- experiments with forward-declaring types of non-imported packages

- adjusted switch syntax (no repeated case: case: anymore)
- enabled some constant expressions that work now

R=r
OCL=14098
CL=14098

usr/gri/gosrc/compilation.go

@@ -52,7 +52,7 @@ func ReadImport(comp* Globals.Compilation, filename string, update bool) (data s
 	// see if it just works
 	data, ok = Platform.ReadSourceFile(filename);
 	if ok {
-		comp.env.Compile(comp.flags, comp.env, filename + Platform.src_file_ext);
+		comp.env.Compile(comp, filename + Platform.src_file_ext);
 		data, ok = ReadImport(comp, filename, false);
 		if ok {
 			return data, ok;
@@ -73,30 +73,28 @@ export func Import(comp *Globals.Compilation, pkg_file string) *Globals.Package
 }
 
 
-export func Export(comp *Globals.Compilation) string {
+export func Export(comp *Globals.Compilation, pkg_file string) {
-	panic "UNIMPLEMENTED";
+	data := Exporter.Export(comp);
-	return "";
+	ok := Platform.WriteObjectFile(pkg_file, data);
+	if !ok {
+		panic "export failed";
+	}
 }
 
 
-export func Compile(flags *Globals.Flags, env* Globals.Environment, filename string) {
+export func Compile(comp *Globals.Compilation, src_file string) {
-	// setup compilation
+	src, ok := Platform.ReadSourceFile(src_file);
-	comp := new(Globals.Compilation);
-	comp.flags = flags;
-	comp.env = env;
-	
-	src, ok := sys.readfile(filename);
 	if !ok {
-		print "cannot open ", filename, "\n"
+		print "cannot open ", src_file, "\n"
 		return;
 	}
 	
-	if flags.verbosity > 0 {
+	if comp.flags.verbosity > 0 {
-		print filename, "\n";
+		print src_file, "\n";
 	}
 
 	scanner := new(Scanner.Scanner);
-	scanner.Open(filename, src);
+	scanner.Open(src_file, src);
 	
 	var tstream *chan *Scanner.Token;
 	if comp.flags.token_chan {
@@ -122,5 +120,5 @@ export func Compile(flags *Globals.Flags, env* Globals.Environment, filename str
 		Printer.PrintObject(comp, comp.pkg_list[0].obj, false);
 	}
 	
-	Exporter.Export(comp, filename);
+	Export(comp, src_file);
 }

usr/gri/gosrc/export.go

@@ -174,6 +174,12 @@ func (E *Exporter) WriteType(typ *Globals.Type) {
 	}
 	
 	switch typ.form {
+	case Type.FORWARD:
+		// corresponding package must be forward-declared too
+		if typ.obj == nil || E.comp.pkg_list[typ.obj.pnolev].key != "" {
+			panic "inconsistency in package.type forward declaration";
+		}
+		
 	case Type.ALIAS, Type.MAP:
 		E.WriteType(typ.aux);
 		E.WriteType(typ.elt);
@@ -237,54 +243,7 @@ func (E *Exporter) WriteObject(obj *Globals.Object) {
 }
 
 
-func (E *Exporter) Export(comp* Globals.Compilation, file_name string) {
+func (E *Exporter) Export(comp* Globals.Compilation) string {
-	E.comp = comp;
-	E.debug = comp.flags.debug;
-	E.buf_pos = 0;
-	E.pkg_ref = 0;
-	E.type_ref = 0;
-	
-	if E.debug {
-		print "exporting to ", file_name, "\n";
-	}
-
-	// write magic bits
-	magic := Platform.MAGIC_obj_file;  // TODO remove once len(constant) works
-	for i := 0; i < len(magic); i++ {
-		E.WriteByte(magic[i]);
-	}
-	
-	// Predeclared types are "pre-exported".
-	// TODO run the loop below only in debug mode
-	{	i := 0;
-		for p := Universe.types.first; p != nil; p = p.next {
-			if p.typ.ref != i {
-				panic "incorrect ref for predeclared type";
-			}
-			i++;
-		}
-	}
-	E.type_ref = Universe.types.len_;
-	
-	// export package 0
-	pkg := comp.pkg_list[0];
-	E.WritePackage(pkg);
-	E.WriteScope(pkg.scope);
-	
-	if E.debug {
-		print "\n(", E.buf_pos, " bytes)\n";
-	}
-	
-	data := string(E.buf)[0 : E.buf_pos];
-	ok := sys.writefile(file_name, data);
-	
-	if !ok {
-		panic "export failed";
-	}
-}
-
-
-func (E *Exporter) Export2(comp* Globals.Compilation) string {
 	E.comp = comp;
 	E.debug = comp.flags.debug;
 	E.buf_pos = 0;
@@ -322,13 +281,7 @@ func (E *Exporter) Export2(comp* Globals.Compilation) string {
 }
 
 
-export func Export(comp* Globals.Compilation, pkg_name string) {
+export func Export(comp* Globals.Compilation) string {
 	var E Exporter;
-	(&E).Export(comp, Utils.TrimExt(Utils.BaseName(pkg_name), Platform.src_file_ext) + Platform.obj_file_ext);
+	return (&E).Export(comp);
-}
-
-
-export func Export2(comp* Globals.Compilation) string {
-	var E Exporter;
-	return (&E).Export2(comp);
 }

usr/gri/gosrc/globals.go

@@ -77,8 +77,8 @@ export type Flags struct {
 export type Environment struct {
 	Error *func(comp *Compilation);  // TODO complete this
 	Import *func(comp *Compilation, pkg_file string) *Package;
-	Export *func(comp *Compilation) string;
+	Export *func(comp *Compilation, pkg_file string);
-	Compile *func(flags *Flags, env* Environment, file string);
+	Compile *func(comp *Compilation, src_file string);
 }
 
 
@@ -147,7 +147,7 @@ export func NewPackage(file_name string, obj *Object, scope *Scope) *Package {
 	pkg := new(Package);
 	pkg.ref = -1;  // not yet exported
 	pkg.file_name = file_name;
-	pkg.key = "<the package key>";  // TODO fix this
+	pkg.key = "<the package key>";  // empty key means package forward declaration
 	pkg.obj = obj;
 	pkg.scope = scope;
 	return pkg;

usr/gri/gosrc/go.go

@@ -89,6 +89,12 @@ func main() {
 	
 	// compile files
 	for p := files.first; p != nil; p = p.next {
-		Compilation.Compile(flags, env, p.str);
+		// setup compilation
+		comp := new(Globals.Compilation);
+		comp.flags = flags;
+		comp.env = env;
+		
+		// compile
+		Compilation.Compile(comp, p.str);
 	}
 }

usr/gri/gosrc/import.go

@@ -132,9 +132,11 @@ func (I *Importer) ReadPackage() *Globals.Package {
 		if I.comp.flags.verbosity > 1 {
 			print `import: implicitly adding package `, ident, ` "`, file_name, `" (pno = `, obj.pnolev, ")\n";
 		}
-	} else if key != pkg.key {
+	} else if key != "" && key != pkg.key {
 		// the package was imported before but the package
-		// key has changed
+		// key has changed (a "" key indicates a forward-
+		// declared package - it's key is consistent with
+		// any actual package of the same name)
 		panic "package key inconsistency";
 	}
 	I.pkg_list[I.pkg_ref] = pkg;
@@ -198,6 +200,10 @@ func (I *Importer) ReadType() *Globals.Type {
 	I.type_ref++;
 
 	switch (typ.form) {
+	case Type.FORWARD:
+		typ.scope = Globals.NewScope(nil);
+		break;
+		
 	case Type.ALIAS, Type.MAP:
 		typ.aux = I.ReadType();
 		typ.elt = I.ReadType();

usr/gri/gosrc/parser.go

@@ -715,9 +715,50 @@ func (P *Parser) ParsePointerType() *Globals.Type {
 	typ := Globals.NewType(Type.POINTER);
 	
 	var elt *Globals.Type;
-	if P.semantic_checks && P.tok == Scanner.IDENT {
+	if P.semantic_checks {
+		if P.tok == Scanner.STRING && !P.comp.flags.sixg {
+			// implicit package.type forward declaration
+			// TODO eventually the scanner should strip the quotes
+			pkg_name := P.val[1 : len(P.val) - 1];  // strip quotes
+			pkg := P.comp.Lookup(pkg_name);
+			if pkg == nil {
+				// package doesn't exist yet - add it to the package list
+				obj := Globals.NewObject(P.pos, Object.PACKAGE, ".pkg");
+				pkg = Globals.NewPackage(pkg_name, obj, Globals.NewScope(nil));
+				pkg.key = "";  // mark as forward-declared package
+				P.comp.Insert(pkg);
+			} else {
+				// package exists already - must be forward declaration
+				if pkg.key != "" {
+					P.Error(P.pos, `cannot use implicit package forward declaration for imported package "` + P.val + `"`);
+					panic "wrong package forward decl";
+					// TODO introduce dummy package so we can continue safely
+				}
+			}
+			
+			P.Next();  // consume package name
+			P.Expect(Scanner.PERIOD);
+			pos, ident := P.ParseIdent();
+			obj := pkg.scope.Lookup(ident);
+			if obj == nil {
+				elt = Globals.NewType(Type.FORWARD);
+				elt.scope = P.top_scope;  // not really needed here, but for consistency
+				obj = Globals.NewObject(pos, Object.TYPE, ident);
+				obj.exported = true;  // the type name must be visible
+				obj.typ = elt;
+				elt.obj = obj;  // primary type object;
+				pkg.scope.Insert(obj);
+				obj.pnolev = pkg.obj.pnolev;
+			} else {
+				if obj.kind != Object.TYPE || obj.typ.form != Type.FORWARD {
+					panic "inconsistency in package.type forward declaration";
+				}
+				elt = obj.typ;
+			}
+			
+		} else if P.tok == Scanner.IDENT {
 			if P.Lookup(P.val) == nil {
-			// implicit forward declaration
+				// implicit type forward declaration
 				// create a named forward type 
 				pos, ident := P.ParseIdent();
 				obj := Globals.NewObject(pos, Object.TYPE, ident);
@@ -746,6 +787,10 @@ func (P *Parser) ParsePointerType() *Globals.Type {
 			elt = P.ParseType();
 		}
 	
+	} else {
+		elt = P.ParseType();
+	}
+
 	typ.elt = elt;
 	
 	P.Ecart();
@@ -1556,22 +1601,10 @@ func (P *Parser) ParseCase() {
 }
 
 
-func (P *Parser) ParseCaseList() {
-	P.Trace("CaseList");
-	
-	P.ParseCase();
-	for P.tok == Scanner.CASE || P.tok == Scanner.DEFAULT {
-		P.ParseCase();
-	}
-	
-	P.Ecart();
-}
-
-
 func (P *Parser) ParseCaseClause() {
 	P.Trace("CaseClause");
 	
-	P.ParseCaseList();
+	P.ParseCase();
 	if P.tok != Scanner.FALLTHROUGH && P.tok != Scanner.RBRACE {
 		P.ParseStatementList();
 		P.Optional(Scanner.SEMICOLON);
@@ -1796,18 +1829,34 @@ func (P *Parser) ParseConstSpec(exported bool) {
 func (P *Parser) ParseTypeSpec(exported bool) {
 	P.Trace("TypeSpec");
 
+	var typ *Globals.Type;
+	
+	pos, ident := P.ParseIdent();
+	obj := P.Lookup(ident);
+	
+	if !P.comp.flags.sixg && obj != nil {
+		if obj.typ.form == Type.FORWARD {
+			// imported forward-declared type
+			if !exported {
+				panic "foo";
+			}
+		} else {
+			panic "bar";
+		}
+		
+	} else {
 		// Immediately after declaration of the type name, the type is
 		// considered forward-declared. It may be referred to from inside
 		// the type specification only via a pointer type.
-	typ := Globals.NewType(Type.FORWARD);
+		typ = Globals.NewType(Type.FORWARD);
 		typ.scope = P.top_scope;  // not really needed here, but for consistency
 
-	pos, ident := P.ParseIdent();
+		obj = Globals.NewObject(pos, Object.TYPE, ident);
-	obj := Globals.NewObject(pos, Object.TYPE, ident);
 		obj.exported = exported;
 		obj.typ = typ;
 		typ.obj = obj;  // primary type object
 		P.Declare(obj);
+	}
 
 	// If the next token is an identifier and we have a legal program,
 	// it must be a typename. In that case this declaration introduces

usr/gri/gosrc/platform.go

@@ -4,6 +4,9 @@
 
 package Platform
 
+import Utils "utils"
+
+
 // ----------------------------------------------------------------------------
 // Environment
 
@@ -54,7 +57,14 @@ export func ReadObjectFile(filename string) (data string, ok bool) {
 }
 
 
-export func ReadSourceFile(filename string) (data string, ok bool) {
+export func ReadSourceFile(name string) (data string, ok bool) {
-	data, ok = sys.readfile(filename + src_file_ext);
+	name = Utils.TrimExt(name, src_file_ext) + src_file_ext;
+	data, ok = sys.readfile(name);
 	return data, ok;
 }
+
+
+export func WriteObjectFile(name string, data string) bool {
+	name = Utils.TrimExt(Utils.BaseName(name), src_file_ext) + obj_file_ext;
+	return sys.writefile(name, data);
+}

usr/gri/gosrc/printer.go

@@ -178,7 +178,15 @@ func (P *Printer) PrintObjectStruct(obj *Globals.Object) {
 
 func (P *Printer) PrintObject(obj *Globals.Object) {
 	if obj.pnolev > 0 {
-		print P.comp.pkg_list[obj.pnolev].obj.ident, ".";
+		pkg := P.comp.pkg_list[obj.pnolev];
+		if pkg.key == "" {
+			// forward-declared package
+			print `"`, pkg.file_name, `"`;
+		} else {
+			// imported package
+			print pkg.obj.ident;
+		}
+		print "."
 	}
 	print obj.ident;
 }

usr/gri/gosrc/scanner.go

@@ -276,12 +276,11 @@ func (S *Scanner) Next() {
 		Bit3 = 4;
 		Bit4 = 3;
 
-		// TODO 6g constant evaluation incomplete
+		T1 = (1 << (Bit1 + 1) - 1) ^ 0xFF;  // 0000 0000
-		T1 = 0x00;  // (1 << (Bit1 + 1) - 1) ^ 0xFF;  // 0000 0000
+		Tx = (1 << (Bitx + 1) - 1) ^ 0xFF;  // 1000 0000
-		Tx = 0x80;  // (1 << (Bitx + 1) - 1) ^ 0xFF;  // 1000 0000
+		T2 = (1 << (Bit2 + 1) - 1) ^ 0xFF;  // 1100 0000
-		T2 = 0xC0;  // (1 << (Bit2 + 1) - 1) ^ 0xFF;  // 1100 0000
+		T3 = (1 << (Bit3 + 1) - 1) ^ 0xFF;  // 1110 0000
-		T3 = 0xE0;  // (1 << (Bit3 + 1) - 1) ^ 0xFF;  // 1110 0000
+		T4 = (1 << (Bit4 + 1) - 1) ^ 0xFF;  // 1111 0000
-		T4 = 0xF0;  // (1 << (Bit4 + 1) - 1) ^ 0xFF;  // 1111 0000
 
 		Rune1 = 1 << (Bit1 + 0*Bitx) - 1;  // 0000 0000 0111 1111
 		Rune2 = 1 << (Bit2 + 1*Bitx) - 1;  // 0000 0111 1111 1111