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| 402 : | mso-level-number-position:left; | ||
| 403 : | text-indent:-.25in;} | ||
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| 406 : | nick | 1.1 | mso-level-number-position:left; |
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| 408 : | sfranklin | 1.5 | @list l9:level4 |
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| 410 : | nick | 1.1 | mso-level-number-position:left; |
| 411 : | text-indent:-.25in;} | ||
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| 414 : | nick | 1.1 | mso-level-number-position:left; |
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| 418 : | nick | 1.1 | mso-level-number-position:left; |
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| 424 : | sfranklin | 1.5 | @list l9:level8 |
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| 428 : | sfranklin | 1.5 | @list l9:level9 |
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| 430 : | nick | 1.1 | mso-level-number-position:left; |
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| 458 : | nick | 1.1 | mso-level-number-position:left; |
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| 489 : | sfranklin | 1.5 | @list l11:level4 |
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| 499 : | mso-level-number-position:left; | ||
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| 503 : | mso-level-number-position:left; | ||
| 504 : | text-indent:-.25in;} | ||
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| 507 : | nick | 1.1 | mso-level-number-position:left; |
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| 511 : | nick | 1.1 | mso-level-number-position:left; |
| 512 : | sfranklin | 1.3 | text-indent:-.25in;} |
| 513 : | nick | 1.1 | ol |
| 514 : | {margin-bottom:0in;} | ||
| 515 : | ul | ||
| 516 : | {margin-bottom:0in;} | ||
| 517 : | --> | ||
| 518 : | </style> | ||
| 519 : | <!--[if gte mso 10]> | ||
| 520 : | <style> | ||
| 521 : | /* Style Definitions */ | ||
| 522 : | table.MsoNormalTable | ||
| 523 : | {mso-style-name:"Table Normal"; | ||
| 524 : | mso-tstyle-rowband-size:0; | ||
| 525 : | mso-tstyle-colband-size:0; | ||
| 526 : | mso-style-noshow:yes; | ||
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| 533 : | font-family:"Times New Roman";} | ||
| 534 : | </style> | ||
| 535 : | <![endif]--> | ||
| 536 : | </head> | ||
| 537 : | |||
| 538 : | nick | 1.2 | <body lang=EN-US link="#0000EE" vlink=purple style='tab-interval:.5in'> |
| 539 : | nick | 1.1 | |
| 540 : | <div class=Section1> | ||
| 541 : | |||
| 542 : | <h1>Generalized Undo Support in Eclipse</h1> | ||
| 543 : | |||
| 544 : | nick | 1.2 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>Last |
| 545 : | sfranklin | 1.5 | updated:<span style='mso-spacerun:yes'> </span></span><st1:date Year="2005" |
| 546 : | Day="22" Month="2"><span style='font-size:10.0pt;font-family:Arial'>Feb. 22, | ||
| 547 : | 2005</span></st1:date><span style='font-size:10.0pt;font-family:Arial'><o:p></o:p></span></p> | ||
| 548 : | nick | 1.2 | |
| 549 : | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>Status:<span | ||
| 550 : | sfranklin | 1.5 | style='mso-spacerun:yes'> </span>Proposal – Implemented in 3.1M5<o:p></o:p></span></p> |
| 551 : | sfranklin | 1.3 | |
| 552 : | sfranklin | 1.4 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>(<span |
| 553 : | sfranklin | 1.5 | class=GramE>see</span> also bug <span style='mso-spacerun:yes'> </span></span><a |
| 554 : | nick | 1.2 | href="https://bugs.eclipse.org/bugs/show_bug.cgi?id=37716">37716</a>)<span |
| 555 : | style='font-size:10.0pt;font-family:Arial'><o:p></o:p></span></p> | ||
| 556 : | |||
| 557 : | sfranklin | 1.3 | <h2>Problem Description</h2> |
| 558 : | nick | 1.1 | |
| 559 : | sfranklin | 1.5 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>In R3.0.1 |
| 560 : | of the Eclipse SDK, there is no generalized support for undoing user | ||
| 561 : | actions.<span style='mso-spacerun:yes'> </span>Each plug-in is left to | ||
| 562 : | implement its own strategy for undo, if at all.<span style='mso-spacerun:yes'> | ||
| 563 : | </span>This approach can cause problems for both Eclipse users and plug-in | ||
| 564 : | developers:<o:p></o:p></span></p> | ||
| 565 : | sfranklin | 1.3 | |
| 566 : | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'><span | ||
| 567 : | style='mso-spacerun:yes'> </span><o:p></o:p></span></p> | ||
| 568 : | |||
| 569 : | <ul style='margin-top:0in' type=disc> | ||
| 570 : | sfranklin | 1.5 | <li class=MsoNormal style='mso-list:l3 level1 lfo3;tab-stops:list .5in'><span |
| 571 : | sfranklin | 1.3 | style='font-size:10.0pt;font-family:Arial'>Undo and redo actions appear in |
| 572 : | different menus, causing user confusion and UI clutter<o:p></o:p></span></li> | ||
| 573 : | sfranklin | 1.5 | <li class=MsoNormal style='mso-list:l3 level1 lfo3;tab-stops:list .5in'><span |
| 574 : | sfranklin | 1.3 | style='font-size:10.0pt;font-family:Arial'>Undo and redo implementations |
| 575 : | may have different semantics.<o:p></o:p></span></li> | ||
| 576 : | sfranklin | 1.5 | <li class=MsoNormal style='mso-list:l3 level1 lfo3;tab-stops:list .5in'><span |
| 577 : | sfranklin | 1.3 | style='font-size:10.0pt;font-family:Arial'>Plug-ins that depend on other |
| 578 : | plug-ins which implement their own undo strategy are forced to choose | ||
| 579 : | between different implementations and possibly write integration code to | ||
| 580 : | allow the different frameworks to coexist.<o:p></o:p></span></li> | ||
| 581 : | </ul> | ||
| 582 : | nick | 1.1 | |
| 583 : | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></p> | ||
| 584 : | |||
| 585 : | sfranklin | 1.3 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>Further, |
| 586 : | the meaning of undo can be very different depending on what the user is | ||
| 587 : | doing.<span style='mso-spacerun:yes'> </span>The most common type of undo is | ||
| 588 : | text undo.<span style='mso-spacerun:yes'> </span>The user can undo lightweight | ||
| 589 : | edit operations such as inserting, replacing, or deleting text.<span | ||
| 590 : | style='mso-spacerun:yes'> </span>Other types of undo may involve more complex, | ||
| 591 : | heavyweight operations that affect an underlying model of many elements.<span | ||
| 592 : | style='mso-spacerun:yes'> </span>For example, the JDT refactoring support | ||
| 593 : | provides undo support for refactoring operations that involve many Java | ||
| 594 : | elements at different levels, such as Java packages, compilation units, | ||
| 595 : | classes, and methods.<o:p></o:p></span></p> | ||
| 596 : | |||
| 597 : | <h2>Operations Framework</h2> | ||
| 598 : | nick | 1.1 | |
| 599 : | sfranklin | 1.3 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>The |
| 600 : | sfranklin | 1.5 | proposed framework defines an interface for describing work, called an “undoable |
| 601 : | operation” (<span class=SpellE>IUndoableOperation</span><span class=GramE>), | ||
| 602 : | that</span> can be executed, undone, and redone.<span | ||
| 603 : | style='mso-spacerun:yes'> </span>Undoable operations are created, executed, | ||
| 604 : | and added to an operations history (<span class=SpellE>IOperationHistory</span>).<span | ||
| 605 : | sfranklin | 1.4 | style='mso-spacerun:yes'> </span>Operations which are comprised of distinct |
| 606 : | sfranklin | 1.5 | steps should be represented as compound operations, which are executed, undone, |
| 607 : | or redone as a unit, and can never be partially undone.<span | ||
| 608 : | style='mso-spacerun:yes'> </span><o:p></o:p></span></p> | ||
| 609 : | nick | 1.1 | |
| 610 : | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></p> | ||
| 611 : | |||
| 612 : | sfranklin | 1.3 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>Operations |
| 613 : | sfranklin | 1.5 | can be assigned one or more contexts (<span class=SpellE>IUndoContext</span>) |
| 614 : | to which they apply.<span style='mso-spacerun:yes'> </span>An undo context | ||
| 615 : | describes the context in which the user is working when an operation is performed, | ||
| 616 : | undone, or redone.<span style='mso-spacerun:yes'> </span>Undo contexts can be | ||
| 617 : | used by workbench parts to filter the operations history, so that only those | ||
| 618 : | operations that have been assigned the context of interest to a particular part | ||
| 619 : | are available for undo/redo when that part is active.<o:p></o:p></span></p> | ||
| 620 : | nick | 1.1 | |
| 621 : | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></p> | ||
| 622 : | |||
| 623 : | sfranklin | 1.3 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>The |
| 624 : | sfranklin | 1.5 | interface for undo contexts is left very general so that operation implementers |
| 625 : | may choose the appropriate representation for their contexts.<span | ||
| 626 : | sfranklin | 1.3 | style='mso-spacerun:yes'> </span>In some cases, a part-oriented context may be |
| 627 : | appropriate. For example, a text editor’s context is related to the editor | ||
| 628 : | itself and its life-cycle is similar to that of the editor.<span | ||
| 629 : | sfranklin | 1.5 | style='mso-spacerun:yes'> </span>The resource navigator’s context is closely |
| 630 : | related to the workspace model objects, and the context related to the | ||
| 631 : | workspace has a life cycle to similar to that of the workspace itself.<o:p></o:p></span></p> | ||
| 632 : | sfranklin | 1.3 | |
| 633 : | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></p> | ||
| 634 : | nick | 1.1 | |
| 635 : | sfranklin | 1.3 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>Contexts |
| 636 : | can be assigned to operations in multiple ways:<o:p></o:p></span></p> | ||
| 637 : | nick | 1.1 | |
| 638 : | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></p> | ||
| 639 : | |||
| 640 : | sfranklin | 1.5 | <p class=MsoNormal style='margin-left:39.0pt;text-indent:-.25in;mso-list:l11 level1 lfo5; |
| 641 : | sfranklin | 1.3 | tab-stops:list 39.0pt'><![if !supportLists]><span style='font-size:10.0pt; |
| 642 : | font-family:Arial;mso-fareast-font-family:Arial'><span style='mso-list:Ignore'>1.<span | ||
| 643 : | style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span | ||
| 644 : | style='font-size:10.0pt;font-family:Arial'>The context can be assigned | ||
| 645 : | initially when the operation is created.<span style='mso-spacerun:yes'> | ||
| 646 : | </span>For example, text operations are triggered by typing in the editor, and | ||
| 647 : | the editor can assign its context to the operation before adding it to the | ||
| 648 : | history.<span style='mso-spacerun:yes'> </span><o:p></o:p></span></p> | ||
| 649 : | |||
| 650 : | sfranklin | 1.5 | <p class=MsoNormal style='margin-left:39.0pt;text-indent:-.25in;mso-list:l11 level1 lfo5; |
| 651 : | sfranklin | 1.3 | tab-stops:list 39.0pt'><![if !supportLists]><span style='font-size:10.0pt; |
| 652 : | font-family:Arial;mso-fareast-font-family:Arial'><span style='mso-list:Ignore'>2.<span | ||
| 653 : | style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span | ||
| 654 : | style='font-size:10.0pt;font-family:Arial'>A listener interface on the | ||
| 655 : | operations history allows listeners to detect when an operation is added to the | ||
| 656 : | history.<span style='mso-spacerun:yes'> </span>Listeners can decide if their | ||
| 657 : | context should be added to the operation.<span style='mso-spacerun:yes'> | ||
| 658 : | nick | 1.1 | </span><o:p></o:p></span></p> |
| 659 : | |||
| 660 : | sfranklin | 1.5 | <p class=MsoNormal style='margin-left:39.0pt;text-indent:-.25in;mso-list:l11 level1 lfo5; |
| 661 : | tab-stops:list 39.0pt'><![if !supportLists]><span style='font-size:10.0pt; | ||
| 662 : | font-family:Arial;mso-fareast-font-family:Arial'><span style='mso-list:Ignore'>3.<span | ||
| 663 : | style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span | ||
| 664 : | style='font-size:10.0pt;font-family:Arial'>Operations can be executed in a | ||
| 665 : | batch mode.<span style='mso-spacerun:yes'> </span>When a batching operation is | ||
| 666 : | being executed, any other operations that execute have their contexts assigned | ||
| 667 : | to the batch operation.<o:p></o:p></span></p> | ||
| 668 : | |||
| 669 : | sfranklin | 1.3 | <p class=MsoNormal style='margin-left:21.0pt'><span style='font-size:10.0pt; |
| 670 : | font-family:Arial'><o:p> </o:p></span></p> | ||
| 671 : | |||
| 672 : | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>An | ||
| 673 : | operation may have more than one context.<span style='mso-spacerun:yes'> | ||
| 674 : | </span>For example, an operation may affect many elements in the workspace, | ||
| 675 : | including one that is currently open in an editor.<span | ||
| 676 : | style='mso-spacerun:yes'> </span>That operation could be assigned two | ||
| 677 : | independent contexts, so that it can be undone from both the editor and the | ||
| 678 : | view manipulating the model.<span style='mso-spacerun:yes'> </span><o:p></o:p></span></p> | ||
| 679 : | |||
| 680 : | nick | 1.1 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></p> |
| 681 : | |||
| 682 : | sfranklin | 1.3 | <h2>Levels of Integration and Migration</h2> |
| 683 : | |||
| 684 : | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>Many | ||
| 685 : | plug-ins have already invested heavily in building objects that describe | ||
| 686 : | undoable user commands or operations.<span style='mso-spacerun:yes'> </span>It | ||
| 687 : | is not expected that all plug-ins will adopt the framework completely, given | ||
| 688 : | the individual schedules and other constraints for each plug-in.<span | ||
| 689 : | style='mso-spacerun:yes'> </span>However, the integration can be achieved in | ||
| 690 : | phases that will immediately provide value to dependent plug-ins.<span | ||
| 691 : | style='mso-spacerun:yes'> </span>The following adoption strategy is strongly | ||
| 692 : | encouraged:<o:p></o:p></span></p> | ||
| 693 : | nick | 1.1 | |
| 694 : | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></p> | ||
| 695 : | |||
| 696 : | <ol style='margin-top:0in' start=1 type=1> | ||
| 697 : | sfranklin | 1.5 | <li class=MsoNormal style='mso-list:l10 level1 lfo8;tab-stops:list .5in'><span |
| 698 : | style='font-size:10.0pt;font-family:Arial'>Existing command/undo | ||
| 699 : | frameworks can implement the <span class=SpellE>IUndoableOperation</span> | ||
| 700 : | interface on their existing command objects, while still maintaining their | ||
| 701 : | individual strategies for managing undo stacks or histories.<span | ||
| 702 : | sfranklin | 1.4 | style='mso-spacerun:yes'> </span>If there is a substantial investment in |
| 703 : | an existing model-based operation or command framework, wrappers could be | ||
| 704 : | sfranklin | 1.5 | used to map <span class=SpellE>IUndoableOperation</span> protocol to the |
| 705 : | existing protocol.<span style='mso-spacerun:yes'> </span>The | ||
| 706 : | commands/operations need not be assigned a context or added to a common | ||
| 707 : | operation history.<span style='mso-spacerun:yes'> </span>This level of | ||
| 708 : | integration allows command hierarchies built in different frameworks to be | ||
| 709 : | treated the same by plug-ins that depend upon these different | ||
| 710 : | frameworks.<span style='mso-spacerun:yes'> </span>Clients of existing | ||
| 711 : | command frameworks may then use the workbench operation history, assign | ||
| 712 : | contexts to operations as needed, and even add operations to the history, | ||
| 713 : | while still using commands built on earlier frameworks.<o:p></o:p></span></li> | ||
| 714 : | <li class=MsoNormal style='mso-list:l10 level1 lfo8;tab-stops:list .5in'><span | ||
| 715 : | sfranklin | 1.3 | style='font-size:10.0pt;font-family:Arial'>Existing command/undo |
| 716 : | frameworks may use the listener interfaces provided by the operations | ||
| 717 : | history to listen for operations that are of interest.<span | ||
| 718 : | style='mso-spacerun:yes'> </span>These commands may be wrapped or | ||
| 719 : | otherwise recorded so that they can be undone from privately maintained | ||
| 720 : | undo implementations.<span style='mso-spacerun:yes'> </span>This level of | ||
| 721 : | integration allows views and editors to appear more tightly integrated | ||
| 722 : | with the operations framework, since workbench operations of interest can | ||
| 723 : | be undone or redone from private undo implementations.<o:p></o:p></span></li> | ||
| 724 : | sfranklin | 1.5 | <li class=MsoNormal style='mso-list:l10 level1 lfo8;tab-stops:list .5in'><span |
| 725 : | sfranklin | 1.3 | style='font-size:10.0pt;font-family:Arial'>Full integration is achieved by |
| 726 : | using the workbench operation history to record the undo and redo history | ||
| 727 : | as operations occur.<span style='mso-spacerun:yes'> </span>Once all | ||
| 728 : | plug-ins share an operation history, clients will be able to use unified | ||
| 729 : | listeners and handlers to track execution of operations, undo, and redo | ||
| 730 : | them.<span style='mso-spacerun:yes'> </span><o:p></o:p></span></li> | ||
| 731 : | nick | 1.1 | </ol> |
| 732 : | |||
| 733 : | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></p> | ||
| 734 : | |||
| 735 : | sfranklin | 1.3 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>Framework |
| 736 : | sfranklin | 1.5 | interfaces will be defined in the <span class=SpellE>org.eclipse.core.commands.operations</span> |
| 737 : | package in the <span class=SpellE>org.eclipse.core.commands</span> | ||
| 738 : | plug-in.<span style='mso-spacerun:yes'> </span>This plug-in has no | ||
| 739 : | dependencies on the Eclipse runtime architecture (apart from some runtime classes | ||
| 740 : | such as <span class=SpellE>IProgressMonitor</span>, <span class=SpellE>IStatus</span>, | ||
| 741 : | <span class=SpellE><span class=GramE>IAdaptable</span></span>), so raw <span | ||
| 742 : | class=SpellE>JFace</span> clients may make use of it.<o:p></o:p></span></p> | ||
| 743 : | |||
| 744 : | <h2>Operations and Concurrency</h2> | ||
| 745 : | |||
| 746 : | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>The | ||
| 747 : | operations framework relies on the notion of sequential execution of undoable | ||
| 748 : | operations.<span style='mso-spacerun:yes'> </span>For R3.1, there will be no | ||
| 749 : | specific support built into the framework for concurrent operations that | ||
| 750 : | execute inside platform Jobs.<span style='mso-spacerun:yes'> </span>Actions whose | ||
| 751 : | work is currently executed inside a Job may be converted to <span class=SpellE>IUndoableOperation</span>, | ||
| 752 : | but they should not be added to the operation history until after they have | ||
| 753 : | finished their execution.<span style='mso-spacerun:yes'> </span>The undo and | ||
| 754 : | redo behavior for these kinds of <span class=SpellE>IUndoableOperation</span> must | ||
| 755 : | be implemented in a synchronous manner for R3.1, since the validity of other | ||
| 756 : | operations in the operation history may not be properly determined if an undo | ||
| 757 : | or redo is executing asynchronously in a Job.<span style='mso-spacerun:yes'> | ||
| 758 : | </span>More robust support for concurrent, undoable operations may be | ||
| 759 : | considered in future releases as requirements are discovered.<o:p></o:p></span></p> | ||
| 760 : | sfranklin | 1.3 | |
| 761 : | <h2>Framework interfaces</h2> | ||
| 762 : | |||
| 763 : | sfranklin | 1.5 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>Initial |
| 764 : | implementations of the proposed framework interfaces appear in R3.1 M5.<span | ||
| 765 : | style='mso-spacerun:yes'> </span>See the <span class=SpellE>Javadoc</span> for | ||
| 766 : | the described classes for the complete specification.<span | ||
| 767 : | style='mso-spacerun:yes'> </span>Please note that the specification is still | ||
| 768 : | evolving and early adopters should be prepared for API changes throughout the | ||
| 769 : | R3.1 development cycle.<o:p></o:p></span></p> | ||
| 770 : | |||
| 771 : | <h3><span class=SpellE>IUndoableOperation</span></h3> | ||
| 772 : | sfranklin | 1.3 | |
| 773 : | sfranklin | 1.4 | <p class=MsoNormal><span class=SpellE><span style='font-size:10.0pt;font-family: |
| 774 : | sfranklin | 1.5 | Arial'>IUndoableOperation</span></span><span style='font-size:10.0pt; |
| 775 : | font-family:Arial'> defines an operation that can be executed, undone, and | ||
| 776 : | redone.<span style='mso-spacerun:yes'> </span>Operations typically have fully | ||
| 777 : | defined parameters. That is, they are usually created after the user has been | ||
| 778 : | queried for any input needed to define the operation.<o:p></o:p></span></p> | ||
| 779 : | nick | 1.1 | |
| 780 : | sfranklin | 1.3 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></p> |
| 781 : | nick | 1.1 | |
| 782 : | sfranklin | 1.3 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>Operations |
| 783 : | determine their ability to execute, undo, or redo according to the current | ||
| 784 : | state of the application. They do not make decisions about their validity based | ||
| 785 : | on where they occur in the operation history. That is left to the particular | ||
| 786 : | operation history.<o:p></o:p></span></p> | ||
| 787 : | nick | 1.1 | |
| 788 : | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></p> | ||
| 789 : | |||
| 790 : | sfranklin | 1.4 | <h3><span class=SpellE>IOperationHistory</span></h3> |
| 791 : | nick | 1.1 | |
| 792 : | sfranklin | 1.4 | <p class=MsoNormal><span class=SpellE><span style='font-size:10.0pt;font-family: |
| 793 : | Arial'>IOperationHistory</span></span><span style='font-size:10.0pt;font-family: | ||
| 794 : | Arial'> tracks a history of operations that can be undone or redone. Operations | ||
| 795 : | sfranklin | 1.5 | are added to the history after they have been initially executed. Clients may |
| 796 : | sfranklin | 1.4 | choose whether to have the operations history perform the initial execution or |
| 797 : | simply add the operation to the history. Once operations are added to the | ||
| 798 : | sfranklin | 1.5 | history, the methods <span class=SpellE><span class=GramE>canRedo</span></span><span |
| 799 : | class=GramE>(</span>) and <span class=SpellE>canUndo</span>() are used to | ||
| 800 : | determine whether there is an operation available for undo and redo in a given undo | ||
| 801 : | context.<span style='mso-spacerun:yes'> </span>The context-based protocol | ||
| 802 : | implies that there is only one operation that can be undone or redone at a | ||
| 803 : | given time in a given context. This is typical of a linear undo model, when | ||
| 804 : | only the most recently executed operation is available for undo. When this | ||
| 805 : | protocol is used, a linear model is enforced by the history. It is up to | ||
| 806 : | clients to determine how to maintain a history that is invalid or stale. For | ||
| 807 : | example, when the most recent operation for a context cannot be performed, | ||
| 808 : | clients may wish to flush the history for that context.<o:p></o:p></span></p> | ||
| 809 : | nick | 1.1 | |
| 810 : | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></p> | ||
| 811 : | |||
| 812 : | sfranklin | 1.3 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>Additional |
| 813 : | protocol allows direct undo and redo of a specified operation, regardless of | ||
| 814 : | its position in the history. When a more flexible undo model is supported, | ||
| 815 : | these methods can be implemented to undo and redo directly specified | ||
| 816 : | sfranklin | 1.4 | operations. If an implementer of <span class=SpellE>IOperationHistory</span> |
| 817 : | does not allow direct undo and redo, these methods can return a status | ||
| 818 : | indicating that it is not allowed.<o:p></o:p></span></p> | ||
| 819 : | sfranklin | 1.3 | |
| 820 : | nick | 1.1 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></p> |
| 821 : | |||
| 822 : | sfranklin | 1.4 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>Listeners (<span |
| 823 : | class=SpellE>IOperationHistoryListener</span>) can listen for notifications | ||
| 824 : | about changes in the history (operations added or removed), and for | ||
| 825 : | notification before and after any operation is executed, undone or redone. | ||
| 826 : | Notification of operation execution only occurs when clients direct the history | ||
| 827 : | to execute the operation. If the operation is added after it is executed, there | ||
| 828 : | can be no notification of its execution.<o:p></o:p></span></p> | ||
| 829 : | nick | 1.1 | |
| 830 : | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></p> | ||
| 831 : | |||
| 832 : | sfranklin | 1.4 | <p class=MsoNormal><span class=SpellE><span style='font-size:10.0pt;font-family: |
| 833 : | Arial'>IOperationApprover</span></span><span style='font-size:10.0pt; | ||
| 834 : | font-family:Arial'> defines an interface for approving an undo or redo before | ||
| 835 : | it occurs. This is useful for injecting policy-decisions into the model - | ||
| 836 : | whether direct undo and redo are supported, or warning the user about certain | ||
| 837 : | kinds of operations. It can also be used when objects have state related to the | ||
| 838 : | operation and need to determine whether an undo or redo will cause any | ||
| 839 : | conflicts with their local state.<o:p></o:p></span></p> | ||
| 840 : | nick | 1.1 | |
| 841 : | sfranklin | 1.4 | <h3><span class=SpellE>IOperationApprover</span></h3> |
| 842 : | nick | 1.1 | |
| 843 : | sfranklin | 1.4 | <p class=MsoNormal><span class=SpellE><span style='font-size:10.0pt;font-family: |
| 844 : | Arial'>IOperationApprover</span></span><span style='font-size:10.0pt; | ||
| 845 : | font-family:Arial'> defines an interface for approving the undo or redo of a | ||
| 846 : | particular operation within an operation history. Operations that are | ||
| 847 : | candidates for undo or redo have already been validated against their current | ||
| 848 : | state and according to the rules of the history.<o:p></o:p></span></p> | ||
| 849 : | nick | 1.1 | |
| 850 : | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></p> | ||
| 851 : | |||
| 852 : | sfranklin | 1.3 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>By the time |
| 853 : | sfranklin | 1.4 | an <span class=SpellE>IOperationApprover</span> is consulted, the undo has |
| 854 : | already been requested. Approvers should true if the operation should proceed, | ||
| 855 : | and false if it should not. When an operation is rejected, it is expected that | ||
| 856 : | the object rejecting the operation has already consulted the user if necessary | ||
| 857 : | or otherwise provided any necessary information to the user about the | ||
| 858 : | sfranklin | 1.5 | rejection.<span style='mso-spacerun:yes'> </span>If an undo or redo is |
| 859 : | triggered from the UI, clients provide UI info (such as an <span class=SpellE>org.eclipse.swt.Shell</span>) | ||
| 860 : | to assist in prompting the user where necessary.<o:p></o:p></span></p> | ||
| 861 : | nick | 1.1 | |
| 862 : | sfranklin | 1.4 | <h3><span class=SpellE>IOperationHistoryListener</span></h3> |
| 863 : | nick | 1.1 | |
| 864 : | sfranklin | 1.5 | <p class=MsoNormal><span class=SpellE><span style='font-size:10.0pt;font-family: |
| 865 : | Arial'>IOperationHistoryListener</span></span><span style='font-size:10.0pt; | ||
| 866 : | font-family:Arial'> defines the interface for being notified about particular | ||
| 867 : | events that take place inside the operation history.<o:p></o:p></span></p> | ||
| 868 : | nick | 1.1 | |
| 869 : | sfranklin | 1.5 | <h3><span class=SpellE>OperationHistoryEvent</span></h3> |
| 870 : | nick | 1.1 | |
| 871 : | sfranklin | 1.5 | <p class=MsoNormal><span class=SpellE><span style='font-size:10.0pt;font-family: |
| 872 : | Arial'>OperationHistoryEvent</span></span><span style='font-size:10.0pt; | ||
| 873 : | font-family:Arial'> defines the different types of events that occur inside an | ||
| 874 : | operation history.<span style='mso-spacerun:yes'> </span><span class=GramE>Listeners | ||
| 875 : | are notified before and after an operation is</span> executed, undone, or | ||
| 876 : | redone.<span style='mso-spacerun:yes'> </span>Listeners are also notified when | ||
| 877 : | operations are added or removed from the history.<o:p></o:p></span></p> | ||
| 878 : | nick | 1.1 | |
| 879 : | sfranklin | 1.5 | <h3><span class=SpellE>OperationHistoryFactory</span></h3> |
| 880 : | nick | 1.1 | |
| 881 : | sfranklin | 1.5 | <p class=MsoNormal><span class=SpellE><span style='font-size:10.0pt;font-family: |
| 882 : | Arial'>OperationHistoryFactory</span></span><span style='font-size:10.0pt; | ||
| 883 : | font-family:Arial'> provides access to a singleton instance of an operation | ||
| 884 : | history.<span style='mso-spacerun:yes'> </span>This factory will provide a | ||
| 885 : | default implementation for an operation history if one is not set by a | ||
| 886 : | caller.<span style='mso-spacerun:yes'> </span>Once the singleton is obtained | ||
| 887 : | by any client, the instance cannot be reset.<o:p></o:p></span></p> | ||
| 888 : | nick | 1.1 | |
| 889 : | sfranklin | 1.3 | <h2>UI Support Classes<span style='font-size:10.0pt'><o:p></o:p></span></h2> |
| 890 : | |||
| 891 : | sfranklin | 1.4 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>Additional |
| 892 : | sfranklin | 1.5 | support classes are provided in the package <span class=SpellE>org.eclipse.ui.operations</span>.<span |
| 893 : | sfranklin | 1.3 | style='mso-spacerun:yes'> </span>These classes handle policy decisions about |
| 894 : | the undo model to be used by the workbench.<span style='mso-spacerun:yes'> | ||
| 895 : | sfranklin | 1.5 | </span>Access to the undo and redo handlers, as well as the operations history, |
| 896 : | sfranklin | 1.3 | will be provided through workbench.<o:p></o:p></span></p> |
| 897 : | nick | 1.1 | |
| 898 : | sfranklin | 1.3 | <h3>Workbench Operation History</h3> |
| 899 : | |||
| 900 : | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>The | ||
| 901 : | sfranklin | 1.5 | workbench will configure the default operation history supplied by the <span |
| 902 : | class=SpellE>OperationHistoryFactory</span> and register an <span class=SpellE>IUndoContext</span> | ||
| 903 : | adapter onto the workspace.<span style='mso-spacerun:yes'> | ||
| 904 : | </span>Configuration of the operation history includes setting an undo limit | ||
| 905 : | for the workspace undo context and adding an <span class=SpellE>IOperationApprover</span> | ||
| 906 : | that enforces a per-context linear undo model.<span style='mso-spacerun:yes'> | ||
| 907 : | </span><o:p></o:p></span></p> | ||
| 908 : | nick | 1.1 | |
| 909 : | sfranklin | 1.3 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></p> |
| 910 : | nick | 1.1 | |
| 911 : | sfranklin | 1.5 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>Undo |
| 912 : | contexts will be defined for text editors and for the workspace.<span | ||
| 913 : | style='mso-spacerun:yes'> </span>Throughout the development of R3.1, plug-ins | ||
| 914 : | will be encouraged to define operations that represent their existing actions | ||
| 915 : | or command handlers.<span style='mso-spacerun:yes'> </span>Additional contexts | ||
| 916 : | may be defined by plug-ins as necessary.<span style='mso-spacerun:yes'> | ||
| 917 : | </span>Undoable operations will be added incrementally once the framework is in | ||
| 918 : | sfranklin | 1.3 | place.<span style='mso-spacerun:yes'> </span><o:p></o:p></span></p> |
| 919 : | nick | 1.1 | |
| 920 : | sfranklin | 1.5 | <h3><span class=SpellE>IWorkbenchOperationSupport</span></h3> |
| 921 : | nick | 1.1 | |
| 922 : | sfranklin | 1.5 | <p class=MsoNormal><span class=SpellE><span style='font-size:10.0pt;font-family: |
| 923 : | Arial'>IWorkbenchOperationSupport</span></span><span style='font-size:10.0pt; | ||
| 924 : | font-family:Arial'> provides access to the workbench operation history and the | ||
| 925 : | workspace undo context.<span style='mso-spacerun:yes'> </span>Although these objects | ||
| 926 : | are actually managed elsewhere (in the <span class=SpellE>OperationHistoryFactory</span> | ||
| 927 : | and as an adapter on the workspace), <span class=SpellE>IWorkbenchOperationSupport</span> | ||
| 928 : | provides integrated access to all undo facilities used by the workbench.<span | ||
| 929 : | style='mso-spacerun:yes'> </span>Plug-ins aware of the workbench will typically | ||
| 930 : | get the <span class=SpellE>IWorkbenchOperationSupport</span> from the workbench | ||
| 931 : | to obtain the appropriate context and operation history.<span | ||
| 932 : | style='mso-spacerun:yes'> </span>Lower-level (headless) plug-ins that implement | ||
| 933 : | undo support will use the lower level constructs, such as the <span | ||
| 934 : | class=SpellE>OperationHistoryFactory</span>, to obtain these objects.</span><o:p></o:p></p> | ||
| 935 : | nick | 1.1 | |
| 936 : | sfranklin | 1.5 | <h3><span class=SpellE>UndoActionHandler</span> and <span class=SpellE>RedoActionHandler</span></h3> |
| 937 : | nick | 1.1 | |
| 938 : | sfranklin | 1.3 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>The |
| 939 : | Edit>Undo and Edit>Redo commands should be handled by any parts that wish | ||
| 940 : | to support undo.<span style='mso-spacerun:yes'> </span>Common handlers for the | ||
| 941 : | undo and redo commands will be provided.<span style='mso-spacerun:yes'> | ||
| 942 : | sfranklin | 1.5 | </span>These handlers can be assigned an undo context that should be used to |
| 943 : | filter the undo and redo history.<span style='mso-spacerun:yes'> </span>The | ||
| 944 : | handlers are responsible for the following:<o:p></o:p></span></p> | ||
| 945 : | sfranklin | 1.3 | |
| 946 : | <ul style='margin-top:0in' type=disc> | ||
| 947 : | sfranklin | 1.5 | <li class=MsoNormal style='mso-list:l9 level1 lfo11;tab-stops:list .5in'><span |
| 948 : | sfranklin | 1.3 | style='font-size:10.0pt;font-family:Arial'>Undo and Redo commands will be |
| 949 : | enabled based on the status of the history.<o:p></o:p></span></li> | ||
| 950 : | sfranklin | 1.5 | <li class=MsoNormal style='mso-list:l9 level1 lfo11;tab-stops:list .5in'><span |
| 951 : | sfranklin | 1.3 | style='font-size:10.0pt;font-family:Arial'>The Undo and Redo commands will |
| 952 : | be appended with the label of the operation for the handler’s context.<o:p></o:p></span></li> | ||
| 953 : | sfranklin | 1.5 | <li class=MsoNormal style='mso-list:l9 level1 lfo11;tab-stops:list .5in'><span |
| 954 : | style='font-size:10.0pt;font-family:Arial'>The handlers can be configured | ||
| 955 : | to flush the undo and redo history for their context whenever the most | ||
| 956 : | recent operation in the history is invalid.<span | ||
| 957 : | style='mso-spacerun:yes'> </span>This aggressive maintenance of the | ||
| 958 : | history is the most conservative approach for ensuring that the history | ||
| 959 : | contains valid operations, and this strategy may evolve with experience.<span | ||
| 960 : | style='mso-spacerun:yes'> </span>Localized undo contexts, such as text | ||
| 961 : | edits, may not need this aggressive pruning of the history.<o:p></o:p></span></li> | ||
| 962 : | sfranklin | 1.3 | </ul> |
| 963 : | |||
| 964 : | <h3>Undo and Redo Toolbar Items</h3> | ||
| 965 : | |||
| 966 : | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>Time | ||
| 967 : | permitting, classes that support toolbar dropdown items for undo and redo will | ||
| 968 : | be developed.<span style='mso-spacerun:yes'> </span>These will also be | ||
| 969 : | assigned a context.<span style='mso-spacerun:yes'> </span>By clicking on the | ||
| 970 : | drop-down arrow, the user will see the history for that particular | ||
| 971 : | context.<span style='mso-spacerun:yes'> </span>The user will only be able to | ||
| 972 : | select a range, starting from the top item, to be undone or redone.<span | ||
| 973 : | style='mso-spacerun:yes'> </span>It is expected that the ability to view the | ||
| 974 : | history is more valuable to the user than the ability to multi-select | ||
| 975 : | operations for undo.<o:p></o:p></span></p> | ||
| 976 : | nick | 1.1 | |
| 977 : | sfranklin | 1.3 | <h3>Operation Approvers</h3> |
| 978 : | nick | 1.1 | |
| 979 : | sfranklin | 1.5 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>The <span |
| 980 : | class=SpellE>IOperationApprover</span> installed by the workbench enforces a | ||
| 981 : | per-context linear undo model by consulting all contexts of an operation to | ||
| 982 : | determine whether undo or redo should proceed.<span style='mso-spacerun:yes'> | ||
| 983 : | </span>The policy is described as follows:<o:p></o:p></span></p> | ||
| 984 : | nick | 1.1 | |
| 985 : | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></p> | ||
| 986 : | |||
| 987 : | sfranklin | 1.3 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>The |
| 988 : | workbench will allow undo or redo of any valid operation in the history, <i | ||
| 989 : | style='mso-bidi-font-style:normal'>as long as there are no more recent | ||
| 990 : | operations in the history that share a context with the operation to be | ||
| 991 : | sfranklin | 1.4 | executed.</i><span style='mso-spacerun:yes'> </span>If the operation to be |
| 992 : | sfranklin | 1.3 | undone or redone has contexts that are also present in operations appearing |
| 993 : | later in the history, then the undo or redo of the operation will not be | ||
| 994 : | permitted.<o:p></o:p></span></p> | ||
| 995 : | nick | 1.1 | |
| 996 : | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></p> | ||
| 997 : | |||
| 998 : | sfranklin | 1.3 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>A concrete |
| 999 : | example will help explain this.<span style='mso-spacerun:yes'> </span><o:p></o:p></span></p> | ||
| 1000 : | |||
| 1001 : | <ol style='margin-top:0in' start=1 type=1> | ||
| 1002 : | sfranklin | 1.5 | <li class=MsoNormal style='mso-list:l4 level1 lfo14;tab-stops:list .5in'><span |
| 1003 : | sfranklin | 1.3 | style='font-size:10.0pt;font-family:Arial'>The user makes local edits in |
| 1004 : | editor A.<o:p></o:p></span></li> | ||
| 1005 : | sfranklin | 1.5 | <li class=MsoNormal style='mso-list:l4 level1 lfo14;tab-stops:list .5in'><span |
| 1006 : | sfranklin | 1.3 | style='font-size:10.0pt;font-family:Arial'>The user initiates a |
| 1007 : | refactoring operation whose context is “A” and “workspace.”<o:p></o:p></span></li> | ||
| 1008 : | sfranklin | 1.5 | <li class=MsoNormal style='mso-list:l4 level1 lfo14;tab-stops:list .5in'><span |
| 1009 : | sfranklin | 1.3 | style='font-size:10.0pt;font-family:Arial'>The user makes additional local |
| 1010 : | edits to editor A.<o:p></o:p></span></li> | ||
| 1011 : | sfranklin | 1.5 | <li class=MsoNormal style='mso-list:l4 level1 lfo14;tab-stops:list .5in'><span |
| 1012 : | sfranklin | 1.3 | style='font-size:10.0pt;font-family:Arial'>The user goes to the navigator |
| 1013 : | and selects Undo.<o:p></o:p></span></li> | ||
| 1014 : | </ol> | ||
| 1015 : | nick | 1.1 | |
| 1016 : | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></p> | ||
| 1017 : | |||
| 1018 : | sfranklin | 1.4 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>In the |
| 1019 : | proposed implementation, the navigator requests an undo for the workspace | ||
| 1020 : | context.<span style='mso-spacerun:yes'> </span>The refactoring operation | ||
| 1021 : | triggered in the editor is the most recent operation that has the workspace | ||
| 1022 : | context, but it also contains context “A.”<span style='mso-spacerun:yes'> | ||
| 1023 : | </span>Since subsequent operations in the history also have context “A,”, the | ||
| 1024 : | operation will not be allowed.<span style='mso-spacerun:yes'> </span>An | ||
| 1025 : | explanation will be provided to the user after the fact:<span | ||
| 1026 : | style='mso-spacerun:yes'> </span>“Cannot undo the refactoring operation | ||
| 1027 : | because there have been subsequent changes to A.”<span | ||
| 1028 : | style='mso-spacerun:yes'> </span><o:p></o:p></span></p> | ||
| 1029 : | nick | 1.1 | |
| 1030 : | sfranklin | 1.3 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></p> |
| 1031 : | |||
| 1032 : | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>Future | ||
| 1033 : | releases may warn the user or provide a preference to determine whether the | ||
| 1034 : | undo should proceed anyway, and whether the subsequent changes to “A” should | ||
| 1035 : | also be undone, or be flushed from the history. Early prototypes of the | ||
| 1036 : | framework showed that such warnings interrupt workflow and can be very | ||
| 1037 : | difficult to understand, so the initial UI will be to prohibit the undo, | ||
| 1038 : | explaining why.<span style='mso-spacerun:yes'> </span><o:p></o:p></span></p> | ||
| 1039 : | |||
| 1040 : | <h2>Migration Examples</h2> | ||
| 1041 : | nick | 1.1 | |
| 1042 : | sfranklin | 1.3 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>The |
| 1043 : | following examples explain how existing code can be migrated to use the | ||
| 1044 : | operations framework.<span style='mso-spacerun:yes'> </span>An early prototype | ||
| 1045 : | used these techniques to integrate the SDK text editor, refactoring framework, | ||
| 1046 : | and sample applications into a common undo framework.<span | ||
| 1047 : | style='mso-spacerun:yes'> </span></span></p> | ||
| 1048 : | |||
| 1049 : | <h3>Mapping existing actions or command handlers to operations</h3> | ||
| 1050 : | |||
| 1051 : | sfranklin | 1.5 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>Converting an |
| 1052 : | existing action to use operations is straightforward, apart from implementing | ||
| 1053 : | the undo and redo behavior for the action.<span style='mso-spacerun:yes'> | ||
| 1054 : | </span>The run() or <span class=SpellE>runWithEvent</span> method inside the | ||
| 1055 : | action should create an operation, execute it, and add it to the operations | ||
| 1056 : | history, rather than run the code inside the method.<span | ||
| 1057 : | sfranklin | 1.3 | style='mso-spacerun:yes'> </span>The following code shows the existing run() |
| 1058 : | sfranklin | 1.4 | method in the <span class=SpellE>EditorAction</span> of the <span class=SpellE>readme</span> |
| 1059 : | tool example (<span class=SpellE>org.eclipse.ui.examples.readmetool</span>):<o:p></o:p></span></p> | ||
| 1060 : | nick | 1.1 | |
| 1061 : | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></p> | ||
| 1062 : | |||
| 1063 : | sfranklin | 1.4 | <pre>public void run() {</pre><pre><span style='mso-spacerun:yes'> </span>String <span |
| 1064 : | class=SpellE>editorName</span> = <span class=SpellE>MessageUtil.getString</span>("<span | ||
| 1065 : | class=SpellE>Empty_Editor_Name</span>"); </pre><pre><span style='mso-spacerun:yes'> </span>if (<span | ||
| 1066 : | sfranklin | 1.5 | class=SpellE>activeEditor</span> != null)</pre><pre><span style='mso-spacerun:yes'> </span><span |
| 1067 : | sfranklin | 1.4 | class=SpellE>editorName</span> = <span class=SpellE>activeEditor.getTitle</span>();</pre><pre><span style='mso-spacerun:yes'> </span><span |
| 1068 : | class=SpellE>MessageDialog</span></pre><pre><span style='mso-spacerun:yes'> </span>.<span | ||
| 1069 : | class=SpellE>openInformation</span>(</pre><pre><span style='mso-spacerun:yes'> </span>shell,</pre><pre><span style='mso-spacerun:yes'> </span><span | ||
| 1070 : | class=SpellE>MessageUtil.getString</span>("<span class=SpellE>Readme_Editor</span>"), </pre><pre><span style='mso-spacerun:yes'> </span><span | ||
| 1071 : | class=SpellE>MessageUtil.format</span>("<span class=SpellE>ReadmeEditorActionExecuted</span>", </pre><pre><span | ||
| 1072 : | style='mso-tab-count:4'> </span>new Object[] { <span | ||
| 1073 : | class=SpellE>getText</span>(), <span class=SpellE>editorName</span> })); </pre><pre><span style='mso-spacerun:yes'> </span>}</pre><pre><span | ||
| 1074 : | sfranklin | 1.3 | style='font-family:Arial'>Using operations, the run method simplifies:<o:p></o:p></span></pre><pre><span |
| 1075 : | sfranklin | 1.4 | style='font-family:Arial'><o:p> </o:p></span></pre><pre><span style='mso-spacerun:yes'> </span>public void run() {</pre><pre><span style='mso-spacerun:yes'> </span>String <span |
| 1076 : | class=SpellE>editorName</span> = <span class=SpellE>MessageUtil.getString</span>("<span | ||
| 1077 : | sfranklin | 1.5 | class=SpellE>Empty_Editor_Name</span>"); </pre><pre><span style='mso-spacerun:yes'> </span>if (<span |
| 1078 : | sfranklin | 1.4 | class=SpellE>activeEditor</span> != null)</pre><pre><span style='mso-spacerun:yes'> </span><span |
| 1079 : | class=SpellE>editorName</span> = <span class=SpellE>activeEditor.getTitle</span>();</pre><pre><span style='mso-spacerun:yes'> </span>// create the operation</pre><pre><span style='mso-spacerun:yes'> </span><span | ||
| 1080 : | sfranklin | 1.5 | class=SpellE>IUndoableOperation</span> operation = new <span class=SpellE><span |
| 1081 : | class=GramE>EditorOperation</span></span><span class=GramE>(</span></pre><pre><span | ||
| 1082 : | sfranklin | 1.4 | style='mso-tab-count:2'> </span><span class=SpellE>getText</span>(),shell, <span |
| 1083 : | sfranklin | 1.5 | class=SpellE>editorName</span>);</pre><pre><span style='mso-spacerun:yes'> </span>// execute (and add to the history)</pre><pre><span style='mso-spacerun:yes'> </span><span |
| 1084 : | class=SpellE>history.execute</span>(operation, null, null);<span style='mso-spacerun:yes'> </span></pre><pre><span style='mso-spacerun:yes'> </span>}</pre><pre><span | ||
| 1085 : | sfranklin | 1.3 | style='font-family:Arial'>The operation encapsulates the old run behavior, as well as the undo and redo for the operation:<o:p></o:p></span></pre><pre><span |
| 1086 : | sfranklin | 1.4 | style='font-family:Arial'><o:p> </o:p></span></pre><pre>class <span |
| 1087 : | class=SpellE>EditorOperation</span> extends <span class=SpellE>AbstractOperation</span> {</pre><pre><span style='mso-spacerun:yes'> </span>Shell <span | ||
| 1088 : | class=SpellE>fShell</span>;</pre><pre><span style='mso-spacerun:yes'> </span>String <span | ||
| 1089 : | sfranklin | 1.5 | class=SpellE>fEditorName</span>;</pre><pre><span style='mso-spacerun:yes'> </span>public <span |
| 1090 : | sfranklin | 1.4 | class=SpellE>EditorOperation</span>(String label, Shell <span class=SpellE>shell</span>, String <span |
| 1091 : | class=SpellE>editorName</span>) {</pre><pre><span style='mso-spacerun:yes'> </span>super(label);</pre><pre><span style='mso-spacerun:yes'> </span><span | ||
| 1092 : | class=SpellE>fShell</span> = shell;</pre><pre><span style='mso-spacerun:yes'> </span><span | ||
| 1093 : | sfranklin | 1.5 | class=SpellE>fEditorName</span> = <span class=SpellE>editorName</span>;</pre><pre><span style='mso-spacerun:yes'> </span></pre><pre><span style='mso-spacerun:yes'> </span><span style='mso-spacerun:yes'> </span>}</pre><pre><span style='mso-spacerun:yes'> </span>public <span |
| 1094 : | class=SpellE>IStatus</span> execute(<span class=SpellE>IProgressMonitor</span> monitor) {</pre><pre><span style='mso-spacerun:yes'> </span><span | ||
| 1095 : | sfranklin | 1.4 | class=SpellE>MessageDialog.openInformation</span>(</pre><pre><span style='mso-spacerun:yes'> </span><span |
| 1096 : | class=SpellE>fShell</span>,</pre><pre><span style='mso-spacerun:yes'> </span><span | ||
| 1097 : | class=SpellE>MessageUtil.getString</span>("<span class=SpellE>Readme_Editor</span>"), </pre><pre><span style='mso-spacerun:yes'> </span><span | ||
| 1098 : | class=SpellE>MessageUtil.format</span>("<span class=SpellE>ReadmeEditorActionExecuted</span>", </pre><pre><span | ||
| 1099 : | style='mso-tab-count:3'> </span>new Object[] { <span | ||
| 1100 : | class=SpellE>getLabel</span>(), <span class=SpellE>fEditorName</span> }));<span style='mso-spacerun:yes'> </span></pre><pre><span style='mso-spacerun:yes'> </span>return <span | ||
| 1101 : | class=SpellE>Status.OK_STATUS</span>;</pre><pre><span style='mso-spacerun:yes'> </span>}</pre><pre><span style='mso-spacerun:yes'> </span>public <span | ||
| 1102 : | class=SpellE>IStatus</span> undo(<span class=SpellE>IProgressMonitor</span> monitor) {</pre><pre><span style='mso-spacerun:yes'> </span>// implement the undo here</pre><pre><span style='mso-spacerun:yes'> </span>return <span | ||
| 1103 : | sfranklin | 1.5 | class=SpellE>Status.OK_STATUS</span>;</pre><pre><span style='mso-spacerun:yes'> </span>}</pre><pre><span style='mso-spacerun:yes'> </span><span style='mso-spacerun:yes'> </span>public <span |
| 1104 : | sfranklin | 1.4 | class=SpellE>IStatus</span> redo(<span class=SpellE>IProgressMonitor</span> monitor) {</pre><pre><span style='mso-spacerun:yes'> </span>// implement the redo here</pre><pre><span style='mso-spacerun:yes'> </span>return <span |
| 1105 : | class=SpellE>Status.OK_STATUS</span>;</pre><pre><span style='mso-spacerun:yes'> </span>}</pre><pre><span style='mso-spacerun:yes'> </span>}</pre><pre><o:p> </o:p></pre><pre><span | ||
| 1106 : | style='font-family:Arial'>If an <span class=SpellE>IHandler</span> is provided for a command instead of using actions, the execute method of the handler is mapped similarly to the run method in an action:<o:p></o:p></span></pre><pre><span | ||
| 1107 : | style='font-family:Arial'><o:p> </o:p></span></pre><pre><span style='mso-spacerun:yes'> </span>public Object execute(Map <span | ||
| 1108 : | class=SpellE>params</span>) throws <span class=SpellE>ExecutionException</span> {</pre><pre><span style='mso-spacerun:yes'> </span>try {</pre><pre><span | ||
| 1109 : | style='mso-tab-count:1'> </span><span style='mso-spacerun:yes'> </span><span | ||
| 1110 : | class=SpellE>IEditorPart</span> <span class=SpellE>activeEditor</span> = <span | ||
| 1111 : | class=SpellE>params.get</span>("ACTIVE_EDITOR");</pre><pre><span | ||
| 1112 : | style='mso-tab-count:1'> </span><span style='mso-spacerun:yes'> </span>Shell <span | ||
| 1113 : | class=SpellE>shell</span> = <span class=SpellE>params.get</span>("SHELL");</pre><pre><span | ||
| 1114 : | style='mso-tab-count:1'> </span><span style='mso-spacerun:yes'> </span>String label = <span | ||
| 1115 : | class=SpellE>params.get</span>("NAME");</pre><pre><span | ||
| 1116 : | style='mso-tab-count:1'> </span><span style='mso-spacerun:yes'> </span>String <span | ||
| 1117 : | class=SpellE>editorName</span> = <span class=SpellE>MessageUtil.getString</span>("<span | ||
| 1118 : | class=SpellE>Empty_Editor_Name</span>"); </pre><pre><span style='mso-spacerun:yes'> </span>if (<span | ||
| 1119 : | class=SpellE>activeEditor</span> != null)</pre><pre><span style='mso-spacerun:yes'> </span><span | ||
| 1120 : | class=SpellE>editorName</span> = <span class=SpellE>activeEditor.getTitle</span>();</pre><pre><span style='mso-spacerun:yes'> </span>// create the operation</pre><pre><span style='mso-spacerun:yes'> </span><span | ||
| 1121 : | sfranklin | 1.5 | class=SpellE>IUndoableOperation</span> operation =new <span class=SpellE><span |
| 1122 : | class=GramE>EditorOperation</span></span><span class=GramE>(</span>label, shell, <span | ||
| 1123 : | sfranklin | 1.4 | class=SpellE>editorName</span>);</pre><pre><o:p> </o:p></pre><pre><span style='mso-spacerun:yes'> </span>// execute (and add to the history)</pre><pre><span style='mso-spacerun:yes'> </span><span |
| 1124 : | sfranklin | 1.5 | class=SpellE><span class=GramE>history.execute</span></span><span class=GramE>(</span>operation, null, null);</pre><pre><span style='mso-spacerun:yes'> </span>} catch (Exception e) {</pre><pre><span style='mso-spacerun:yes'> </span>throw new <span |
| 1125 : | sfranklin | 1.4 | class=SpellE>ExecutionException</span>(</pre><pre><span style='mso-spacerun:yes'> </span>"While executing the operation, an exception occurred", e); </pre><pre><span style='mso-spacerun:yes'> </span>}</pre><pre><span style='mso-spacerun:yes'> </span>return null;</pre><pre><span style='mso-spacerun:yes'> </span>}</pre><pre><span |
| 1126 : | style='font-family:Arial'><o:p> </o:p></span></pre> | ||
| 1127 : | |||
| 1128 : | <p class=MsoNormal><span class=GramE><span style='font-size:10.0pt;font-family: | ||
| 1129 : | Arial'>When an action launches a wizard.</span></span><span style='font-size: | ||
| 1130 : | 10.0pt;font-family:Arial'> <span class=GramE>then</span> the operation is | ||
| 1131 : | typically created as part of processing the “Finish” button in the wizard.<span | ||
| 1132 : | style='mso-spacerun:yes'> </span>Some restructuring may be required.<span | ||
| 1133 : | style='mso-spacerun:yes'> </span>For example, wizards are often implemented in | ||
| 1134 : | hierarchies and make use of convenience methods in the wizard hierarchy.<span | ||
| 1135 : | style='mso-spacerun:yes'> </span>Some of these methods may have to move to a | ||
| 1136 : | corresponding hierarchy of operations. <o:p></o:p></span></p> | ||
| 1137 : | sfranklin | 1.3 | |
| 1138 : | <h3>Refactoring example:<span style='mso-spacerun:yes'> </span>mapping | ||
| 1139 : | sfranklin | 1.5 | existing protocol to <span class=SpellE>IUndoableOperation</span></h3> |
| 1140 : | sfranklin | 1.3 | |
| 1141 : | sfranklin | 1.5 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>In the |
| 1142 : | current SDK implementation, <span class=SpellE>org.eclipse.ltk.core.refactoring</span> | ||
| 1143 : | sfranklin | 1.4 | provides an undo framework for undoing refactoring operations.<span |
| 1144 : | style='mso-spacerun:yes'> </span>This framework is based on the notion of | ||
| 1145 : | “Change” objects.<span style='mso-spacerun:yes'> </span>Change objects that | ||
| 1146 : | can be undone are responsible for returning the undo version of a change when | ||
| 1147 : | they are executed.<span style='mso-spacerun:yes'> </span>An undo stack is | ||
| 1148 : | maintained by an internal undo manager.<span style='mso-spacerun:yes'> | ||
| 1149 : | </span>This undo manager invalidates the history whenever an unknown workspace | ||
| 1150 : | change occurs.<span style='mso-spacerun:yes'> </span>Undo-aware objects send | ||
| 1151 : | signals to the undo manager as they perform operations, so that the undo | ||
| 1152 : | manager will not invalidate the history.<o:p></o:p></span></p> | ||
| 1153 : | nick | 1.1 | |
| 1154 : | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></p> | ||
| 1155 : | |||
| 1156 : | sfranklin | 1.3 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>A prototype |
| 1157 : | integrated the refactoring change framework with the operations framework as | ||
| 1158 : | follows:<o:p></o:p></span></p> | ||
| 1159 : | nick | 1.1 | |
| 1160 : | sfranklin | 1.5 | <p class=MsoNormal style='margin-left:39.0pt;text-indent:-.25in;mso-list:l5 level1 lfo16; |
| 1161 : | sfranklin | 1.3 | tab-stops:list 39.0pt'><![if !supportLists]><span style='font-size:10.0pt; |
| 1162 : | font-family:Arial;mso-fareast-font-family:Arial'><span style='mso-list:Ignore'>1.<span | ||
| 1163 : | style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span | ||
| 1164 : | sfranklin | 1.5 | style='font-size:10.0pt;font-family:Arial'>The change objects are <span |
| 1165 : | class=SpellE>wrappered</span> with a class that implements <span class=SpellE>IUndoableOperation</span> | ||
| 1166 : | and maps the operation protocol to the Change protocol.<o:p></o:p></span></p> | ||
| 1167 : | sfranklin | 1.3 | |
| 1168 : | sfranklin | 1.5 | <p class=MsoNormal style='margin-left:39.0pt;text-indent:-.25in;mso-list:l5 level1 lfo16; |
| 1169 : | sfranklin | 1.3 | tab-stops:list 39.0pt'><![if !supportLists]><span style='font-size:10.0pt; |
| 1170 : | font-family:Arial;mso-fareast-font-family:Arial'><span style='mso-list:Ignore'>2.<span | ||
| 1171 : | style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span | ||
| 1172 : | sfranklin | 1.5 | style='font-size:10.0pt;font-family:Arial'>The refactoring undo manager is |
| 1173 : | sfranklin | 1.3 | replaced with an alternate implementation that uses the operations history to |
| 1174 : | maintain the undo and redo history.<o:p></o:p></span></p> | ||
| 1175 : | nick | 1.1 | |
| 1176 : | sfranklin | 1.5 | <p class=MsoNormal style='margin-left:39.0pt;text-indent:-.25in;mso-list:l5 level1 lfo16; |
| 1177 : | sfranklin | 1.3 | tab-stops:list 39.0pt'><![if !supportLists]><span style='font-size:10.0pt; |
| 1178 : | font-family:Arial;mso-fareast-font-family:Arial'><span style='mso-list:Ignore'>3.<span | ||
| 1179 : | style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span | ||
| 1180 : | sfranklin | 1.5 | style='font-size:10.0pt;font-family:Arial'>The workspace listener and |
| 1181 : | validation strategy used in the Change framework is maintained, since the | ||
| 1182 : | timing of the notifications was critical.<span style='mso-spacerun:yes'> | ||
| 1183 : | </span>Additional integration work could be done to use the operations history | ||
| 1184 : | listeners for the same purpose, or to change the validation strategy as more | ||
| 1185 : | workspace operations are supported outside of refactoring.<o:p></o:p></span></p> | ||
| 1186 : | nick | 1.1 | |
| 1187 : | sfranklin | 1.5 | <p class=MsoNormal style='margin-left:39.0pt;text-indent:-.25in;mso-list:l5 level1 lfo16; |
| 1188 : | sfranklin | 1.3 | tab-stops:list 39.0pt'><![if !supportLists]><span style='font-size:10.0pt; |
| 1189 : | font-family:Arial;mso-fareast-font-family:Arial'><span style='mso-list:Ignore'>4.<span | ||
| 1190 : | style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span | ||
| 1191 : | sfranklin | 1.5 | style='font-size:10.0pt;font-family:Arial'>When a refactoring change is |
| 1192 : | executed, an operation is “opened” in the operations history.<span | ||
| 1193 : | style='mso-spacerun:yes'> </span>Subsequent operations added to the history | ||
| 1194 : | are considered part of the open operation, and their contexts are assigned to | ||
| 1195 : | the original operation.<span style='mso-spacerun:yes'> </span>When the | ||
| 1196 : | refactoring change is finished, the operation is closed.<span | ||
| 1197 : | style='mso-spacerun:yes'> </span><o:p></o:p></span></p> | ||
| 1198 : | nick | 1.1 | |
| 1199 : | sfranklin | 1.5 | <p class=MsoNormal style='margin-left:39.0pt;text-indent:-.25in;mso-list:l5 level1 lfo16; |
| 1200 : | sfranklin | 1.3 | tab-stops:list 39.0pt'><![if !supportLists]><span style='font-size:10.0pt; |
| 1201 : | font-family:Arial;mso-fareast-font-family:Arial'><span style='mso-list:Ignore'>5.<span | ||
| 1202 : | style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span | ||
| 1203 : | style='font-size:10.0pt;font-family:Arial'>Refactoring operations could be | ||
| 1204 : | undone and redone from any view or editor that installed the undo and redo | ||
| 1205 : | handlers on the workspace context.<o:p></o:p></span></p> | ||
| 1206 : | |||
| 1207 : | sfranklin | 1.4 | <h3>Text editor example:<span style='mso-spacerun:yes'> </span>implementing <span |
| 1208 : | sfranklin | 1.5 | class=SpellE>IUndoableOperation</span> in preexisting commands</h3> |
| 1209 : | sfranklin | 1.3 | |
| 1210 : | sfranklin | 1.4 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>The <span |
| 1211 : | class=SpellE>JFace</span> text framework supports undo and redo of text editing | ||
| 1212 : | operations.<span style='mso-spacerun:yes'> </span>This implementation relies | ||
| 1213 : | on private undo stacks that are maintained by each editor.<span | ||
| 1214 : | style='mso-spacerun:yes'> </span>The <span class=SpellE>JFace</span> <span | ||
| 1215 : | class=SpellE>IUndoManager</span> listens to text changes coming from the | ||
| 1216 : | underlying widget, and builds a <span class=SpellE>TextCommand</span> for each | ||
| 1217 : | undoable edit.<span style='mso-spacerun:yes'> </span><o:p></o:p></span></p> | ||
| 1218 : | nick | 1.1 | |
| 1219 : | sfranklin | 1.3 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></p> |
| 1220 : | nick | 1.1 | |
| 1221 : | sfranklin | 1.3 | <p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>A prototype |
| 1222 : | sfranklin | 1.4 | integrated the text undo in <span class=SpellE>JFace</span> with the operations |
| 1223 : | framework as follows:<o:p></o:p></span></p> | ||
| 1224 : | nick | 1.1 | |
| 1225 : | sfranklin | 1.3 | <ol style='margin-top:0in' start=1 type=1> |
| 1226 : | sfranklin | 1.5 | <li class=MsoNormal style='mso-list:l8 level1 lfo19;tab-stops:list .5in'><span |
| 1227 : | sfranklin | 1.4 | style='font-size:10.0pt;font-family:Arial'>The existing <span |
| 1228 : | class=SpellE>TextCommand</span> was altered to implement the <span | ||
| 1229 : | sfranklin | 1.5 | class=SpellE>IUndoableOperation</span> interface.<o:p></o:p></span></li> |
| 1230 : | <li class=MsoNormal style='mso-list:l8 level1 lfo19;tab-stops:list .5in'><span | ||
| 1231 : | sfranklin | 1.3 | style='font-size:10.0pt;font-family:Arial'>Specialized contexts (one |
| 1232 : | instance for each text editor) are assigned to the operations.<o:p></o:p></span></li> | ||
| 1233 : | sfranklin | 1.5 | <li class=MsoNormal style='mso-list:l8 level1 lfo19;tab-stops:list .5in'><span |
| 1234 : | sfranklin | 1.4 | style='font-size:10.0pt;font-family:Arial'>The existing <span |
| 1235 : | class=SpellE>UndoManager</span> was replaced with an alternate | ||
| 1236 : | implementation that added text commands to the operations history instead | ||
| 1237 : | of a local stack, and used the operation history protocol when handling | ||
| 1238 : | undo and redo commands.<o:p></o:p></span></li> | ||
| 1239 : | sfranklin | 1.3 | </ol> |
| 1240 : | nick | 1.1 | |
| 1241 : | sfranklin | 1.3 | <p class=MsoNormal style='text-align:justify'><span style='font-size:10.0pt; |
| 1242 : | font-family:Arial'><o:p> </o:p></span></p> | ||
| 1243 : | nick | 1.1 | |
| 1244 : | </div> | ||
| 1245 : | |||
| 1246 : | </body> | ||
| 1247 : | |||
| 1248 : | </html> |
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