1// Copyright 2017 The Bazel Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5// The skylark command interprets a Skylark file.
6// With no arguments, it starts a read-eval-print loop (REPL).
7package main
8
9import (
10	"flag"
11	"fmt"
12	"log"
13	"os"
14	"runtime/pprof"
15	"sort"
16	"strings"
17
18	"github.com/google/skylark"
19	"github.com/google/skylark/repl"
20	"github.com/google/skylark/resolve"
21)
22
23// flags
24var (
25	cpuprofile = flag.String("cpuprofile", "", "gather CPU profile in this file")
26	showenv    = flag.Bool("showenv", false, "on success, print final global environment")
27)
28
29// non-standard dialect flags
30func init() {
31	flag.BoolVar(&resolve.AllowFloat, "fp", resolve.AllowFloat, "allow floating-point numbers")
32	flag.BoolVar(&resolve.AllowSet, "set", resolve.AllowSet, "allow set data type")
33	flag.BoolVar(&resolve.AllowLambda, "lambda", resolve.AllowLambda, "allow lambda expressions")
34	flag.BoolVar(&resolve.AllowNestedDef, "nesteddef", resolve.AllowNestedDef, "allow nested def statements")
35	flag.BoolVar(&resolve.AllowBitwise, "bitwise", resolve.AllowBitwise, "allow bitwise operations (&, |, ^, ~, <<, and >>)")
36}
37
38func main() {
39	log.SetPrefix("skylark: ")
40	log.SetFlags(0)
41	flag.Parse()
42
43	if *cpuprofile != "" {
44		f, err := os.Create(*cpuprofile)
45		if err != nil {
46			log.Fatal(err)
47		}
48		if err := pprof.StartCPUProfile(f); err != nil {
49			log.Fatal(err)
50		}
51		defer pprof.StopCPUProfile()
52	}
53
54	thread := &skylark.Thread{Load: repl.MakeLoad()}
55	globals := make(skylark.StringDict)
56
57	switch len(flag.Args()) {
58	case 0:
59		fmt.Println("Welcome to Skylark (github.com/google/skylark)")
60		repl.REPL(thread, globals)
61	case 1:
62		// Execute specified file.
63		filename := flag.Args()[0]
64		var err error
65		globals, err = skylark.ExecFile(thread, filename, nil, nil)
66		if err != nil {
67			repl.PrintError(err)
68			os.Exit(1)
69		}
70	default:
71		log.Fatal("want at most one Skylark file name")
72	}
73
74	// Print the global environment.
75	if *showenv {
76		var names []string
77		for name := range globals {
78			if !strings.HasPrefix(name, "_") {
79				names = append(names, name)
80			}
81		}
82		sort.Strings(names)
83		for _, name := range names {
84			fmt.Fprintf(os.Stderr, "%s = %s\n", name, globals[name])
85		}
86	}
87}
88