Ease of Editing

As a language engineer, you can make editing a little bit easier for your users. Freon offers two options to do so.

Reference Shortcuts

In the actual abstract syntax tree, a reference property is stored as a node that holds the information about, and a link to, the referred node. The type of this node is FreNodeReference. When creating a new reference property, this means that two actions need to be executed by Freon. First, the FreNodeReference instance needs to be created, and second, the link needs to be established between this FreNodeReference instance and the node that is referred to.

To hide exposing this two-step process to the user, the language engineer may define a reference shortcut. This is a property defined directly on the concept, and when selected by the user causes this two-step process to be performed as one. This can be useful, especially when dealing with expressions.

Our running example provides the expression concept InsurancePartRef.

// Insurance/src/defs/language-expressions.ast#L54-L57

// Expression used to refer to the insurance parts of a product
expression InsurancePartRef base DocuExpression {
    reference part: InsurancePart;
}

For this concept the following projection is defined.

// Insurance/src/defs/editor-expressions-default.edit#L35-L38

InsurancePartRef {
    [${self.part}]
    referenceShortcut = ${self.part}
}

Triggers

When the user wants to create an instance of a concept using the keyboard, a special character or string of characters can be used to trigger the creation of that instance. This makes entering expressions in the projectional editor feel more like typing them in a text-based editor. The character or string of characters is called a trigger.

The example shows a trigger for entering a function call expression.

// Insurance/src/defs/editor-expressions-default.edit#L30-L34

FunctionCallExpression {
    [${funcDefinition} ( ${args horizontal separator[,] } )]
    referenceShortcut = ${funcDefinition}
    trigger = "calc"
}