| Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||
| Parser |
|
| 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 |