Difference between revisions of "Henshin/Units"
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| − | + | [[Category:Henshin]][[Category:Modeling]] | |
| − | + | In Henshin, control flow is specified using '''units'''. | |
| + | Units have a fixed number of sub-units, allowing for arbitrary nesting. | ||
| + | This article describes the available units. | ||
| − | + | Units can be categorized by their possible number of sub-units. | |
| + | For '''unary units''' the number of sub-units is exactly one. | ||
| + | '''Multi-units''' have an arbitrary number of sub-units. | ||
| + | The specific unit ''Conditional Unit'' has two or three sub-units. | ||
| + | |||
| + | Each unit checks the executability of at least one sub-unit, if a sub-unit exists. | ||
| + | This check means the sub-unit is executed. | ||
== Usage == | == Usage == | ||
| Line 38: | Line 46: | ||
=== Loop Unit === | === Loop Unit === | ||
| − | [[Image:Henshin_Loop_Unit.png|right]] | + | [[Image:Henshin_Loop_Unit.png|right|thumb|Apply A as often as possible]] |
* '''Number of sub-units:''' 1 | * '''Number of sub-units:''' 1 | ||
| Line 48: | Line 56: | ||
=== Iterated Unit === | === Iterated Unit === | ||
| − | [[Image:Henshin_Iterated_Unit.png|right]] | + | [[Image:Henshin_Iterated_Unit.png|right|thumb|Apply A three times]] |
* '''Number of sub-units:''' 1 | * '''Number of sub-units:''' 1 | ||
| Line 59: | Line 67: | ||
** '''strict=true, rollback=false:''' If one of the iterations cannot be executed, the execution stops. | ** '''strict=true, rollback=false:''' If one of the iterations cannot be executed, the execution stops. | ||
** '''strict=true, rollback=true:''' If one of the iterations cannot be executed, the execution stops and previous executions are reverted. | ** '''strict=true, rollback=true:''' If one of the iterations cannot be executed, the execution stops and previous executions are reverted. | ||
| + | * '''Examples:''' [https://www.eclipse.org/henshin/examples.php?example=combpattern Grid & Comb Pattern] | ||
== Conditional Unit == | == Conditional Unit == | ||
| − | [[Image:Henshin_Conditional_Unit.png|right]] | + | [[Image:Henshin_Conditional_Unit.png|right|thumb|If A applicable then apply B, else apply C]] |
* '''Number of sub-units:''' 2 or 3 | * '''Number of sub-units:''' 2 or 3 | ||
| Line 68: | Line 77: | ||
* '''Execution successful if:''' ''if'' unit and ''then'' unit are successful or ''if'' unit is unsuccessful while ''else'' unit is successful or not present. | * '''Execution successful if:''' ''if'' unit and ''then'' unit are successful or ''if'' unit is unsuccessful while ''else'' unit is successful or not present. | ||
* '''Control flow:''' If a match for the ''if'' unit can be found, the ''then'' unit is executed. Otherwise, if present, the ''else'' unit is executed. | * '''Control flow:''' If a match for the ''if'' unit can be found, the ''then'' unit is executed. Otherwise, if present, the ''else'' unit is executed. | ||
| + | * '''Examples:''' [https://www.eclipse.org/henshin/examples.php?example=java2statemachine Java2StateMachine] | ||
== Multi-Units == | == Multi-Units == | ||
| Line 75: | Line 85: | ||
=== Sequential Unit=== | === Sequential Unit=== | ||
| − | [[Image:Henshin_Sequential_Unit.png|right]] | + | [[Image:Henshin_Sequential_Unit.png|right|thumb|Apply A then B then C]] |
* '''Number of sub-units:''' arbitrary (0..*) | * '''Number of sub-units:''' arbitrary (0..*) | ||
| Line 90: | Line 100: | ||
=== Priority Unit === | === Priority Unit === | ||
| − | [[Image:Henshin_Priority_Unit.png|right]] | + | [[Image:Henshin_Priority_Unit.png|right|thumb|Try to apply A. If A not applicable, try B etc.]] |
* '''Number of sub-units:''' arbitrary (0..*) | * '''Number of sub-units:''' arbitrary (0..*) | ||
| Line 100: | Line 110: | ||
=== Independent Unit === | === Independent Unit === | ||
| − | [[Image:Henshin_Independent_Unit.png|right]] | + | [[Image:Henshin_Independent_Unit.png|right|thumb|Choose A, B or C in non-deterministic order. If not applicable, try another one in non-deterministic order. If it is not applicable...]] |
* '''Number of sub-units:''' arbitrary (0..*) | * '''Number of sub-units:''' arbitrary (0..*) | ||
Revision as of 09:28, 7 May 2018
In Henshin, control flow is specified using units.
Units have a fixed number of sub-units, allowing for arbitrary nesting.
This article describes the available units.
Units can be categorized by their possible number of sub-units. For unary units the number of sub-units is exactly one. Multi-units have an arbitrary number of sub-units. The specific unit Conditional Unit has two or three sub-units.
Each unit checks the executability of at least one sub-unit, if a sub-unit exists. This check means the sub-unit is executed.
Contents
Usage
Unit creation in graphical editor
To add a unit to a Henshin project in the graphical editor, first open the *.henshin_diagram file. Then select Unit from the Palette on the right of the window. Afterwards left-click any empty space of the Henshin diagram and choose the desired unit from the appearing menu.
If the selected unit is a Multi-Unit, some sub-units have to be added manually. Therefore select Invocation from the Palette and click on the according Multi-Unit. Then type the name of the desired rule or unit. Currently every sub-unit is inserted behind all existing sub-units, which is especially relevant for PriorityUnits and SequentialUnits. If that's not the desired behaviour it is recommended to use the Properties view or the tree-based editor for sub-unit insertion or reordering.
Unit creation in tree-based editor
To add a unit to a Henshin project in the tree-based editor, first open the *.henshin file. Then right-click on the parent Module. Select New Child and afterwards the desired unit from the context menu. After creation the units can be edited in their Properties view.
Unary Units
A Unary Unit has exactly one sub-unit.
Loop Unit
- Number of sub-units: 1
- Available Flags/Properties: none
- Execution successful: always
- Control flow: The sub-unit is executed as often as it is executable.
- Examples: Java2StateMachine, Ecore2Genmodel
Iterated Unit
- Number of sub-units: 1
- Available Flags/Properties: iterations (integer), strict, rollback (both of type boolean)
- Execution successful if:
- strict=true: all iterations successful
- strict=false: at least one iteration successful
- Control flow: The sub-unit is executed as often as specified in the iterations property.
- strict=false, rollback=true/false: If one of the iterations cannot be executed, the next iteration is executed. As the execution never stops, the rollback flag has no effect.
- strict=true, rollback=false: If one of the iterations cannot be executed, the execution stops.
- strict=true, rollback=true: If one of the iterations cannot be executed, the execution stops and previous executions are reverted.
- Examples: Grid & Comb Pattern
Conditional Unit
- Number of sub-units: 2 or 3
- Available Flags/Properties: none
- Execution successful if: if unit and then unit are successful or if unit is unsuccessful while else unit is successful or not present.
- Control flow: If a match for the if unit can be found, the then unit is executed. Otherwise, if present, the else unit is executed.
- Examples: Java2StateMachine
Multi-Units
A Multi-Unit has an arbitrary number of sub-units.
Sequential Unit
- Number of sub-units: arbitrary (0..*)
- Available Flags/Properties: strict, rollback (both of type boolean)
- Execution successful if:
- strict=true: all sub-units successful or no sub-units existing
- strict=false: at least one sub-unit successful or no sub-units existing
- Control flow: The sub-units are executed in the given order.
- strict=false: If one of the sub-units cannot be executed, the next sub-unit is executed. As the execution never stops, the rollback flag has no effect.
- strict=true, rollback=false: If one of the sub-units cannot be executed, the execution stops.
- strict=true, rollback=true: If one of the sub-units cannot be executed, the execution stops and previous executions are reverted.
- Examples: Ecore2RDB, Java2StateMachine, Ecore2Genmodel, Grid & Comb Pattern, Movies
Priority Unit
- Number of sub-units: arbitrary (0..*)
- Available Flags/Properties: none
- Execution successful if: one sub-unit successful (Empty priority units always fail.)
- Control flow: The sub-units are checked in the given order for executability. The first sub-unit found to be executable is executed.
- Examples: Java2StateMachine
Independent Unit
- Number of sub-units: arbitrary (0..*)
- Available Flags/Properties: none
- Execution successful: one sub-unit succesful (Empty independent units always fail.)
- Control flow: The sub-units are checked in nondeterministic order for executability. The first sub-unit found to be executable is executed.
- Examples: Ecore2Genmodel