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--------+++ Description

The =concrete-syntax= package provides =parse-cs, 
a generic program for parsing programs with embedded 
[[concrete syntax]]. The program is parameterized with meta-data indicating
components for various aspects such as parsing, exploding,
desugaring, and pretty-printing. The meta data can be specified in
a .meta file specific for a program to be parsed, or it can be
associated with an extension and registered in an XTC repository.

For example, the following is the contents of pl.meta, the
meta-data for Prolog programs with embedded syntax. The assumption
(in this example) is that syntax embeddings use a standard
(ToTerm) convention for indicating the boundary between meta- and
object-syntax.

<verbatim>
  Meta([
	 Syntax("Prolog"),
	 ParseTable("Prolog.tbl"),
	 Explode("prolog-explode"),
	 PrettyPrintTable("Prolog-pretty.pp.af")
  ])
</verbatim>

This information can be overridden in a file specific .meta file
with the same extension. For example, the following indicates an
embedding of ABIR in Prolog and a specific desugaring tool for
this format:

<verbatim>
  Meta([
	 Syntax("PrologABIR"),
	 PostExplodeDesugar("abir-in-prolog-implode")
  ])
</verbatim>

It overrides the syntax component, and adds a desugaring component.

In order to define such meta-data for a whole class of programs,
it can be defined in a meta file associated with a new
extension. For example, the following is the contents plabir.meta,
which defines all meta-data for preprocessing Prolog with embedded
ABIR in files with extension .plabir.
<verbatim>
  Meta([
	 Syntax("PrologABIR"),
	 Explode("prolog-explode"),
	 PostExplodeDesugar("abir-in-prolog-implode"),
	 PrettyPrintTable("Prolog-pretty.pp.af")
  ])
</verbatim>


------+++ Concrete Syntax Tools

Parse-cs is the only tool provided by the package at the moment. Other
tools that might be provided in the future include:

	* embed-syntax : combines two syntax definitions embedding one in the other by generating quotation productions and variable schemas according to a standard schema which might be adapted.

	* gen-explode : a generic explosion transformation for embeddings that can be expressed locally (term-like API in host language) and generically

------+++ Implementation

Browse the implementation in the subversion repository:

	* https://svn.cs.uu.nl:12443/repos/StrategoXT/trunk/StrategoXT/concrete-syntax/

The package is available in the [[ContinuousDistribution][daily distribution]] of StrategoXT and will be
available in StrategoRelease094.

The instantiation of the tool for Prolog is available in the PrologTools package.