Introduction to Stars

This engine come from an online project called Si Mei Ren.

• adapt spring framework
• simplify the serialization/re-serialization of request/respond
• use aop, e.g. verify pre-condition of request
• change the distribution framework (like dubbo)

This expression util supply the basic operation for game, including most used relation operator, logic operator and a simple select operator. There are some example as follows.

level > 0                       // the level of player is greater than 0
1 + 2 == 3                      // the sum of 1 and 2 is equal to 3
level > 10 && vip > 0           // the level of player is greater than 10 and the vip is greater than 0
level in (10, 11, 12)           // the level of player is 10, or 11, or 12
level between (10, 20)          // the level of player is between 10(inclusive) and 20(inclusive)
[itemBag, quality > 10] > 20    // the count of item in itemBag where quality is greater than 10 is greater than 20
{isopen, 'friend'}              // call the 'isopen' function, passing the parameter 'friend'

• There are two types in the expression, number and string, which to long and String in Java.
• The result of relational operation and logical operation will turn into number, non-zero for true, 0 for false.
• Because number is just long in Java, number behave as what long like in Java.
• The in operator use for a range check. x in (u, v, w) means that x == u || x == v || x == w.
• The between operator use for a range check. x between (y, z) means that x >= y && x <= z.
• The [] operator like select in SQL. [itemBag, quality > 10] means that select count(1) from itemBag where quality > 10. Be notice that it is a time consuming operation.
• The {} operator use for a function invocation. {ismoduleopen, 'friend'} means that call the function ismoduleopen and pass a parameter 'friend'.

ExprNode expr = new ExprParser(new ExprLexer("1 + 1")).parse();
long result = (long) expr.eval();