1 files changed, 141 insertions, 0 deletions
diff --git a/cmd/starlark/starlark.go b/cmd/starlark/starlark.go
new file mode 100644
index 0000000..3825f00
--- /dev/null
+++ b/cmd/starlark/starlark.go
@@ -0,0 +1,141 @@
+// Copyright 2017 The Bazel 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 starlark command interprets a Starlark file.
+// With no arguments, it starts a read-eval-print loop (REPL).
+package main // import "go.starlark.net/cmd/starlark"
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"os"
+	"runtime"
+	"runtime/pprof"
+	"strings"
+
+	"go.starlark.net/internal/compile"
+	"go.starlark.net/repl"
+	"go.starlark.net/resolve"
+	"go.starlark.net/starlark"
+	"go.starlark.net/starlarkjson"
+)
+
+// flags
+var (
+	cpuprofile = flag.String("cpuprofile", "", "gather Go CPU profile in this file")
+	memprofile = flag.String("memprofile", "", "gather Go memory profile in this file")
+	profile    = flag.String("profile", "", "gather Starlark time profile in this file")
+	showenv    = flag.Bool("showenv", false, "on success, print final global environment")
+	execprog   = flag.String("c", "", "execute program `prog`")
+)
+
+func init() {
+	flag.BoolVar(&compile.Disassemble, "disassemble", compile.Disassemble, "show disassembly during compilation of each function")
+
+	// non-standard dialect flags
+	flag.BoolVar(&resolve.AllowFloat, "float", resolve.AllowFloat, "obsolete; no effect")
+	flag.BoolVar(&resolve.AllowSet, "set", resolve.AllowSet, "allow set data type")
+	flag.BoolVar(&resolve.AllowLambda, "lambda", resolve.AllowLambda, "allow lambda expressions")
+	flag.BoolVar(&resolve.AllowRecursion, "recursion", resolve.AllowRecursion, "allow while statements and recursive functions")
+	flag.BoolVar(&resolve.AllowGlobalReassign, "globalreassign", resolve.AllowGlobalReassign, "allow reassignment of globals, and if/for/while statements at top level")
+}
+
+func main() {
+	os.Exit(doMain())
+}
+
+func doMain() int {
+	log.SetPrefix("starlark: ")
+	log.SetFlags(0)
+	flag.Parse()
+
+	if *cpuprofile != "" {
+		f, err := os.Create(*cpuprofile)
+		check(err)
+		err = pprof.StartCPUProfile(f)
+		check(err)
+		defer func() {
+			pprof.StopCPUProfile()
+			err := f.Close()
+			check(err)
+		}()
+	}
+	if *memprofile != "" {
+		f, err := os.Create(*memprofile)
+		check(err)
+		defer func() {
+			runtime.GC()
+			err := pprof.Lookup("heap").WriteTo(f, 0)
+			check(err)
+			err = f.Close()
+			check(err)
+		}()
+	}
+
+	if *profile != "" {
+		f, err := os.Create(*profile)
+		check(err)
+		err = starlark.StartProfile(f)
+		check(err)
+		defer func() {
+			err := starlark.StopProfile()
+			check(err)
+		}()
+	}
+
+	thread := &starlark.Thread{Load: repl.MakeLoad()}
+	globals := make(starlark.StringDict)
+
+	// Ideally this statement would update the predeclared environment.
+	// TODO(adonovan): plumb predeclared env through to the REPL.
+	starlark.Universe["json"] = starlarkjson.Module
+
+	switch {
+	case flag.NArg() == 1 || *execprog != "":
+		var (
+			filename string
+			src      interface{}
+			err      error
+		)
+		if *execprog != "" {
+			// Execute provided program.
+			filename = "cmdline"
+			src = *execprog
+		} else {
+			// Execute specified file.
+			filename = flag.Arg(0)
+		}
+		thread.Name = "exec " + filename
+		globals, err = starlark.ExecFile(thread, filename, src, nil)
+		if err != nil {
+			repl.PrintError(err)
+			return 1
+		}
+	case flag.NArg() == 0:
+		fmt.Println("Welcome to Starlark (go.starlark.net)")
+		thread.Name = "REPL"
+		repl.REPL(thread, globals)
+	default:
+		log.Print("want at most one Starlark file name")
+		return 1
+	}
+
+	// Print the global environment.
+	if *showenv {
+		for _, name := range globals.Keys() {
+			if !strings.HasPrefix(name, "_") {
+				fmt.Fprintf(os.Stderr, "%s = %s\n", name, globals[name])
+			}
+		}
+	}
+
+	return 0
+}
+
+func check(err error) {
+	if err != nil {
+		log.Fatal(err)
+	}
+}