A Simple Bean Language

The language allows to create Java objects by reflection. The compiles code of this language into a corresponding object.

• Creation by constructors. Example:

  URL url = (URL) BeanCompiler.compile(URL.class, "URL(http, localhost,8080, '/index.html')");
  

• Creation by static methods. Example:

  Object object = BeanCompiler.compile(String.class, "java.lang.System.getProperty('user.name')");
  

• Defining attributes via setters. Example:

  DecimalFormat format 
      = (DecimalFormat) BeanCompiler.compile(DecimalFormat.class,
             "DecimalFormat{multiplier=42,negativePrefix='a',parseBigDecimal=true}");
  

• Collection arguments. Example:

  DateFormatSymbols symbols 
      = (DateFormatSymbols) BeanCompiler.compile(DateFormatSymbols.class,
             "DateFormatSymbols{weekdays = [M,T,W,T,F,S,S]}");
  

• Recursive definitions: Constructor and method arguments are objects defined by this language. Example:

  DecimalFormat format 
      = (DecimalFormat) BeanCompiler.compile(DecimalFormat.class,
              "DecimalFormat('0.00', DecimalFormatSymbols{decimalSeparator=*})");
  

• Short class names instead of fully qualified class names are recognized in many places as the above examples show.

bean: QUOTED_TEXT | (METHOD_NAME_OR_STRING arguments? properties?) | collection;
arguments: '(' (bean (',' bean)* )? ')';
properties: '{' (property (',' property)* )? '}';
property: POPERTY_NAME '=' bean;
collection: '[' (bean (',' bean)* )? ']';

The backslash character '\' can be used at any place to escape the next character. Note, that white spaces are ignored except in QUOTED_TEXT. The uses knowledge about classes (gained by reflection) to decides how to interpret a METHOD_NAME_OR_STRING. For example, if the argument of a constructor is of type double or Double it try to parses the string as a floating point number.

If the compiler expects an object which is neither a String nor a wrapper object of a primitive type it tries to find a constructor or a static method. It tests the following hypotheses about METHOD_NAME_OR_STRING:

1. It is a static method. That is, it doesn't end with a dot character '.' but contains at least one '.' and the character after the last '.' is a lower-case letter reflecting the standard convention that a Java method should start with a lower-case letter. If a static method has been detected the string before the last '.' is interpreted as the fully-qualified class name.
2. It is a constructor of a fully-qualified Java class.
3. It is a constructor for class from a list of expected Java classes. The end of the fully-qualified name of one class of this list has to be matched by METHOD_NAME_OR_STRING. This list may have more then one element because of ambiguity due to overloaded methods or constructors.