| 摘要 |
A mechanism for facilitating backtracking is disclosed. In processing a source entity with a transformation entity to derive a result entity, an action set forth in a portion of the transformation entity is executed. A portion of the source entity is the subject of this action. When this action is executed, a particular portion of the result entity is generated as a consequence. After this portion of the result entity is generated, a set of history information is associated therewith. This history information comprises a reference to the portion of the transformation entity that gave rise to the action, and a reference to the portion of the source entity that was the subject of the action. Given this information, it is possible to perform backtracking at a later time. For example, when this particular portion of the result entity is later selected, the history information is accessed. From the history information, the references to the portions of the transformation and source entities are obtained. Thereafter, those portions of the transformation and source entities are indicated to a user to let the user know what caused this particular portion of the result entity to be generated. Backtracking is thus implemented.
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