David Piepgrass edited this page Mar 31, 2016 · 6 revisions

LeMP: Lexical Macro Processor

Update: LeMP has a home page now!

LeMP has evolved into a rather separate idea from LES and Enhanced C#. It behaves essentially like the lexical macro processor in LISP languages, but it (currently) requires you to compile the macros in advance in their own assembly. As an example, here is a simple macro that converts any expression into a string at compile-time (which could be useful as part of something larger, such as a macro that implements INotifyPropertyChanged for you)

public partial class StandardMacros 
	 "Converts an expression to a string (note: original formatting is not preserved)")]
	public static LNode stringify(LNode node, IMacroContext sink)
		if (node.ArgCount != 1)
			return null;
		// Use the syntax of the current programming language, whatever that may be
		return LNode.Literal(ParsingService.Current.Print(node.Args[0], sink, ParsingService.Exprs));

Note: I have developed lots of standard macros so that most users will not have to develop their own macros.

While developing LLLPG, I started by creating something extremely simple and modest, a very simple macro language that compiles down to C#. I originally called this "micro-LEL", and I used it to bootstrap the parser generator, LLLPG, by enabling me to input a grammar into it. However, "micro-LEL" did not seem like an appropriate name because it is not descriptive and may not closely resemble whatever I finally create and call "LEL".

I decided to rename micro-LEL to LeMP (Lexical Macro Processor), which more correctly describes what it is: a fancy preprocessor. When I completed the Enhanced C# parser, I also used LeMP to process the EC# code. Thus LeMP was no longer a layer built on top of LES, but rather something syntax-independent. So one can refer to LeMP-on-top-of-LES as LeMP-LES and LeMP-on-top-of-EC# as LeMP-EC#. As of January 2015, "Enhanced C#" really refers to the EC# parser plus LeMP.

You can’t perform that action at this time.
You signed in with another tab or window. Reload to refresh your session. You signed out in another tab or window. Reload to refresh your session.
Press h to open a hovercard with more details.