Erubis-J Users' Guide
3 Guide for Developers
3-1 Generator, Converter, and Evaluator
There are three important interface in Erubis-J.
- interface Converter
- Parse embedded text and convert it to target-language code. It requires Generator object. This is language-independent.
- interface Generator
- Generate JavaScript/Java/Ruby code. This is language-specific.
- interface Evaluator
- Evaluate JavaScript code. This is language-specific.
Here is the class diagram (click to display in large size).
The following is an example code of Genrator, Converter, Evaluator, and their concrete classes.
ErubisExample01.java:
import erubis.*;
import java.util.*;
public class ErubisExample01 {
public static void main(String[] args) {
// embedded text
String input = ""
+ "<% for (i = 0, n = list.length; i < n; i++) { %>\n"
+ "<b><%= list[i] %></b>\n"
+ "<% } %>\n"
;
// context data (or 'bidning object')
List list = new ArrayList();
list.add("Foo"); list.add("Bar"); list.add("Baz");
Map context = new HashMap();
context.put("list", list);
// convert embedded text info JavaScript code
Generator generator = new erubis.js.Generator();
Converter converter = new StandardConverter(generator);
String code = converter.convert(input);
// evaluate javaScript code
Evaluator evaluator = new erubis.js.Evaluator();
String result = (String)evaluator.evaluate(code, context);
System.out.print(result);
}
}
If you want to use Processing Instructions as embedded pattern, use PIConverter class instead of StandardConverter class.
....
// convert embedded text info JavaScript code
Generator generator = new erubis.js.Generator();
Converter converter = new PIConverter(generator, true, "js", "@");
String code = converter.convert(input);
....
3-2 Processor
There is a facade class (interface) for convenience.
- Processor (interface)
- A composition of Converter and Evaluator.
The following is an example of Processor interface and it's concrete class.
ErubisExample02.java
import erubis.*;
import java.util.*;
public class ErubisExample02 {
public static void main(String[] args) {
// embedded text
String input = ""
+ "<% for (var i = 0, n = list.length; i < n; i++) { %>\n"
+ "<b><%= list[i] %></b>\n"
+ "<% } %>\n"
;
// context data (or 'bidning object')
List list = new ArrayList();
list.add("Foo"); list.add("Bar"); list.add("Baz");
Map context = new HashMap();
context.put("list", list);
// convert and evaluate
Processor processor = new erubis.js.Processor();
String result = processor.process(input, context);
// or
// String code = processor.convert(input);
// String result = (String)processor.evaluate(code, context);
System.out.print(result);
}
}
If you want to parse Processing Instructions pattern, use erubis.js.PIProcessor class instead of erubis.js.Processor class.
....
// convert and evaluate
Processor processor = new erubis.js.PIProcessor(true, "js", "@");
String result = processor.process(input, context);
....
3-3 Decorator
Decorator is an implementation class of Decorator Pattern.
- abstract class GeneratorDecorator
- Decorator class for Generator. It implements Genertor interface.
- abstract class GeneratorConverter
- Decorator class for Converter. It implements Converter interface.
- abstract class GeneratorEvaluator
- Decorator class for Evaluator. It implements Evaluator interface.
Currently, GeneratorDecorator's subclasses are provided.
- erubis.decorator.NoTextDecorator
- erubis.decorator.NoCodeDecorator
- erubis.decorator.BodyOnlyDecorator
The following is an example of GeneratorDecorator and it's concrete classes.
ErubisExample03.java
import erubis.*;
import java.util.*;
public class ErubisExample03 {
public static void main(String[] args) {
// embedded text
String input = ""
+ "<% for (i = 0, n = list.length; i < n; i++) { %>\n"
+ "<b><%= list[i] %></b>\n"
+ "<% } %>\n"
;
// context data (or 'bidning object')
List list = new ArrayList();
list.add("Foo"); list.add("Bar"); list.add("Baz");
Map context = new HashMap();
context.put("list", list);
// generator and decorator
Generator generator = new erubis.js.Generator();
generator = new erubis.decorator.NoTextDecorator(generator);
generator = new erubis.decorator.BodyOnlyDecorator(generator);
// convert text into JavaScript code
Converter converter = new StandardConverter(generator);
String code = converter.convert(input);
System.out.print(code);
}
}
3-4 Escape Expression
To escape '<%= ... %> by default (equivarent to '-e' option),
- Use Converter#setEscaped(boolean) or Processor#setEscaped(boolean).
- Or pass true to constructor of Converter or Processor.
Generator generator = new erubis.js.Generator() Converter converter = new StandardConverter(generator); converter.setEscaped(true); // or Converter converter = new StandardConverter(generator, true); // or Processor processor = erubis.js.Processor(); processor.setEscaped(true); // or Processor processor = erubis.js.Processor(true);
To change JavaScript escape function name from '_escape()' to other,
- Create subclass of Generator and override Generator#escapedExpression().
- Or call Generator#setEscapeFunctionName(String funcname).
public class MyJavaScriptGenerator extends erubis.js.Generator {
public String escapedExpression(String code) {
//return "_escape(" + code.trim() + ")";
return "escapeXml(" + code.trim() + ")";
}
}
// or
Generator generator = new erubis.js.Generator();
generator.setEscapeFunctionName("escapeXml");
Converter converter = new StandardConverter(generator);
To change the definition of _escape() function,
- Use Evaluator#setInitCode(String) or Processor#setInitCode(String)
- Or pass initialization code to constructor of JavaScriptEvaluator.
Evaluator evaluator = new erubis.js.Evaluator();
evaluator.setInitCode("function _escape(value) { ... }");
// or
Processor processor = new erubis.js.Processor();
processor.setInitCode("function _escape(value) { ... }");
// or
String initCode = "function _escape(value) { ... }";
Evaluator evaluator = new erubis.js.Evaluator(true, initCode);