * The values of specific keycodes are determined by the keymap and the
 * underlying input system.  For example, with an X11-compatible keymap
 * and Linux evdev scan codes (see `linux/input.h`), a fixed offset is used:
 *
 * The keymap defines a canonical name for each key, plus possible aliases.
 * Historically, the XKB protocol restricts these names to at most 4 (ASCII)
 * characters, but this library does not share this limit.
 *
 * @code
 * xkb_keycode_t keycode_A = KEY_A + 8;
 * @endcode
 *
 * @sa xkb_keycode_is_legal_ext() xkb_keycode_is_legal_x11()
 */
typedef uint32_t xkb_keycode_t;

/**
 * A number used to represent the symbols generated from a key on a keyboard.
 *
 * A key, represented by a keycode, may generate different symbols according
 * to keyboard state.  For example, on a QWERTY keyboard, pressing the key
 * labled \<A\> generates the symbol ‘a’.  If the Shift key is held, it
 * generates the symbol ‘A’.  If a different layout is used, say Greek,
 * it generates the symbol ‘α’.  And so on.
 *
 * Each such symbol is represented by a *keysym* (short for “key symbol”).
 * Note that keysyms are somewhat more general, in that they can also represent
 * some “function”, such as “Left” or “Right” for the arrow keys.  For more
 * information, see: Appendix A [“KEYSYM Encoding”][encoding] of the X Window
 * System Protocol.
 *
 * Specifically named keysyms can be found in the
 * xkbcommon/xkbcommon-keysyms.h header file.  Their name does not include
 * the `XKB_KEY_` prefix.
 *
 * Besides those, any Unicode/ISO&nbsp;10646 character in the range U+0100 to
 * U+10FFFF can be represented by a keysym value in the range 0x01000100 to
 * 0x0110FFFF.  The name of Unicode keysyms is `U<codepoint>`, e.g. `UA1B2`.
 *
 * The name of other unnamed keysyms is the hexadecimal representation of
 * their value, e.g. `0xabcd1234`.
 *
 * Keysym names are case-sensitive.
 *
 * @note **Encoding:** Keysyms are 32-bit integers with the 3 most significant
 * bits always set to zero.  Thus valid keysyms are in the range
 * `0 .. 0x1fffffff` = @ref XKB_KEYSYM_MAX.
 * See: Appendix A [“KEYSYM Encoding”][encoding] of the X Window System Protocol.
 *
 * [encoding]: https://www.x.org/releases/current/doc/xproto/x11protocol.html#keysym_encoding
 *
 * @ingroup keysyms
 * @sa `::XKB_KEYSYM_MAX`
 */
typedef uint32_t xkb_keysym_t;

/**
 * Index of a keyboard layout.
 *
 * The layout index is a state component which determines which <em>keyboard
 * layout</em> is active.  These may be different alphabets, different key
 * arrangements, etc.
 *
 * Layout indices are consecutive.  The first layout has index 0.
 *
 * Each layout is not required to have a name, and the names are not
 * guaranteed to be unique (though they are usually provided and unique).
 * Therefore, it is not safe to use the name as a unique identifier for a
 * layout.  Layout names are case-sensitive.
 *
 * Layout names are specified in the layout’s definition, for example
 * “English (US)”.  These are different from the (conventionally) short names
 * which are used to locate the layout, for example `us` or `us(intl)`.  These
 * names are not present in a compiled keymap.
 *
 * If the user selects layouts from a list generated from the XKB registry
 * (using libxkbregistry or directly), and this metadata is needed later on, it
 * is recommended to store it along with the keymap.
 *
 * Layouts are also called *groups* by XKB.
 *
 * @sa xkb_keymap::xkb_keymap_num_layouts()
 * @sa xkb_keymap::xkb_keymap_num_layouts_for_key()
 */
typedef uint32_t xkb_layout_index_t;
/** A mask of layout indices. */
typedef uint32_t xkb_layout_mask_t;

/**
 * Index of a shift level.
 *
 * Any key, in any layout, can have several <em>shift levels</em>.  Each
 * shift level can assign different keysyms to the key.  The shift level
 * to use is chosen according to the current keyboard state; for example,
 * if no keys are pressed, the first level may be used; if the Left Shift
 * key is pressed, the second; if Num Lock is pressed, the third; and
 * many such combinations are possible (see `xkb_mod_index_t`).
 *
 * Level indices are consecutive.  The first level has index 0.
 */
typedef uint32_t xkb_level_index_t;

/**
 * Index of a modifier.
 *
 * A @e modifier is a state component which changes the way keys are
 * interpreted.  A keymap defines a set of modifiers, such as Alt, Shift,
 * Num Lock or Meta, and specifies which keys may @e activate which
 * modifiers (in a many-to-many relationship, i.e. a key can activate
 * several modifiers, and a modifier may be activated by several keys.
 * Different keymaps do this differently).
 *
 * When retrieving the keysyms for a key, the active modifier set is
 * consulted; this determines the correct shift level to use within the
 * currently active layout (see `xkb_level_index_t`).
 *
 * Modifier indices are consecutive.  The first modifier has index 0.
 *
 * Each modifier must have a name, and the names are unique.  Therefore, it
 * is safe to use the name as a unique identifier for a modifier.  The names
 * of some common modifiers are provided in the `xkbcommon/xkbcommon-names.h`
 * header file.  Modifier names are case-sensitive.
 *
 * @sa xkb_keymap_num_mods()
 */
typedef uint32_t xkb_mod_index_t;
/** A mask of modifier indices. */
typedef uint32_t xkb_mod_mask_t;

/**
 * Index of a keyboard LED.
 *
 * LEDs are logical objects which may be @e active or @e inactive.  They
 * typically correspond to the lights on the keyboard. Their state is
 * determined by the current keyboard state.
 *
 * LED indices are non-consecutive.  The first LED has index 0.
 *
 * Each LED must have a name, and the names are unique. Therefore,
 * it is safe to use the name as a unique identifier for a LED.  The names
 * of some common LEDs are provided in the `xkbcommon/xkbcommon-names.h`
 * header file.  LED names are case-sensitive.
 *
 * @warning A given keymap may specify an exact index for a given LED.
 * Therefore, LED indexing is not necessarily sequential, as opposed to
 * modifiers and layouts.  This means that when iterating over the LEDs
 * in a keymap using e.g. xkb_keymap::xkb_keymap_num_leds(), some indices might
 * be invalid.
 * Given such an index, functions like xkb_keymap::xkb_keymap_led_get_name()
 * will return `NULL`, and `xkb_state::xkb_state_led_index_is_active()` will
 * return -1.
 *
 * LEDs are also called *indicators* by XKB.
 *
 * @sa `xkb_keymap::xkb_keymap_num_leds()`
 */
typedef uint32_t xkb_led_index_t;
/** A mask of LED indices. */
typedef uint32_t xkb_led_mask_t;

/** Invalid keycode */
#define XKB_KEYCODE_INVALID (0xffffffff)
/** Invalid layout index */
#define XKB_LAYOUT_INVALID  (0xffffffff)
/** Invalid level index */
#define XKB_LEVEL_INVALID   (0xffffffff)
/** Invalid modifier index */
#define XKB_MOD_INVALID     (0xffffffff)
/** Invalid LED index */
#define XKB_LED_INVALID     (0xffffffff)

/** Maximum legal keycode */
#define XKB_KEYCODE_MAX     (0xffffffff - 1)

/**
 * Maximum keysym value
 *
 * @since 1.6.0
 * @sa xkb_keysym_t
 * @ingroup keysyms
 */
#define XKB_KEYSYM_MAX      0x1fffffff

/**
 * Test whether a value is a valid extended keycode.
 * @sa xkb_keycode_t
 **/
#define xkb_keycode_is_legal_ext(key) ((key) <= XKB_KEYCODE_MAX)

/**
 * Test whether a value is a valid X11 keycode.
 * @sa xkb_keycode_t
 */
#define xkb_keycode_is_legal_x11(key) ((key) >= 8 && (key) <= 255)

/**
 * @defgroup rules-api Rules
 * Utility functions related to *rules*, whose purpose is introduced in:
 * @ref xkb-the-config "".
 *
 * @{
 */

/**
 * @struct xkb_rmlvo_builder
 * Opaque [RMLVO] configuration object.
 *
 * It denotes the configuration values by which a user picks a keymap.
 *
 * @see [Introduction to RMLVO][RMLVO]
 * @see @ref rules-api ""
 * @since 1.11.0
 *
 * [RMLVO]: @ref RMLVO-intro
 */
struct xkb_rmlvo_builder;

enum xkb_rmlvo_builder_flags {
    XKB_RMLVO_BUILDER_NO_FLAGS = 0
};

/**
 * Create a new [RMLVO] builder.
 *
 * @param context The context in which to create the builder.
 * @param rules   The ruleset.
 * If `NULL` or the empty string `""`, a default value is used.
 * If the `XKB_DEFAULT_RULES` environment variable is set, it is used
 * as the default.  Otherwise the system default is used.
 * @param model   The keyboard model.
 * If `NULL` or the empty string `""`, a default value is used.
 * If the `XKB_DEFAULT_MODEL` environment variable is set, it is used
 * as the default.  Otherwise the system default is used.
 * @param flags   Optional flags for the builder, or 0.
 *
 * @returns A `xkb_rmlvo_builder`, or `NULL` if the compilation failed.
 *
 * @see `xkb_rule_names` for a detailed description of `rules` and `model`.
 * @since 1.11.0
 * @memberof xkb_rmlvo_builder
 *
 * [RMLVO]: @ref RMLVO-intro
 */
XKB_EXPORT struct xkb_rmlvo_builder*
xkb_rmlvo_builder_new(struct xkb_context *context,
                      const char *rules, const char *model,
                      enum xkb_rmlvo_builder_flags flags);

/**
 * Append a layout to the given [RMLVO] builder.
 *
 * @param rmlvo         The builder to modify.
 * @param layout        The name of the layout.
 * @param variant       The name of the layout variant, or `NULL` to
 * select the default variant.
 * @param options       An array of options to apply only to this layout, or
 * `NULL` if there is no such options.
 * @param options_len   The length of @p options.
 *
 * @note The options are only effectual if the corresponding ruleset has the
 * proper rules to handle them as *layout-specific* options.
 * @note See `rxkb_option_is_layout_specific()` to query whether an option
 * supports the layout-specific feature.
 *
 * @returns `true` if the call succeeded, otherwise `false`.
 *
 * @since 1.11.0
 * @memberof xkb_rmlvo_builder
 *
 * [RMLVO]: @ref RMLVO-intro
 */
XKB_EXPORT bool
xkb_rmlvo_builder_append_layout(struct xkb_rmlvo_builder *rmlvo,
                                const char *layout, const char *variant,
                                const char* const* options, size_t options_len);

/**
 * Append an option to the given [RMLVO] builder.
 *
 * @param rmlvo   The builder to modify.
 * @param option  The name of the option.
 *
 * @returns `true` if the call succeeded, otherwise `false`.
 *
 * @since 1.11.0
 * @memberof xkb_rmlvo_builder
 *
 * [RMLVO]: @ref RMLVO-intro
 */
XKB_EXPORT bool
xkb_rmlvo_builder_append_option(struct xkb_rmlvo_builder *rmlvo,
                                const char *option);

/**
 * Take a new reference on a [RMLVO] builder.
 *
 * @param rmlvo The builder to reference.
 *
 * @returns The passed in builder.
 *
 * @since 1.11.0
 * @memberof xkb_rmlvo_builder
 *
 * [RMLVO]: @ref RMLVO-intro
 */
XKB_EXPORT struct xkb_rmlvo_builder *
xkb_rmlvo_builder_ref(struct xkb_rmlvo_builder *rmlvo);

/**
 * Release a reference on a [RMLVO] builder, and possibly free it.
 *
 * @param rmlvo The builder.  If it is `NULL`, this function does nothing.
 *
 * @since 1.11.0
 * @memberof xkb_rmlvo_builder
 *
 * [RMLVO]: @ref RMLVO-intro
 */
XKB_EXPORT void
xkb_rmlvo_builder_unref(struct xkb_rmlvo_builder *rmlvo);

/**
 * Names to compile a keymap with, also known as [RMLVO].
 *
 * The names are the common configuration values by which a user picks
 * a keymap.
 *
 * If the entire struct is `NULL`, then each field is taken to be `NULL`.
 * You should prefer passing `NULL` instead of choosing your own defaults.
 *
 * @see [Introduction to RMLVO][RMLVO]
 * @see @ref rules-api ""
 *
 * [RMLVO]: @ref RMLVO-intro
 */
struct xkb_rule_names {
    /**
     * The rules file to use. The rules file describes how to interpret
     * the values of the model, layout, variant and options fields.
     *
     * If `NULL` or the empty string `""`, a default value is used.
     * If the `XKB_DEFAULT_RULES` environment variable is set, it is used
     * as the default.  Otherwise the system default is used.
     */
    const char *rules;
    /**
     * The keyboard model by which to interpret keycodes and LEDs.
     *
     * If `NULL` or the empty string `""`, a default value is used.
     * If the `XKB_DEFAULT_MODEL` environment variable is set, it is used
     * as the default.  Otherwise the system default is used.
     */
    const char *model;
    /**
     * A comma separated list of layouts (languages) to include in the
     * keymap.
     *
     * If `NULL` or the empty string `""`, a default value is used.
     * If the `XKB_DEFAULT_LAYOUT` environment variable is set, it is used
     * as the default.  Otherwise the system default is used.
     */
    const char *layout;
    /**
     * A comma separated list of variants, one per layout, which may
     * modify or augment the respective layout in various ways.
     *
     * Generally, should either be empty or have the same number of values
     * as the number of layouts. You may use empty values as in `intl,,neo`.
     *
     * If `NULL` or the empty string `""`, and a default value is also used
     * for the layout, a default value is used.  Otherwise no variant is
     * used.
     * If the `XKB_DEFAULT_VARIANT` environment variable is set, it is used
     * as the default.  Otherwise the system default is used.
     */
    const char *variant;
    /**
     * A comma separated list of options, through which the user specifies
     * non-layout related preferences, like which key combinations are used
     * for switching layouts, or which key is the Compose key.
     *
     * If `NULL`, a default value is used.  If the empty string `""`, no
     * options are used.
     * If the `XKB_DEFAULT_OPTIONS` environment variable is set, it is used
     * as the default.  Otherwise the system default is used.
     *
     * Each option can additionally have a *layout index specifier*, so that it
     * applies only if matching the given layout.  The index is specified by
     * appending `!` immediately after the option name, then the 1-indexed
     * target layout in decimal format: e.g. `ns:option!2`.  When no layout is
     * specified, it matches any layout.
     *
     * @note The layout index specifier is only effectual if the corresponding
     * ruleset has the proper rules to handle the option as *layout-specific*.
     * @note See `rxkb_option_is_layout_specific()` to query whether an option
     * supports the layout-specific feature.
     *
     * @since 1.11.0: Layout index specifier using `!`.
     */
    const char *options;
};

/**
 * Keymap components, also known as [KcCGST].
 *
 * The components are the result of the [RMLVO] resolution.
 *
 * @see [Introduction to RMLVO][RMLVO]
 * @see [Introduction to KcCGST][KcCGST]
 * @see @ref rules-api ""
 *
 * [RMLVO]: @ref RMLVO-intro
 * [KcCGST]: @ref KcCGST-intro
 */
struct xkb_component_names {
    char *keycodes;
    char *compatibility;
    char *geometry;
    char *symbols;
    char *types;
};

/**
 * Resolve [RMLVO] names to [KcCGST] components.
 *
 * This function is used primarily for *debugging*. See
 * `xkb_keymap::xkb_keymap_new_from_names2()` for creating keymaps from
 * [RMLVO] names.
 *
 * @param[in]  context    The context in which to resolve the names.
 * @param[in]  rmlvo_in   The [RMLVO] names to use.
 * @param[out] rmlvo_out  The [RMLVO] names actually used after resolving
 * missing values.
 * @param[out] components_out The [KcCGST] components resulting of the [RMLVO]
 * resolution.
 *
 * @c rmlvo_out and @c components can be omitted by using `NULL`, but not both.
 *
 * If @c components is not `NULL`, it is filled with dynamically-allocated
 * strings that should be freed by the caller.
 *
 * @returns `true` if the [RMLVO] names could be resolved, `false` otherwise.
 *
 * @see [Introduction to RMLVO][RMLVO]
 * @see [Introduction to KcCGST][KcCGST]
 * @see xkb_rule_names
 * @see xkb_component_names
 * @see xkb_keymap::xkb_keymap_new_from_names2()
 *
 * @since 1.9.0
 * @memberof xkb_component_names
 *
 * [RMLVO]: @ref RMLVO-intro
 * [KcCGST]: @ref KcCGST-intro
 */
XKB_EXPORT bool
xkb_components_names_from_rules(struct xkb_context *context,
                                const struct xkb_rule_names *rmlvo_in,
                                struct xkb_rule_names *rmlvo_out,
                                struct xkb_component_names *components_out);

/** @} */

/**
 * @defgroup keysyms Keysyms
 * Utility functions related to *keysyms* (short for “key symbols”).
 *
 * @{
 */

/**
 * @page keysym-transformations Keysym Transformations
 *
 * Keysym translation is subject to several *keysym transformations*,
 * as described in the XKB specification.  These are:
 *
 * <dl>
 * <dt>Capitalization transformation</dt>
 * <dd>
 * If the Caps Lock modifier is
 * active and was not consumed by the translation process, keysyms
 * are transformed to their upper-case form (if applicable).
 * Similarly, the UTF-8/UTF-32 string produced is capitalized.
 *
 * This is described in:
 * https://www.x.org/releases/current/doc/kbproto/xkbproto.html#Interpreting_the_Lock_Modifier
 * </dd>
 * <dt>Control transformation</dt>
 * <dd>
 * If the Control modifier is active and
 * was not consumed by the translation process, the string produced
 * is transformed to its matching ASCII control character (if
 * applicable).  Keysyms are not affected.
 *
 * This is described in:
 * https://www.x.org/releases/current/doc/kbproto/xkbproto.html#Interpreting_the_Control_Modifier
 * </dd>
 * </dl>
 *
 * Each relevant function discusses which transformations it performs.
 *
 * These transformations are not applicable when a key produces multiple
 * keysyms.
 */


/**
 * Get the name of a keysym.
 *
 * For a description of how keysyms are named, see @ref xkb_keysym_t.
 *
 * @param[in]  keysym The keysym.
 * @param[out] buffer A string buffer to write the name into.
 * @param[in]  size   Size of the buffer.
 *
 * @warning If the buffer passed is too small, the string is truncated
 * (though still `NULL`-terminated); a size of at least 64 bytes is recommended.
 *
 * @returns The number of bytes in the name, excluding the `NULL` byte. If
 * the keysym is invalid, returns -1.
 *
 * You may check if truncation has occurred by comparing the return value
 * with the length of buffer, similarly to the `snprintf(3)` function.
 *
 * @sa `xkb_keysym_t`
 */
XKB_EXPORT int
xkb_keysym_get_name(xkb_keysym_t keysym, char *buffer, size_t size);

/** Flags for xkb_keysym_from_name(). */
enum xkb_keysym_flags {
    /** Do not apply any flags. */
    XKB_KEYSYM_NO_FLAGS = 0,
    /** Find keysym by case-insensitive search. */
    XKB_KEYSYM_CASE_INSENSITIVE = (1 << 0)
};

/**
 * Get a keysym from its name.
 *
 * @param name The name of a keysym. See remarks in `xkb_keysym_get_name()`;
 * this function will accept any name returned by that function.
 * @param flags A set of flags controlling how the search is done. If
 * invalid flags are passed, this will fail with `XKB_KEY_NoSymbol`.
 *
 * If you use the `::XKB_KEYSYM_CASE_INSENSITIVE` flag and two keysym names
 * differ only by case, then the lower-case keysym name is returned.  For
 * instance, for KEY_a and KEY_A, this function would return KEY_a for the
 * case-insensitive search.  If this functionality is needed, it is
 * recommended to first call this function without this flag; and if that
 * fails, only then to try with this flag, while possibly warning the user
 * he had misspelled the name, and might get wrong results.
 *
 * Case folding is done according to the C locale; the current locale is not
 * consulted.
 *
 * @returns The keysym. If the name is invalid, returns `XKB_KEY_NoSymbol`.
 *
 * @sa xkb_keysym_t
 * @since 1.9.0: Enable support for C0 and C1 control characters in the Unicode
 * notation.
 */
XKB_EXPORT xkb_keysym_t
xkb_keysym_from_name(const char *name, enum xkb_keysym_flags flags);

/**
 * Get the Unicode/UTF-8 representation of a keysym.
 *
 * @param[in]  keysym The keysym.
 * @param[out] buffer A buffer to write the UTF-8 string into.
 * @param[in]  size   The size of buffer.  Must be at least 5.
 *
 * @returns The number of bytes written to the buffer (including the
 * terminating byte).  If the keysym does not have a Unicode
 * representation, returns 0.  If the buffer is too small, returns -1.
 *
 * This function does not perform any @ref keysym-transformations.
 * Therefore, prefer to use `xkb_state::xkb_state_key_get_utf8()` if possible.
 *
 * @sa `xkb_state::xkb_state_key_get_utf8()`
 */
XKB_EXPORT int
xkb_keysym_to_utf8(xkb_keysym_t keysym, char *buffer, size_t size);

/**
 * Get the Unicode/UTF-32 representation of a keysym.
 *
 * @returns The Unicode/UTF-32 representation of keysym, which is also
 * compatible with UCS-4.  If the keysym does not have a Unicode
 * representation, returns 0.
 *
 * This function does not perform any @ref keysym-transformations.
 * Therefore, prefer to use xkb_state_key_get_utf32() if possible.
 *
 * @sa `xkb_state::xkb_state_key_get_utf32()`
 */
XKB_EXPORT uint32_t
xkb_keysym_to_utf32(xkb_keysym_t keysym);

/**
 * Get the keysym corresponding to a Unicode/UTF-32 codepoint.
 *
 * @returns The keysym corresponding to the specified Unicode
 * codepoint, or XKB_KEY_NoSymbol if there is none.
 *
 * This function is the inverse of @ref xkb_keysym_to_utf32. In cases
 * where a single codepoint corresponds to multiple keysyms, returns
 * the keysym with the lowest value.
 *
 * Unicode codepoints which do not have a special (legacy) keysym
 * encoding use a direct encoding scheme. These keysyms don’t usually
 * have an associated keysym constant (`XKB_KEY_*`).
 *
 * @sa `xkb_keysym_to_utf32()`
 * @since 1.0.0
 * @since 1.9.0: Enable support for all noncharacters.
 */
XKB_EXPORT xkb_keysym_t
xkb_utf32_to_keysym(uint32_t ucs);

/**
 * Convert a keysym to its uppercase form.
 *
 * If there is no such form, the keysym is returned unchanged.
 *
 * The conversion rules are the *simple* (i.e. one-to-one) Unicode case
 * mappings (with some exceptions, see hereinafter) and do not depend
 * on the locale. If you need the special case mappings (i.e. not
 * one-to-one or locale-dependent), prefer to work with the Unicode
 * representation instead, when possible.
 *
 * Exceptions to the Unicode mappings:
 *
 * | Lower keysym | Lower letter | Upper keysym | Upper letter | Comment |
 * | ------------ | ------------ | ------------ | ------------ | ------- |
 * | `ssharp`     | `U+00DF`: ß  | `U1E9E`      | `U+1E9E`: ẞ  | [Council for German Orthography] |
 *
 * [Council for German Orthography]: https://www.rechtschreibrat.com/regeln-und-woerterverzeichnis/
 *
 * @since 0.8.0: Initial implementation, based on `libX11`.
 * @since 1.8.0: Use Unicode 16.0 mappings for complete Unicode coverage.
 * @since 1.12.0: Update to Unicode 17.0.
 */
XKB_EXPORT xkb_keysym_t
xkb_keysym_to_upper(xkb_keysym_t ks);

/**
 * Convert a keysym to its lowercase form.
 *
 * If there is no such form, the keysym is returned unchanged.
 *
 * The conversion rules are the *simple* (i.e. one-to-one) Unicode case
 * mappings and do not depend on the locale. If you need the special
 * case mappings (i.e. not one-to-one or locale-dependent), prefer to
 * work with the Unicode representation instead, when possible.
 *
 * @since 0.8.0: Initial implementation, based on `libX11`.
 * @since 1.8.0: Use Unicode 16.0 mappings for complete Unicode coverage.
 * @since 1.12.0: Update to Unicode 17.0.
 */
XKB_EXPORT xkb_keysym_t
xkb_keysym_to_lower(xkb_keysym_t ks);

/** @} */

/**
 * @defgroup context Library Context
 * Creating, destroying and using library contexts.
 *
 * Every keymap compilation request must have a context associated with
 * it.  The context keeps around state such as the include path.
 *
 * @{
 */

/**
 * @page envvars Environment Variables
 *
 * The user may set some environment variables which affect the library:
 *
 * - `XKB_CONFIG_ROOT`, `XKB_CONFIG_UNVERSIONED_EXTENSIONS_PATH`,
 *   `XKB_CONFIG_VERSIONED_EXTENSIONS_PATH`, `XKB_CONFIG_EXTRA_PATH`,
 *   `XDG_CONFIG_DIR`, `HOME` - see @ref include-path.
 * - `XKB_LOG_LEVEL` - see `xkb_context::xkb_context_set_log_level()`.
 * - `XKB_LOG_VERBOSITY` - see `xkb_context::xkb_context_set_log_verbosity()`.
 * - `XKB_DEFAULT_RULES`, `XKB_DEFAULT_MODEL`, `XKB_DEFAULT_LAYOUT`,
 *   `XKB_DEFAULT_VARIANT`, `XKB_DEFAULT_OPTIONS` - see `xkb_rule_names`.
 */

/** Flags for context creation. */
enum xkb_context_flags {
    /** Do not apply any context flags. */
    XKB_CONTEXT_NO_FLAGS = 0,
    /**
     * Create this context with an empty include path.
     *
     * This may be useful e.g.:
     * - to have full control over the included paths;
     * - for clients that do not need to access the XKB directories, e.g.
     *   if only retrieving keymap from the Wayland or X server. It avoids
     *   potential issues with directory access permissions.
     */
    XKB_CONTEXT_NO_DEFAULT_INCLUDES = (1 << 0),
    /**
     * Don’t take RMLVO names from the environment.
     *
     * @since 0.3.0
     */
    XKB_CONTEXT_NO_ENVIRONMENT_NAMES = (1 << 1),
    /**
     * Disable the use of secure_getenv for this context, so that privileged
     * processes can use environment variables. Client uses at their own risk.
     *
     * @since 1.5.0
     */
    XKB_CONTEXT_NO_SECURE_GETENV = (1 << 2)
};

/**
 * Create a new context.
 *
 * @param flags Optional flags for the context, or 0.
 *
 * @returns A new context, or `NULL` on failure.
 *
 * @memberof xkb_context
 */
XKB_EXPORT struct xkb_context *
xkb_context_new(enum xkb_context_flags flags);

/**
 * Take a new reference on a context.
 *
 * @returns The passed in context.
 *
 * @memberof xkb_context
 */
XKB_EXPORT struct xkb_context *
xkb_context_ref(struct xkb_context *context);

/**
 * Release a reference on a context, and possibly free it.
 *
 * @param context The context.  If it is `NULL`, this function does nothing.
 *
 * @memberof xkb_context
 */
XKB_EXPORT void
xkb_context_unref(struct xkb_context *context);

/**
 * Store custom user data in the context.
 *
 * This may be useful in conjunction with `xkb_context::xkb_context_set_log_fn()`
 * or other callbacks.
 *
 * @memberof xkb_context
 */
XKB_EXPORT void
xkb_context_set_user_data(struct xkb_context *context, void *user_data);

/**
 * Retrieves stored user data from the context.
 *
 * @returns The stored user data.  If the user data wasn’t set, or the
 * passed in context is `NULL`, returns `NULL`.
 *
 * This may be useful to access private user data from callbacks like a
 * custom logging function.
 *
 * @memberof xkb_context
 **/
XKB_EXPORT void *
xkb_context_get_user_data(struct xkb_context *context);

/** @} */

/**
 * @defgroup include-path Include Paths
 * Manipulating the include paths in a context.
 *
 * The include paths are the file-system paths that are searched when an
 * include statement is encountered during keymap compilation.
 *
 * The default include paths are, in that lookup order:
 * - The path `$XDG_CONFIG_HOME/xkb`, where `$XDG_CONFIG_HOME` is the value of
     the environment variable `XDG_CONFIG_HOME`, with the usual fallback to
     `$HOME/.config/` if unset.
 * - The path `$HOME/.xkb`, where `$HOME` is the value of the environment
 *   variable `HOME`.
 * - The `XKB_CONFIG_EXTRA_PATH` environment variable, if defined, otherwise the
 *   system configuration directory, defined at library configuration time
 *   (usually `/etc/xkb`).
 * - Each subdirectory of each XKB extensions directory (versioned, then
 *   unversioned if no corresponding versioned subdirectory), listed in
 *   lexicographic order. The extensions directories are defined by the
 *   environment variables `XKB_CONFIG_VERSIONED_EXTENSIONS_PATH` and
 *   `XKB_CONFIG_UNVERSIONED_EXTENSIONS_PATH` and default to the system XKB
 *   root extensions directories, defined at library configuration time (usually
 *   `/usr/share/xkeyboard-config-<VERSION>.d` and
 *   `/usr/share/xkeyboard-config.d`).
 * - The `XKB_CONFIG_ROOT` environment variable, if defined, otherwise
 *   the system XKB root, defined at library configuration time
 *   (usually `/usr/share/xkeyboard-config-<VERSION>` or `/usr/share/X11/xkb`).
 *
 * @{
 */

/**
 * Append a new entry to the context’s include path.
 *
 * @returns 1 on success, or 0 if the include path could not be added or is
 * inaccessible.
 *
 * @memberof xkb_context
 */
XKB_EXPORT int
xkb_context_include_path_append(struct xkb_context *context, const char *path);

/**
 * Append the default include paths to the context’s include path.
 *
 * @returns 1 on success, or 0 if no default include path could be added.
 *
 * @memberof xkb_context
 */
XKB_EXPORT int
xkb_context_include_path_append_default(struct xkb_context *context);

/**
 * Reset the context’s include path to the default.
 *
 * Removes all entries from the context’s include path, and inserts the
 * default paths.
 *
 * @returns 1 on success, or 0 if the primary include path could not be added.
 *
 * @memberof xkb_context
 */
XKB_EXPORT int
xkb_context_include_path_reset_defaults(struct xkb_context *context);

/**
 * Remove all entries from the context’s include path.
 *
 * @memberof xkb_context
 */
XKB_EXPORT void
xkb_context_include_path_clear(struct xkb_context *context);

/**
 * Get the number of paths in the context’s include path.
 *
 * @memberof xkb_context
 */
XKB_EXPORT unsigned int
xkb_context_num_include_paths(struct xkb_context *context);

/**
 * Get a specific include path from the context’s include path.
 *
 * @returns The include path at the specified index.  If the index is
 * invalid, returns NULL.
 *
 * @memberof xkb_context
 */
XKB_EXPORT const char *
xkb_context_include_path_get(struct xkb_context *context, unsigned int index);

/** @} */

/**
 * @defgroup logging Logging Handling
 * Manipulating how logging from this library is handled.
 *
 * @{
 */

/** Specifies a logging level. */
enum xkb_log_level {
    XKB_LOG_LEVEL_CRITICAL = 10, /**< Log critical internal errors only. */
    XKB_LOG_LEVEL_ERROR = 20,    /**< Log all errors. */
    XKB_LOG_LEVEL_WARNING = 30,  /**< Log warnings and errors. */
    XKB_LOG_LEVEL_INFO = 40,     /**< Log information, warnings, and errors. */
    XKB_LOG_LEVEL_DEBUG = 50     /**< Log everything. */
};

/**
 * Set the current logging level.
 *
 * @param context The context in which to set the logging level.
 * @param level   The logging level to use.  Only messages from this level
 * and below will be logged.
 *
 * The default level is `::XKB_LOG_LEVEL_ERROR`.  The environment variable
 * `XKB_LOG_LEVEL`, if set in the time the context was created, overrides the
 * default value.  It may be specified as a level number or name.
 *
 * @memberof xkb_context
 */
XKB_EXPORT void
xkb_context_set_log_level(struct xkb_context *context,
                          enum xkb_log_level level);

/**
 * Get the current logging level.
 *
 * @memberof xkb_context
 */
XKB_EXPORT enum xkb_log_level
xkb_context_get_log_level(struct xkb_context *context);

/**
 * Sets the current logging verbosity.
 *
 * The library can generate a number of warnings which are not helpful to
 * ordinary users of the library.  The verbosity may be increased if more
 * information is desired (e.g. when developing a new keymap).
 *
 * The default verbosity is 0.  The environment variable `XKB_LOG_VERBOSITY`,
 * if set in the time the context was created, overrides the default value.
 *
 * @param context   The context in which to use the set verbosity.
 * @param verbosity The verbosity to use.  Currently used values are
 * 1 to 10, higher values being more verbose.  0 would result in no verbose
 * messages being logged.
 *
 * Most verbose messages are of level `::XKB_LOG_LEVEL_WARNING` or lower.
 *
 * @memberof xkb_context
 */
XKB_EXPORT void
xkb_context_set_log_verbosity(struct xkb_context *context, int verbosity);

/**
 * Get the current logging verbosity of the context.
 *
 * @memberof xkb_context
 */
XKB_EXPORT int
xkb_context_get_log_verbosity(struct xkb_context *context);

/**
 * Set a custom function to handle logging messages.
 *
 * @param context The context in which to use the set logging function.
 * @param log_fn  The function that will be called for logging messages.
 * Passing `NULL` restores the default function, which logs to stderr.
 *
 * By default, log messages from this library are printed to stderr.  This
 * function allows you to replace the default behavior with a custom
 * handler.  The handler is only called with messages which match the
 * current logging level and verbosity settings for the context.
 * level is the logging level of the message.  @a format and @a args are
 * the same as in the `vprintf(3)` function.
 *
 * You may use `xkb_context::xkb_context_set_user_data()` on the context, and
 * then call `xkb_context::xkb_context_get_user_data()` from within the logging
 * function to provide it with additional private context.
 *
 * @memberof xkb_context
 */
XKB_EXPORT void
xkb_context_set_log_fn(struct xkb_context *context,
                       void (*log_fn)(struct xkb_context *context,
                                      enum xkb_log_level level,
                                      const char *format, va_list args));

/** @} */

/**
 * @defgroup keymap Keymap Creation
 * Creating and destroying keymaps.
 *
 * @{
 */

/** Flags for keymap compilation. */
enum xkb_keymap_compile_flags {
    /** Do not apply any flags. */
    XKB_KEYMAP_COMPILE_NO_FLAGS = 0
};

/**
 * The possible keymap formats.
 *
 * See @ref keymap-text-format-v1-v2 "" for the complete description of the
 * formats and @ref keymap-support "" for detailed differences between the
 * formats.
 *
 * @remark A keymap can be parsed in one format and serialized in another,
 * thanks to automatic fallback mechanisms.
 *
 * <table>
 * <caption>
 * Keymap format to use depending on the target protocol
 * </caption>
 * <thead>
 * <tr>
 * <th colspan="2">Protocol</th>
 * <th colspan="2">libxkbcommon keymap format</th>
 * </tr>
 * <tr>
 * <th>Name</th>
 * <th>Keymap format</th>
 * <th>Parsing</th>
 * <th>Serialization</th>
 * </tr>
 * </thead>
 * <tbody>
 * <tr>
 * <th>X11</th>
 * <td>XKB</td>
 * <td>
 * `::XKB_KEYMAP_FORMAT_TEXT_V1`
 * </td>
 * <td>
 * *Always* use `::XKB_KEYMAP_FORMAT_TEXT_V1`, since the other formats are
 * incompatible.
 * </td>
 * </tr>
 * <tr>
 * <th>Wayland</th>
 * <td><code>[xkb_v1]</code></td>
 * <td>
 * <dl>
 * <dt>Wayland compositors<dt>
 * <dd>
 * The format depends on the keyboard layout database (usually [xkeyboard-config]).
 * Note that since v2 is a superset of v1, compositors are encouraged to use
 * `::XKB_KEYMAP_FORMAT_TEXT_V2` whenever possible.
 * </dd>
 * <dt>Client apps</dt>
 * <dd>
 * Clients should use `::XKB_KEYMAP_FORMAT_TEXT_V1` to parse the keymap sent
 * by a Wayland compositor, at least until `::XKB_KEYMAP_FORMAT_TEXT_V2`
 * stabilizes.
 * </dd>
 * </td>
 * <td>
 * At the time of writing (July 2025), the Wayland <code>[xkb_v1]</code> keymap
 * format is only defined as “libxkbcommon compatible”. In theory it enables
 * flexibility, but the set of supported features varies depending on the
 * libxkbcommon version and libxkbcommon keymap format used. Unfortunately there
 * is currently no Wayland API for keymap format *negotiation*.
 *
 * Therefore the **recommended** serialization format is
 * `::XKB_KEYMAP_FORMAT_TEXT_V1`, in order to ensure maximum compatibility for
 * interchange.
 *
 * Serializing using `::XKB_KEYMAP_FORMAT_TEXT_V2` should be considered
 * **experimental**, as some clients may fail to parse the resulting string.
 * </td>
 * </tr>
 * </tbody>
 * </table>
 *
 * [xkb_v1]: https://wayland.freedesktop.org/docs/html/apa.html#protocol-spec-wl_keyboard-enum-keymap_format
 * [xkeyboard-config]: https://gitlab.freedesktop.org/xkeyboard-config/xkeyboard-config
 */
enum xkb_keymap_format {
    /**
     * The classic XKB text format, as generated by `xkbcomp -xkb`.
     *
     * @important This format should *always* be used when *serializing* a
     * keymap for **X11**.
     *
     * @important For the **Wayland** <code>[xkb_v1]</code> format, it is
     * advised to use this format as well for serializing, in order to ensure
     * maximum compatibility for interchange.
     *
     * [xkb_v1]: https://wayland.freedesktop.org/docs/html/apa.html#protocol-spec-wl_keyboard-enum-keymap_format
     */
    XKB_KEYMAP_FORMAT_TEXT_V1 = 1,
    /**
     * Xkbcommon extensions of the classic XKB text format, **incompatible with
     * X11**.
     *
     * @important Do *not* use when *serializing* a keymap for **X11**
     * (incompatible).
     *
     * @important Considered *experimental* when *serializing* for **Wayland**:
     * at the time of writing (July 2025), there is only one XKB keymap format
     * <code>[xkb_v1]</code> in Wayland and no Wayland API for keymap format
     * *negotiation*, so the clients may not be able to parse the keymap if it
     * uses v2-specific features. Therefore a compositor may *parse* keymaps
     * using `::XKB_KEYMAP_FORMAT_TEXT_V2` but it should serialize them using
     * `::XKB_KEYMAP_FORMAT_TEXT_V1` and rely on the automatic *fallback*
     * mechanisms.
     *
     * @since 1.11.0
     *
     * [xkb_v1]: https://wayland.freedesktop.org/docs/html/apa.html#protocol-spec-wl_keyboard-enum-keymap_format
     */
    XKB_KEYMAP_FORMAT_TEXT_V2 = 2
};

/**
 * Create a keymap from a [RMLVO] builder.
 *
 * The primary keymap entry point: creates a new XKB keymap from a set of
 * [RMLVO] \(Rules + Model + Layouts + Variants + Options) names.
 *
 * @param rmlvo   The [RMLVO] builder to use.  See `xkb_rmlvo_builder`.
 * @param format  The text format of the keymap file to compile.
 * @param flags   Optional flags for the keymap, or 0.
 *
 * @returns A keymap compiled according to the [RMLVO] names, or `NULL` if
 * the compilation failed.
 *
 * @since 1.11.0
 * @sa `xkb_keymap_new_from_names2()`
 * @sa `xkb_rmlvo_builder`
 * @memberof xkb_keymap
 *
 * [RMLVO]: @ref RMLVO-intro
 */
XKB_EXPORT struct xkb_keymap *
xkb_keymap_new_from_rmlvo(const struct xkb_rmlvo_builder *rmlvo,
                          enum xkb_keymap_format format,
                          enum xkb_keymap_compile_flags flags);

/**
 * Create a keymap from [RMLVO] names.
 *
 * Same as `xkb_keymap_new_from_names2()`, but with the keymap format fixed to:
 * `::XKB_KEYMAP_FORMAT_TEXT_V2`.
 *
 * @deprecated Use `xkb_keymap_new_from_names2()` instead.
 * @since 1.11.0: Deprecated
 * @since 1.11.0: Use internally `::XKB_KEYMAP_FORMAT_TEXT_V2` instead of
 * `::XKB_KEYMAP_FORMAT_TEXT_V1`
 * @sa `xkb_keymap_new_from_names2()`
 * @sa `xkb_rule_names`
 * @sa `xkb_keymap_new_from_rmlvo()`
 * @memberof xkb_keymap
 *
 * [RMLVO]: @ref RMLVO-intro
 */
XKB_EXPORT struct xkb_keymap *
xkb_keymap_new_from_names(struct xkb_context *context,
                          const struct xkb_rule_names *names,
                          enum xkb_keymap_compile_flags flags);

/**
 * Create a keymap from [RMLVO] names.
 *
 * The primary keymap entry point: creates a new XKB keymap from a set of
 * [RMLVO] \(Rules + Model + Layouts + Variants + Options) names.
 *
 * @param context The context in which to create the keymap.
 * @param names   The [RMLVO] names to use.  See xkb_rule_names.
 * @param format  The text format of the keymap file to compile.
 * @param flags   Optional flags for the keymap, or 0.
 *
 * @returns A keymap compiled according to the [RMLVO] names, or `NULL` if
 * the compilation failed.
 *
 * @sa `xkb_rule_names`
 * @sa `xkb_keymap_new_from_rmlvo()`
 * @memberof xkb_keymap
 * @since 1.11.0
 *
 * [RMLVO]: @ref RMLVO-intro
 */
XKB_EXPORT struct xkb_keymap *
xkb_keymap_new_from_names2(struct xkb_context *context,
                           const struct xkb_rule_names *names,
                           enum xkb_keymap_format format,
                           enum xkb_keymap_compile_flags flags);

/**
 * Create a keymap from a keymap file.
 *
 * @param context The context in which to create the keymap.
 * @param file    The keymap file to compile.
 * @param format  The text format of the keymap file to compile.
 * @param flags   Optional flags for the keymap, or 0.
 *
 * @returns A keymap compiled from the given XKB keymap file, or `NULL` if
 * the compilation failed.
 *
 * The file must contain a complete keymap.  For example, in the
 * `::XKB_KEYMAP_FORMAT_TEXT_V1` format, this means the file must contain one
 * top level `%xkb_keymap` section, which in turn contains other required
 * sections.
 *
 * @memberof xkb_keymap
 */
XKB_EXPORT struct xkb_keymap *
xkb_keymap_new_from_file(struct xkb_context *context, FILE *file,
                         enum xkb_keymap_format format,
                         enum xkb_keymap_compile_flags flags);

/**
 * Create a keymap from a keymap string.
 *
 * This is just like `xkb_keymap_new_from_file()`, but instead of a file, gets
 * the keymap as one enormous string.
 *
 * @see `xkb_keymap_new_from_file()`
 * @memberof xkb_keymap
 */
XKB_EXPORT struct xkb_keymap *
xkb_keymap_new_from_string(struct xkb_context *context, const char *string,
                           enum xkb_keymap_format format,
                           enum xkb_keymap_compile_flags flags);

/**
 * Create a keymap from a memory buffer.
 *
 * This is just like `xkb_keymap_new_from_string()`, but takes a length argument
 * so the input string does not have to be zero-terminated.
 *
 * @see `xkb_keymap_new_from_string()`
 * @memberof xkb_keymap
 * @since 0.3.0
 */
XKB_EXPORT struct xkb_keymap *
xkb_keymap_new_from_buffer(struct xkb_context *context, const char *buffer,
                           size_t length, enum xkb_keymap_format format,
                           enum xkb_keymap_compile_flags flags);

/**
 * Take a new reference on a keymap.
 *
 * @returns The passed in keymap.
 *
 * @memberof xkb_keymap
 */
XKB_EXPORT struct xkb_keymap *
xkb_keymap_ref(struct xkb_keymap *keymap);

/**
 * Release a reference on a keymap, and possibly free it.
 *
 * @param keymap The keymap.  If it is `NULL`, this function does nothing.
 *
 * @memberof xkb_keymap
 */
XKB_EXPORT void
xkb_keymap_unref(struct xkb_keymap *keymap);

/**
 * Get the keymap as a string in the format from which it was created.
 * @sa `xkb_keymap::xkb_keymap_get_as_string()`
 **/
#define XKB_KEYMAP_USE_ORIGINAL_FORMAT ((enum xkb_keymap_format) -1)

/**
 * Flags to control keymap serialization.
 *
 * @since 1.12.0
 */
enum xkb_keymap_serialize_flags {
    /** Do not apply any flags. */
    XKB_KEYMAP_SERIALIZE_NO_FLAGS = 0,
    /** Enable pretty-printing */
    XKB_KEYMAP_SERIALIZE_PRETTY = (1 << 0),
    /** Do not drop unused bits (key types, compatibility entries) */
    XKB_KEYMAP_SERIALIZE_KEEP_UNUSED = (1 << 1),
};

/**
 * Get the compiled keymap as a string.
 *
 * Same as `xkb_keymap::xkb_keymap_get_as_string2()` using
 * `::XKB_KEYMAP_SERIALIZE_NO_FLAGS`.
 *
 * @since 1.12.0: Drop unused types and compatibility entries and do not
 * pretty-print.
 *
 * @sa `xkb_keymap::xkb_keymap_get_as_string2()`
 * @memberof xkb_keymap
 */
XKB_EXPORT char *
xkb_keymap_get_as_string(struct xkb_keymap *keymap,
                         enum xkb_keymap_format format);

/**
 * Get the compiled keymap as a string.
 *
 * @param keymap The keymap to get as a string.
 * @param format The keymap format to use for the string.  You can pass
 * in the special value `::XKB_KEYMAP_USE_ORIGINAL_FORMAT` to use the format
 * from which the keymap was originally created. When used as an *interchange*
 * format such as Wayland <code>[xkb_v1]</code>, the format should be explicit.
 * @param flags  Optional flags to control the serialization, or 0.
 *
 * @returns The keymap as a `NULL`-terminated string, or `NULL` if unsuccessful.
 *
 * The returned string may be fed back into `xkb_keymap_new_from_string()`
 * to get the exact same keymap (possibly in another process, etc.).
 *
 * The returned string is *dynamically allocated* and should be freed by the
 * caller.
 *
 * @since 1.12.0
 *
 * @sa `xkb_keymap_get_as_string()`
 * @sa `xkb_keymap_new_from_string()`
 * @memberof xkb_keymap
 *
 * [xkb_v1]: https://wayland.freedesktop.org/docs/html/apa.html#protocol-spec-wl_keyboard-enum-keymap_format
 */
XKB_EXPORT char *
xkb_keymap_get_as_string2(struct xkb_keymap *keymap,
                          enum xkb_keymap_format format,
                          enum xkb_keymap_serialize_flags flags);

/** @} */

/**
 * @defgroup components Keymap Components
 * Enumeration of state components in a keymap.
 *
 * @{
 */

/**
 * Get the minimum keycode in the keymap.
 *
 * @sa xkb_keycode_t
 * @memberof xkb_keymap
 * @since 0.3.1
 */
XKB_EXPORT xkb_keycode_t
xkb_keymap_min_keycode(struct xkb_keymap *keymap);

/**
 * Get the maximum keycode in the keymap.
 *
 * @sa xkb_keycode_t
 * @memberof xkb_keymap
 * @since 0.3.1
 */
XKB_EXPORT xkb_keycode_t
xkb_keymap_max_keycode(struct xkb_keymap *keymap);

/**
 * The iterator used by `xkb_keymap_key_for_each()`.
 *
 * @sa xkb_keymap_key_for_each
 * @memberof xkb_keymap
 * @since 0.3.1
 */
typedef void
(*xkb_keymap_key_iter_t)(struct xkb_keymap *keymap, xkb_keycode_t key,
                         void *data);

/**
 * Run a specified function for every valid keycode in the keymap.  If a
 * keymap is sparse, this function may be called fewer than
 * (max_keycode - min_keycode + 1) times.
 *
 * @sa xkb_keymap_min_keycode()
 * @sa xkb_keymap_max_keycode()
 * @sa xkb_keycode_t
 * @memberof xkb_keymap
 * @since 0.3.1
 */
XKB_EXPORT void
xkb_keymap_key_for_each(struct xkb_keymap *keymap, xkb_keymap_key_iter_t iter,
                        void *data);

/**
 * Find the name of the key with the given keycode.
 *
 * This function always returns the canonical name of the key (see
 * description in `xkb_keycode_t`).
 *
 * @returns The key name. If no key with this keycode exists,
 * returns `NULL`.
 *
 * @sa xkb_keycode_t
 * @memberof xkb_keymap
 * @since 0.6.0
 */
XKB_EXPORT const char *
xkb_keymap_key_get_name(struct xkb_keymap *keymap, xkb_keycode_t key);

/**
 * Find the keycode of the key with the given name.
 *
 * The name can be either a canonical name or an alias.
 *
 * @returns The keycode. If no key with this name exists,
 * returns `::XKB_KEYCODE_INVALID`.
 *
 * @sa xkb_keycode_t
 * @memberof xkb_keymap
 * @since 0.6.0
 */
XKB_EXPORT xkb_keycode_t
xkb_keymap_key_by_name(struct xkb_keymap *keymap, const char *name);

/**
 * Get the number of modifiers in the keymap.
 *
 * @sa xkb_mod_index_t
 * @memberof xkb_keymap
 */
XKB_EXPORT xkb_mod_index_t
xkb_keymap_num_mods(struct xkb_keymap *keymap);

/**
 * Get the name of a modifier by index.
 *
 * @returns The name.  If the index is invalid, returns `NULL`.
 *
 * @sa xkb_mod_index_t
 * @memberof xkb_keymap
 */
XKB_EXPORT const char *
xkb_keymap_mod_get_name(struct xkb_keymap *keymap, xkb_mod_index_t idx);

/**
 * Get the index of a modifier by name.
 *
 * @returns The index.  If no modifier with this name exists, returns
 * `::XKB_MOD_INVALID`.
 *
 * @sa xkb_mod_index_t
 * @memberof xkb_keymap
 */
XKB_EXPORT xkb_mod_index_t
xkb_keymap_mod_get_index(struct xkb_keymap *keymap, const char *name);

/**
 * Get the encoding of a modifier by name.
 *
 * In X11 terminology it corresponds to the mapping to the *[real modifiers]*.
 *
 * @returns The encoding of a modifier.  Note that it may be 0 if the name does
 * not exist or if the modifier is not mapped.
 *
 * @since 1.10.0
 * @sa `xkb_keymap_mod_get_mask2()`
 * @memberof xkb_keymap
 *
 * [real modifiers]: @ref real-modifier-def
 */
XKB_EXPORT xkb_mod_mask_t
xkb_keymap_mod_get_mask(struct xkb_keymap *keymap, const char *name);

/**
 * Get the encoding of a modifier by index.
 *
 * In X11 terminology it corresponds to the mapping to the *[real modifiers]*.
 *
 * @returns The encoding of a modifier.  Note that it may be 0 if the modifier is
 * not mapped.
 *
 * @since 1.11.0
 * @sa `xkb_keymap_mod_get_mask()`
 * @memberof xkb_keymap
 *
 * [real modifiers]: @ref real-modifier-def
 */
XKB_EXPORT xkb_mod_mask_t
xkb_keymap_mod_get_mask2(struct xkb_keymap *keymap, xkb_mod_index_t idx);

/**
 * Get the number of layouts in the keymap.
 *
 * @sa `xkb_layout_index_t`
 * @sa `xkb_rule_names`
 * @sa `xkb_keymap_num_layouts_for_key()`
 * @memberof xkb_keymap
 */
XKB_EXPORT xkb_layout_index_t
xkb_keymap_num_layouts(struct xkb_keymap *keymap);

/**
 * Get the name of a layout by index.
 *
 * @returns The name.  If the index is invalid, or the layout does not have
 * a name, returns `NULL`.
 *
 * @sa xkb_layout_index_t
 *     For notes on layout names.
 * @memberof xkb_keymap
 */
XKB_EXPORT const char *
xkb_keymap_layout_get_name(struct xkb_keymap *keymap, xkb_layout_index_t idx);

/**
 * Get the index of a layout by name.
 *
 * @returns The index.  If no layout exists with this name, returns
 * `::XKB_LAYOUT_INVALID`.  If more than one layout in the keymap has this name,
 * returns the lowest index among them.
 *
 * @sa `xkb_layout_index_t` for notes on layout names.
 * @memberof xkb_keymap
 */
XKB_EXPORT xkb_layout_index_t
xkb_keymap_layout_get_index(struct xkb_keymap *keymap, const char *name);

/**
 * Get the number of LEDs in the keymap.
 *
 * @warning The range [ 0...`xkb_keymap_num_leds()` ) includes all of the LEDs
 * in the keymap, but may also contain inactive LEDs.  When iterating over
 * this range, you need the handle this case when calling functions such as
 * `xkb_keymap_led_get_name()` or `xkb_state::xkb_state_led_index_is_active()`.
 *
 * @sa xkb_led_index_t
 * @memberof xkb_keymap
 */
XKB_EXPORT xkb_led_index_t
xkb_keymap_num_leds(struct xkb_keymap *keymap);

/**
 * Get the name of a LED by index.
 *
 * @returns The name.  If the index is invalid, returns `NULL`.
 *
 * @memberof xkb_keymap
 */
XKB_EXPORT const char *
xkb_keymap_led_get_name(struct xkb_keymap *keymap, xkb_led_index_t idx);

/**
 * Get the index of a LED by name.
 *
 * @returns The index.  If no LED with this name exists, returns
 * `::XKB_LED_INVALID`.
 *
 * @memberof xkb_keymap
 */
XKB_EXPORT xkb_led_index_t
xkb_keymap_led_get_index(struct xkb_keymap *keymap, const char *name);

/**
 * Get the number of layouts for a specific key.
 *
 * This number can be different from `xkb_keymap_num_layouts()`, but is always
 * smaller.  It is the appropriate value to use when iterating over the
 * layouts of a key.
 *
 * @sa xkb_layout_index_t
 * @memberof xkb_keymap
 */
XKB_EXPORT xkb_layout_index_t
xkb_keymap_num_layouts_for_key(struct xkb_keymap *keymap, xkb_keycode_t key);

/**
 * Get the number of shift levels for a specific key and layout.
 *
 * If @c layout is out of range for this key (that is, larger or equal to
 * the value returned by `xkb_keymap_num_layouts_for_key()`), it is brought
 * back into range in a manner consistent with
 * `xkb_state::xkb_state_key_get_layout()`.
 *
 * @sa xkb_level_index_t
 * @memberof xkb_keymap
 */
XKB_EXPORT xkb_level_index_t
xkb_keymap_num_levels_for_key(struct xkb_keymap *keymap, xkb_keycode_t key,
                              xkb_layout_index_t layout);

/**
 * Retrieves every possible modifier mask that produces the specified
 * shift level for a specific key and layout.
 *
 * This API is useful for inverse key transformation; i.e. finding out
 * which modifiers need to be active in order to be able to type the
 * keysym(s) corresponding to the specific key code, layout and level.
 *
 * @warning It returns only up to masks_size modifier masks. If the
 * buffer passed is too small, some of the possible modifier combinations
 * will not be returned.
 *
 * @param[in] keymap      The keymap.
 * @param[in] key         The keycode of the key.
 * @param[in] layout      The layout for which to get modifiers.
 * @param[in] level       The shift level in the layout for which to get the
 * modifiers. This should be smaller than:
 * @code xkb_keymap_num_levels_for_key(keymap, key) @endcode
 * @param[out] masks_out  A buffer in which the requested masks should be
 * stored.
 * @param[out] masks_size The number of elements in the buffer pointed to by
 * masks_out.
 *
 * If @c layout is out of range for this key (that is, larger or equal to
 * the value returned by `xkb_keymap_num_layouts_for_key()`), it is brought
 * back into range in a manner consistent with
 * `xkb_state::xkb_state_key_get_layout()`.
 *
 * @returns The number of modifier masks stored in the masks_out array.
 * If the key is not in the keymap or if the specified shift level cannot
 * be reached it returns 0 and does not modify the masks_out buffer.
 *
 * @sa xkb_level_index_t
 * @sa xkb_mod_mask_t
 * @memberof xkb_keymap
 * @since 1.0.0
 */
XKB_EXPORT size_t
xkb_keymap_key_get_mods_for_level(struct xkb_keymap *keymap,
                                  xkb_keycode_t key,
                                  xkb_layout_index_t layout,
                                  xkb_level_index_t level,
                                  xkb_mod_mask_t *masks_out,
                                  size_t masks_size);

/**
 * Get the keysyms obtained from pressing a key in a given layout and
 * shift level.
 *
 * This function is like `xkb_state::xkb_state_key_get_syms()`, only the layout
 * and shift level are not derived from the keyboard state but are instead
 * specified explicitly.
 *
 * @param[in] keymap    The keymap.
 * @param[in] key       The keycode of the key.
 * @param[in] layout    The layout for which to get the keysyms.
 * @param[in] level     The shift level in the layout for which to get the
 * keysyms. This should be smaller than:
 * @code xkb_keymap_num_levels_for_key(keymap, key) @endcode
 * @param[out] syms_out An immutable array of keysyms corresponding to the
 * key in the given layout and shift level.
 *
 * If @c layout is out of range for this key (that is, larger or equal to
 * the value returned by `xkb_keymap_num_layouts_for_key()`), it is brought
 * back into range in a manner consistent with
 * `xkb_state::xkb_state_key_get_layout()`.
 *
 * @returns The number of keysyms in the syms_out array.  If no keysyms
 * are produced by the key in the given layout and shift level, returns 0
 * and sets @p syms_out to `NULL`.
 *
 * @sa `xkb_state::xkb_state_key_get_syms()`
 * @memberof xkb_keymap
 */
XKB_EXPORT int
xkb_keymap_key_get_syms_by_level(struct xkb_keymap *keymap,
                                 xkb_keycode_t key,
                                 xkb_layout_index_t layout,
                                 xkb_level_index_t level,
                                 const xkb_keysym_t **syms_out);

/**
 * Determine whether a key should repeat or not.
 *
 * A keymap may specify different repeat behaviors for different keys.
 * Most keys should generally exhibit repeat behavior; for example, holding
 * the `a` key down in a text editor should normally insert a single ‘a’
 * character every few milliseconds, until the key is released.  However,
 * there are keys which should not or do not need to be repeated.  For
 * example, repeating modifier keys such as Left/Right Shift or Caps Lock
 * is not generally useful or desired.
 *
 * @returns 1 if the key should repeat, 0 otherwise.
 *
 * @memberof xkb_keymap
 */
XKB_EXPORT int
xkb_keymap_key_repeats(struct xkb_keymap *keymap, xkb_keycode_t key);

/** @} */

/**
 * @defgroup state Keyboard State
 * Creating, destroying and manipulating keyboard state objects.
 *
 * @{
 */

/**
 * Create a new keyboard state object.
 *
 * @param keymap The keymap which the state will use.
 *
 * @returns A new keyboard state object, or `NULL` on failure.
 *
 * @memberof xkb_state
 */
XKB_EXPORT struct xkb_state *
xkb_state_new(struct xkb_keymap *keymap);

/**
 * Take a new reference on a keyboard state object.
 *
 * @returns The passed in object.
 *
 * @memberof xkb_state
 */
XKB_EXPORT struct xkb_state *
xkb_state_ref(struct xkb_state *state);

/**
 * Release a reference on a keyboard state object, and possibly free it.
 *
 * @param state The state.  If it is `NULL`, this function does nothing.
 *
 * @memberof xkb_state
 */
XKB_EXPORT void
xkb_state_unref(struct xkb_state *state);

/**
 * Get the keymap which a keyboard state object is using.
 *
 * @returns The keymap which was passed to `xkb_state_new()` when creating
 * this state object.
 *
 * This function does not take a new reference on the keymap; you must
 * explicitly reference it yourself if you plan to use it beyond the
 * lifetime of the state.
 *
 * @memberof xkb_state
 */
XKB_EXPORT struct xkb_keymap *
xkb_state_get_keymap(struct xkb_state *state);

/**
 * @page server-client-state Server State and Client State
 * @parblock
 *
 * The xkb_state API is used by two distinct actors in most window-system
 * architectures:
 *
 * 1. A *server* - for example, a Wayland compositor, an X11 server, an evdev
 *    listener.
 *
 *    Servers maintain the XKB state for a device according to input events from
 *    the device, such as key presses and releases, and out-of-band events from
 *    the user, like UI layout switchers.
 *
 * 2. A *client* - for example, a Wayland client, an X11 client.
 *
 *    Clients do not listen to input from the device; instead, whenever the
 *    server state changes, the server serializes the state and notifies the
 *    clients that the state has changed; the clients then update the state
 *    from the serialization.
 *
 * Some entry points in the xkb_state API are only meant for servers and some
 * are only meant for clients, and the two should generally not be mixed.
 *
 * @endparblock
 */

/** Specifies the direction of the key (press / release). */
enum xkb_key_direction {
    XKB_KEY_UP,   /**< The key was released. */
    XKB_KEY_DOWN  /**< The key was pressed. */
};

/**
 * Modifier and layout types for state objects.  This enum is bitmaskable,
 * e.g. (`::XKB_STATE_MODS_DEPRESSED` | `::XKB_STATE_MODS_LATCHED`) is valid to
 * exclude locked modifiers.
 *
 * In XKB, the `DEPRESSED` components are also known as *base*.
 */
enum xkb_state_component {
    /** Depressed modifiers, i.e. a key is physically holding them. */
    XKB_STATE_MODS_DEPRESSED = (1 << 0),
    /** Latched modifiers, i.e. will be unset after the next non-modifier
     *  key press. */
    XKB_STATE_MODS_LATCHED = (1 << 1),
    /** Locked modifiers, i.e. will be unset after the key provoking the
     *  lock has been pressed again. */
    XKB_STATE_MODS_LOCKED = (1 << 2),
    /** Effective modifiers, i.e. currently active and affect key
     *  processing (derived from the other state components).
     *  Use this unless you explicitly care how the state came about. */
    XKB_STATE_MODS_EFFECTIVE = (1 << 3),
    /** Depressed layout, i.e. a key is physically holding it. */
    XKB_STATE_LAYOUT_DEPRESSED = (1 << 4),
    /** Latched layout, i.e. will be unset after the next non-modifier
     *  key press. */
    XKB_STATE_LAYOUT_LATCHED = (1 << 5),
    /** Locked layout, i.e. will be unset after the key provoking the lock
     *  has been pressed again. */
    XKB_STATE_LAYOUT_LOCKED = (1 << 6),
    /** Effective layout, i.e. currently active and affects key processing
     *  (derived from the other state components).
     *  Use this unless you explicitly care how the state came about. */
    XKB_STATE_LAYOUT_EFFECTIVE = (1 << 7),
    /** LEDs (derived from the other state components). */
    XKB_STATE_LEDS = (1 << 8)
};

/**
 * Update the keyboard state to reflect a given key being pressed or
 * released.
 *
 * This entry point is intended for *server* applications and should not be used
 * by *client* applications; see @ref server-client-state for details.
 *
 * A series of calls to this function should be consistent; that is, a call
 * with `::XKB_KEY_DOWN` for a key should be matched by an `::XKB_KEY_UP`; if a
 * key is pressed twice, it should be released twice; etc. Otherwise (e.g. due
 * to missed input events), situations like “stuck modifiers” may occur.
 *
 * This function is often used in conjunction with the function
 * `xkb_state_key_get_syms()` (or `xkb_state_key_get_one_sym()`), for example,
 * when handling a key event.  In this case, you should prefer to get the
 * keysyms *before* updating the key, such that the keysyms reported for
 * the key event are not affected by the event itself.  This is the
 * conventional behavior.
 *
 * @returns A mask of state components that have changed as a result of
 * the update.  If nothing in the state has changed, returns 0.
 *
 * @memberof xkb_state
 *
 * @sa `xkb_state_update_mask()`
 */
XKB_EXPORT enum xkb_state_component
xkb_state_update_key(struct xkb_state *state, xkb_keycode_t key,
                     enum xkb_key_direction direction);

/**
 * Update the keyboard state to change the latched and locked state of
 * the modifiers and layout.
 *
 * This entry point is intended for *server* applications and should not be used
 * by *client* applications; see @ref server-client-state for details.
 *
 * Use this function to update the latched and locked state according to
 * “out of band” (non-device) inputs, such as UI layout switchers.
 *
 * @par Layout out of range
 * @parblock
 *
 * If the effective layout, after taking into account the depressed, latched and
 * locked layout, is out of range (negative or greater than the maximum layout),
 * it is brought into range. Currently, the layout is wrapped using integer
 * modulus (with negative values wrapping from the end). The wrapping behavior
 * may be made configurable in the future.
 *
 * @endparblock
 *
 * @param state The keyboard state object.
 * @param affect_latched_mods
 * @param latched_mods
 *     Modifiers to set as latched or unlatched. Only modifiers in
 *     @p affect_latched_mods are considered.
 * @param affect_latched_layout
 * @param latched_layout
 *     Layout to latch. Only considered if @p affect_latched_layout is true.
 *     Maybe be out of range (including negative) -- see note above.
 * @param affect_locked_mods
 * @param locked_mods
 *     Modifiers to set as locked or unlocked. Only modifiers in
 *     @p affect_locked_mods are considered.
 * @param affect_locked_layout
 * @param locked_layout
 *     Layout to lock. Only considered if @p affect_locked_layout is true.
 *     Maybe be out of range (including negative) -- see note above.
 *
 * @returns A mask of state components that have changed as a result of
 * the update.  If nothing in the state has changed, returns 0.
 *
 * @memberof xkb_state
 *
 * @sa xkb_state_update_mask()
 */
XKB_EXPORT enum xkb_state_component
xkb_state_update_latched_locked(struct xkb_state *state,
                                xkb_mod_mask_t affect_latched_mods,
                                xkb_mod_mask_t latched_mods,
                                bool affect_latched_layout,
                                int32_t latched_layout,
                                xkb_mod_mask_t affect_locked_mods,
                                xkb_mod_mask_t locked_mods,
                                bool affect_locked_layout,
                                int32_t locked_layout);

/**
 * Update a keyboard state from a set of explicit masks.
 *
 * This entry point is intended for *client* applications; see @ref
 * server-client-state for details. *Server* applications should use
 * `xkb_state_update_key()` instead.
 *
 * All parameters must always be passed, or the resulting state may be
 * incoherent.
 *
 * @warning The serialization is lossy and will not survive round trips; it must
 * only be used to feed client state objects, and must not be used to update the
 * server state.
 *
 * @returns A mask of state components that have changed as a result of
 * the update.  If nothing in the state has changed, returns 0.
 *
 * @memberof xkb_state
 *
 * @sa `xkb_state_component`
 * @sa `xkb_state_update_key()`
 */
XKB_EXPORT enum xkb_state_component
xkb_state_update_mask(struct xkb_state *state,
                      xkb_mod_mask_t depressed_mods,
                      xkb_mod_mask_t latched_mods,
                      xkb_mod_mask_t locked_mods,
                      xkb_layout_index_t depressed_layout,
                      xkb_layout_index_t latched_layout,
                      xkb_layout_index_t locked_layout);

/**
 * Get the keysyms obtained from pressing a particular key in a given
 * keyboard state.
 *
 * Get the keysyms for a key according to the current active layout,
 * modifiers and shift level for the key, as determined by a keyboard
 * state.
 *
 * @param[in]  state    The keyboard state object.
 * @param[in]  key      The keycode of the key.
 * @param[out] syms_out An immutable array of keysyms corresponding the
 * key in the given keyboard state.
 *
 * As an extension to XKB, this function can return more than one keysym.
 * If you do not want to handle this case, you can use
 * `xkb_state_key_get_one_sym()` for a simpler interface.
 *
 * @returns The number of keysyms in the syms_out array.  If no keysyms
 * are produced by the key in the given keyboard state, returns 0 and sets
 * syms_out to `NULL`.
 *
 * This function performs Capitalization @ref keysym-transformations.
 *
 * @memberof xkb_state
 *
 * @since 1.9.0 This function now performs @ref keysym-transformations.
 */
XKB_EXPORT int
xkb_state_key_get_syms(struct xkb_state *state, xkb_keycode_t key,
                       const xkb_keysym_t **syms_out);

/**
 * Get the Unicode/UTF-8 string obtained from pressing a particular key
 * in a given keyboard state.
 *
 * @param[in]  state  The keyboard state object.
 * @param[in]  key    The keycode of the key.
 * @param[out] buffer A buffer to write the string into.
 * @param[in]  size   Size of the buffer.
 *
 * @warning If the buffer passed is too small, the string is truncated
 * (though still `NULL`-terminated).
 *
 * @returns The number of bytes required for the string, excluding the
 * `NULL` byte.  If there is nothing to write, returns 0.
 *
 * You may check if truncation has occurred by comparing the return value
 * with the size of @p buffer, similarly to the `snprintf(3)` function.
 * You may safely pass `NULL` and 0 to @p buffer and @p size to find the
 * required size (without the `NULL`-byte).
 *
 * This function performs Capitalization and Control @ref
 * keysym-transformations.
 *
 * @memberof xkb_state
 * @since 0.4.1
 */
XKB_EXPORT int
xkb_state_key_get_utf8(struct xkb_state *state, xkb_keycode_t key,
                       char *buffer, size_t size);

/**
 * Get the Unicode/UTF-32 codepoint obtained from pressing a particular
 * key in a a given keyboard state.
 *
 * @returns The UTF-32 representation for the key, if it consists of only
 * a single codepoint.  Otherwise, returns 0.
 *
 * This function performs Capitalization and Control @ref
 * keysym-transformations.
 *
 * @memberof xkb_state
 * @since 0.4.1
 */
XKB_EXPORT uint32_t
xkb_state_key_get_utf32(struct xkb_state *state, xkb_keycode_t key);

/**
 * Get the single keysym obtained from pressing a particular key in a
 * given keyboard state.
 *
 * This function is similar to `xkb_state_key_get_syms()`, but intended
 * for users which cannot or do not want to handle the case where
 * multiple keysyms are returned (in which case this function is
 * preferred).
 *
 * @returns The keysym.  If the key does not have exactly one keysym,
 * returns `XKB_KEY_NoSymbol`.
 *
 * This function performs Capitalization @ref keysym-transformations.
 *
 * @sa xkb_state_key_get_syms()
 * @memberof xkb_state
 */
XKB_EXPORT xkb_keysym_t
xkb_state_key_get_one_sym(struct xkb_state *state, xkb_keycode_t key);

/**
 * Get the effective layout index for a key in a given keyboard state.
 *
 * @returns The layout index for the key in the given keyboard state.  If
 * the given keycode is invalid, or if the key is not included in any
 * layout at all, returns `::XKB_LAYOUT_INVALID`.
 *
 * @invariant If the returned layout is valid, the following always holds:
 * @code
 * xkb_state_key_get_layout(state, key) < xkb_keymap_num_layouts_for_key(keymap, key)
 * @endcode
 *
 * @memberof xkb_state
 */
XKB_EXPORT xkb_layout_index_t
xkb_state_key_get_layout(struct xkb_state *state, xkb_keycode_t key);

/**
 * Get the effective shift level for a key in a given keyboard state and
 * layout.
 *
 * @param state The keyboard state.
 * @param key The keycode of the key.
 * @param layout The layout for which to get the shift level.  This must be
 * smaller than:
 * @code xkb_keymap_num_layouts_for_key(keymap, key) @endcode
 * usually it would be:
 * @code xkb_state_key_get_layout(state, key) @endcode
 *
 * @return The shift level index.  If the key or layout are invalid,
 * returns `::XKB_LEVEL_INVALID`.
 *
 * @invariant If the returned level is valid, the following always holds:
 * @code
 * xkb_state_key_get_level(state, key, layout) < xkb_keymap_num_levels_for_key(keymap, key, layout)
 * @endcode
 *
 * @memberof xkb_state
 */
XKB_EXPORT xkb_level_index_t
xkb_state_key_get_level(struct xkb_state *state, xkb_keycode_t key,
                        xkb_layout_index_t layout);

/**
 * Match flags for `xkb_state::xkb_state_mod_indices_are_active()` and
 * `xkb_state::xkb_state_mod_names_are_active()`, specifying the conditions for a
 * successful match.  `::XKB_STATE_MATCH_NON_EXCLUSIVE` is bitmaskable with
 * the other modes.
 */
enum xkb_state_match {
    /** Returns true if any of the modifiers are active. */
    XKB_STATE_MATCH_ANY = (1 << 0),
    /** Returns true if all of the modifiers are active. */
    XKB_STATE_MATCH_ALL = (1 << 1),
    /** Makes matching non-exclusive, i.e. will not return false if a
     *  modifier not specified in the arguments is active. */
    XKB_STATE_MATCH_NON_EXCLUSIVE = (1 << 16)
};

/**
 * The counterpart to `xkb_state::xkb_state_update_mask()` for modifiers, to be
 * used on the server side of serialization.
 *
 * This entry point is intended for *server* applications; see @ref
 * server-client-state for details. *Client* applications should use the
 * `xkb_state_mod_*_is_active` API.
 *
 * @param state      The keyboard state.
 * @param components A mask of the modifier state components to serialize.
 * State components other than `XKB_STATE_MODS_*` are ignored.
 * If `::XKB_STATE_MODS_EFFECTIVE` is included, all other state components are
 * ignored.
 *
 * @returns A `xkb_mod_mask_t` representing the given components of the
 * modifier state.
 *
 * @memberof xkb_state
 */
XKB_EXPORT xkb_mod_mask_t
xkb_state_serialize_mods(struct xkb_state *state,
                         enum xkb_state_component components);

/**
 * The counterpart to `xkb_state::xkb_state_update_mask()` for layouts, to be
 * used on the server side of serialization.
 *
 * This entry point is intended for *server* applications; see @ref
 * server-client-state for details. *Client* applications should use the
 * xkb_state_layout_*_is_active API.
 *
 * @param state      The keyboard state.
 * @param components A mask of the layout state components to serialize.
 * State components other than `XKB_STATE_LAYOUT_*` are ignored.
 * If `::XKB_STATE_LAYOUT_EFFECTIVE` is included, all other state components are
 * ignored.
 *
 * @returns A layout index representing the given components of the
 * layout state.
 *
 * @memberof xkb_state
 */
XKB_EXPORT xkb_layout_index_t
xkb_state_serialize_layout(struct xkb_state *state,
                           enum xkb_state_component components);

/**
 * Test whether a modifier is active in a given keyboard state by name.
 *
 * @warning For [virtual modifiers], this function may *overmatch* in case
 * there are virtual modifiers with overlapping mappings to [real modifiers].
 *
 * @returns 1 if the modifier is active, 0 if it is not.  If the modifier
 * name does not exist in the keymap, returns -1.
 *
 * @memberof xkb_state
 *
 * @since 0.1.0: Works only with *real* modifiers
 * @since 1.8.0: Works also with *virtual* modifiers
 *
 * [virtual modifiers]: @ref virtual-modifier-def
 * [real modifiers]: @ref real-modifier-def
 */
XKB_EXPORT int
xkb_state_mod_name_is_active(struct xkb_state *state, const char *name,
                             enum xkb_state_component type);

/**
 * Test whether a set of modifiers are active in a given keyboard state by
 * name.
 *
 * @warning For [virtual modifiers], this function may *overmatch* in case
 * there are virtual modifiers with overlapping mappings to [real modifiers].
 *
 * @param state The keyboard state.
 * @param type  The component of the state against which to match the
 * given modifiers.
 * @param match The manner by which to match the state against the
 * given modifiers.
 * @param ...   The set of of modifier names to test, terminated by a NULL
 * argument (sentinel).
 *
 * @returns 1 if the modifiers are active, 0 if they are not.  If any of
 * the modifier names do not exist in the keymap, returns -1.
 *
 * @memberof xkb_state
 *
 * @since 0.1.0: Works only with *real* modifiers
 * @since 1.8.0: Works also with *virtual* modifiers
 *
 * [virtual modifiers]: @ref virtual-modifier-def
 * [real modifiers]: @ref real-modifier-def
 */
XKB_EXPORT int
xkb_state_mod_names_are_active(struct xkb_state *state,
                               enum xkb_state_component type,
                               enum xkb_state_match match,
                               ...);

/**
 * Test whether a modifier is active in a given keyboard state by index.
 *
 * @warning For [virtual modifiers], this function may *overmatch* in case
 * there are virtual modifiers with overlapping mappings to [real modifiers].
 *
 * @returns 1 if the modifier is active, 0 if it is not.  If the modifier
 * index is invalid in the keymap, returns -1.
 *
 * @memberof xkb_state
 *
 * @since 0.1.0: Works only with *real* modifiers
 * @since 1.8.0: Works also with *virtual* modifiers
 *
 * [virtual modifiers]: @ref virtual-modifier-def
 * [real modifiers]: @ref real-modifier-def
 */
XKB_EXPORT int
xkb_state_mod_index_is_active(struct xkb_state *state, xkb_mod_index_t idx,
                              enum xkb_state_component type);

/**
 * Test whether a set of modifiers are active in a given keyboard state by
 * index.
 *
 * @warning For [virtual modifiers], this function may *overmatch* in case
 * there are virtual modifiers with overlapping mappings to [real modifiers].
 *
 * @param state The keyboard state.
 * @param type  The component of the state against which to match the
 * given modifiers.
 * @param match The manner by which to match the state against the
 * given modifiers.
 * @param ...   The set of of modifier indices to test, terminated by a
 * `::XKB_MOD_INVALID` argument (sentinel).
 *
 * @returns 1 if the modifiers are active, 0 if they are not.  If any of
 * the modifier indices are invalid in the keymap, returns -1.
 *
 * @memberof xkb_state
 *
 * @since 0.1.0: Works only with *real* modifiers
 * @since 1.8.0: Works also with *virtual* modifiers
 *
 * [virtual modifiers]: @ref virtual-modifier-def
 * [real modifiers]: @ref real-modifier-def
 */
XKB_EXPORT int
xkb_state_mod_indices_are_active(struct xkb_state *state,
                                 enum xkb_state_component type,
                                 enum xkb_state_match match,
                                 ...);

/**
 * @page consumed-modifiers Consumed Modifiers
 * @parblock
 *
 * Some functions, like `xkb_state::xkb_state_key_get_syms()`, look at the state
 * of the modifiers in the keymap and derive from it the correct shift level
 * to use for the key.  For example, in a US layout, pressing the key
 * labeled `<A>` while the Shift modifier is active, generates the keysym
 * `A`.  In this case, the Shift modifier is said to be *consumed*.
 * However, the Num Lock modifier does not affect this translation at all,
 * even if it is active, so it is not consumed by this translation.
 *
 * It may be desirable for some application to not reuse consumed modifiers
 * for further processing, e.g. for hotkeys or keyboard shortcuts.  To
 * understand why, consider some requirements from a standard shortcut
 * mechanism, and how they are implemented:
 *
 * 1. The shortcut’s modifiers must match exactly to the state.  For
 *    example, it is possible to bind separate actions to `<Alt><Tab>`
 *    and to `<Alt><Shift><Tab>`.  Further, if only `<Alt><Tab>` is
 *    bound to an action, pressing `<Alt><Shift><Tab>` should not
 *    trigger the shortcut.
 *    Effectively, this means that the modifiers are compared using the
 *    equality operator (`==`).
 *
 * 2. Only relevant modifiers are considered for the matching.  For example,
 *    Caps Lock and Num Lock should not generally affect the matching, e.g.
 *    when matching `<Alt><Tab>` against the state, it does not matter
 *    whether Num Lock is active or not.  These relevant, or *significant*,
 *    modifiers usually include Alt, Control, Shift, Super and similar.
 *    Effectively, this means that non-significant modifiers are masked out,
 *    before doing the comparison as described above.
 *
 * 3. The matching must be independent of the layout/keymap.  For example,
 *    the `<Plus>` (+) symbol is found on the first level on some layouts,
 *    but requires holding Shift on others.  If you simply bind the action
 *    to the `<Plus>` keysym, it would work for the unshifted kind, but
 *    not for the others, because the match against Shift would fail.  If
 *    you bind the action to `<Shift><Plus>`, only the shifted kind would
 *    work.  So what is needed is to recognize that Shift is used up in the
 *    translation of the keysym itself, and therefore should not be included
 *    in the matching.
 *    Effectively, this means that consumed modifiers (Shift in this example)
 *    are masked out as well, before doing the comparison.
 *
 * In summary, this is approximately how the matching would be performed:
 *
 * ```c
 *   (keysym == shortcut_keysym) &&
 *   ((state_mods & ~consumed_mods & significant_mods) == shortcut_mods)
 * ```
 *
 * @c state_mods are the modifiers reported by
 * `xkb_state::xkb_state_mod_index_is_active()` and similar functions.
 * @c consumed_mods are the modifiers reported by
 * `xkb_state::xkb_state_mod_index_is_consumed()` and similar functions.
 * @c significant_mods are decided upon by the application/toolkit/user;
 * it is up to them to decide whether these are configurable or hard-coded.
 *
 * @endparblock
 */

/**
 * Consumed modifiers mode.
 *
 * There are several possible methods for deciding which modifiers are
 * consumed and which are not, each applicable for different systems or
 * situations. The mode selects the method to use.
 *
 * Keep in mind that in all methods, the keymap may decide to *preserve*
 * a modifier, meaning it is not reported as consumed even if it would
 * have otherwise.
 */
enum xkb_consumed_mode {
    /**
     * This is the mode defined in the XKB specification and used by libX11.
     *
     * A modifier is consumed if and only if it *may affect* key translation.
     *
     * For example, if `Control+Alt+<Backspace>` produces some assigned keysym,
     * then when pressing just `<Backspace>`, `Control` and `Alt` are consumed,
     * even though they are not active, since if they *were* active they would
     * have affected key translation.
     */
    XKB_CONSUMED_MODE_XKB,
    /**
     * This is the mode used by the GTK+ toolkit.
     *
     * The mode consists of the following two independent heuristics:
     *
     * - The currently active set of modifiers, excluding modifiers which do
     *   not affect the key (as described for @ref XKB_CONSUMED_MODE_XKB), are
     *   considered consumed, if the keysyms produced when all of them are
     *   active are different from the keysyms produced when no modifiers are
     *   active.
     *
     * - A single modifier is considered consumed if the keysyms produced for
     *   the key when it is the only active modifier are different from the
     *   keysyms produced when no modifiers are active.
     */
    XKB_CONSUMED_MODE_GTK
};

/**
 * Get the mask of modifiers consumed by translating a given key.
 *
 * @param state The keyboard state.
 * @param key   The keycode of the key.
 * @param mode  The consumed modifiers mode to use; see enum description.
 *
 * @returns a mask of the consumed [real modifiers] modifiers.
 *
 * @memberof xkb_state
 * @since 0.7.0
 *
 * [real modifiers]: @ref real-modifier-def
 */
XKB_EXPORT xkb_mod_mask_t
xkb_state_key_get_consumed_mods2(struct xkb_state *state, xkb_keycode_t key,
                                 enum xkb_consumed_mode mode);

/**
 * Same as `xkb_state_key_get_consumed_mods2()` with mode `::XKB_CONSUMED_MODE_XKB`.
 *
 * @memberof xkb_state
 * @since 0.4.1
 */
XKB_EXPORT xkb_mod_mask_t
xkb_state_key_get_consumed_mods(struct xkb_state *state, xkb_keycode_t key);

/**
 * Test whether a modifier is consumed by keyboard state translation for
 * a key.
 *
 * @warning For [virtual modifiers], this function may *overmatch* in case
 * there are virtual modifiers with overlapping mappings to [real modifiers].
 *
 * @param state The keyboard state.
 * @param key   The keycode of the key.
 * @param idx   The index of the modifier to check.
 * @param mode  The consumed modifiers mode to use; see enum description.
 *
 * @returns 1 if the modifier is consumed, 0 if it is not.  If the modifier
 * index is not valid in the keymap, returns -1.
 *
 * @sa xkb_state_mod_mask_remove_consumed()
 * @sa xkb_state_key_get_consumed_mods()
 * @memberof xkb_state
 * @since 0.7.0: Works only with *real* modifiers
 * @since 1.8.0: Works also with *virtual* modifiers
 *
 * [virtual modifiers]: @ref virtual-modifier-def
 * [real modifiers]: @ref real-modifier-def
 */
XKB_EXPORT int
xkb_state_mod_index_is_consumed2(struct xkb_state *state,
                                 xkb_keycode_t key,
                                 xkb_mod_index_t idx,
                                 enum xkb_consumed_mode mode);

/**
 * Same as `xkb_state_mod_index_is_consumed2()` with mode `::XKB_CONSUMED_MOD_XKB`.
 *
 * @warning For [virtual modifiers], this function may *overmatch* in case
 * there are virtual modifiers with overlapping mappings to [real modifiers].
 *
 * @memberof xkb_state
 * @since 0.4.1: Works only with *real* modifiers
 * @since 1.8.0: Works also with *virtual* modifiers
 *
 * [virtual modifiers]: @ref virtual-modifier-def
 * [real modifiers]: @ref real-modifier-def
 */
XKB_EXPORT int
xkb_state_mod_index_is_consumed(struct xkb_state *state, xkb_keycode_t key,
                                xkb_mod_index_t idx);

/**
 * Remove consumed modifiers from a modifier mask for a key.
 *
 * @deprecated Use `xkb_state_key_get_consumed_mods2()` instead.
 *
 * Takes the given modifier mask, and removes all modifiers which are
 * consumed for that particular key (as in `xkb_state_mod_index_is_consumed()`).
 *
 * @returns a mask of [real modifiers] modifiers.
 *
 * @sa xkb_state_mod_index_is_consumed()
 * @memberof xkb_state
 * @since 0.5.0: Works only with *real* modifiers
 * @since 1.8.0: Works also with *virtual* modifiers
 *
 * [real modifiers]: @ref real-modifier-def
 */
XKB_EXPORT xkb_mod_mask_t
xkb_state_mod_mask_remove_consumed(struct xkb_state *state, xkb_keycode_t key,
                                   xkb_mod_mask_t mask);

/**
 * Test whether a layout is active in a given keyboard state by name.
 *
 * @returns 1 if the layout is active, 0 if it is not.  If no layout with
 * this name exists in the keymap, return -1.
 *
 * If multiple layouts in the keymap have this name, the one with the lowest
 * index is tested.
 *
 * @sa xkb_layout_index_t
 * @memberof xkb_state
 */
XKB_EXPORT int
xkb_state_layout_name_is_active(struct xkb_state *state, const char *name,
                                enum xkb_state_component type);

/**
 * Test whether a layout is active in a given keyboard state by index.
 *
 * @returns 1 if the layout is active, 0 if it is not.  If the layout index
 * is not valid in the keymap, returns -1.
 *
 * @sa xkb_layout_index_t
 * @memberof xkb_state
 */
XKB_EXPORT int
xkb_state_layout_index_is_active(struct xkb_state *state,
                                 xkb_layout_index_t idx,
                                 enum xkb_state_component type);

/**
 * Test whether a LED is active in a given keyboard state by name.
 *
 * @returns 1 if the LED is active, 0 if it not.  If no LED with this name
 * exists in the keymap, returns -1.
 *
 * @sa xkb_led_index_t
 * @memberof xkb_state
 */
XKB_EXPORT int
xkb_state_led_name_is_active(struct xkb_state *state, const char *name);

/**
 * Test whether a LED is active in a given keyboard state by index.
 *
 * @returns 1 if the LED is active, 0 if it not.  If the LED index is not
 * valid in the keymap, returns -1.
 *
 * @sa xkb_led_index_t
 * @memberof xkb_state
 */
XKB_EXPORT int
xkb_state_led_index_is_active(struct xkb_state *state, xkb_led_index_t idx);

/** @} */

/* Leave this include last, so it can pick up our types, etc. */
#include <xkbcommon/xkbcommon-compat.h>

#ifdef __cplusplus
} /* extern "C" */
#endif

#endif /* _XKBCOMMON_H_ */
