Expressions¶

Expressions can contain literal values, identifiers (constants, formulas, local and global variables) and operators. Literals for Booleans, integers and doubles are written in the standard way: true, false, 4, 3.14.

Operators¶

The following operators can be used in expressions, ordered by their precedence (most strongly binding operators first):

[...], ., (...) (array indexing, member access, function call)
- (unary minus)
*, / (multiplication, division)
+, - (addition, subtraction)
>, >=, <, <= (relational operators)
=, != (equality operators)
! (unary negation)
& (logical and)
| (logical or)
=> (implication)
... ? ... : ... (ternary if-then-else)

Built-in functions¶

The following built-in functions are provided:

min(x, y, ...) and max(x, y, ...) which select the minimum or maximum of two or more numbers, respectively.
floor(x) and ceil(x) which round x up and down, respectively, to the nearest integer.
pow(x, y) which computes x to the power of y.
mod(i, n) for integer modulo.
log(x, b) which computes the logarithm of x to base b.
active(f) returns true if the feature f is in the current feature combination.
iactive(f) returns 1 if the feature f is in the current feature combination, and 0 otherwise.