InfAdoptedOperation

InfAdoptedOperation — Operation that can be processed by InfAdoptedAlgorithm.

Stability Level

Unstable, unless otherwise indicated

Functions

Types and Values

Object Hierarchy

    GEnum
    ╰── InfAdoptedConcurrencyId
    GFlags
    ╰── InfAdoptedOperationFlags
    GInterface
    ╰── InfAdoptedOperation

Prerequisites

InfAdoptedOperation requires GObject.

Known Implementations

InfAdoptedOperation is implemented by InfAdoptedNoOperation and InfAdoptedSplitOperation.

Includes

#include <libinfinity/adopted/inf-adopted-operation.h>

Description

The InfAdoptedOperation interface must be implemented by operations that are supposed to be used by InfAdoptedAlgorithm. They basically need to define transformation rules for transformation against other operations.

Functions

inf_adopted_operation_need_concurrency_id ()

gboolean
inf_adopted_operation_need_concurrency_id
                               (InfAdoptedOperation *operation,
                                InfAdoptedOperation *against);

This function returns whether transforming operation against against is not defined unambiguously. In that case, transformation requires a so-called concurrency ID which determines which of the two operations is transformed.

Parameters

operation

The InfAdoptedOperation to transform.

 

against

The operation to transform against.

 

Returns

Whether transformation of operation against against requires a concurrency ID to be defined.


inf_adopted_operation_transform ()

InfAdoptedOperation *
inf_adopted_operation_transform (InfAdoptedOperation *operation,
                                 InfAdoptedOperation *against,
                                 InfAdoptedOperation *operation_lcs,
                                 InfAdoptedOperation *against_lcs,
                                 gint concurrency_id);

Performs an inclusion transformation of operation against against , meaning that the effect of against is included in operation .

If inf_adopted_operation_need_concurrency_id() returns TRUE for operation and against , then operation_lcs and against_lcs must not be NULL. In this case they must be the same operations as operation and against at the earlierst state to which both of them can be transformed. This information can then be used to resolve any conflicts in the transformation of operation against against .

The concurrency_id parameter is used if inf_adopted_operation_need_concurrency_id() returns TRUE and no conflict resolution can be deduced from operation_lcs and against_lcs . In this case concurrency_id defines a unique way to transform the two operations. Usually, this is derived from the user IDs of the users who issued the two conflicting operations.

Parameters

operation

The InfAdoptedOperation to transform.

 

against

The operation to transform against.

 

operation_lcs

The operation at a previous state, or NULL.

 

against_lcs

The against operation at a previous state, or NULL.

 

concurrency_id

The concurrency ID for the transformation.

 

Returns

The transformed InfAdoptedOperation, or NULL if the transformation failed.

[transfer full][allow-none]


inf_adopted_operation_copy ()

InfAdoptedOperation *
inf_adopted_operation_copy (InfAdoptedOperation *operation);

Returns a copy of operation .

Parameters

operation

The InfAdoptedOperation to copy.

 

Returns

A copy of operation .

[transfer full]


inf_adopted_operation_get_flags ()

InfAdoptedOperationFlags
inf_adopted_operation_get_flags (InfAdoptedOperation *operation);

Returns the flags for operation .

Parameters

operation

A InfAdoptedOperation.

 

Returns

InfAdoptedOperationFlags for operation .


inf_adopted_operation_apply ()

gboolean
inf_adopted_operation_apply (InfAdoptedOperation *operation,
                             InfAdoptedUser *by,
                             InfBuffer *buffer,
                             GError **error);

Applies operation to buffer . The operation is considered to be applied by user by . If the operation cannot be applied then error is set and the function returns FALSE.

Parameters

operation

A InfAdoptedOperation.

 

by

A InfAdoptedUser.

 

buffer

The InfBuffer to apply the operation to.

 

error

Location to store error information, if any, or NULL.

 

Returns

TRUE on success or FALSE on error.


inf_adopted_operation_apply_transformed ()

InfAdoptedOperation *
inf_adopted_operation_apply_transformed
                               (InfAdoptedOperation *operation,
                                InfAdoptedOperation *transformed,
                                InfAdoptedUser *by,
                                InfBuffer *buffer,
                                GError **error);

Applies transformed to buffer . The operation is considered to be applied by user by . The operation transformed must have originated from operation by transformation with inf_adopted_operation_transform().

If operation is reversible or does not affect the buffer (see InfAdoptedOperationFlags), this function is equivalent to

inf_adopted_operation_apply(transformed, by, buffer), with

the exception of the return value. In that case the return value will be operation itself, with a reference added.

However, if operation is not reversible and affects the buffer, the function attempts to construct an operation which is identical to operation , but reversible, and returns it. The function can use information from the transformed operation and the buffer to construct the reversible operation. If a reversible operation cannot be constructed, the function returns an additional reference on operation , and still applies the transformed operation to the buffer.

For example, an operation that deletes text in a text editor would be transmitting only the position and the length of the text to delete over the network. From that information alone, the operation cannot be made reversible. However, when the operation is applied to the buffer, the actual text that is being removed can be restored by looking it up in the buffer, making the operation reversible.

Parameters

operation

A InfAdoptedOperation.

 

transformed

A transformed version of operation .

 

by

The InfAdoptedUser applying the operation.

 

buffer

The InfBuffer to apply the operation to.

 

error

Location to store error information, if any, or NULL.

 

Returns

A InfAdoptedOperation, or NULL on error. Free with g_object_unref() when no longer needed.

[transfer full]


inf_adopted_operation_is_reversible ()

gboolean
inf_adopted_operation_is_reversible (InfAdoptedOperation *operation);

Returns whether operation is reversible.

Parameters

operation

A InfAdoptedOperation.

 

Returns

Whether operation is reversible.


inf_adopted_operation_revert ()

InfAdoptedOperation *
inf_adopted_operation_revert (InfAdoptedOperation *operation);

Returns a new InfAdoptedOperation that undoes the effect of operation . If operation and then its reverse operation are applied to a buffer (in that order), the buffer remains unchanged.

operation must be reversible for this function to be called (i.e. inf_adopted_operation_is_reversible() must return TRUE).

Parameters

operation

A InfAdoptedOperation.

 

Returns

The reverse operation of operation .

[transfer full]

Types and Values

InfAdoptedOperation

typedef struct _InfAdoptedOperation InfAdoptedOperation;

InfAdoptedOperation is an opaque data type. You should only access it via the public API functions.


struct InfAdoptedOperationInterface

struct InfAdoptedOperationInterface {
  gboolean (*need_concurrency_id)(InfAdoptedOperation* operation,
                                  InfAdoptedOperation* against);

  InfAdoptedOperation* (*transform)(InfAdoptedOperation* operation,
                                    InfAdoptedOperation* against,
                                    InfAdoptedOperation* operation_lcs,
                                    InfAdoptedOperation* against_lcs,
                                    InfAdoptedConcurrencyId concurrency_id);

  InfAdoptedOperation* (*copy)(InfAdoptedOperation* operation);

  InfAdoptedOperationFlags (*get_flags)(InfAdoptedOperation* operation);

  gboolean (*apply)(InfAdoptedOperation* operation,
                    InfAdoptedUser* by,
                    InfBuffer* buffer,
                    GError** error);

  InfAdoptedOperation* (*apply_transformed)(InfAdoptedOperation* operation,
                                            InfAdoptedOperation* transformed,
                                            InfAdoptedUser* by,
                                            InfBuffer* buffer,
                                            GError** error);

  InfAdoptedOperation* (*revert)(InfAdoptedOperation* operation);
};

The virtual methods that need to be implemented by an operation to be used with InfAdoptedAlgorithm.

Members

need_concurrency_id ()

Virtual function to determine whether a concurrency ID is required to transform operation against against .

 

transform ()

Virtual function that transform operation against against and returns a new InfAdoptedOperation as the result of the transformation. concurrency_id is either 1 or -1 and can be used to make a decision in case there is no other criteria to decide how to do the transformation, for example when both operation and against are inserting text at the same position in the buffer.

 

copy ()

Virtual function that returns a copy of the operation.

 

get_flags ()

Virtual function that returns the flags of the operation, see InfAdoptedOperationFlags.

 

apply ()

Virtual function that applies the operation to the buffer. by is the user that applies the operation.

 

apply_transformed ()

Virtual function that applies a transformed version of the operation to the buffer. It attempts to use information from the buffer to make the original operation reversible, if it is not already. The implementation of this function is optional, and only needs to be implemented if the operation is not reversible but can be made reversible with additional information from the buffer or the transformed operation.

 

revert ()

Virtual function that creates a new operation that undoes the effect of the operation. If get_flags does never return the INF_ADOPTED_OPERATION_REVERSIBLE flag set, then this is allowed to be NULL.

 

enum InfAdoptedOperationFlags

Various flags for InfAdoptedOperation.

Members

INF_ADOPTED_OPERATION_AFFECTS_BUFFER

The operation changes the content of the buffer.

 

INF_ADOPTED_OPERATION_REVERSIBLE

The operation is reversible, which means that inf_adopted_operation_revert() can be called to generate an operation that undoes the effect of the operation.

 

enum InfAdoptedConcurrencyId

A concurrency ID is used to determine which operation to transform in case two similar operations are transformed against each other.

Members

INF_ADOPTED_CONCURRENCY_SELF

Transform the operation itself.

 

INF_ADOPTED_CONCURRENCY_NONE

Unspecified which operation to transform.

 

INF_ADOPTED_CONCURRENCY_OTHER

Transform the other operation.

 

See Also

InfAdoptedRequest, InfAdoptedAlgorithm