Since 3.2, Acceleo offers a full-featured live request interpreter. Since 3.5, It offers the same full-featured live request interpreter for the ocl language. We just need to select the used language (Acceleo, OCL) then type the expression to evaluate and select its context. In addition, Acceleo offers now an evaluation of a complete OCL resource. In this case, we just need to type or import an existing ocl file to the view then select a context to evaluate. We will focus here on detailing all of this view's possibilities.
- 1 Breakdown
- 2 Changing the interpreter context
- 3 Extensibility
First things first, what are all of these menus and fields for?
The title of the interpreter features a drop-down menu that allows the user to select the language of his expressions. By default, Acceleo provides the interpreter for itself 'Acceleo' and proposes the pure 'OCL' language as an alternative language and allow to evaluate a complete ocl resource by selecting the 'Complete OCL' choice, but any third-party plugin can come and add its own language to the list. More on the extension in the Extensibility section.
The expression section allows users to enter and edit expressions for the selected language. Note that for the OCL Language users can evaluate single constraints and complete OCL Resources. The expression can be fully customized by language providers and can thus become as powerful as a full-fledged editor for that language. Completion proposals and syntax highlighting are available by default for the selected language in the interpreter.
The expression will be interpreted on the fly as it is typed if the Real-time toggle is activated (located at the upper-right of the view, 6 in the above breakdown). Otherwise, users can call for the evaluation at any given time through either :
- Right-click in the expression view, then hit evaluate
- Hit the Evaluate icon of the expression section
- Use the CTRL + SHIFT + D keyboard shortcut
This section displays the result of evaluations in the form of a tree. There are multiple possibilities as to the result look-and-feel :
- Collection result : each of the collection's values will be displayed as one row of the result tree.
- Single object : if the result consists of a single, plain object, it will be displayed as the only row of the tree.
Each row of the tree can be displayed in a number of ways, depending on the object's type. The objects are usually displayed as they would in their own editors, but two types of generated objects are displayed in a special manner :
If the result is a string, its very first line will be displayed as the Tree's row.
If the string is longer than a single line, its full length can be seen in two ways :
- Hover : Hovering the mouse over the row
- Popup : Double-clicking the row
The interpreter allows you to generate "files". No file will actually be generated on disk; instead the interpreter will display them in their own special way, with the icon corresponding to their type (as known to Eclipse) and their content as a child row :
A double-click on the "file" row will open a read-only editor for the file, along with all of the syntax highlighting this editor may have. (partial exemple of a "java" file opened through this action below)
This section is OCL specific and will be empty for other languages. It displays the ocl sub-expressions of the entered user expression in the form of tree.
Each sub expression can be evaluated by clicking on the corresponding tree row in the "Sub-Expressions" section. The result is displayed in the form of tree for each sub-expression.
The variables will be displayed as a Tree, with variable names as the root, and their value(s) as children. They can be used in any expression with only their name :
Existing variables can be renamed or deleted through the right-click menu, or through the F2 (rename) and del (delete) keyboard shortcuts.
New variable wizard
A wizard to create new primitive variables can be initiated through a right-click in the Variables view and selecting the New Variable action.
The wizard itself consists of a single page that allows users to select a name for the new variable, and a primitive value (String, Boolean, Integer or Float).
If the selected name matches that of an existing variable, the new value will be added to that existing variable's list of values.
Drag and Drop
The variable view supports drag and drop from almost any other view, or editor. As long as the "other view" enables dragging, the variable viewer will accept the "drop" and create a new variable with the dropped element as its value. Dropped elements can be either primitives (String, integer, float...), EObjects (elements dropped from an EMF model) or plain Java Objects.
What you can do with the values of these variables, however, depends on the current interpreted language.
The interpreter view will use this field in order to display the various issues and information the user might need. Namely, the compilation warnings and errors if any are sprung by the current expression, evaluation warnings and errors if the compilation went fine, but the evaluation did not... and if all went well, the evaluation result's type and length.
Some examples of this include :
The toolbar of this view features a number of actions, the first part being provided by the view itself while the second half is contributed by extending language interpreters. Following is the rundown of the actions that are available by default, when a specific language is selected in the interpreter.
This toggle allows users to hide or display the "Sub-Expressions" section of the interpreter.
This toggle allows ursers to hide or display the "Variables" section of the interpreter.
This toggle activates or disables the real-time compilation of expressions, letting the user decide when to launch evaluations or doing it on-the-fly while he types.
This action is provided by the interpreter view itself, yet it is up to the selected language to accept the link or not. In the case of Acceleo, this action is honored if the current editor is an Acceleo editor opened on an Acceleo module.
Hitting this action when an Acceleo editor is opened links the interpreter with the opened module, enabling the user to use the queries and templates defined, imported or inherited by that module.
This action is Acceleo specific and will not be displayed for other languages. It will allow the user to save the current expression as a new template or a new query in a module of his choice.
Changing the interpreter context
Linking with an editor
Working with the debugging context
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