Macros

Table of Contents

Declaration
Types
@macro_context annotation
The context

Declaration

MacroDecl = "macro" identifier "(" ParameterList ")" MacroBody "end" ;
MacroBody = { ( identifier | TemplateStmt ) ";" } ;

TemplateStmt      = LineTemplateStmt | BlockTemplateStmt ;
LineTemplateStmt  = "$" TemplateContent ;
BlockTemplateStmt = "!!" { TemplateContent } "!!" ;

TemplateContent is a bit more complex: it essentially is normal lapyst sourcecode but with one addition: everywhere a TemplateInterpolation can be placed.

TemplateInterpolation = "{{" identifier "}}" ;

A TemplateInterpolation itself is just used to inject a variable’s value inside the template.


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macro declare_method(ident name, type ret)
    $ dec {{ret}} {{name}}();
end
macro make_method(ident name, type ret, expr value)
    !!
        def {{ret}} {{name}}()
            return {{value}}
        end
    !!
end

Types

TODO: document this

`@macro_context` annotation

TODO: maybe rework this a bit

This annotation can give your macro extra information where the macro itself can be used.


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@macro_context{ in=[ :shape ] }
macro attr_reader(ident name)
    type = context.getField(name).getType();
    !!
        def {{type}} !{{name}}
            return self.{{name}}
        end
    !!
end

It’s only has the attribute in which accepts an array of symbols.

These symbols can be:


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:shape
:function
:method
:namespace
:global
:constructor

The `context`

TODO: expand more on the context

In each macro, the context variable holds the context in which the macro is currently being evaluated. With this, you have read access to all definitions / declarations in this context until the point of the macro call.


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@macro_context{ in=[ :shape ] }
macro attr_reader(ident name)
    type = context.getField(name).getType();
end

This line querys the current context (a shape) for an specific field. From this field it then retrieves the type of that field.

Macros

Declaration

Types

@macro_context annotation

The context

`@macro_context` annotation

The `context`