Schema


1   /* ****************************************************************************
2    * Schema.java
3    * ****************************************************************************/
4   
5   /* J_LZ_COPYRIGHT_BEGIN *******************************************************
6   * Copyright 2001-2004 Laszlo Systems, Inc.  All Rights Reserved.              *
7   * Use is subject to license terms.                                            *
8   * J_LZ_COPYRIGHT_END *********************************************************/
9   
10  package org.openlaszlo.xml.internal;
11  import org.jdom.Element;
12  import java.util.*;
13  
14  /**
15   * Describes the content model of an XML document.
16   *
17   * @author Oliver Steele
18   * @version 1.0
19   */
20  public abstract class Schema {
21      
22      /** Hold mapping from Javascript type names to Types */
23      static Map typeNames = new HashMap();
24  
25      /** Represents the type of an attribute whose type isn't known. */
26      public static final Type UNKNOWN_TYPE = newType("unknown");
27      /** Represents a String. */
28      public static final Type STRING_TYPE = newType("string");
29      /** Represents a number. */
30      public static final Type NUMBER_TYPE = newType("number");
31      /** Represents an XML ID. */
32      public static final Type ID_TYPE = newType("ID");
33  
34      /** The type of an attribute. */
35      public static class Type {
36          private String   mName;
37  
38          public Type(String   name) {
39              mName = name;
40          }
41          
42          public String   toString() {
43              return mName;
44          }
45      }
46      
47      /** Returns a unique type.
48       * @return a unique type
49       */
50      public static Type newType(String   typeName) {
51          Type newtype = new Type(typeName);
52          typeNames.put(typeName, newtype);
53          return newtype;
54      }
55      
56      /** Look up the Type object from a Javascript type name */
57      public Type getTypeForName (String   typeName) {
58          return (Type) typeNames.get(typeName);
59      }
60  
61      /** An empty Schema, all of whose attribute types are unknown. */
62      public static final Schema DEFAULT_SCHEMA =
63          new Schema() {
64              /** @see Schema */
65              public Type getAttributeType(Element element, String   name) {
66                  return UNKNOWN_TYPE;
67              }
68          };
69      
70      /**
71       * Returns a value representing the type of an attribute within an
72       * XML element.
73       * 
74       * @param element an Element
75       * @param attributeName an attribute name
76       * @return a value represting the type of the attribute's
77       */
78      public abstract Type getAttributeType(Element element,
79                                           String   attributeName);
80  }
81
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