01: package org.ofbiz.rules.parse;
02:
03: import java.util.*;
04:
05: /**
06: * <p><b>Title:</b> Assembler
07: * <p><b>Description:</b> None
08: * <p>Copyright (c) 1999 Steven J. Metsker.
09: * <p>Copyright (c) 2001 The Open For Business Project - www.ofbiz.org
10: *
11: * <p>Permission is hereby granted, free of charge, to any person obtaining a
12: * copy of this software and associated documentation files (the "Software"),
13: * to deal in the Software without restriction, including without limitation
14: * the rights to use, copy, modify, merge, publish, distribute, sublicense,
15: * and/or sell copies of the Software, and to permit persons to whom the
16: * Software is furnished to do so, subject to the following conditions:
17: *
18: * <p>The above copyright notice and this permission notice shall be included
19: * in all copies or substantial portions of the Software.
20: *
21: * <p>THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
22: * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
23: * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
24: * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
25: * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT
26: * OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR
27: * THE USE OR OTHER DEALINGS IN THE SOFTWARE.
28: *
29: * <br>
30: * <p>Parsers that have an Assembler ask it to work on an
31: * assembly after a successful match.
32: * <p>
33: * By default, terminals push their matches on a assembly's
34: * stack after a successful match.
35: * <p>
36: * Parsers recognize text, and assemblers provide any
37: * sort of work that should occur after this recognition.
38: * This work usually has to do with the state of the assembly,
39: * which is why assemblies have a stack and a target.
40: * Essentially, parsers trade advancement on a assembly
41: * for work on the assembly's stack or target.
42: *
43: * @author Steven J. Metsker
44: * @version 1.0
45: */
46: public abstract class Assembler {
47:
48: /**
49: * Returns a vector of the elements on an assembly's stack
50: * that appear before a specified fence.
51: * <p>
52: * Sometimes a parser will recognize a list from within
53: * a pair of parentheses or brackets. The parser can mark
54: * the beginning of the list with a fence, and then retrieve
55: * all the items that come after the fence with this method.
56: *
57: * @param assembly a assembly whose stack should contain
58: * some number of items above a fence marker
59: *
60: * @param object the fence, a marker of where to stop
61: * popping the stack
62: *
63: * @return List the elements above the specified fence
64: *
65: */
66: public static List elementsAbove(Assembly a, Object fence) {
67: List items = new ArrayList();
68:
69: while (!a.stackIsEmpty()) {
70: Object top = a.pop();
71:
72: if (top.equals(fence)) {
73: break;
74: }
75: items.add(top);
76: }
77: return items;
78: }
79:
80: /**
81: * This is the one method all subclasses must implement. It
82: * specifies what to do when a parser successfully
83: * matches against a assembly.
84: *
85: * @param Assembly the assembly to work on
86: */
87: public abstract void workOn(Assembly a);
88: }
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