Preprocessor¶

TJS2 can process conditional compilation expressions (the equivalent of C's #if and #endif). These are processed before the script is actually parsed, and can be used to exclude or include parts of the script depending on conditions.

Unlike C preprocessor directives, conditional compilation expressions are free-form and can be written anywhere. There is no requirement, as with C directives, to write only one directive per line.

@set Directive¶

The @set directive evaluates a conditional compilation expression and discards the result. The syntax is as follows.

    @set(expression)

"expression" is a conditional compilation expression. The following operators can be used in it.

    ,  =  !=  ==  ||  &&  |  ^  &  <  >  <=  >=  +  -  %  *  /  !  +  -  ( )

For the meaning of these operators, see Expressions and Operators. However, the only data type that can be handled is integer.

You can also use arbitrary variables and immediate values. Variable names follow the same naming rules as TJS2 variables, and immediate values the same rules as the immediate values in Tokens.

However, variables used in the preprocessor and variables used in TJS2 scripts do not interfere with each other (they do not share the same namespace).

@if and @endif Directives¶

The @if directive evaluates a conditional compilation expression; if the result is 0, everything up to the next @endif is not parsed. If the result is nonzero, it is parsed.

The syntax is as follows.

    @if(expression)              ...         @endif

"expression" is a conditional compilation expression. @if ... @endif can be nested.

    @if(flag==0)  // a variable that has not been assigned anything is treated as 0
        @set(flag=1)
        ****
    @endif
    // ↑ makes the script written in the **** part compile only once

    @if(version>=0x02040009)
        @if(flag)
            ****
        @endif
    @endif
    // ↑ compiles the **** part only when version is 0x02040009 (2.4.9) or later and flag is nonzero

Predefined Variables¶

The version variable represents the current TJS2 version.

It is a number in the hexadecimal form 0x0XYYZZZZ, where X is the major version, YY is the minor version, and ZZZZ is the release number. For example, 0x02040009 means version 2.4.9.