Command Line Compiler Quick Start Guide (pre 0.13)

An -based Project.

SCCharts are typically modeled using the textual SCT language defined as an Xtext grammar in KIELER. Generally, if you do not know which elements can be placed at a certain cursor position you are assisted by a content-assist that can be called pressing <Ctrl>+<Space>. It will display all possible valid elements also considering scoping of variables.

In the following we will demonstrate SCT using the famous ABRO example (the hello world of synchronous programming/modelling). We will then give details for modelling other SCCharts language constructs with SCT. For details on their semantics please be referred to  our PLDI paper [1].

• ABRO Example
• Detailed SCT Syntax of SCCharts Elements
  • SCChart, Initial State, State, Transition and Immediate Transition
  • Variable
  • Transition: Trigger & Effect
  • Super State
  • Super State: Final States & Termination Transition
  • Super State: Weak Abort Transition
  • Super State: Strong Abort Transition
  • Concurrent Regions (inside a Super State)
  • Entry Action, During Action, Exit Action
  • Shallow History Transition
  • Deep History Transition
  • Deferred Transition
  • Transition with Count Delay
  • Array
  • Signal
  • Reference States
• Hostcode
  • Function Calls
  • Hostcode (inline)
• Annotations
• Overview of Operators

[1] R. von Hanxleden, B. Duderstadt, C. Motika, S. Smyth, M. Mendler, J. Aguado, S. Mercer, and O. O’Brien. SCCharts: Sequentially Constructive Statecharts for Safety-Critical Applications. In Proc. ACM SIGPLAN Conference on Programming Language Design and Implementation (PLDI’14), Edinburgh, UK, June 2014. (pdf)

ABRO Example

In the following we will describe some basic elements using the famous ABRO example:

1. In the first line you see how an SCChart is defined using the scchart keyword where the ID of the SCChart will be ABRO. An optional label can be inserted after ABRO using "<LABEL>".
2. In the next three lines variables are declared, namely, A, B, R and O, where O is initialized with the value false. A, B, and R are inputs which must not be initialized and get there valued from the environment.
3. An SCChart typically contains concurrent regions which are introduced with the keyword region as shown in Line 9.
4. Every region must at least have one state, and every region must exactly have one initial state. An initial state ABO is defined for region Main in Line 6.
5. Every state is terminated by a ; as shown in line 11 for state HandleA.
6. If you like to specify internal behavior of a state, you can add concurrent regions to a state in { <regions> } as done for state ABO or state WaitAB.
7. Transitions outgoing from a state must be declared right before a state is terminated with ;. For example a transition from state wA to state dA is declared in Line 11.
8. Transitions can have triggers and effects which are separated by a dash: <trigger>/<effects>. Multiple sequential effects are separated by a ;. The transition in Line 11 declares just a trigger A (a dash is not necessary in this case), while the transition from line 18 declares only an effect O = true (here the dash is mandatory).
9. There are three types of transitions: 1. normal/weak abort transitions -->,  2. strong abort transitions o-> and 3. termination/join transitions >->.

Detailed SCT Syntax of SCCharts Elements

SCChart, Initial State, State, Transition and Immediate Transition

Variable

Transition: Trigger & Effect

Super State

Super State: Final States & Termination Transition

Super State: Weak Abort Transition

Super State: Strong Abort Transition

Concurrent Regions (inside a Super State)

Entry Action, During Action, Exit Action

Shallow History Transition

Deep History Transition

Deferred Transition

Transition with Count Delay

Array

Signal

Reference States

Important: To use the referenced SCCharts feature, activate the Xtext nature for your project!

Hostcode

You can also use you host language directly.

Function Calls

Call host code functions with dependency analysis. Use angle brackets to point to an extern function. You can also declare extern variables.

Hostcode (inline)

Inline hostcode just as it is. Use the @hostcode annotation to add hostcode line before the tick function. Also use hostcode in single quotes as hostcode effects.

Important: Inline hostcode is not type-safe. Be careful.

Annotations

The textual SCCharts language supports several annotations to influence the visual representation of the model.

Annotation are processed in sequential order.

Overview of Operators

The following briefly describes the operators that can be used in expressions.

Increment