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[GNU-COBOL] PCCTS again and a question

To: gnu-cobol@acm.cs.umr.edu
Subject: [GNU-COBOL] PCCTS again and a question
From: Michael McKernan <mck@tivoli.mv.com>
Date: Fri, 23 Jul 1999 11:16:39 -0400
Reply-To: gnu-cobol@acm.cs.umr.edu
Sender: owner-gnu-cobol@acm.cs.umr.edu
Alright, I couldn't help myself.  Last night I got rid of the
remaining ambiguities in the old pccts grammar, so now it's an
unambiguous LL(1) grammar unless, of course, I've covered something
up that I shouldn't have :)

It's still incomplete, of course, and may not be entirely correct,
but it generates a parser in seconds and creates no significant
strain on resources.

I should mention that there was a rule in verb-perform.g which was
truly ambiguous, so forcing a parse would have made no sense.

   perform_from_line
   	: FROM (ident | index_name | numeric)
        ;

The non-terminals "index_name" and "numeric" derive precisely the
same terminal.  I did not try to work out the significance of these
terms, but simply removed "index_name" leaving the original line as a
comment.

I had also broken the "if" rule in my last submission.  It's better
now. 

What's going on with respect to the tool search these days?  I am
interested know which parser generators have been considered, and
which are still in the running.

Mike

Here's the new diff.

diff -Naur Cobol2C/src/clause-condition.g Cobol2C.new/src/clause-condition.g
--- Cobol2C/src/clause-condition.g	Thu Dec 11 09:01:20 1997
+++ Cobol2C.new/src/clause-condition.g	Fri Jul 16 09:35:48 1999
@@ -12,9 +12,10 @@
 	; 
 general_cond
 	: arith_expr
-	  ( cond_arg
-	  | class_arg  /* need to check if above arith_expr is ident */
-	  | sign_arg
+	  ( (cond_arg)? cond_arg
+	  | ((class_arg)? class_arg  /* need to check if arith_expr is ident */
+	    | sign_arg
+	    )
 	  )
 	;
 	/*: (string_literal | arith_expr | index_name)*/
diff -Naur Cobol2C/src/clause-file-control.g Cobol2C.new/src/clause-file-contro
l.g
--- Cobol2C/src/clause-file-control.g	Thu Dec 11 09:01:21 1997
+++ Cobol2C.new/src/clause-file-control.g	Thu Jul 22 22:11:58 1999
@@ -5,8 +5,6 @@
 		<< CheckFlag(&file_control_flags, FC_ASSIGN, "ASSIGN"); >>
 	  | padding_line
 		<< CheckFlag(&file_control_flags, FC_PADDING, "PADDING"); >>
-	  | record_line
-		<< CheckFlag(&file_control_flags, FC_RECORD_DELIM, "RECORD"); >>
 	  | reserve_line
 		<< CheckFlag(&file_control_flags, FC_RESERVE, "RESERVE"); >>
 	  | org_line
@@ -15,10 +13,14 @@
 		<< CheckFlag(&file_control_flags, FC_ACCESS_MODE, "ACCESS MODE"); >>
 	  | file_status_line
 		<< CheckFlag(&file_control_flags, FC_FILE_STATUS, "FILE STATUS"); >>
-	  | record_key_line
-		<< CheckFlag(&file_control_flags, FC_RECORD_KEY, "RECORD"); >>
 	  | alt_key_line
 		<< CheckFlag(&file_control_flags, FC_ALT_RECORD, "ALTERNATE"); >>
+	  | ((RECORD DELIMITER)?
+	       record_line
+	     << CheckFlag(&file_control_flags, FC_RECORD_DELIM, "RECORD"); >>
+	     | record_key_line
+		<< CheckFlag(&file_control_flags, FC_RECORD_KEY, "RECORD"); >>
+	     )	
 	  )*
 	  PERIOD
 		<< FileControlActions();
diff -Naur Cobol2C/src/clause-file-descr.g Cobol2C.new/src/clause-file-descr.g
--- Cobol2C/src/clause-file-descr.g	Thu Dec 11 09:01:21 1997
+++ Cobol2C.new/src/clause-file-descr.g	Thu Jul 22 22:04:45 1999
@@ -4,10 +4,11 @@
 	     #endif
 	  >>
 	  fd_line
-	  ( external_line
+	  ( ((external_line)? external_line
 		<< CheckFlag(&file_descr_flags, FD_EXTERNAL, "EXTERNAL"); >>
 	  | global_line
 		<< CheckFlag(&file_descr_flags, FD_GLOBAL, "GLOBAL"); >>
+	    )
 	  | block_line
 		<< CheckFlag(&file_descr_flags, FD_BLOCK, "BLOCK"); >>
 	  | record_line_f
@@ -41,7 +42,7 @@
 		<< WarnNotImpl("GLOBAL clause"); >>
 	;
 block_line
-	: BLOCK {CONTAINS} {integer TO} integer (RECORDS | CHARACTERS)
+	: BLOCK {CONTAINS} integer {TO integer} (RECORDS | CHARACTERS)
 		<< WarnNotImpl("BLOCK clause"); >>
 	;
 record_line_f
diff -Naur Cobol2C/src/clause-record-descr.g Cobol2C.new/src/clause-record-desc
r.g
--- Cobol2C/src/clause-record-descr.g	Thu Dec 11 09:01:21 1997
+++ Cobol2C.new/src/clause-record-descr.g	Thu Jul 22 21:18:16 1999
@@ -2,10 +2,10 @@
 	: level_number (ident << strcpy(DDIdent, Ident); >>
 			| {FILLER} << strcpy(DDIdent, ""); >>
 			)
-	  ( redefines_line
-		<< CheckFlag(&data_descr_flags, DD_REDEFINES, "REDEFINES"); >>
-	  | external_line_r
+	  ( (external_line_r)?  external_line_r
 		<< CheckFlag(&data_descr_flags, DD_EXTERNAL, "EXTERNAL"); >>
+	  | redefines_line
+		<< CheckFlag(&data_descr_flags, DD_REDEFINES, "REDEFINES"); >>
 	  | global_line_r
 		<< CheckFlag(&data_descr_flags, DD_GLOBAL, "GLOBAL"); >>
 	  | picture_line
@@ -45,7 +45,7 @@
 		<< WarnNotImpl("EXTERNAL clause"); >>
 	;
 global_line_r
-	: IS GLOBAL
+	: {IS} GLOBAL
 		<< WarnNotImpl("IS GLOBAL clause"); >>
 	;
 picture_line
diff -Naur Cobol2C/src/clause-relation.g Cobol2C.new/src/clause-relation.g
--- Cobol2C/src/clause-relation.g	Thu Dec 11 09:01:21 1997
+++ Cobol2C.new/src/clause-relation.g	Fri Jul 16 10:25:16 1999
@@ -1,10 +1,10 @@
 relation
 	: {IS} {NOT << SetFlag(&verb_flags, RELATION_NOT); >> } 
 	  ( geneq
-	  | gengt
-	  | genlt
-	  | genge
-	  | genle
+	  | ((genge)? genge
+	    | gengt)
+	  | ((genle)? genle
+	    | genlt)
 	  )
 	  << ClearFlag(&verb_flags, RELATION_NOT); >>
 	;
diff -Naur Cobol2C/src/clause-size-err.g Cobol2C.new/src/clause-size-err.g
--- Cobol2C/src/clause-size-err.g	Thu Dec 11 09:01:21 1997
+++ Cobol2C.new/src/clause-size-err.g	Thu Jul 22 22:09:55 1999
@@ -2,10 +2,10 @@
 
 size_err
 	: {NOT} {ON} SIZE ERROR imperative
-	  second_size_line
+	  {({NOT} {ON} SIZE)? second_size_line}
 	;
 second_size_line
-	: {{NOT} {ON} SIZE ERROR imperative}
+	: {NOT} {ON} SIZE ERROR imperative
 	;
 /*
 	: ({NOT} {ON} SIZE ERROR imperative)?
diff -Naur Cobol2C/src/verb-accept.g Cobol2C.new/src/verb-accept.g
--- Cobol2C/src/verb-accept.g	Thu Dec 11 09:01:21 1997
+++ Cobol2C.new/src/verb-accept.g	Fri Jul 16 10:28:32 1999
@@ -1,6 +1,6 @@
 accept_stmt
 	: ACCEPT (
-		  ident << 
+		  (ident FROM ident)? ident << 
 			   { int rv = emit_accept(Ident); 
 			     if (rv != 0) ErrUndefVar(Ident);
 			   }
diff -Naur Cobol2C/src/verb-compute.g Cobol2C.new/src/verb-compute.g
--- Cobol2C/src/verb-compute.g	Thu Dec 11 09:01:21 1997
+++ Cobol2C.new/src/verb-compute.g	Thu Jul 22 21:11:11 1999
@@ -14,7 +14,8 @@
 	>>
 	;
 compute_sizing
-	: {size_err}
+	: ({NOT} {ON} SIZE)? size_err
+	|
 	;
 /*
 	: (size_err)?
@@ -22,7 +23,8 @@
 	;
 */
 compute_ending
-	: {END_COMPUTE}
+	: (END_COMPUTE)? END_COMPUTE
+	|
 	;
 /*
 	: (END_COMPUTE)?
diff -Naur Cobol2C/src/verb-go.g Cobol2C.new/src/verb-go.g
--- Cobol2C/src/verb-go.g	Thu Dec 11 09:01:21 1997
+++ Cobol2C.new/src/verb-go.g	Fri Jul 16 11:23:51 1999
@@ -1,6 +1,6 @@
 
 go_stmt
-	: GO {TO} (ident /* procedure name */
-		  |(ident)+ DEPENDING {ON} ident
+	: GO {TO} (((ident)+ DEPENDING)? (ident)+ DEPENDING {ON} ident
+		  | ident /* procedure name */
 		  )
 	;
diff -Naur Cobol2C/src/verb-if.g Cobol2C.new/src/verb-if.g
--- Cobol2C/src/verb-if.g	Thu Dec 11 09:01:21 1997
+++ Cobol2C.new/src/verb-if.g	Wed Jul 21 11:11:02 1999
@@ -6,19 +6,22 @@
 	: IF_C << emit_if_start(); >> 
 	  condition {THEN} << emit_if_block(); >>
 		( NEXT SENTENCE << emit_if_next_sentence(); >>
-		| (statement)+ ) << emit_if_end(); >>
+		| ((statement)? statement)* ) << emit_if_end(); >>
 	  else_clause
+          if_ending
 	;
 else_clause
-	: ( ELSE_C << emit_else_start(); >>
-		NEXT SENTENCE << emit_else_next_sentence(); >>
-	  | ELSE_C << emit_else_start(); >>
-		(statement)+ {END_IF} << emit_else_end(); >>
-	  | {END_IF} 
-	  )
+	: (ELSE_C)? ELSE_C << emit_else_start(); >> 
+		( NEXT SENTENCE << emit_else_next_sentence(); >>
+		| ((statement)? statement)* << emit_else_end(); >>
+	   )
+	|
 	;
 
-
+if_ending
+	: (END_IF)? END_IF
+	| 
+        ;
 
 /*
 if_stmt
diff -Naur Cobol2C/src/verb-perform.g Cobol2C.new/src/verb-perform.g
--- Cobol2C/src/verb-perform.g	Thu Dec 11 09:01:22 1997
+++ Cobol2C.new/src/verb-perform.g	Thu Jul 22 21:34:51 1999
@@ -1,9 +1,11 @@
 perform_stmt
         : PERFORM << { int rv=0; rv = emit_perform_start(); 
 			if (rv != 0) ErrEmit(); } >>
-	  ( perform_proc_line { perform_times_line
-			      | { perform_test_line } perform_until_line
-			      }
+	  ( (perform_proc_line)?  perform_proc_line
+		( perform_times_line
+		| { perform_test_line } perform_until_line
+		|
+		)
 	  | ( perform_times_line 
 	    | { perform_test_line } perform_until_line 
 	    ) 
@@ -57,7 +59,8 @@
 		<< WarnNotImpl("VARYING clause"); >>
 	;
 perform_from_line
-	: FROM (ident | index_name | numeric)
+	: FROM (ident | numeric)
+//	: FROM (ident | index_name | numeric)
 	;
 perform_by_line
 	: BY (ident | numeric) UNTIL condition







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