Initial version

lang/m2/comp/program.g

@@ -0,0 +1,116 @@
+/*
+	Program: Modula-2 grammar in LL(1) form
+	Version: Mon Feb 24 14:29:39 MET 1986
+*/
+
+/*
+	The grammar as given by Wirth is already almost LL(1); the
+	main problem is that the full form of a qualified designator
+	may be:
+		[ module_ident '.' ]* IDENT [ '.' field_ident ]*
+	which is quite confusing to an LL(1) parser. Rather than
+	resorting to context-sensitive techniques, I have decided
+	to render this as:
+		IDENT [ '.' IDENT ]*
+	on the grounds that it is quite natural to consider the first
+	IDENT to be the name of the object and regard the others as
+	field identifiers.
+*/
+
+{
+#include "idf.h"
+#include "idlist.h"
+
+static  char *RcsId = "$Header$";
+}
+
+%lexical LLlex;
+
+%start	CompUnit, CompilationUnit;
+
+ModuleDeclaration:
+	MODULE IDENT priority? ';' import* export? block IDENT
+;
+
+priority:
+	'[' ConstExpression ']'
+;
+
+export
+{
+	struct id_list *ExportList;
+} :
+	EXPORT QUALIFIED? IdentList(&ExportList) ';'
+;
+
+import
+{
+	struct id_list *ImportList;
+} :
+	[ FROM
+	  IDENT
+	]?
+	IMPORT IdentList(&ImportList) ';'
+	/*
+	   When parsing a global module, this is the place where we must
+	   read already compiled definition modules.
+	   If the FROM clause is present, the identifier in it is a module
+	   name, otherwise the names in the import list are module names.
+	*/
+;
+
+DefinitionModule:
+	DEFINITION
+	{
+#ifdef DEBUG
+		debug("Definition module");
+#endif DEBUG
+	}
+	MODULE IDENT ';' import* 
+	/* export?
+
+	   New Modula-2 does not have export lists in definition modules.
+	*/
+	definition* END IDENT '.'
+;
+
+definition:
+	CONST [ ConstantDeclaration ';' ]*
+|
+	TYPE
+	[ IDENT 
+	  [ '=' type 
+	  | /* empty */
+	    /*
+	       Here, the exported type has a hidden implementation.
+	       The export is said to be opaque.
+	       It is restricted to pointer types.
+	    */
+	  ]
+	  ';'
+	]*
+|
+	VAR [ VariableDeclaration ';' ]*
+|
+	ProcedureHeading ';'
+;
+
+ProgramModule:
+	MODULE
+	{
+#ifdef DEBUG
+		debug("Program module");
+#endif DEBUG
+	}
+	IDENT priority? ';' import* block IDENT '.'
+;
+
+Module:
+	DefinitionModule
+|
+	IMPLEMENTATION? ProgramModule
+;
+
+CompilationUnit:
+	Module
+;