Terms - Literals and Variables
0 -1 17 2048 -9988 // decimal integers true false // booleans 'a' '0' '\n' '\098' // characters "An example string" // a string
The simplest expressions in Virgil are called terms, which are
expressions that have no nested subexpressions. These are literals,
which are used to represent values of primitive types and variables.
The code on the right contains examples of
integer literals, boolean literals, characters, and a string.
MyVar _foo _bar0 // legal identifiers 0aa $foo @bar // illegal
In Virgil, variables, such as local variables, parameters and fields are
simply referred to by their name. All legal variable names must begin with an
underscore or an alphabetic character, followed by zero or
more alpha-numeric characters (letters and numbers) or underscores. All variable
names are case-sensitive in Virgil; thus MyVar and myvar
are distinct variables.
Operators
expr + expr expr - expr expr * expr -expr (expr)
Virgil expressions can consist of the familiar infix binary operators
(+ - / % * & | ^ etc) and prefix unary operators (! ~ -),
which are each defined on the appropriate types of data. Each operator has
a pre-defined binding precedence; for correct associativity,
expressions can be nested inside parentheses ( ... ) in
the familiar way. For more detail on the supported operators, see
the operator reference.
Conditional Expression
expr ? expr : expr
Virgil supports the ? : conditional operator that should be
familiar to C and Java programmers. The conditional operator takes three
expressions: the first is the condition to evaluate, which must be of type
boolean; the second is the expression to evaluate if the
result is true, and the third is the expression to evaluate
if the result of the condition is false.
Method Invocation
expr(expr, ...)
This operator is used to call methods in a Virgil program. This operator is covered in more detail in the methods tutorial.
Array and Raw Subscript Operator
expr[expr]
This operator can be used to access individual bits of a raw type or to access the elements of an array. This operator is covered in more detail in the raw types tutorial and arrays tutorial.
New Array Operator
new type[expr]
This operator allocates a new array of a specified type with a specified dimension. This operator is covered in more detail in the arrays tutorial.
New Object Operator
new type(expr, ...)
This operator allocates a new object of a specified type with the specified arguments to the constructor. This operator is covered in more detail in the classes tutorial.
Member Access Operator
expr.member
This operator accesses the member of an object by member name. This operator is covered in more detail in the classes and delegate tutorial pages.
Type Query Operator
expr <: type
This operator dynamically tests whether an object is of a specified type. This operator is covered in more detail in the classes tutorial page.
Type Conversion / Cast Operator
expr :: type
This operator can be used to convert values of primitive types to other primitive types and can be used to dynamically typecast an expression of an object type to another type. This operator is covered in more detail in the classes and primitives tutorial pages.
Go back to the tutorial.