From 278ac1e7247b43dcde6abbbd62e4dea64fb10c47 Mon Sep 17 00:00:00 2001
From: "Jurgen J. Vinju" <Jurgen.Vinju@cwi.nl>
Date: Thu, 22 Jun 2023 16:38:45 +0200
Subject: [PATCH] scaffolding a little compiler for generating cached parsers

---
 .../grammar/storage/ModuleParserStorage.rsc   | 46 +++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 src/org/rascalmpl/library/lang/rascal/grammar/storage/ModuleParserStorage.rsc

diff --git a/src/org/rascalmpl/library/lang/rascal/grammar/storage/ModuleParserStorage.rsc b/src/org/rascalmpl/library/lang/rascal/grammar/storage/ModuleParserStorage.rsc
new file mode 100644
index 0000000000..95390e6c55
--- /dev/null
+++ b/src/org/rascalmpl/library/lang/rascal/grammar/storage/ModuleParserStorage.rsc
@@ -0,0 +1,46 @@
+@synopsis{Functionality for caching module parsers}
+@description{
+The Rascal interpreter can take a lot of time while loading modules.
+In particular in deployed situations (Eclipse and VScode plugins), the 
+time it takes to load the parser generator for generating the parsers
+which are required for analyzing concrete syntax fragments is prohibitive (20s).
+This means that the first syntax highlighting sometimes can only appear
+after more than 20s after loading an extension (VScode) or plugin (Eclipse).
+
+This "compiler" takes any number of Rascal modules and extracts a grammar
+for each of them, in order to use the ((Library::ParseTree)) module's
+functions ((saveParsers)) on them respectively to store each parser
+in a `.parsers` file. 
+
+After that the Rascal interpreter has a special mode for using ((loadParsers))
+while importing a new module if a cache `.parsers` file is present next to 
+the `.rsc` respective file.
+}
+@benefits{
+* loading modules without having to first load and use a parser generator can be up 1000 times faster.
+}
+@pitfalls{
+:::warning
+This caching feature is _static_. There is no automated cache clearance.
+If your grammars change, any saved `.parsers` files do not change with it. 
+It is advised that you programmatically execute this compiler at deployment time
+to store the `.parsers` file _only_ in deployed `jar` files. That way, you can not
+be bitten by a concrete syntax parser that is out of date at development time.
+:::
+}
+@license{
+  Copyright (c) 2009-2023 NWO-I CWI
+  All rights reserved. This program and the accompanying materials
+  are made available under the terms of the Eclipse Public License v1.0
+  which accompanies this distribution, and is available at
+  http://www.eclipse.org/legal/epl-v10.html
+}
+@contributor{Jurgen J. Vinju - Jurgen.Vinju@cwi.nl - CWI}
+@bootstrapParser
+module lang::rascal::grammar::storage::ModuleParserStorage
+
+import lang::rascal::grammar::definition::Modules;
+import lang::rascal::\syntax::Rascal;
+import util::Reflective;
+
+