IObjectFactory abstract#

Factory for creating runtime objects and managing instance identifiers.

The object factory is a runtime artifact responsible for:

• Creating instances of EXPRESS schema types (entities, enums, selects)
• Managing unique instance identifier allocation
• Handling binary deserialization of instances
• Creating specialized runtime components like template controllers

Constructors#

IObjectFactory()#

Properties#

hashCode no setter inherited#

The hash code for this object.

A hash code is a single integer which represents the state of the object that affects operator == comparisons.

All objects have hash codes. The default hash code implemented by Object represents only the identity of the object, the same way as the default operator == implementation only considers objects equal if they are identical (see identityHashCode).

If operator == is overridden to use the object state instead, the hash code must also be changed to represent that state, otherwise the object cannot be used in hash based data structures like the default Set and Map implementations.

Hash codes must be the same for objects that are equal to each other according to operator ==. The hash code of an object should only change if the object changes in a way that affects equality. There are no further requirements for the hash codes. They need not be consistent between executions of the same program and there are no distribution guarantees.

Objects that are not equal are allowed to have the same hash code. It is even technically allowed that all instances have the same hash code, but if clashes happen too often, it may reduce the efficiency of hash-based data structures like HashSet or HashMap.

If a subclass overrides hashCode, it should override the operator == operator as well to maintain consistency.

Inherited from Object.

external int get hashCode;

runtimeType no setter inherited#

A representation of the runtime type of the object.

Inherited from Object.

external Type get runtimeType;

Methods#

createEnum()#

Creates an EXPRESS enumeration instance.

typeId: Hash-based type identifier of the enumeration typeName: EXPRESS type name of the enumeration value: Integer value to initialize the enumeration stringValue: String representation value to initialize the enumeration

Returns null enum if typeId or typeName does not correspond to a valid EXPRESS enumeration type.

PIEnum createEnum(
    {int? typeId, String? typeName, int? value, String? stringValue});

createInstance()#

Creates an ENTITY instance of the specified type.

typeName: EXPRESS entity type name to create typeId: Hash-based type identifier to create setId: If true, automatically assigns a new instance identifier. Set to false for header instances or when manual ID assignment is needed.

Returns a new IInstance of the requested type.

IInstance createInstance({String? typeName, int? typeId, bool setId = true});

createInstanceReference()#

Creates an instance reference from an instance handle.

instHandle: The InstanceHandle containing reference information

Returns a lightweight reference instance pointing to the specified target.

IInstance createInstanceReference(InstanceHandle instHandle);

createNullInstance()#

Creates a null instance representing an unset or missing value.

Returns a special IInstance that represents a null value.

IInstance createNullInstance();

createSelect()#

Creates an EXPRESS SELECT instance.

typeId: Hash-based type identifier of the SELECT type typeName: EXPRESS type name of the SELECT type selectedType: Optional initial selected type identifier

Returns a configured ISelect instance ready for use.

ISelect createSelect(
    {int? typeId,
    String? typeName,
    int? selectedType,
    String? selectedTypeName});

instanceFromJson()#

Creates an instance declaratively from JSON data.

This method provides a convenient way to create IFC instances using a JSON-like structure that mirrors the object composition hierarchy. It handles the complete instantiation process including object creation, attribute setting, and relationship establishment.

The JSON structure uses special keys and conventions:

• '@type': Specifies the IFC type name for the instance (required for root objects)
• Nested objects: Represent composed child instances or complex attributes
• Arrays: Represent aggregate attributes (LIST, SET, ARRAY)
• Select types: Use the selected type name as key with object as value

Parameters:

• json: A JSON-like map representing the instance structure and attributes. The map must contain at least an '@type' key for the root object.

Returns the created IInstance, or null instance if:

• The '@type' key is missing or invalid
• The JSON structure is malformed or inconsistent
• Attribute values are incompatible with the target types

Example usage:

// Create a simple Cartesian point
final point = instanceFromJson({
  '@type': 'IfcCartesianPoint',
  'Coordinates': [1.0, 2.0, 3.0]
});

// Create property sets with complex values
final pset = instanceFromJson({
  '@type': 'IfcPropertySet',
  'Name': 'Pset_WallCommon',
  'HasProperties': [
    {
      '@type': 'IfcPropertySingleValue',
      'Name': 'Reference',
      'NominalValue': {
        'IfcSimpleValue' : {
          'IfcIdentifier': 'EXTERIOR_WALL_001'
         }
      }
    },
    {
      '@type': 'IfcPropertySingleValue',
      'Name': 'LoadBearing',
      'NominalValue': {
        'IfcSimpleValue' : {
            'IfcBoolean': true
         }
      }
    }
  ]
});

IInstance instanceFromJson(Map<String, dynamic> json);

nextInstanceId()#

Gets the next available instance identifier.

incrementId: If true, advances the internal ID counter after retrieval. If false, returns the next ID without changing the counter.

Returns the next available instance identifier that will be assigned.

int nextInstanceId([bool incrementId = false]);

noSuchMethod() inherited#

Invoked when a nonexistent method or property is accessed.

A dynamic member invocation can attempt to call a member which doesn't exist on the receiving object. Example:

dynamic object = 1;
object.add(42); // Statically allowed, run-time error

This invalid code will invoke the noSuchMethod method of the integer 1 with an Invocation representing the .add(42) call and arguments (which then throws).

Classes can override noSuchMethod to provide custom behavior for such invalid dynamic invocations.

A class with a non-default noSuchMethod invocation can also omit implementations for members of its interface. Example:

class MockList<T> implements List<T> {
  noSuchMethod(Invocation invocation) {
    log(invocation);
    super.noSuchMethod(invocation); // Will throw.
  }
}
void main() {
  MockList().add(42);
}

This code has no compile-time warnings or errors even though the MockList class has no concrete implementation of any of the List interface methods. Calls to List methods are forwarded to noSuchMethod, so this code will log an invocation similar to Invocation.method(#add, [42]) and then throw.

If a value is returned from noSuchMethod, it becomes the result of the original invocation. If the value is not of a type that can be returned by the original invocation, a type error occurs at the invocation.

The default behavior is to throw a NoSuchMethodError.

Inherited from Object.

@pragma("vm:entry-point")
@pragma("wasm:entry-point")
external dynamic noSuchMethod(Invocation invocation);

setNextInstanceId()#

Sets the next instance identifier to use.

nextId: The next instance identifier value to set.

Use with caution: Setting this value affects all subsequent instance creations and may cause identifier conflicts if not managed carefully.

void setNextInstanceId(int nextId);

toString() inherited#

A string representation of this object.

Some classes have a default textual representation, often paired with a static parse function (like int.parse). These classes will provide the textual representation as their string representation.

Other classes have no meaningful textual representation that a program will care about. Such classes will typically override toString to provide useful information when inspecting the object, mainly for debugging or logging.

Inherited from Object.

external String toString();

Operators#

operator ==() inherited#

The equality operator.

The default behavior for all Objects is to return true if and only if this object and other are the same object.

Override this method to specify a different equality relation on a class. The overriding method must still be an equivalence relation. That is, it must be:

• Total: It must return a boolean for all arguments. It should never throw.

• Reflexive: For all objects o, o == o must be true.

• Symmetric: For all objects o1 and o2, o1 == o2 and o2 == o1 must either both be true, or both be false.

• Transitive: For all objects o1, o2, and o3, if o1 == o2 and o2 == o3 are true, then o1 == o3 must be true.

The method should also be consistent over time, so whether two objects are equal should only change if at least one of the objects was modified.

If a subclass overrides the equality operator, it should override the hashCode method as well to maintain consistency.

Inherited from Object.

external bool operator ==(Object other);