Scripting:Syntax

From STNE Wiki

Revision as of 00:37, 16 August 2010

This page describes the syntax of the STNE scripting engine.

As with C style languages, a statement is always terminated by a semicolon. A statement can be a function call, variable declaration or assignment.

Variable declaration

Variables are declared with the code 'Var [VarName] As VarType'. This is best illustrated with a small example:

Var WelcomeMessage As String; // Declares a variable named 'WelcomeMessage' of type String
Var DataTable As CTable;      // Declares a variable named 'DataTable' of type CTable


/* It is also possible to immediately assign a value when declaring variables */

Var WelcomeMessage As String = "Hello galaxy!"; // Declares a string and assigns it a value
Var DataTable      As CTable = New CTable();    // Declares a variable and assigns a newly created CTable to it
Var InfoTable      As New CTable();             // Also declares a variable and assigns a newly created CTable to it, but with less code

Conditional statements

It is possible to wrap code in conditional code blocks by using If, Else and ElseIf statements. If and ElseIf statements are followed by a boolean expression between round brackets. Code blocks following the If/Else/ElseIf statements have to be wrapped in curly brackets.

An example:

If (x <= 5) {
  WriteLine("Five or less.");
}
ElseIf (x <= 10) {
  WriteLine("More than five.");
  WriteLine("Ten or less.");
}
Else {
  WriteLine("More than ten.");
}

Loops

There are a few kind of loop statements: For, For Each, While and Do...While loops. They work similar to the equally named loops in other programming languages.

The For loop will increment a specified counter by a given step until a certain value is reached. The initial value, limit and step can be negative values and (negative) floating point values.

The For Each loop iterates all elements of a class implementing the interface ICollection. You can recognize classes implementing this interface by the few methods in the interface. Note that using For Each on a dictionaries and hash tables will loop the DictionaryEntry structs in the dictionary and not the keys or values. You can however loop Dictionary.Keys or Dictionary.Values if you are only interested in either the keys or the values. If you need both the keys and values, it is recommended to loop the DictionaryEntry structs.

The While and Do...While loops continue to loop while a boolean expression results in True. The difference between the While and Do...While loops is when the boolean expression is evaluated. While loops check the expression at the beginning of each iteration, Do...While loops check the expression at the end of each iteration. As a result, Do...While loops are always executed at least once.

An example:

/* This will print each number from 0 to 10. 0 and 10 included. */
Var i As Integer;
For (i = 0 To 10) {
  WriteLine(i);
}

/* This will print all even numbers from 10 to 0. 10 and 0 included, in reverse order. */
Var i As Integer;
For (i = 10 To 0 Step -2) {
  WriteLine(i);
}

/* This will print the name of each ship in the SRS report of the ship with NCC 123456 */
Var MyShip As New CMyShip(123456);
Var Current As CShip;
For (Each Current In MyShip.SRS) {
  WriteLine(Current.Name);
}

/* This will print each number from 0 to 10. 0 and 10 included. */
i = 0;
While (i <= 10) {
 WriteLine(i++);    // i++ increases i by one and returns the old value, see Operators for details.
}

/* This will also print each number from 0 to 11. 0 and 11 included! */
i = 0;
Do {
 WriteLine(i++);
}
While(i <= 10)