gotype: commandline tool to typecheck go programs

First version. Handles scope analysis only at the
moment.

R=rsc, r, eds
CC=golang-dev
https://golang.org/cl/4259065

src/cmd/Makefile

@@ -43,6 +43,7 @@ CLEANDIRS=\
 	godoc\
 	gofmt\
 	goinstall\
+	gotype\
 	goyacc\
 	hgpatch\
 

src/cmd/gotype/Makefile

+# Copyright 2011 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.
+
+include ../../Make.inc
+
+TARG=gotype
+GOFILES=\
+	gotype.go\
+
+include ../../Make.cmd

src/cmd/gotype/doc.go

+// Copyright 2011 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.
+
+/*
+The gotype command does syntactic and semantic analysis of Go files
+and packages similar to the analysis performed by the front-end of
+a Go compiler. Errors are reported if the analysis fails; otherwise
+gotype is quiet (unless -v is set).
+
+Without a list of paths, gotype processes the standard input, which must
+be the source of a single package file.
+
+Given a list of file names, each file must be a source file belonging to
+the same package unless the package name is explicitly specified with the
+-p flag.
+
+Given a directory name, gotype collects all .go files in the directory
+and processes them as if they were provided as an explicit list of file
+names. Each directory is processed independently. Files starting with .
+or not ending in .go are ignored.
+
+Usage:
+	gotype [flags] [path ...]
+
+The flags are:
+	-p pkgName
+		process only those files in package pkgName.
+	-r
+		recursively process subdirectories.
+	-v
+		verbose mode.
+
+Debugging flags:
+	-trace
+		print parse trace (disables concurrent parsing).
+	-ast
+		print AST (disables concurrent parsing).
+
+
+Examples
+
+To check the files file.go, old.saved, and .ignored:
+
+	gotype file.go old.saved .ignored
+
+To check all .go files belonging to package main in the current directory
+and recursively in all subdirectories:
+
+	gotype -p main -r .
+
+To verify the output of a pipe:
+
+	echo "package foo" | gotype
+
+*/
+package documentation

src/cmd/gotype/gotype.go

+// Copyright 2011 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.
+
+package main
+
+import (
+	"flag"
+	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/scanner"
+	"go/token"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+
+var (
+	// main operation modes
+	pkgName   = flag.String("p", "", "process only those files in package pkgName")
+	recursive = flag.Bool("r", false, "recursively process subdirectories")
+	verbose   = flag.Bool("v", false, "verbose mode")
+
+	// debugging support
+	printTrace = flag.Bool("trace", false, "print parse trace")
+	printAST   = flag.Bool("ast", false, "print AST")
+)
+
+
+var (
+	fset       = token.NewFileSet()
+	exitCode   = 0
+	parserMode = parser.DeclarationErrors
+)
+
+
+func usage() {
+	fmt.Fprintf(os.Stderr, "usage: gotype [flags] [path ...]\n")
+	flag.PrintDefaults()
+	os.Exit(2)
+}
+
+
+func processFlags() {
+	flag.Usage = usage
+	flag.Parse()
+	if *printTrace {
+		parserMode |= parser.Trace
+	}
+}
+
+
+func report(err os.Error) {
+	scanner.PrintError(os.Stderr, err)
+	exitCode = 2
+}
+
+
+// parseFile returns the AST for the given file.
+// The result
+func parseFile(filename string) *ast.File {
+	if *verbose {
+		fmt.Println(filename)
+	}
+
+	// get source
+	src, err := ioutil.ReadFile(filename)
+	if err != nil {
+		report(err)
+		return nil
+	}
+
+	// ignore files with different package name
+	if *pkgName != "" {
+		file, err := parser.ParseFile(fset, filename, src, parser.PackageClauseOnly)
+		if err != nil {
+			report(err)
+			return nil
+		}
+		if file.Name.Name != *pkgName {
+			if *verbose {
+				fmt.Printf("\tignored (package %s)\n", file.Name.Name)
+			}
+			return nil
+		}
+	}
+
+	// parse entire file
+	file, err := parser.ParseFile(fset, filename, src, parserMode)
+	if err != nil {
+		report(err)
+		return nil
+	}
+	if *printAST {
+		ast.Print(fset, file)
+	}
+
+	return file
+}
+
+
+// BUG(gri): At the moment, only single-file scope analysis is performed.
+
+func processPackage(filenames []string) {
+	var files []*ast.File
+	pkgName := ""
+	for _, filename := range filenames {
+		file := parseFile(filename)
+		if file == nil {
+			continue // ignore file
+		}
+		// package names must match
+		// TODO(gri): this check should be moved into a
+		//            function making the package below
+		if pkgName == "" {
+			// first package file
+			pkgName = file.Name.Name
+		} else {
+			if file.Name.Name != pkgName {
+				report(os.NewError(fmt.Sprintf("file %q is in package %q not %q", filename, file.Name.Name, pkgName)))
+				continue
+			}
+		}
+		files = append(files, file)
+	}
+
+	// TODO(gri): make a ast.Package and analyze it
+	_ = files
+}
+
+
+func isGoFilename(filename string) bool {
+	// ignore non-Go files
+	return !strings.HasPrefix(filename, ".") && strings.HasSuffix(filename, ".go")
+}
+
+
+func processDirectory(dirname string) {
+	f, err := os.Open(dirname, os.O_RDONLY, 0)
+	if err != nil {
+		report(err)
+		return
+	}
+	filenames, err := f.Readdirnames(-1)
+	f.Close()
+	if err != nil {
+		report(err)
+		// continue since filenames may not be empty
+	}
+	for i, filename := range filenames {
+		filenames[i] = filepath.Join(dirname, filename)
+	}
+	processFiles(filenames, false)
+}
+
+
+func processFiles(filenames []string, allFiles bool) {
+	i := 0
+	for _, filename := range filenames {
+		switch info, err := os.Stat(filename); {
+		case err != nil:
+			report(err)
+		case info.IsRegular():
+			if allFiles || isGoFilename(info.Name) {
+				filenames[i] = filename
+				i++
+			}
+		case info.IsDirectory():
+			if allFiles || *recursive {
+				processDirectory(filename)
+			}
+		}
+	}
+	processPackage(filenames[0:i])
+}
+
+
+func main() {
+	processFlags()
+
+	if flag.NArg() == 0 {
+		processPackage([]string{os.Stdin.Name()})
+	} else {
+		processFiles(flag.Args(), true)
+	}
+
+	os.Exit(exitCode)
+}

src/pkg/Makefile

@@ -156,6 +156,7 @@ DIRS=\
 	../cmd/ebnflint\
 	../cmd/godoc\
 	../cmd/gofmt\
+	../cmd/gotype\
 	../cmd/goinstall\
 	../cmd/govet\
 	../cmd/goyacc\
@@ -191,6 +192,7 @@ NOTEST=\
 	../cmd/ebnflint\
 	../cmd/godoc\
 	../cmd/gofmt\
+	../cmd/gotype\
 	../cmd/govet\
 	../cmd/goyacc\
 	../cmd/hgpatch\