a new beginning

Signed-off-by: Folling <mail@folling.io>

include/CMakeLists.txt

@@ -0,0 +1,8 @@
+file(
+    GLOB_RECURSE
+    FILES
+    "*.h"
+)
+
+set(INCLUDE_FILES ${FILES} PARENT_SCOPE)
+

include/ikarus/macros.h

@@ -0,0 +1,27 @@
+#pragma once
+
+#if defined(__unix__)
+
+#define IKA_OS_FAMILY_UNIX
+#define IKA_API __attribute__((visibility("default")))
+
+#if defined(linux)
+#define IKA_OS_LINUX
+#endif
+
+#elif defined(_WIN32) || defined(WIN32)
+#define IKA_OS_WIN
+#define IKA_API __declspec(dllexport)
+#endif
+
+#ifndef IKA_API
+#define IKA_API
+#endif
+
+#ifdef __cplusplus
+#define IKARUS_BEGIN_HEADER extern "C" {
+#define IKARUS_END_HEADER   }
+#else
+#define IKARUS_BEGIN_HEADER
+#define IKARUS_END_HEADER
+#endif

include/ikarus/stdtypes.h

@@ -0,0 +1,8 @@
+#pragma once
+
+#ifdef __cplusplus
+#include <cstdint>
+using std::size_t;
+#else
+#include <stdint.h>
+#endif

include/ikarus/types/id.h

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+// IMPLEMENTATION_DETAIL_DATABASE
+
+/// \file id.h
+/// \author Folling <mail@folling.io>
+
+#pragma once
+
+#include <ikarus/macros.h>
+
+IKARUS_BEGIN_HEADER
+
+#include <ikarus/stdtypes.h>
+#include <ikarus/types/object_type.h>
+
+/// \defgroup id Ids
+/// \brief Ids are used to identify objects in the database.
+/// \details They are stored as 64 bit integers with the following layout:
+/// - first 8 bits: #IkarusObjectType - 255 possible values, 0 for special values
+/// - last 56 bits: incremented counter generated by the database
+/// @{
+
+/// \brief A wrapper around a 64 bit integer that represents the id of an object.
+/// \details They are stored as 64 bit integers with the following layout:
+/// - first 8 bits: #IkarusObjectType - 255 possible values, 0 for special values
+/// - last 56 bits: incremented counter generated by the database
+struct IkarusId {
+    /// \private \brief The value of the id.
+    uint64_t value;
+};
+
+/// \brief A special id returned by failed functions.
+IkarusId const IKARUS_ID_NONE{0};
+/// \brief A special id used to indicate an optional id not being specified.
+IkarusId const IKARUS_ID_UNSPECIFIED{1};
+
+/// \private \brief Generates a new id for the given object type.
+/// \param object_type The type of the object to generate an id for.
+/// \return The generated id.
+IkarusId ikarus_id_from_integer(IkarusObjectType object_type);
+
+/// \brief Fetches the object type of the given id.
+/// \param id The id to fetch the object type for.
+/// \return The object type of the given id.
+IKA_API IkarusObjectType ikarus_id_get_object_type(IkarusId id);
+
+/// \brief Checks if the given id is IKARUS_ID_NONE.
+/// \param id The id to check.
+/// \return True if the id is IKARUS_ID_NONE, false otherwise.
+IKA_API bool ikarus_id_is_none(IkarusId id);
+
+/// \brief Checks if the given id is IKARUS_ID_UNSPECIFIED.
+/// \param id The id to check.
+/// \return True if the id is IKARUS_ID_UNSPECIFIED, false otherwise.
+IKA_API bool ikarus_id_is_unspecified(IkarusId id);
+
+/// @}
+
+IKARUS_END_HEADER

include/ikarus/types/object.h

@@ -0,0 +1,164 @@
+#pragma once
+
+// IMPLEMENTATION_DETAIL_OBJECT_TYPES
+// IMPLEMENTATION_DETAIL_LAZY_VALUE_CREATION
+// IMPLEMENTATION_DETAIL_PROPERTY_TYPES
+
+/// \file id.h
+/// \author Folling <mail@folling.io>
+
+/// \defgroup object Objects
+/// \brief Objects are a compound type of all types of objects in the database.
+/// \details The following objects currently exist:
+/// - blueprints
+/// - properties
+/// - entities
+/// - blueprint folders
+/// - property folders
+/// - entity folders
+/// @{
+
+#include <ikarus/types/id.h>
+
+IKARUS_BEGIN_HEADER
+
+/// \brief A blueprint object.
+/// \details  A blueprint is a collection of properties which can be linked to entities.
+/// Each entity the blueprint is linked to will have values for the blueprints properties.
+struct IkarusBlueprint {
+    IkarusId id;
+};
+
+/// \brief Properties are the placeholders of values for entities.
+/// \details Each entity can have any number of properties.
+/// Every property has a type that identifies the kind of data that can be put in.
+///
+/// The following types currently exist:
+/// - Toggle: A true/false boolean-like value
+/// - Number: An arbitrary numeric value
+/// - Text: An arbitrary textual value
+///
+/// Property Examples:
+/// - Is Dead (Toggle)
+/// - Age (Number)
+/// - ISBN (Text)
+///
+/// Every property has settings which can be used to customise the property further.
+/// Two settings that are shared among all properties are the following:
+/// - Multiple
+/// - Allow undefined
+///
+/// The former transforms a property into a list. Instead of one number, you could then specify a series of numbers.
+/// The latter allows you to specify an "unknown" value for a property.
+/// It might not be known if a character is dead or not for example.
+///
+/// Each entity associated with the property has a value for it.
+///
+/// Properties can also be added to blueprints in which case they are available for all entities associated with the
+/// blueprint.
+///
+/// We call properties within entities "Entity Properties" and properties within blueprints "Blueprint Properties".
+///
+/// \remark Values for properties are lazily created as space saving measure.
+/// Fetching the value for some property of some entity will return the property's default value if none is specified.
+/// This default value is specified when the property is created and can be updated later.
+///
+/// \remark Properties' tree structures are scoped to the entity or blueprint they are associated with.
+struct IkarusProperty {
+    /// \private \brief The ID of the property.
+    IkarusId id;
+};
+
+/// \brief Entities are the core building blocks of Ikarus.
+/// \detials Blueprints and Properties define the structure of the data.
+/// Entities define the data itself.
+///
+/// Properties can be associated with Entities in two ways:
+/// - Directly: The property is linked to the entity.
+/// - Indirectly: The property is linked to a blueprint of the entity.
+///
+/// For each property an entity is linked to, it has a value. These values depend on the property's type.
+/// For more information on the types see the property documentation.
+///
+/// Values are the core type of data within Ikarus.
+/// Each value is associated with one page and one property.
+///
+/// \remark Values are typed, the type of a value is specified by its associated property.
+/// For more information on the types see the property documentation.
+///
+/// \remark Values are guaranteed to be in valid format for a given type
+/// but not guaranteed to be valid under the settings of the property.
+/// This is because changing the settings can invalidate existing values without resetting them.
+struct IkarusEntity {
+    /// \private \brief The ID of the entity.
+    IkarusId id;
+};
+
+/// \brief A blueprint folder.
+/// \see Folder
+struct IkarusBlueprintFolder {
+    /// \private \brief The ID of the folder.
+    IkarusId id;
+};
+
+/// \brief A property folder.
+/// \remark Property folders are scoped to the blueprint or entity they are associated with.
+/// \see Folder
+struct IkarusPropertyFolder {
+    /// \private \brief The ID of the folder.
+    IkarusId id;
+};
+
+/// \brief An entity folder.
+/// \see Folder
+struct IkarusEntityFolder {
+    /// \private \brief The ID of the folder.
+    IkarusId id;
+};
+
+/// \private \brief The data of a folder.
+union IkarusFolderData {
+    /// \private \brief The blueprint folder data of the folder.
+    IkarusBlueprintFolder blueprint_folder;
+    /// \private \brief The property folder data of the folder.
+    IkarusPropertyFolder property_folder;
+    /// \private \brief The entity folder data of the folder.
+    IkarusEntityFolder entity_folder;
+};
+
+/// \brief A generic folder. Similar to how Objects wrap all types of objects, Folders wrap all types of folders.
+struct IkarusFolder {
+    /// \private \brief The data of the folder.
+    IkarusFolderData data;
+
+    /// \private \brief The type of the folder.
+    IkarusFolderType type;
+};
+
+/// \private \brief The data of an object.
+union IkarusObjectData {
+    /// \private \brief The blueprint data of the object.
+    IkarusBlueprint blueprint;
+    /// \private \brief The property data of the object.
+    IkarusProperty property;
+    /// \private \brief The entity data of the object.
+    IkarusEntity entity;
+    /// \private \brief The blueprint folder data of the object.
+    IkarusBlueprintFolder blueprint_folder;
+    /// \private \brief The property folder data of the object.
+    IkarusPropertyFolder property_folder;
+    /// \private \brief The entity folder data of the object.
+    IkarusEntityFolder entity_folder;
+};
+
+/// \brief A generic object. Wraps all types of objects, including folders.
+struct IkarusObject {
+    /// \private \brief The data of the object.
+    IkarusObjectData data;
+    /// \private \brief The type of the object.
+    IkarusObjectType type;
+};
+
+// @}
+
+IKARUS_END_HEADER

include/ikarus/types/object_scope.h

@@ -0,0 +1,149 @@
+// IMPLEMENTATION_DETAIL_OBJECT_SCOPES, IMPLEMENTATION_DETAIL_TREE_LAYOUT
+
+/// \file object_scope.h
+/// \author Folling <mail@folling.io>
+
+/// \defgroup object_scopes Object Scopes
+/// \brief Scopes define where objects belong to.
+/// \details They are required to differentiate between different types of objects with NULL as their parent.
+/// @{
+
+#pragma once
+
+#include <ikarus/macros.h>
+#include <ikarus/types/object.h>
+
+IKARUS_BEGIN_HEADER
+
+/// \brief The global scope of all blueprints.
+struct IkarusBlueprintScope {
+    /// \private \brief Empty structs aren't allowed in C, so we need a dummy field.
+    short _dummy;
+};
+
+/// \brief Data for a property scope. This can either be a blueprint or an entity.
+union IkarusPropertyScopeData {
+    /// \private \brief The blueprint the property is scoped to.
+    IkarusBlueprint _blueprint;
+    /// \private \brief The entity the property is scoped to.
+    IkarusEntity _entity;
+};
+
+/// \brief The type of a property scope. This can either be a blueprint or an entity.
+enum IkarusPropertyScopeType {
+    /// \brief The property is scoped to a blueprint.
+    IkarusPropertyScopeType_Blueprint,
+    /// \brief The property is scoped to an entity.
+    IkarusPropertyScopeType_Entity
+};
+
+/// \brief The scope of a property
+struct IkarusPropertyScope {
+    /// \private \brief Represents the type of the scope.
+    IkarusPropertyScopeType _type;
+    /// \private \brief Represents the data of the scope.
+    IkarusPropertyScopeData _data;
+};
+
+/// The global scope of all entities.
+struct IkarusEntityScope {
+    /// \private \brief Empty structs aren't allowed in C, so we need a dummy field.
+    short _dummy;
+};
+
+/// \private \brief The data for an object scope.
+union IkarusObjectScopeData {
+    /// \private \brief The blueprint data of the scope.
+    IkarusBlueprintScope _blueprint;
+    /// \private \brief The property data of the scope.
+    IkarusPropertyScope _property;
+    /// \private \brief The entity data of the scope.
+    IkarusEntityScope _entity;
+};
+
+/// The type of an object scope.
+enum IkarusObjectScopeType {
+    /// \brief The scope is a blueprint scope.
+    IkarusObjectScopeType_Blueprint,
+    /// \brief The scope is a property scope.
+    IkarusObjectScopeType_Property,
+    /// \brief The scope is an entity scope.
+    IkarusObjectScopeType_Entity
+};
+
+/// \brief The scope of an object.
+struct IkarusObjectScope {
+    /// \private \brief Represents the type of the scope.
+    IkarusObjectScopeType _type;
+    /// \private \brief Represents the data of the scope.
+    IkarusObjectScopeData _data;
+};
+
+/// \brief Creates a blueprint scope.
+/// \return The created blueprint scope.
+IKA_API IkarusBlueprintScope ikarus_blueprint_scope_create();
+/// \brief Converts a blueprint scope to an object scope.
+/// \param scope The scope to convert.
+/// \return The converted scope.
+IKA_API IkarusObjectScope ikarus_blueprint_scope_to_object_scope(IkarusBlueprintScope const * scope);
+
+/// \brief Creates a property scope from a blueprint.
+/// \param blueprint The blueprint the property is scoped to.
+/// \return The created property scope.
+IKA_API IkarusPropertyScope ikarus_property_scope_create_blueprint(IkarusBlueprint const * blueprint);
+/// \brief Creates a property scope from a entity.
+/// \param entity The entity the property is scoped to.
+/// \return The created property scope.
+IKA_API IkarusPropertyScope ikarus_property_scope_create_entity(IkarusEntity const * entity);
+/// \brief Converts a property scope to an object scope.
+/// \param scope The scope to convert.
+/// \return The converted scope.
+IKA_API IkarusObjectScope ikarus_property_scope_to_object_scope(IkarusPropertyScope const * scope);
+
+/// \brief Fetches the type of an property scope.
+/// \param scope The scope to fetch the type of.
+/// \return The type of the scope.
+IKA_API IkarusPropertyScopeType ikarus_property_scope_get_type(IkarusPropertyScope const * scope);
+
+/// \brief Visits a property scope, calling the appropriate function.
+/// \param scope The scope to to visit
+/// \param blueprint The function to call if the property is scoped to a blueprint.
+/// \param entity The function to call if the property is scoped to an entity.
+/// \param data Optional data to pass to the functions.
+void ikarus_property_scope_visit(
+    IkarusPropertyScope const * scope,
+    void (*blueprint)(IkarusBlueprint const *, void *),
+    void (*entity)(IkarusEntity const *, void *),
+    void * data
+);
+
+/// \brief Creates an entity scope.
+/// \return The created entity scope.
+IKA_API IkarusEntityScope ikarus_entity_scope_create();
+/// Converts an entity scope to an object scope.
+/// \param scope The scope to convert.
+/// \return The converted scope.
+IKA_API IkarusObjectScope ikarus_entity_scope_to_object_scope(IkarusEntityScope const * scope);
+
+/// \brief Fetches the type of an object scope.
+/// \param scope The scope to fetch the type of.
+/// \return The type of the scope.
+IKA_API IkarusObjectScopeType ikarus_object_scope_get_type(IkarusObjectScope const * scope);
+
+/// \brief Visits an object scope, calling the appropriate function.
+/// \param scope The scope to visit.
+/// \param blueprint The function to call if the scope is an #IkarusBlueprintScope.
+/// \param property The function to call if the scope is an #IkarusPropertyScope.
+/// \param entity The function to call if the scope is an #IkarusEntityScope.
+/// \remark function pointers may be null in which case they are not called.
+IKA_API void ikarus_object_scope_visit(
+    IkarusObjectScope const * scope,
+    void (*blueprint)(IkarusBlueprintScope const *, void *),
+    void (*property)(IkarusPropertyScope const *, void *),
+    void (*entity)(IkarusEntityScope const *, void *),
+    void * data
+);
+
+/// @}
+
+IKARUS_END_HEADER

include/ikarus/types/object_type.h

@@ -0,0 +1,63 @@
+#pragma once
+
+#include <ikarus/macros.h>
+
+IKARUS_BEGIN_HEADER
+
+/// \defgroup object_types ObjectTypes
+/// \brief ObjectTypes are used to identify the type of objects.
+/// @{
+
+/// \brief The type of a folder.
+/// \remark folders have the first bit set and then mirror the object type of the underlying object
+enum IkarusFolderType {
+    /// \brief Not a folder or no folder.
+    IkarusFolderType_None = 0,
+    /// \brief An IkarusBlueprintFolder
+    IkarusFolderType_BlueprintFolder = 0b1000'0001,
+    /// \brief An IkarusPropertyFolder
+    IkarusFolderType_PropertyFolder = 0b1000'0010,
+    /// \brief An IkarusEntityFolder
+    IkarusFolderType_EntityFolder = 0b1000'0011,
+};
+
+/// \brief The type of an object.
+/// \remark folders have the first bit set and then mirror the object type of the underlying object
+enum IkarusObjectType {
+    /// \brief Not an object or no object.
+    ObjectType_None = 0,
+    /// \brief An IkarusBlueprint.
+    ObjectType_Blueprint = 0b0000'0001,
+    /// \brief An IkarusProperty.
+    ObjectType_Property = 0b0000'0010,
+    /// \brief An IkarusEntity.
+    ObjectType_Entity = 0b0000'0011,
+    /// \brief An IkarusBlueprintFolder
+    ObjectType_BlueprintFolder = 0b1000'0001,
+    /// \brief An IkarusPropertyFolder
+    ObjectType_PropertyFolder = 0b1000'0010,
+    /// \brief An IkarusEntityFolder
+    ObjectType_EntityFolder = 0b1000'0011,
+};
+
+/// \brief A bitset of IkarusObjectType%s.
+enum ObjectTypes {
+    /// \brief No object type.
+    ObjectTypes_None = 0,
+    /// \brief An IkarusBlueprint.
+    ObjectTypes_Blueprint = 1 << ObjectType_Blueprint,
+    /// \brief An IkarusProperty.
+    ObjectTypes_Property = 1 << ObjectType_Property,
+    /// \brief An IkarusEntity.
+    ObjectTypes_Entity = 1 << ObjectType_Entity,
+    /// \brief An IkarusBlueprintFolder
+    ObjectTypes_BlueprintFolder = 1 << ObjectType_BlueprintFolder,
+    /// \brief An IkarusPropertyFolder
+    ObjectTypes_PropertyFolder = 1 << ObjectType_PropertyFolder,
+    /// \brief An IkarusEntityFolder
+    ObjectTypes_EntityFolder = 1 << ObjectType_EntityFolder,
+};
+
+// @}
+
+IKARUS_END_HEADER

include/ikarus/types/property_type.h

@@ -0,0 +1,31 @@
+#pragma once
+
+// IMPLEMENTATION_DETAIL_PROPERTY_TYPES
+
+/// \file id.h
+/// \author Folling <mail@folling.io>
+
+#include <ikarus/macros.h>
+
+IKARUS_BEGIN_HEADER
+
+/// \defgroup property_types Property Types
+/// \brief Property Types delineate the type of data stored by a property.
+/// @{
+
+/// \brief The type of a property.
+/// \details Designates the type of data stored by the property as well as which settings are
+/// available.
+/// \see IkarusPropertySettings
+enum IkarusPropertyType {
+    /// \brief A true/false boolean-like value.
+    IkarusPropertyType_Toggle,
+    /// \brief An arbitrary numeric value.
+    IkarusPropertyType_Number,
+    /// \brief An arbitrary textual value.
+    IkarusPropertyType_Text,
+};
+
+/// @}
+
+IKARUS_END_HEADER

include/ikarus/types/value.h

@@ -0,0 +1,161 @@
+#pragma once
+
+// IMPLEMENTATION_DETAIL_PROPERTY_TYPES
+
+#include <ikarus/macros.h>
+#include <ikarus/stdtypes.h>
+#include <ikarus/types/property_type.h>
+
+IKARUS_BEGIN_HEADER
+
+/// \defgroup entity_value Entity Values
+/// \brief The values stored in entities.
+/// \details Each entity has a value for each property it is associated with.
+/// The value is of the type specified by the property and constrained by the property's settings.
+/// \see PropertyType PropertySettings
+/// @{
+
+/// \brief A true/false boolean-like value. For example "IsDead".
+struct IkarusToggleValue {
+    /// \private \brief The value of the property.
+    bool _value;
+};
+
+/// \brief An arbitrary numeric value. For example "Age".
+struct IkarusNumberValue {
+    /// \private \brief The value of the property.
+    long double _value;
+};
+
+/// \brief An arbitrary textual value. For example "First Name".
+struct IkarusTextValue {
+    /// \private \brief The value of the property.
+    char const * _value;
+};
+
+/// \private \brief The data for a value.
+union IkarusEntityValueData {
+    /// \private \brief The value as a toggle.
+    IkarusToggleValue toggle;
+    /// \private \brief The value as a number.
+    IkarusNumberValue number;
+    /// \private \brief The value as text.
+    IkarusTextValue text;
+};
+
+/// \brief The state of an entity value.
+/// \details States provide insight into the nature of a value.
+enum IkarusEntityValueState {
+    /// \brief The value is invalid.
+    IkarusEntityValueState_Invalid,
+    /// \brief The value is normal and can be used as-is.
+    IkarusEntityValueState_Normal,
+    /// \brief The value is unknown.
+    IkarusEntityValueState_Indeterminate,
+};
+
+/// \brief The value of an entity associated with a property.
+struct IkarusEntityValue {
+    /// \private \brief The type of the value.
+    IkarusPropertyType _type;
+    /// \private \brief The data for the value.p
+    IkarusEntityValueData _data;
+    /// \private \brief The state of the value.
+    IkarusEntityValueState _state;
+};
+
+/// \brief Creates an entity value from a toggle value.
+/// \param value The toggle value.
+/// \return The entity value.
+IKA_API IkarusEntityValue ikarus_value_create_toggle(bool value);
+/// \brief Creates an entity value from a number value.
+/// \param value The number value.
+/// \return The entity value.
+/// \remark If the value is NaN or infinity an InvalidEntityValue is returned.
+IKA_API IkarusEntityValue ikarus_value_create_number(long double value);
+/// \brief Creates an entity value from a text value.
+/// \param value The text value.
+/// \return The entity value.
+/// \remark If the value is null an InvalidEntityValue is returned.
+IKA_API IkarusEntityValue ikarus_value_create_text(char const * value);
+
+/// \brief Creates an indeterminate entity value of a given type.
+/// \param type The type of the value.
+/// \return The entity value.
+IKA_API IkarusEntityValue ikarus_value_create_indeterminate(IkarusPropertyType type);
+
+/// \brief Fetches the default value for a property type.
+/// \remark Not to be confused with the default value of a property. See ikarus_property_get_default_value
+/// \param type The property type.
+/// \return The default value for the property type.
+IKA_API IkarusEntityValue ikarus_value_get_default(IkarusPropertyType type);
+
+/// \brief Fetches the underlying value of a toggle value.
+/// \param value The toggle value.
+/// \return The underlying value.
+IKA_API bool ikarus_toggle_value_get_underlying(IkarusToggleValue const * value);
+
+/// \brief Fetches the underlying value of a number value.
+/// \param value The number value.
+/// \return The underlying value.
+IKA_API long double ikarus_number_value_get_underlying(IkarusNumberValue const * value);
+
+/// \brief Fetches the underlying value of a text value.
+/// \param value The text value.
+/// \return The underlying value.
+IKA_API char const * ikarus_text_value_get_underlying(IkarusTextValue const * value);
+
+/// \brief Checks if a toggle value is equal to a boolean.
+/// \param value The toggle value.
+/// \param check The boolean value.
+/// \return False if value is null. True if it is equal to check, false otherwise.
+IKA_API bool ikarus_toggle_value_is_equal(IkarusToggleValue const * value, bool check);
+
+/// \brief Checks if a number value is equal to a number.
+/// \param value The number value.
+/// \param check The number value.
+/// \return False if value is null. True if it is equal to check, false otherwise.
+IKA_API bool ikarus_number_value_is_equal(IkarusNumberValue const * value, long double check);
+
+/// \brief Checks if a text value is equal to a string.
+/// \param value The text value.
+/// \param check The string value.
+/// \return False if value or check are null. True if it is equal to check, false otherwise.
+IKA_API bool ikarus_text_value_is_equal(IkarusTextValue const * value, char const * check);
+
+/// \brief Checks if two entity values are equal.
+/// \details Two entity values are equal if they are of the same type and their value is considered equal.
+/// Note that floating point values can only be checked for approximate equality.
+/// \param left The left-hand entity value.
+/// \param right The right-hand entity value.
+/// \return True if the values are considered equal, false otherwise.
+/// \remark Null values compare false to all other values. As do invalid values. Indeterminate values however, compare true to
+/// other indeterminate values of the same type.
+IKA_API bool ikarus_value_is_equal(IkarusEntityValue const * left, IkarusEntityValue const * right);
+
+/// \brief Checks if an entity value is invalid.
+/// \param value The entity value.
+/// \return True if the value is invalid or null, false otherwise.
+IKA_API bool ikarus_value_is_invalid(IkarusEntityValue const * value);
+
+/// \brief Fetches the type of an entity value.
+/// \param value The entity value.
+/// \return The type of the entity value.
+IKA_API IkarusPropertyType ikarus_value_get_type(IkarusEntityValue const * value);
+
+/// \brief Visits an entity value, calling the appropriate function for the value's type.
+/// \param value The entity value to visit.
+/// \param toggle The function to call if the value is a toggle value.
+/// \param number The function to call if the value is a number value.
+/// \param text The function to call if the value is a text value.
+/// \param data The data to pass to the functions.
+/// \remark function pointers may be null in which case they are not called.
+IKA_API void ikarus_value_visit(
+    IkarusEntityValue const * value,
+    void (*toggle)(IkarusToggleValue const *, void *),
+    void (*number)(IkarusNumberValue const *, void *),
+    void (*text)(IkarusTextValue const *, void *),
+    void * data
+);
+
+IKARUS_END_HEADER