The Content Assist facilities described here are used by the Interactive OCL Console. They are not used by the new Xtext-based Editors or the Interactive Xtext OCL Console.
The
OCLHelper
API provides support for content-assist in rich editors, by parsing partial OCL
expressions and supplying completion suggestions. The
List<Choice> getSyntaxHelp(ConstraintKind, String) operation
returns a list of suggestions for the next token to follow the end of the
expression fragment.
The
Choice
objects returned by the helper include some convenient text strings (name and
description) to formulate basic JFace content-assist proposals. Each choice
also carries a reference to the element that it represents, the kind of element
indicated by the
ChoiceKind enumeration, for a more
sophisticated content assist that might inlude context information, documentation,
etc. as in Eclipse JDT. The list of choices depends in part on the kind of
constraint expression that is to be completed, as for example, the
oclIsNew() operation is only permitted in operation
post-conditions.
helper.setContext(EXTLibraryPackage.Literals.BOOK);
List<Choice> choices = helper.getSyntaxHelp(ConstraintKind.INVARIANT,
"Book.allInstances()->collect(author)->");
for (Choice next : choices) {
switch (next.getKind()) {
case OPERATION:
case SIGNAL:
// the description is already complete
System.out.println(next.getDescription());
case PROPERTY:
case ENUMERATION_LITERAL:
case VARIABLE:
System.out.println(next.getName() + " : " + next.getDescription();
break;
default:
System.out.println(next.getName());
break;
}
}
The computation of
Choice s is supported for the
following tokens, which may be used by a client as auto-assist triggers:
| Token | Completion choices |
|---|---|
.
|
Features applicable to the type of the expression to the left of the dot, or its element type if it is a collection. association classes (in the UML environment only) |
->
|
Collection operations and iterators |
::
|
Packages, types, enumeration literals, and states (in the UML environment only) |
^
|
Operations and signals (in the UML environment only) |
^^
|
|
In other situations, the choices the current context variables and implicit references to features of the
self variable. For example, if the input is something like
"" or
"self.isOrdered and "
|
Content-assist triggers
The completion of partially specified identifiers is also supported, by backtracking to look for one of these triggering tokens. This supports interactively narrowing the choices while the content-assist window is active.
choices = helper.getSyntaxHelp(ConstraintKind.POSTCONDITION,
"self.author.oclIs");