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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
       featuring 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 sym-
       bolic debugger 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  re-
       generation  of  the  definition modules,	regeneration of	the scanner is
       often tedious, 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	incon-
       sistencies, LL(1) violations and	so on).

       The following options are really	intended to help with debugging/teach-
       ing  applications.   Their effect may best be seen by judicious experi-
       mentation.

       -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 generated.

       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
       statement.  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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