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COCOR(1)		     General Commands Manual			COCOR(1)

NAME
     cocor - Compiler generator generator

SYNOPSIS
     cocor filename.atg [ options ]...

DESCRIPTION
     cocor  reads  a  specification  from filename.atg and generate a compiler (
     scanner, parser and main module )

OPTIONS
     -C Generate complete compiler driving module, including source listing fea-
     turing interleaved error message reporting.  To use this  option  the  file
     COMPILER.FRM (or <grammar>.FRM ) must be available.

     -D  Generate  Source  line  number  (#line)  for each semantic action. This
     causes the semantic actions in the generated C program to be labelled  with
     reference	to the original .ATG file, so that one can use a symbolic debug-
     ger on the .ATG file.

     -L (Listing) Force listing (Normally the listing of  the  grammar	is  sup-
     pressed if the compilation is error free).

     -P (Parser only) Suppress generation of the scanner.  As with the regenera-
     tion  of  the  definition modules, regeneration of the scanner is often te-
     dious, and results in no changes from the one first generated.  This option
     must be used with care.  It can also be used if a hand crafted  scanner  is
     to  be  supplied  (see the notes on the use of hand crafted scanners in the
     file COCOL).

     -T (Tests) Suppress Generation of Scanner and Parser.  (If this  option  is
     exercised,  the generation of the scanner and parser is suppressed, but the
     attributed grammar is parsed and checked for  grammatical	inconsistencies,
     LL(1) violations and so on).

     The  following  options are really intended to help with debugging/teaching
     applications.  Their effect may best be seen by judicious experimentation.

     -A Trace automaton

     -F Give Start and Follower sets for each non-terminal in the grammar

     -G Print top-down graph

     -S Print symbol table

     When  using  Coco/R,  the	frame  files  SCAN_C.FRM  and	SCAN_H.FRM   and
     PARSER_C.FRM  and	PARSER_H.FRM  must exist in the current directory, or in
     the directories specified by the environment variable CRFRAMES.

GRAMMAR TESTS
     Coco/R performs several tests to check if the grammar is  well-formed.   If
     one of the following error messages is produced, no compiler parts are gen-
     erated.

     NO PRODUCTION FOR X
     The nonterminal X has been used, but there is no production for it.

     X CANNOT BE REACHED
     There  is	a production for nonterminal X, but X cannot be derived from the
     start symbol.

     X CANNOT BE DERIVED TO TERMINALS
     For example, if there is a production

	   X = "(" X ")" .
	   X = Y.
	   Y = X.

     X and Y are nonterminals with circular derivations.

     TOKENS X AND Y CANNOT BE DISTINGUISHED
     The terminal symbols X and Y are declared to have the same structure,

     e.g.:
	       integer = digit { digit } .
	       real = digit { digit } ["." { digit } ].

     In this example, a digit string appears ambiguously to be recognized as  an
     integer or as a real.

     The  following  messages are warnings.  They may indicate an error but they
     may also describe desired effects.  The generated compiler parts may  still
     be valid.	If an LL(1) error
      is  reported  for  a  construct  X  , one must be aware that the generated
     parser will choose the first of several possible alternatives for X.

     X NULLABLE
     X can be derived to the empty string, e.g.  X = { Y } .

     LL(1) ERROR IN X:Y IS START OF MORE THAN ONE ALTERNATIVE
     Several alternatives in the production of X start with the terminal Y
     e.g.:
	    Statement = ident ":=" Expression
		      | ident [ ActualParameters ] .

     LL(1) ERROR IN X:Y IS START AND SUCCESSOR OF NULLABLE STRUCTURE
     Nullable structures are [ ... ] and { ... }
     e.g.:
	    qualident = [ ident "." ] ident .
	    Statement = "IF" Expression "THEN" Statement
			[ "ELSE" Statement ] .

     The ELSE at the start of the else part may also be a successor of a  state-
     ment.  This LL(1) conflict is known under the name dangling else .

SEE ALSO
     Moessenboeck,  H.,  A  Generator for Fast Compiler Front-Ends.  Report 127,
     Dept. Informatik, ETH Zurich (1990)

     Moessenboeck, H., A generator for production quality compilers.   Proc  3rd
     Int'l Workshop on Compiler-Compilers, Schwerin FRG, 1990

BUGS
     Mail bug reports to:

     C Version: 	     Frankie Arzu (farzu@uvg.edu.gt)

			       local - March 1996			COCOR(1)

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