Difference between revisions of "Henshin/Units"

Revision as of 11:31, 3 March 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.

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.

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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.

Multi-Units

Sequential Unit

Number of sub-units

arbitrary (0..*)

Available Flags/Properties

of type boolean

• strict
• rollback

Execution successful

if

strict=true

all sub-units successful

strict=false

at least one sub-unit successful or no sub-units

Execution unsuccessful

if

strict=true

one sub-unit unsuccessful

strict=false

none of a non-zero number of sub-units successful

Control flow

The sub-units are executed in the given order.

strict=false, rollback=true/false

If one of the sub-units cannot be executed, the next sub-unit is executed.

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.

Priority Unit

Number of sub-units

arbitrary (0..*)

Available Flags/Properties

none

Execution successful

one sub-unit successful

Execution unsuccessful

no sub-unit successful

Control flow

The sub-units are checked in the given order for executability. The first sub-unit found to be executable is executed.

Independent Unit

Number of sub-units

arbitrary (0..*)

Available Flags/Properties

none

Execution successful

one sub-unit succesful

Execution unsuccessful

no sub-unit successful

Control flow

The sub-units are checked in nondeterministic order for executability. The first sub-unit found to be executable is executed.

Unary Units

Loop Unit

Number of sub-units

1

Available Flags/Properties

none

Execution successful

tbd

Execution unsuccessful

tbd

Control flow

The sub-unit is executed as often as it is executable.

Iterated Unit

Number of sub-units

1

Available Flags/Properties

of type positive integer

• iterations

of type boolean

• strict
• rollback

Execution successful

if

strict=true

all iterations successful

strict=false

at least one iteration successful

Execution unsuccessful

if

strict=true

one iteration unsuccessful

strict=false

no 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.

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.

Conditional Unit

Number of sub-units

2 or 3

Available Flags/Properties

none

Execution successful

tbd

Execution unsuccessful

tbd

Control flow

tbd