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Archive-name: auto/comp.lang.smalltalk/T-gen-Version-2-1-for-OWST-4-1

==============================================================================
	T-gen (version 2.1):  A Smalltalk-80 Translator Generator Tool
==============================================================================

Abstract:
	T-gen is a general-purpose object-oriented tool for the 
	automatic generation of string-to-object translators. 
	It is written in Smalltalk and lives in the Smalltalk 
	programming environment.  T-gen supports the generation 
	of both top-down (LL) and bottom-up (LR) parsers, which 
	will automatically generate derivation trees, abstract 
	syntax trees, or arbitrary Smalltalk objects.  The simple 
	specification syntax and graphical user interface are 
	intended to enhance the learning, comprehension, and 
	usefulness of T-gen.

*** Changes from Version 2.0:

	* Regular Right-Part Grammar specifications (i.e. regular
		expression style right-hand sides for productions)
		now really work.  However, translation symbols
		are still not carried along with the grammar 
		transformations, thus limiting the usefulness of
		automatic grammar transformations (maybe next release).
		I have found this feature primarily useful for 
		checking grammars written in a more human-readable form.
		
	* Improved scanner generation algorithm reduces scanner
		generation time for non-trivial scanner specs from
		several hours to a few minutes.

	* The bootstrapping classes DLGScanner and DLGParser have
		been removed.  They were previously used to create
		the classes TokenSpecScanner, TokenSpecParser, 
		GrammarSpecScanner, and GrammarSpecParser.  The
		current versions of these classes were generated
		by T-gen and are table-based (to improve performance).

	* A test suite has been added as a supplemental file-in.
		If you happen to make changes to T-gen itself, it's
		a quick way to check that things still work.  To run
		the test suite, file it in and then evaluate:
			TranslatorGenerator runAllTests.

	* Optimized versions of the 1-token and 2-token lookahead
		scanners are available and generated scanners get
		installed beneath the appropriate superclass.

	* A bug with the optimized parser installation method has 
		been corrected (it used to dump the table incorrectly).

	* Two new transcript-pane operate-button menu items have
		been added: 'save specs' and 'load specs'.  They
		cause the contents of the other three panes to be
		saved to or loaded from a file.  Thanks for this
		useful addition goes to some loyal T-gen user who will
		have to remain anonymous (since I have lost track
		of where it originally came from, sorry 'bout that).

	* Note:  there have been NO changes made to the User's Guide.

Platforms:
	T-gen currently runs under ParcPlace Objectworks/Smalltalk 
	Release 4.0 and Release 4.1.

Distribution:
	Smalltalk-80 source code and a Postscript rendering of a
	User's Guide for T-gen are available via anonymous ftp
	from st.cs.uiuc.edu in the directory:
		/pub/st80_r41/T-gen2.1

	Patches will be placed in this same directory and posted 
	to comp.lang.smalltalk as necessary.

	See the README file in the distribution for installation
	and copyright information.

For more information contact:

	Justin Graver
	graver@comm.mot.com
	(708) 576-1916
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|  Justin Graver                           |  Internet: graver@comm.mot.com  |
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