Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||
Parser |
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| 1.0;1 |
1 | /* | |
2 | * Copyright (C) 1998-2000 Semiotek Inc. All Rights Reserved. | |
3 | * | |
4 | * Redistribution and use in source and binary forms, with or without | |
5 | * modification, are permitted under the terms of either of the following | |
6 | * Open Source licenses: | |
7 | * | |
8 | * The GNU General Public License, version 2, or any later version, as | |
9 | * published by the Free Software Foundation | |
10 | * (http://www.fsf.org/copyleft/gpl.html); | |
11 | * | |
12 | * or | |
13 | * | |
14 | * The Semiotek Public License (http://webmacro.org/LICENSE.) | |
15 | * | |
16 | * This software is provided "as is", with NO WARRANTY, not even the | |
17 | * implied warranties of fitness to purpose, or merchantability. You | |
18 | * assume all risks and liabilities associated with its use. | |
19 | * | |
20 | * See www.webmacro.org for more information on the WebMacro project. | |
21 | */ | |
22 | ||
23 | ||
24 | package org.webmacro.engine; | |
25 | ||
26 | import java.io.IOException; | |
27 | import java.io.Reader; | |
28 | ||
29 | /** | |
30 | * A parser turns an input stream into a BlockBuilder, using any | |
31 | * parsing mechanism that it chooses. It closes the input stream | |
32 | * after parsing its contents. | |
33 | * <p> | |
34 | * A Parser must also have a single argument constructor, where the | |
35 | * single argument is an object of type Broker. This allows the | |
36 | * parser to query the broker for any modules or other things it | |
37 | * may need to load (for example, Directives). The constructor | |
38 | * signature must look like this:<pre> | |
39 | * public SomeParser(Broker broker) throws InitException | |
40 | * </pre>. A Parser may throw an InitException if it cannot load | |
41 | * things it needs using the Broker. | |
42 | * <p> | |
43 | * At runtime, a Parser may be used many times, simultaneously, to | |
44 | * parse many templates. It must therefore be threadsafe. The recommended | |
45 | * way to make a parser threadsafe is to have it not use any class | |
46 | * variables, but rely completely on passing data it needs through | |
47 | * arguments--this can be done fairly conveniently in a recursive | |
48 | * decent parser. | |
49 | * <p> | |
50 | * When designing a Parser and its corresponding Builders, bear | |
51 | * in mind the following WebMacro design decision: It is acceptable to | |
52 | * sacrifice parsing speed in order to speed up runtime execution | |
53 | * of a block, since a template is typically parsed just once, but | |
54 | * executed manyt imes. Thus, do not optimize your parser in ways that | |
55 | * make it difficult to optimize the resulting execution tree. | |
56 | */ | |
57 | public interface Parser | |
58 | { | |
59 | ||
60 | /** | |
61 | * Parse the input in ParseTool as far as the grammar for | |
62 | * this parser allows, but no farther. | |
63 | */ | |
64 | abstract public BlockBuilder parseBlock (String name, Reader in) | |
65 | throws ParseException, IOException; | |
66 | ||
67 | ||
68 | } | |
69 | ||
70 |