Date:  Tuesday, April 4, 1995 1:19:56 PM
Author:  Apple Computer, Inc.
Subject:  PCCTS 1.31

Equipment:  Macintosh

Summary:  PCCTS (The Purdue Compiler-Construction Tool Set) is a public 
domain tool set consisting of a parser generator called ANTLR and a 
lexical analyzer called DLG. ANTLR accepts a grammatical description for 
an input language and generates a recursive-descent parser in C or C++ to 
recognize sentences in that input language; DLG is used to break up the 
input stream of characters into a token stream.

ANTLR combines the flexibility of hand-coded parsing with the convenience 
of a parser generator. ANTLR has many features that make it easier to use 
than other language tools. Most important, ANTLR provides PREDICATES 
which let the programmer systematically direct the parse via arbitrary 
expressions using semantics and syntactic context; in practice, the use 
of predicates eliminates the need to hand-tweak the ANTLR output, even 
for difficult parsing problems. ANTLR also integrates the description of 
lexical and syntactic analysis, accepts LL(k) grammars for k>1 with 
extended BNF notation, and can automatically generate abstract syntax 
trees. 

While PCCTS is a free tool set, it is actively supported by Terence Parr 
of Parr Research Corporation. Contact parrt@acm.org for information or 
join us in the comp.compilers.tools.pccts USENET newsgroup. Our ftp site 
is everest.ee.umn.edu in pub/pccts.

Features:
ANTLR integrates the specification of lexical and syntactic 
analysis. A separate lexical specification is unnecessary as lexical 
regular expressions (token descriptions) can be placed in double-quotes 
and used as normal token references in an ANTLR grammar.

ANTLR accepts grammar constructs in Extended BNF (EBNF) notation. 

ANTLR provides facilities for automatic abstract syntax tree 
construction.

ANTLR generates recursive-descent parsers in C/C++ so that there is 
a clear correspondence between the grammar specification and the ANTLR 
output. Consequently, it is relatively easy for non-parsing experts to 
design and debug an ANTLR grammar. 

ANTLR has automatic error recovery and reporting facilities. 
Although, we are developing a new, advanced error mechanism, called 
``parser exception handling,'' the existing built-in mechanism is simple 
and effective for many parsing situations. 

ANTLR allows each grammar rule to have parameters and return values, 
facilitating attribute passing during the parse. Because ANTLR converts 
each rule to a C/C++ function in a recursive descent parser, a rule 
parameter is simply a function parameter. Additionally, ANTLR rules can 
have multiple return values. 

ANTLR has numerous other features that make it a product rather than 
a research project. ANTLR itself is written in highly portable C; its 
output can be debugged with existing source-level debuggers and is easily 
integrated into programmers' applications. 

Requirements:  Works with MPW out of the box; it also works with Symantec 
C and Metrowerks.  See config.h in the h directory.

Issues:  PCCTS is completely in the public domain.  Please see the ANTLR 
README and RIGHTS files for details.

Keywords:  ANTLR, PCCTS, parser generator, BNF, EBNF, YACC, compiler 
tools

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