blob: 12f9a16cc5ca88b856a63a0c8f02a3c0fd40523b (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
|
// Copyright 2016 The Bazel Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.google.devtools.skylark;
import com.google.devtools.build.lib.events.Event;
import com.google.devtools.build.lib.events.EventHandler;
import com.google.devtools.build.lib.syntax.Environment;
import com.google.devtools.build.lib.syntax.Mutability;
import com.google.devtools.build.lib.syntax.Printer;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.nio.charset.Charset;
/**
* Skylark is a standalone skylark intepreter. The environment doesn't
* contain Bazel-specific functions and variables. Load statements are
* forbidden for the moment.
*/
class Skylark {
private static final String START_PROMPT = ">> ";
private static final String CONTINUATION_PROMPT = ".. ";
public static final EventHandler PRINT_HANDLER = new EventHandler() {
@Override
public void handle(Event event) {
System.out.println(event.getMessage());
}
};
private final BufferedReader reader = new BufferedReader(
new InputStreamReader(System.in, Charset.defaultCharset()));
private final Mutability mutability = Mutability.create("interpreter");
private final Environment env =
Environment.builder(mutability)
.setSkylark()
.setGlobals(Environment.DEFAULT_GLOBALS)
.setEventHandler(PRINT_HANDLER)
.build();
public String prompt() {
StringBuilder input = new StringBuilder();
System.out.print(START_PROMPT);
try {
while (true) {
String line = reader.readLine();
if (line == null) {
return null;
}
if (line.isEmpty()) {
return input.toString();
}
input.append("\n").append(line);
System.out.print(CONTINUATION_PROMPT);
}
} catch (IOException io) {
io.printStackTrace();
return null;
}
}
public void readEvalPrintLoop() {
String input;
while ((input = prompt()) != null) {
try {
Object result = env.eval(input);
if (result != null) {
System.out.println(Printer.repr(result));
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
public static void main(String[] args) {
if (args.length == 0) {
new Skylark().readEvalPrintLoop();
} else {
System.err.println("no argument expected");
System.exit(1);
}
}
}
|
