org.stringtemplate.v4.misc.Aggregate Maven / Gradle / Ivy

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StringTemplate is a java template engine for generating source code, web pages, emails, or any other formatted text output. StringTemplate is particularly good at multi-targeted code generators, multiple site skins, and internationalization/localization. It evolved over years of effort developing jGuru.com. StringTemplate also powers the ANTLR 3 and 4 code generator. Its distinguishing characteristic is that unlike other engines, it strictly enforces model-view separation. Strict separation makes websites and code generators more flexible and maintainable; it also provides an excellent defense against malicious template authors.

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/*
 * [The "BSD license"]
 *  Copyright (c) 2011 Terence Parr
 *  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *  3. The name of the author may not be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 *  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 *  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 *  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 *  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 *  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 *  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.stringtemplate.v4.misc;

import java.util.HashMap;

/** An automatically created aggregate of properties.
 *
 *  I often have lists of things that need to be formatted, but the list
 *  items are actually pieces of data that are not already in an object.  I
 *  need ST to do something like:
 *  
 *  Ter=3432

 *  Tom=32234

 *  ....
 *  
 *  using template:
 *  
 *  {@code $items:{it.name$=$it.type$}$}
 *  
 *  This example will call {@code getName()} on the objects in items attribute, but
 *  what if they aren't objects?  I have perhaps two parallel arrays
 *  instead of a single array of objects containing two fields.  One
 *  solution is allow {@code Map}s to be handled like properties so that {@code it.name}
 *  would fail {@code getName()} but then see that it's a {@code Map} and do
 *  {@code it.get("name")} instead.
 *  
 *  This very clean approach is espoused by some, but the problem is that
 *  it's a hole in my separation rules.  People can put the logic in the
 *  view because you could say: "go get bob's data" in the view:
 *  
 *  Bob's Phone: {@code $db.bob.phone$}
 *  
 *  A view should not be part of the program and hence should never be able
 *  to go ask for a specific person's data.
 *  
 *  After much thought, I finally decided on a simple solution.  I've
 *  added setAttribute variants that pass in multiple property values,
 *  with the property names specified as part of the name using a special
 *  attribute name syntax: {@code "name.{propName1,propName2,...}"}.  This
 *  object is a special kind of {@code HashMap} that hopefully prevents people
 *  from passing a subclass or other variant that they have created as
 *  it would be a loophole.  Anyway, the {@link AggregateModelAdaptor#getProperty}
 *  method looks for {@code Aggregate} as a special case and does a {@link #get} instead
 *  of {@code getPropertyName}.
 */
public class Aggregate {
    public HashMap properties = new HashMap();
    /** Allow StringTemplate to add values, but prevent the end
     *  user from doing so.
     */
    protected void put(String propName, Object propValue) {
        properties.put(propName, propValue);
    }
    public Object get(String propName) {
        return properties.get(propName);
    }
    @Override
    public String toString() {
        return properties.toString();
    }
}