ast:

- renamed Program -> SourceFile
- added Package node representing the AST for an entire package
- added filter function to create a source file mimicking the
  interface of an entire package

parser:
- parser entry to parse entire packages
- unified naming of parser entry points
- factored out entry points into new file (interface.go)

gofmt:
- extended to accept single .go files, and package paths:
  gofmt file.go	     	    // formatting of a single file
  gofmt -x file.go	    // interface of a single file
  gofmt -x ./MyPackage	    // interface of a local package
  gofmt -x math		    // interface of a $GOROOT relative package

Various adjustments in dependent files, documentation.

R=rsc
DELTA=634  (369 added, 153 deleted, 112 changed)
OCL=31743
CL=31748

14 files changed, 468 insertions, 251 deletions

diff --git a/src/cmd/gobuild/util.go b/src/cmd/gobuild/util.go
index 10920d152..3f38cc698 100644
--- a/src/cmd/gobuild/util.go
+++ b/src/cmd/gobuild/util.go
@@ -220,12 +220,7 @@ func LitString(p []*ast.StringLit) (string, os.Error) {
 }
 
 func PackageImports(file string) (pkg string, imports []string, err1 os.Error) {
-	f, err := os.Open(file, os.O_RDONLY, 0);
-	if err != nil {
-		return "", nil, err
-	}
-
-	prog, err := parser.Parse(file, f, parser.ImportsOnly);
+	prog, err := parser.ParseFile(file, nil, parser.ImportsOnly);
 	if err != nil {
 		return "", nil, err;
 	}
diff --git a/src/cmd/godoc/godoc.go b/src/cmd/godoc/godoc.go
index d2150d29e..bb3913233 100644
--- a/src/cmd/godoc/godoc.go
+++ b/src/cmd/godoc/godoc.go
@@ -159,7 +159,7 @@ type parseErrors struct {
 // Parses a file (path) and returns the corresponding AST and
 // a sorted list (by file position) of errors, if any.
 //
-func parse(path string, mode uint) (*ast.Program, *parseErrors) {
+func parse(path string, mode uint) (*ast.File, *parseErrors) {
 	src, err := io.ReadFile(path);
 	if err != nil {
 		log.Stderrf("ReadFile %s: %v", path, err);
@@ -167,7 +167,7 @@ func parse(path string, mode uint) (*ast.Program, *parseErrors) {
 		return nil, &parseErrors{path, errs, nil};
 	}
 
-	prog, err := parser.Parse(path, src, mode);
+	prog, err := parser.ParseFile(path, src, mode);
 	if err != nil {
 		var errs []parseError;
 		if errors, ok := err.(scanner.ErrorList); ok {
@@ -208,7 +208,7 @@ func nodeText(node interface{}) []byte {
 	var buf bytes.Buffer;
 	tw := makeTabwriter(&buf);
 	mode := uint(0);
-	if _, isProgram := node.(*ast.Program); isProgram {
+	if _, isProgram := node.(*ast.File); isProgram {
 		mode = printer.DocComments;
 	}
 	printer.Fprint(tw, node, mode);
@@ -436,7 +436,7 @@ func findPackage(path string) (canonical string, pd *pakDesc, dirs dirList) {
 		return;
 	}
 
-	// the package name is is the directory name within its parent
+	// the package name is the directory name within its parent
 	_, pakname := pathutil.Split(dirname);
 
 	// collect all files belonging to the package and count the
@@ -489,20 +489,21 @@ func (p *pakDesc) doc() (*doc.PackageDoc, *parseErrors) {
 	}
 
 	// compute documentation
+	// TODO(gri) change doc to work on entire ast.Package at once
 	var r doc.DocReader;
 	i := 0;
 	for filename := range p.filenames {
-		prog, err := parse(p.dirname + "/" + filename, parser.ParseComments);
+		src, err := parse(p.dirname + "/" + filename, parser.ParseComments);
 		if err != nil {
 			return nil, err;
 		}
 		if i == 0 {
 			// first file - initialize doc
-			r.Init(prog.Name.Value, p.importpath);
+			r.Init(src.Name.Value, p.importpath);
 		}
 		i++;
-		ast.FilterExports(prog);  // we only care about exports
-		r.AddProgram(prog);
+		ast.FilterExports(src);  // we only care about exports
+		r.AddFile(src);
 	}
 
 	return r.Doc(), nil;
@@ -625,11 +626,12 @@ func usage() {
 		"	godoc -http=:6060\n"
 	);
 	flag.PrintDefaults();
-	os.Exit(1);
+	os.Exit(2);
 }
 
 
 func main() {
+	flag.Usage = usage;
 	flag.Parse();
 
 	// Check usage first; get usage message out early.
diff --git a/src/cmd/gofmt/gofmt.go b/src/cmd/gofmt/gofmt.go
index 57c07d93e..5ece0d70d 100644
--- a/src/cmd/gofmt/gofmt.go
+++ b/src/cmd/gofmt/gofmt.go
@@ -13,13 +13,21 @@ import (
 	"go/scanner";
 	"io";
 	"os";
+	pathutil "path";
 	"sort";
+	"strings";
 	"tabwriter";
 )
 
 
+const pkgDir = "src/pkg";  // relative to $GOROOT
+
+
 var (
+	goroot = flag.String("goroot", os.Getenv("GOROOT"), "Go root directory");
+
 	// operation modes
+	allgo = flag.Bool("a", false, "include all .go files for package");
 	silent = flag.Bool("s", false, "silent mode: parsing only");
 	verbose = flag.Bool("v", false, "verbose mode: trace parsing");
 	exports = flag.Bool("x", false, "show exports only");
@@ -33,9 +41,9 @@ var (
 
 
 func usage() {
-	fmt.Fprintf(os.Stderr, "usage: gofmt [flags] [file.go]\n");
+	fmt.Fprintf(os.Stderr, "usage: gofmt [flags] [file.go | pkgpath]\n");
 	flag.PrintDefaults();
-	os.Exit(1);
+	os.Exit(2);
 }
 
 
@@ -48,6 +56,48 @@ func parserMode() uint {
 }
 
 
+func isPkgFile(filename string) bool {
+	// ignore non-Go files
+	if strings.HasPrefix(filename, ".") || !strings.HasSuffix(filename, ".go") {
+		return false;
+	}
+
+	// ignore test files unless explicitly included
+	return *allgo || !strings.HasSuffix(filename, "_test.go");
+}
+
+
+func getPackage(path string) (*ast.Package, os.Error) {
+	if len(path) == 0 {
+		return nil, os.NewError("no path specified");
+	}
+
+	if strings.HasSuffix(path, ".go") || path == "/dev/stdin" {
+		// single go file
+		src, err := parser.ParseFile(path, nil, parserMode());
+		if err != nil {
+			return nil, err;
+		}
+		dirname, filename := pathutil.Split(path);
+		return &ast.Package{src.Name.Value, dirname, map[string]*ast.File{filename: src}}, nil;
+	}
+
+	// len(path) > 0
+	switch ch := path[0]; {
+	case ch == '.':
+		// cwd-relative path
+		if cwd, err := os.Getwd(); err == nil {
+			path = pathutil.Join(cwd, path);
+		}
+	case ch != '/':
+		// goroot/pkgDir-relative path
+		path = pathutil.Join(pathutil.Join(*goroot, pkgDir), path);
+	}
+
+	return parser.ParsePackage(path, isPkgFile, parserMode());
+}
+
+
 func printerMode() uint {
 	mode := printer.DocComments;
 	if *optcommas {
@@ -70,33 +120,35 @@ func makeTabwriter(writer io.Writer) *tabwriter.Writer {
 
 
 func main() {
+	flag.Usage = usage;
 	flag.Parse();
 
-	var filename string;
+	path := "";
 	switch flag.NArg() {
-	case 0: filename = "/dev/stdin";
-	case 1: filename = flag.Arg(0);
-	default: usage();
+	case 0:
+		path = "/dev/stdin";
+	case 1:
+		path = flag.Arg(0);
+	default:
+		usage();
 	}
 
-	src, err := io.ReadFile(filename);
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "%v\n", err);
-		os.Exit(1);
-	}
-
-	prog, err := parser.Parse(filename, src, parserMode());
+	pkg, err := getPackage(path);
 	if err != nil {
 		scanner.PrintError(os.Stderr, err);
 		os.Exit(1);
 	}
 
 	if !*silent {
+		w := makeTabwriter(os.Stdout);
 		if *exports {
-			ast.FilterExports(prog);  // ignore result
+			src := ast.PackageInterface(pkg);
+			printer.Fprint(w, src, printerMode());  // ignore errors
+		} else {
+			for _, src := range pkg.Files {
+				printer.Fprint(w, src, printerMode());  // ignore errors
+			}
 		}
-		w := makeTabwriter(os.Stdout);
-		printer.Fprint(w, prog, printerMode());  // ignore errors
 		w.Flush();
 	}
 }
diff --git a/src/pkg/Make.deps b/src/pkg/Make.deps
index 1241bb479..ad5d2e4ca 100644
--- a/src/pkg/Make.deps
+++ b/src/pkg/Make.deps
@@ -20,7 +20,7 @@ flag.install: fmt.install os.install strconv.install
 fmt.install: io.install os.install reflect.install strconv.install utf8.install
 go/ast.install: go/token.install unicode.install utf8.install
 go/doc.install: container/vector.install fmt.install go/ast.install go/token.install io.install once.install regexp.install sort.install strings.install template.install
-go/parser.install: bytes.install container/vector.install fmt.install go/ast.install go/scanner.install go/token.install io.install os.install strings.install
+go/parser.install: bytes.install container/vector.install fmt.install go/ast.install go/scanner.install go/token.install io.install os.install path.install strings.install
 go/printer.install: fmt.install go/ast.install go/token.install io.install os.install reflect.install strings.install
 go/scanner.install: bytes.install container/vector.install fmt.install go/token.install io.install os.install sort.install strconv.install unicode.install utf8.install
 go/token.install: strconv.install
diff --git a/src/pkg/Makefile b/src/pkg/Makefile
index c29c0aea7..6fe77af35 100644
--- a/src/pkg/Makefile
+++ b/src/pkg/Makefile
@@ -92,6 +92,7 @@ TEST=\
 	flag\
 	fmt\
 	go/parser\
+	go/printer\
 	go/scanner\
 	gob\
 	hash/adler32\
diff --git a/src/pkg/go/ast/ast.go b/src/pkg/go/ast/ast.go
index 4681e5daf..781ba266a 100644
--- a/src/pkg/go/ast/ast.go
+++ b/src/pkg/go/ast/ast.go
@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 // The AST package declares the types used to represent
-// syntax trees for Go source files.
+// syntax trees for Go packages.
 //
 package ast
 
@@ -764,15 +764,24 @@ func (d *FuncDecl) Visit(v DeclVisitor) { v.DoFuncDecl(d); }
 
 
 // ----------------------------------------------------------------------------
-// Programs
+// Files and packages
 
-// A Program node represents the root node of an AST
-// for an entire source file.
+// A File node represents a Go source file.
 //
-type Program struct {
+type File struct {
 	Doc *CommentGroup;  // associated documentation; or nil
 	token.Position;  // position of "package" keyword
 	Name *Ident;  // package name
 	Decls []Decl;  // top-level declarations
 	Comments []*CommentGroup;  // list of unassociated comments
 }
+
+
+// A Package node represents a set of source files
+// collectively building a Go package.
+//
+type Package struct {
+	Name string;  // package name
+	Path string;  // package path
+	Files map[string]*File;  // path-relative filenames
+}
diff --git a/src/pkg/go/ast/filter.go b/src/pkg/go/ast/filter.go
index 8ecda9f9c..1858db8f5 100644
--- a/src/pkg/go/ast/filter.go
+++ b/src/pkg/go/ast/filter.go
@@ -177,14 +177,53 @@ func filterDecl(decl Decl) bool {
 // FilterExports returns true if there is an exported declaration; it returns
 // false otherwise.
 //
-func FilterExports(prog *Program) bool {
+func FilterExports(src *File) bool {
 	j := 0;
-	for _, d := range prog.Decls {
+	for _, d := range src.Decls {
 		if filterDecl(d) {
-			prog.Decls[j] = d;
+			src.Decls[j] = d;
 			j++;
 		}
 	}
-	prog.Decls = prog.Decls[0 : j];
+	src.Decls = src.Decls[0 : j];
 	return j > 0;
 }
+
+
+// PackageInterface returns an AST containing only the exported declarations
+// of the package pkg. The pkg AST is modified by PackageInterface.
+//
+func PackageInterface(pkg *Package) *File {
+	// filter each package file
+	for filename, s := range pkg.Files {
+		if !FilterExports(s) {
+			pkg.Files[filename] = nil, false;
+		}
+	}
+
+	// compute total number of top-level declarations in all source files
+	var doc *CommentGroup;
+	n := 0;
+	for _, src := range pkg.Files {
+		if doc == nil && src.Doc != nil {
+			// TODO(gri) what to do with multiple package comments?
+			doc = src.Doc;
+		}
+		n += len(src.Decls);
+	}
+
+	// collect top-level declarations of all source files
+	decls := make([]Decl, n);
+	i := 0;
+	for _, src := range pkg.Files {
+		for _, d := range src.Decls {
+			decls[i] = d;
+			i++;
+		}
+	}
+
+	// TODO(gri) should also collect comments so that this function
+	//           can be used by godoc.
+	var noPos token.Position;
+	return &File{doc, noPos, &Ident{noPos, pkg.Name}, decls, nil};
+}
diff --git a/src/pkg/go/doc/doc.go b/src/pkg/go/doc/doc.go
index 0e09a4d5d..860d6d54c 100644
--- a/src/pkg/go/doc/doc.go
+++ b/src/pkg/go/doc/doc.go
@@ -181,32 +181,32 @@ var (
 )
 
 
-// AddProgram adds the AST for a source file to the DocReader.
+// AddFile adds the AST for a source file to the DocReader.
 // Adding the same AST multiple times is a no-op.
 //
-func (doc *DocReader) AddProgram(prog *ast.Program) {
+func (doc *DocReader) AddFile(src *ast.File) {
 	if bug_markers == nil {
 		bug_markers = makeRex("^/[/*][ \t]*BUG\\(.*\\):[ \t]*");  // BUG(uid):
 		bug_content = makeRex("[^ \n\r\t]+");  // at least one non-whitespace char
 	}
 
-	if doc.name != prog.Name.Value {
+	if doc.name != src.Name.Value {
 		panic("package names don't match");
 	}
 
 	// add package documentation
 	// TODO(gri) what to do if there are multiple files?
-	if prog.Doc != nil {
-		doc.doc = prog.Doc
+	if src.Doc != nil {
+		doc.doc = src.Doc
 	}
 
 	// add all declarations
-	for _, decl := range prog.Decls {
+	for _, decl := range src.Decls {
 		doc.addDecl(decl);
 	}
 
 	// collect BUG(...) comments
-	for _, c := range prog.Comments {
+	for _, c := range src.Comments {
 		text := c.List[0].Text;
 		cstr := string(text);
 		if m := bug_markers.Execute(cstr); len(m) > 0 {
diff --git a/src/pkg/go/parser/Makefile b/src/pkg/go/parser/Makefile
index 08d83646f..5e5c51a5a 100644
--- a/src/pkg/go/parser/Makefile
+++ b/src/pkg/go/parser/Makefile
@@ -2,8 +2,9 @@
 # Use of this source code is governed by a BSD-style
 # license that can be found in the LICENSE file.
 
+
 # DO NOT EDIT.  Automatically generated by gobuild.
-# gobuild -m >Makefile
+# gobuild -m parser.go interface.go >Makefile
 
 D=/go/
 
@@ -20,7 +21,7 @@ test: packages
 
 coverage: packages
 	gotest
-	6cov -g `pwd` | grep -v '_test\.go:'
+	6cov -g $$(pwd) | grep -v '_test\.go:'
 
 %.$O: %.go
 	$(GC) -I_obj $*.go
@@ -34,14 +35,21 @@ coverage: packages
 O1=\
 	parser.$O\
 
+O2=\
+	interface.$O\
+
 
-phases: a1
+phases: a1 a2
 _obj$D/parser.a: phases
 
 a1: $(O1)
 	$(AR) grc _obj$D/parser.a parser.$O
 	rm -f $(O1)
 
+a2: $(O2)
+	$(AR) grc _obj$D/parser.a interface.$O
+	rm -f $(O2)
+
 
 newpkg: clean
 	mkdir -p _obj$D
@@ -49,6 +57,7 @@ newpkg: clean
 
 $(O1): newpkg
 $(O2): a1
+$(O3): a2
 
 nuke: clean
 	rm -f $(GOROOT)/pkg/$(GOOS)_$(GOARCH)$D/parser.a
diff --git a/src/pkg/go/parser/interface.go b/src/pkg/go/parser/interface.go
new file mode 100644
index 000000000..f3a46da40
--- /dev/null
+++ b/src/pkg/go/parser/interface.go
@@ -0,0 +1,186 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file contains the exported entry points for invoking the parser.
+
+package parser
+
+import (
+	"bytes";
+	"fmt";
+	"go/ast";
+	"go/parser";
+	"go/scanner";
+	"io";
+	"os";
+	pathutil "path";
+	"strings";
+)
+
+
+// If src != nil, readSource converts src to a []byte if possible;
+// otherwise it returns an error. If src == nil, readSource returns
+// the result of reading the file specified by filename.
+//
+func readSource(filename string, src interface{}) ([]byte, os.Error) {
+	if src != nil {
+		switch s := src.(type) {
+		case string:
+			return strings.Bytes(s), nil;
+		case []byte:
+			return s, nil;
+		case *bytes.Buffer:
+			// is io.Reader, but src is already available in []byte form
+			if s != nil {
+				return s.Data(), nil;
+			}
+		case io.Reader:
+			var buf bytes.Buffer;
+			n, err := io.Copy(s, &buf);
+			if err != nil {
+				return nil, err;
+			}
+			return buf.Data(), nil;
+		default:
+			return nil, os.ErrorString("invalid source");
+		}
+	}
+
+	return io.ReadFile(filename);
+}
+
+
+// ParseExpr parses a Go expression and returns the corresponding
+// AST node. The filename and src arguments have the same interpretation
+// as for ParseFile. If there is an error, the result expression
+// may be nil or contain a partial AST.
+//
+func ParseExpr(filename string, src interface{}) (ast.Expr, os.Error) {
+	data, err := readSource(filename, src);
+	if err != nil {
+		return nil, err;
+	}
+
+	var p parser;
+	p.init(filename, data, 0);
+	x := p.parseExpr();  // TODO 6g bug - function call order in expr lists
+	return x, p.GetError(scanner.Sorted);
+}
+
+
+// ParseStmtList parses a list of Go statements and returns the list
+// of corresponding AST nodes. The filename and src arguments have the same
+// interpretation as for ParseFile. If there is an error, the node
+// list may be nil or contain partial ASTs.
+//
+func ParseStmtList(filename string, src interface{}) ([]ast.Stmt, os.Error) {
+	data, err := readSource(filename, src);
+	if err != nil {
+		return nil, err;
+	}
+
+	var p parser;
+	p.init(filename, data, 0);
+	list := p.parseStmtList();  // TODO 6g bug - function call order in expr lists
+	return list, p.GetError(scanner.Sorted);
+}
+
+
+// ParseFile parses a Go source file and returns a File node.
+//
+// If src != nil, ParseFile parses the file source from src. src may
+// be provided in a variety of formats. At the moment the following types
+// are supported: string, []byte, and io.Reader. In this case, filename is
+// only used for source position information and error messages.
+//
+// If src == nil, ParseFile parses the file specified by filename.
+//
+// The mode parameter controls the amount of source text parsed and other
+// optional parser functionality.
+//
+// If the source couldn't be read, the returned AST is nil and the error
+// indicates the specific failure. If the source was read but syntax
+// errors were found, the result is a partial AST (with ast.BadX nodes
+// representing the fragments of erroneous source code). Multiple errors
+// are returned via a scanner.ErrorList which is sorted by file position.
+//
+func ParseFile(filename string, src interface{}, mode uint) (*ast.File, os.Error) {
+	data, err := readSource(filename, src);
+	if err != nil {
+		return nil, err;
+	}
+
+	var p parser;
+	p.init(filename, data, mode);
+	prog := p.parseFile();  // TODO 6g bug - function call order in expr lists
+	return prog, p.GetError(scanner.NoMultiples);
+}
+
+
+// ParsePkgFile parses the file specified by filename and returns the
+// corresponding AST. If the file cannot be read, has syntax errors, or
+// does not belong to the package (i.e., pkgname != "" and the package
+// name in the file doesn't match pkkname), an error is returned. Mode
+// flags that control the amount of source text parsed are ignored.
+//
+func ParsePkgFile(pkgname, filename string, mode uint) (*ast.File, os.Error) {
+	src, err := io.ReadFile(filename);
+	if err != nil {
+		return nil, err;
+	}
+
+	if pkgname != "" {
+		prog, err := ParseFile(filename, src, PackageClauseOnly);
+		if err != nil {
+			return nil, err;
+		}
+		if prog.Name.Value != pkgname {
+			return nil, os.NewError(fmt.Sprintf("multiple packages found: %s, %s", prog.Name.Value, pkgname));
+		}
+	}
+
+	// ignore flags that control partial parsing
+	return ParseFile(filename, src, mode &^ (PackageClauseOnly | ImportsOnly));
+}
+
+
+// ParsePackage parses all files in the directory specified by path and
+// returns an AST representing the package found. The set of files may be
+// restricted by providing a non-nil filter function; only the files with
+// (path-local) filenames passing through the filter are considered. If
+// zero or more then one package is found, an error is returned. Mode
+// flags that control the amount of source text parsed are ignored.
+//
+func ParsePackage(path string, filter func(string) bool, mode uint) (*ast.Package, os.Error) {
+	fd, err := os.Open(path, os.O_RDONLY, 0);
+	if err != nil {
+		return nil, err;
+	}
+
+	list, err := fd.Readdirnames(-1);
+	if err != nil {
+		return nil, err;
+	}
+
+	name := "";
+	files := make(map[string]*ast.File);
+	for _, filename := range list {
+		if filter == nil || filter(filename) {
+			src, err := ParsePkgFile(name, pathutil.Join(path, filename), mode);
+			if err != nil {
+				return nil, err;
+			}
+			files[filename] = src;
+			if name == "" {
+				name = src.Name.Value;
+			}
+		}
+	}
+
+	if len(files) == 0 {
+		return nil, os.NewError(path + ": no package found");
+	}
+
+	return &ast.Package{name, path, files}, nil;
+}
diff --git a/src/pkg/go/parser/parser.go b/src/pkg/go/parser/parser.go
index b39e98cbd..0f5582da9 100644
--- a/src/pkg/go/parser/parser.go
+++ b/src/pkg/go/parser/parser.go
@@ -2,10 +2,10 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// A parser for Go source text. The input is a stream of lexical tokens
-// provided via the Scanner interface. The output is an abstract syntax
-// tree (AST) representing the Go source. The parser is invoked by calling
-// Parse.
+// A parser for Go source files. Input may be provided in a variety of
+// forms (see the various Parse* functions); the output is an abstract
+// syntax tree (AST) representing the Go source. The parser is invoked
+// through one of the Parse* functions.
 //
 package parser
 
@@ -33,6 +33,22 @@ const (
 var noIndex = [2]int{-1, -1};
 
 
+// noPos is used when there is no corresponding source position for a token.
+var noPos token.Position;
+
+
+// The mode parameter to the Parse* functions is a set of flags (or 0).
+// They control the amount of source code parsed and other optional
+// parser functionality.
+//
+const (
+	PackageClauseOnly uint = 1 << iota;  // parsing stops after package clause
+	ImportsOnly;  // parsing stops after import declarations
+	ParseComments;  // parse comments and add them to AST
+	Trace;  // print a trace of parsed productions
+)
+
+
 // The parser structure holds the parser's internal state.
 type parser struct {
 	scanner.ErrorVector;
@@ -58,8 +74,26 @@ type parser struct {
 };
 
 
-// noPos is used when there is no corresponding source position for a token
-var noPos token.Position;
+// scannerMode returns the scanner mode bits given the parser's mode bits.
+func scannerMode(mode uint) uint {
+	if mode & ParseComments != 0 {
+		return scanner.ScanComments;
+	}
+	return 0;
+}
+
+
+func (p *parser) next()
+
+func (p *parser) init(filename string, src []byte, mode uint) {
+	p.ErrorVector.Init();
+	p.scanner.Init(filename, src, p, scannerMode(mode));
+	p.mode = mode;
+	p.trace = mode & Trace != 0;  // for convenience (p.trace is used frequently)
+	p.comments.Init(0);
+	p.commentsIndex = noIndex;
+	p.next();
+}
 
 
 // ----------------------------------------------------------------------------
@@ -253,9 +287,9 @@ func (p *parser) expect(tok token.Token) token.Position {
 
 func (p *parser) tryType() ast.Expr
 func (p *parser) parseStringList(x *ast.StringLit) []*ast.StringLit
-func (p *parser) parseExpression() ast.Expr
-func (p *parser) parseStatement() ast.Stmt
-func (p *parser) parseDeclaration(getSemi bool) (decl ast.Decl, gotSemi bool)
+func (p *parser) parseExpr() ast.Expr
+func (p *parser) parseStmt() ast.Stmt
+func (p *parser) parseDecl(getSemi bool) (decl ast.Decl, gotSemi bool)
 
 
 func (p *parser) parseIdent() *ast.Ident {
@@ -294,16 +328,16 @@ func (p *parser) parseIdentList(x ast.Expr) []*ast.Ident {
 }
 
 
-func (p *parser) parseExpressionList() []ast.Expr {
+func (p *parser) parseExprList() []ast.Expr {
 	if p.trace {
 		defer un(trace(p, "ExpressionList"));
 	}
 
 	list := vector.New(0);
-	list.Push(p.parseExpression());
+	list.Push(p.parseExpr());
 	for p.tok == token.COMMA {
 		p.next();
-		list.Push(p.parseExpression());
+		list.Push(p.parseExpr());
 	}
 
 	// convert list
@@ -372,7 +406,7 @@ func (p *parser) parseArrayType(ellipsisOk bool) ast.Expr {
 		len = &ast.Ellipsis{p.pos};
 		p.next();
 	} else if p.tok != token.RBRACK {
-		len = p.parseExpression();
+		len = p.parseExpr();
 	}
 	p.expect(token.RBRACK);
 	elt := p.parseType();
@@ -777,7 +811,7 @@ func makeStmtList(list *vector.Vector) []ast.Stmt {
 }
 
 
-func (p *parser) parseStatementList() []ast.Stmt {
+func (p *parser) parseStmtList() []ast.Stmt {
 	if p.trace {
 		defer un(trace(p, "StatementList"));
 	}
@@ -789,7 +823,7 @@ func (p *parser) parseStatementList() []ast.Stmt {
 			p.expect(token.SEMICOLON);
 			expectSemi = false;
 		}
-		list.Push(p.parseStatement());
+		list.Push(p.parseStmt());
 		if p.tok == token.SEMICOLON {
 			p.next();
 		} else if p.optSemi {
@@ -809,7 +843,7 @@ func (p *parser) parseBlockStmt() *ast.BlockStmt {
 	}
 
 	lbrace := p.expect(token.LBRACE);
-	list := p.parseStatementList();
+	list := p.parseStmtList();
 	rbrace := p.expect(token.RBRACE);
 	p.optSemi = true;
 
@@ -899,7 +933,7 @@ func (p *parser) parseOperand() ast.Expr {
 		lparen := p.pos;
 		p.next();
 		p.exprLev++;
-		x := p.parseExpression();
+		x := p.parseExpr();
 		p.exprLev--;
 		rparen := p.expect(token.RPAREN);
 		return &ast.ParenExpr{lparen, x, rparen};
@@ -955,11 +989,11 @@ func (p *parser) parseIndex(x ast.Expr) ast.Expr {
 
 	p.expect(token.LBRACK);
 	p.exprLev++;
-	begin := p.parseExpression();
+	begin := p.parseExpr();
 	var end ast.Expr;
 	if p.tok == token.COLON {
 		p.next();
-		end = p.parseExpression();
+		end = p.parseExpr();
 	}
 	p.exprLev--;
 	p.expect(token.RBRACK);
@@ -976,7 +1010,7 @@ func (p *parser) parseCallOrConversion(fun ast.Expr) *ast.CallExpr {
 	lparen := p.expect(token.LPAREN);
 	var args []ast.Expr;
 	if p.tok != token.RPAREN {
-		args = p.parseExpressionList();
+		args = p.parseExprList();
 	}
 	rparen := p.expect(token.RPAREN);
 
@@ -989,11 +1023,11 @@ func (p *parser) parseElement() ast.Expr {
 		defer un(trace(p, "Element"));
 	}
 
-	x := p.parseExpression();
+	x := p.parseExpr();
 	if p.tok == token.COLON {
 		colon := p.pos;
 		p.next();
-		x = &ast.KeyValueExpr{x, colon, p.parseExpression()};
+		x = &ast.KeyValueExpr{x, colon, p.parseExpr()};
 	}
 
 	return x;
@@ -1204,7 +1238,7 @@ func (p *parser) parseBinaryExpr(prec1 int) ast.Expr {
 }
 
 
-func (p *parser) parseExpression() ast.Expr {
+func (p *parser) parseExpr() ast.Expr {
 	if p.trace {
 		defer un(trace(p, "Expression"));
 	}
@@ -1222,7 +1256,7 @@ func (p *parser) parseSimpleStmt(labelOk bool) ast.Stmt {
 		defer un(trace(p, "SimpleStmt"));
 	}
 
-	x := p.parseExpressionList();
+	x := p.parseExprList();
 
 	switch p.tok {
 	case token.COLON:
@@ -1230,7 +1264,7 @@ func (p *parser) parseSimpleStmt(labelOk bool) ast.Stmt {
 		p.next();
 		if labelOk && len(x) == 1 {
 			if label, isIdent := x[0].(*ast.Ident); isIdent {
-				return &ast.LabeledStmt{label, p.parseStatement()};
+				return &ast.LabeledStmt{label, p.parseStmt()};
 			}
 		}
 		p.Error(x[0].Pos(), "illegal label declaration");
@@ -1244,7 +1278,7 @@ func (p *parser) parseSimpleStmt(labelOk bool) ast.Stmt {
 		// assignment statement
 		pos, tok := p.pos, p.tok;
 		p.next();
-		y := p.parseExpressionList();
+		y := p.parseExprList();
 		if len(x) > 1 && len(y) > 1 && len(x) != len(y) {
 			p.Error(x[0].Pos(), "arity of lhs doesn't match rhs");
 		}
@@ -1269,7 +1303,7 @@ func (p *parser) parseSimpleStmt(labelOk bool) ast.Stmt {
 
 
 func (p *parser) parseCallExpr() *ast.CallExpr {
-	x := p.parseExpression();
+	x := p.parseExpr();
 	if call, isCall := x.(*ast.CallExpr); isCall {
 		return call;
 	}
@@ -1315,7 +1349,7 @@ func (p *parser) parseReturnStmt() *ast.ReturnStmt {
 	p.expect(token.RETURN);
 	var x []ast.Expr;
 	if p.tok != token.SEMICOLON && p.tok != token.CASE && p.tok != token.DEFAULT && p.tok != token.RBRACE {
-		x = p.parseExpressionList();
+		x = p.parseExprList();
 	}
 
 	return &ast.ReturnStmt{pos, x};
@@ -1400,7 +1434,7 @@ func (p *parser) parseIfStmt() *ast.IfStmt {
 	var else_ ast.Stmt;
 	if p.tok == token.ELSE {
 		p.next();
-		else_ = p.parseStatement();
+		else_ = p.parseStmt();
 	}
 
 	return &ast.IfStmt{pos, s1, p.makeExpr(s2), body, else_};
@@ -1417,13 +1451,13 @@ func (p *parser) parseCaseClause() *ast.CaseClause {
 	var x []ast.Expr;
 	if p.tok == token.CASE {
 		p.next();
-		x = p.parseExpressionList();
+		x = p.parseExprList();
 	} else {
 		p.expect(token.DEFAULT);
 	}
 
 	colon := p.expect(token.COLON);
-	body := p.parseStatementList();
+	body := p.parseStmtList();
 
 	return &ast.CaseClause{pos, x, colon, body};
 }
@@ -1445,7 +1479,7 @@ func (p *parser) parseTypeCaseClause() *ast.TypeCaseClause {
 	}
 
 	colon := p.expect(token.COLON);
-	body := p.parseStatementList();
+	body := p.parseStmtList();
 
 	return &ast.TypeCaseClause{pos, typ, colon, body};
 }
@@ -1499,17 +1533,17 @@ func (p *parser) parseCommClause() *ast.CommClause {
 		p.next();
 		if p.tok == token.ARROW {
 			// RecvExpr without assignment
-			rhs = p.parseExpression();
+			rhs = p.parseExpr();
 		} else {
 			// SendExpr or RecvExpr
-			rhs = p.parseExpression();
+			rhs = p.parseExpr();
 			if p.tok == token.ASSIGN || p.tok == token.DEFINE {
 				// RecvExpr with assignment
 				tok = p.tok;
 				p.next();
 				lhs = rhs;
 				if p.tok == token.ARROW {
-					rhs = p.parseExpression();
+					rhs = p.parseExpr();
 				} else {
 					p.expect(token.ARROW);  // use expect() error handling
 				}
@@ -1521,7 +1555,7 @@ func (p *parser) parseCommClause() *ast.CommClause {
 	}
 
 	colon := p.expect(token.COLON);
-	body := p.parseStatementList();
+	body := p.parseStmtList();
 
 	return &ast.CommClause{pos, tok, lhs, rhs, colon, body};
 }
@@ -1595,14 +1629,14 @@ func (p *parser) parseForStmt() ast.Stmt {
 }
 
 
-func (p *parser) parseStatement() ast.Stmt {
+func (p *parser) parseStmt() ast.Stmt {
 	if p.trace {
 		defer un(trace(p, "Statement"));
 	}
 
 	switch p.tok {
 	case token.CONST, token.TYPE, token.VAR:
-		decl, _ := p.parseDeclaration(false);  // do not consume trailing semicolon
+		decl, _ := p.parseDecl(false);  // do not consume trailing semicolon
 		return &ast.DeclStmt{decl};
 	case
 		// tokens that may start a top-level expression
@@ -1694,7 +1728,7 @@ func parseConstSpec(p *parser, doc *ast.CommentGroup, getSemi bool) (spec ast.Sp
 	var values []ast.Expr;
 	if typ != nil || p.tok == token.ASSIGN {
 		p.expect(token.ASSIGN);
-		values = p.parseExpressionList();
+		values = p.parseExprList();
 	}
 	comment, gotSemi := p.parseComment(getSemi);
 
@@ -1725,7 +1759,7 @@ func parseVarSpec(p *parser, doc *ast.CommentGroup, getSemi bool) (spec ast.Spec
 	var values []ast.Expr;
 	if typ == nil || p.tok == token.ASSIGN {
 		p.expect(token.ASSIGN);
-		values = p.parseExpressionList();
+		values = p.parseExprList();
 	}
 	comment, gotSemi := p.parseComment(getSemi);
 
@@ -1831,7 +1865,7 @@ func (p *parser) parseFunctionDecl() *ast.FuncDecl {
 }
 
 
-func (p *parser) parseDeclaration(getSemi bool) (decl ast.Decl, gotSemi bool) {
+func (p *parser) parseDecl(getSemi bool) (decl ast.Decl, gotSemi bool) {
 	if p.trace {
 		defer un(trace(p, "Declaration"));
 	}
@@ -1873,23 +1907,11 @@ func (p *parser) parseDeclaration(getSemi bool) (decl ast.Decl, gotSemi bool) {
 
 
 // ----------------------------------------------------------------------------
-// Packages
+// Source files
 
-// The mode parameter to the Parse function is a set of flags (or 0).
-// They control the amount of source code parsed and other optional
-// parser functionality.
-//
-const (
-	PackageClauseOnly uint = 1 << iota;  // parsing stops after package clause
-	ImportsOnly;  // parsing stops after import declarations
-	ParseComments;  // parse comments and add them to AST
-	Trace;  // print a trace of parsed productions
-)
-
-
-func (p *parser) parsePackage() *ast.Program {
+func (p *parser) parseFile() *ast.File {
 	if p.trace {
-		defer un(trace(p, "Program"));
+		defer un(trace(p, "File"));
 	}
 
 	// package clause
@@ -1912,7 +1934,7 @@ func (p *parser) parsePackage() *ast.Program {
 		if p.mode & ImportsOnly == 0 {
 			// rest of package body
 			for p.tok != token.EOF {
-				decl, _ := p.parseDeclaration(true);  // consume optional semicolon
+				decl, _ := p.parseDecl(true);  // consume optional semicolon
 				list.Push(decl);
 			}
 		}
@@ -1941,119 +1963,5 @@ func (p *parser) parsePackage() *ast.Program {
 		}
 	}
 
-	return &ast.Program{comment, pos, ident, decls, comments};
-}
-
-
-// ----------------------------------------------------------------------------
-// Parser entry points.
-
-func readSource(src interface{}) ([]byte, os.Error) {
-	if src != nil {
-		switch s := src.(type) {
-		case string:
-			return strings.Bytes(s), nil;
-		case []byte:
-			return s, nil;
-		case *bytes.Buffer:
-			// is io.Reader, but src is already available in []byte form
-			if s != nil {
-				return s.Data(), nil;
-			}
-		case io.Reader:
-			var buf bytes.Buffer;
-			n, err := io.Copy(s, &buf);
-			if err != nil {
-				return nil, err;
-			}
-			return buf.Data(), nil;
-		}
-	}
-	return nil, os.ErrorString("invalid source");
-}
-
-
-// scannerMode returns the scanner mode bits given the parser's mode bits.
-func scannerMode(mode uint) uint {
-	if mode & ParseComments != 0 {
-		return scanner.ScanComments;
-	}
-	return 0;
-}
-
-
-func (p *parser) init(filename string, src interface{}, mode uint) os.Error {
-	data, err := readSource(src);
-	if err != nil {
-		return err;
-	}
-
-	// initialize parser state
-	p.ErrorVector.Init();
-	p.scanner.Init(filename, data, p, scannerMode(mode));
-	p.mode = mode;
-	p.trace = mode & Trace != 0;  // for convenience (p.trace is used frequently)
-	p.comments.Init(0);
-	p.commentsIndex = noIndex;
-	p.next();
-
-	return nil;
-}
-
-
-// Parse parses a Go program.
-//
-// The filename is only used in AST position information and error messages
-// and may be empty. The program source src may be provided in a variety of
-// formats. At the moment the following types are supported: string, []byte,
-// and io.Reader. The mode parameter controls the amount of source text parsed
-// and other optional parser functionality.
-//
-// Parse returns a complete AST if no error occured. Otherwise, if the
-// source couldn't be read, the returned program is nil and the error
-// indicates the specific failure. If the source was read but syntax
-// errors were found, the result is a partial AST (with ast.BadX nodes
-// representing the fragments of erroneous source code). Multiple errors
-// are returned via a scanner.ErrorList which is sorted by file position.
-//
-func Parse(filename string, src interface{}, mode uint) (*ast.Program, os.Error) {
-	var p parser;
-	if err := p.init(filename, src, mode); err != nil {
-		return nil, err;
-	}
-
-	prog := p.parsePackage();  // TODO 6g bug - function call order in expr lists
-	return prog, p.GetError(scanner.NoMultiples);
-}
-
-
-// ParseStmts parses a list of Go statements and returns the list of
-// corresponding AST nodes. The filename and src arguments have the
-// same interpretation as for Parse. If there is an error, the node
-// list may be nil or contain partial ASTs.
-//
-func ParseStmts(filename string, src interface{}) ([]ast.Stmt, os.Error) {
-	var p parser;
-	if err := p.init(filename, src, 0); err != nil {
-		return nil, err;
-	}
-
-	list := p.parseStatementList();  // TODO 6g bug - function call order in expr lists
-	return list, p.GetError(scanner.Sorted);
-}
-
-
-// ParseExpr parses a single Go expression and returns the corresponding
-// AST node. The filename and src arguments have the same interpretation
-// as for Parse. If there is an error, the result expression may be nil
-// or contain a partial AST.
-//
-func ParseExpr(filename string, src interface{}) (ast.Expr, os.Error) {
-	var p parser;
-	if err := p.init(filename, src, 0); err != nil {
-		return nil, err;
-	}
-
-	x := p.parseExpression();  // TODO 6g bug - function call order in expr lists
-	return x, p.GetError(scanner.Sorted);
+	return &ast.File{comment, pos, ident, decls, comments};
 }
diff --git a/src/pkg/go/parser/parser_test.go b/src/pkg/go/parser/parser_test.go
index f8501b3b5..3b02c5034 100644
--- a/src/pkg/go/parser/parser_test.go
+++ b/src/pkg/go/parser/parser_test.go
@@ -22,9 +22,9 @@ var illegalInputs = []interface{} {
 
 func TestParseIllegalInputs(t *testing.T) {
 	for _, src := range illegalInputs {
-		prog, err := Parse("", src, 0);
+		prog, err := ParseFile("", src, 0);
 		if err == nil {
-			t.Errorf("Parse(%v) should have failed", src);
+			t.Errorf("ParseFile(%v) should have failed", src);
 		}
 	}
 }
@@ -38,9 +38,9 @@ var validPrograms = []interface{} {
 
 func TestParseValidPrograms(t *testing.T) {
 	for _, src := range validPrograms {
-		prog, err := Parse("", src, 0);
+		prog, err := ParseFile("", src, 0);
 		if err != nil {
-			t.Errorf("Parse(%q) failed: %v", src, err);
+			t.Errorf("ParseFile(%q): %v", src, err);
 		}
 	}
 }
@@ -54,15 +54,38 @@ var validFiles = []string {
 
 func TestParse3(t *testing.T) {
 	for _, filename := range validFiles {
-		src, err := os.Open(filename, os.O_RDONLY, 0);
-		defer src.Close();
+		prog, err := ParseFile(filename, nil, 0);
 		if err != nil {
-			t.Fatal(err);
+			t.Errorf("ParseFile(%s): %v", filename, err);
 		}
+	}
+}
 
-		prog, err := Parse(filename, src, 0);
-		if err != nil {
-			t.Errorf("Parse(%s): %v", filename, err);
+
+func filter(filename string) bool {
+	switch filename {
+	case "parser.go":
+	case "interface.go":
+	case "parser_test.go":
+	default:
+		return false;
+	}
+	return true;
+}
+
+
+func TestParse4(t *testing.T) {
+	path := ".";
+	pkg, err := ParsePackage(path, filter, 0);
+	if err != nil {
+		t.Errorf("ParsePackage(%s): %v", path, err);
+	}
+	if pkg.Name != "parser" {
+		t.Errorf("incorrect package name: %s", pkg.Name);
+	}
+	for filename, _ := range pkg.Files {
+		if !filter(filename) {
+			t.Errorf("unexpected package file: %s", filename);
 		}
 	}
 }
diff --git a/src/pkg/go/printer/printer.go b/src/pkg/go/printer/printer.go
index 4196eb8d8..4b2d8f7ae 100644
--- a/src/pkg/go/printer/printer.go
+++ b/src/pkg/go/printer/printer.go
@@ -891,16 +891,16 @@ func (p *printer) decl(decl ast.Decl) (comment *ast.CommentGroup, optSemi bool)
 
 
 // ----------------------------------------------------------------------------
-// Programs
+// Files
 
-func (p *printer) program(prog *ast.Program) {
-	p.setComments(prog.Comments);  // unassociated comments
+func (p *printer) file(src *ast.File) {
+	p.setComments(src.Comments);  // unassociated comments
 
-	p.leadingComment(prog.Doc);
-	p.print(prog.Pos(), token.PACKAGE, blank);
-	p.expr(prog.Name);
+	p.leadingComment(src.Doc);
+	p.print(src.Pos(), token.PACKAGE, blank);
+	p.expr(src.Name);
 
-	for _, d := range prog.Decls {
+	for _, d := range src.Decls {
 		p.print(newline, newline);
 		comment, _ := p.decl(d);
 		if p.optSemis() {
@@ -917,7 +917,7 @@ func (p *printer) program(prog *ast.Program) {
 // Public interface
 
 // Fprint "pretty-prints" an AST node to output and returns the number of
-// bytes written, and an error, if any. The node type must be *ast.Program,
+// bytes written, and an error, if any. The node type must be *ast.File,
 // or assignment-compatible to ast.Expr, ast.Decl, or ast.Stmt. Printing is
 // controlled by the mode parameter. For best results, the output should be
 // a tabwriter.Writer.
@@ -935,8 +935,8 @@ func Fprint(output io.Writer, node interface{}, mode uint) (int, os.Error) {
 		case ast.Decl:
 			comment, _ := p.decl(n);
 			p.trailingComment(comment);  // no newline at end
-		case *ast.Program:
-			p.program(n);
+		case *ast.File:
+			p.file(n);
 		default:
 			p.errors <- os.NewError("unsupported node type");
 		}
diff --git a/src/pkg/go/printer/printer_test.go b/src/pkg/go/printer/printer_test.go
index dc42098e5..bc21109f9 100644
--- a/src/pkg/go/printer/printer_test.go
+++ b/src/pkg/go/printer/printer_test.go
@@ -39,15 +39,8 @@ func lineString(text []byte, i int) string {
 
 
 func check(t *testing.T, source, golden string, exports bool) {
-	// get source
-	src, err := io.ReadFile(source);
-	if err != nil {
-		t.Error(err);
-		return;
-	}
-
 	// parse source
-	prog, err := parser.Parse(src, parser.ParseComments);
+	prog, err := parser.ParseFile(source, nil, parser.ParseComments);
 	if err != nil {
 		t.Error(err);
 		return;