Expressions

Expressions contain literals or other such expressions of objects, including arithmetic and various conditions.

Expression

• PrimaryExpression
• PostfixExpression
• UnaryExpression
• BinaryExpression
• TernaryExpression

Constant Expressions

Constant expressions are expressions that do not contain mutation of state or function calls. We define them simply as expressions.

ConstantExpression

Expression

Primary Expressions

Primary expressions can be one of:

• An identifier for a constant or variable.
• The super keyword, which references the parent type.
• Any literal.
• A vector literal.
• An expression in parentheses.

PrimaryExpression

• Identifier
• super
• Literal
• VectorLiteralExpression
• ColorLiteralExpression
• ( Expression )

Vector Literal Expressions

Vector literals are not under object literals as they are not constants in the same manner as other literals, since they contain expressions within them. As such, they are expressions, not proper value-based literals.

Literals of vector3 may be made by either grammar. In the former grammar, the first expression (X1) must be a vector2 and the second (X2) must be a double. It will be equivalent to (X1.X, X1.Y, X2). In any other case, all expressions must be double.

VectorLiteralExpression

• ( Expression , Expression )
• ( Expression , Expression , Expression )

Color Literal Expressions

Much like vector literals, color literals are not "real" literals, since they contain expressions. Color literals may be either RGB (where alpha is implied to be maximum) or RGBA. The three (or four) expressions must be int.

ColorLiteralExpression

color ( Expression , Expression , Expression (, Expression)? )

Postfix Expressions

Postfix expressions are affixed at the end of an expression, and are used for a large variety of things, although the actual amount of postfix expressions is small.

The postfix expressions are:

• Function call.
• Type cast.
• Class type reference cast.
• Array access.
• Member access.
• Post-increment, which increments the object after the expression is evaluated.
• Post-decrement, which decrements the object after the expression is evaluated.

PostfixExpression

• Expression ( ArgumentList? )
• Type ( Expression )
• ( class < Type > ) ( Expression )
• Expression [ Expression ]
• Expression . Identifier
• Expression ++
• Expression --

Argument Lists

Function calls may name arguments which have defaults, possibly skipping over other defaulted arguments. After the first named defaultable argument, all other arguments must be named as well.

ArgumentList

Expression (, Expression)* (, Identifier : Expression)*

Unary Expressions

Unary expressions are affixed at the beginning of an expression. The simplest example of a unary expression is the negation operator, -, as in -500.

The unary expressions are:

• Negation.
• Logical negation.
• Pre-increment, which increments the object before the expression is evaluated.
• Pre-decrement, which decrements the object before the expression is evaluated.
• Bit-wise negation. Flips all bits in an integer.
• Affirmation. Doesn't actually do anything.
• Alignment of a type of an expression.
• Size of a type of an expression.

UnaryExpression

• - Expression
• ! Expression
• ++ Expression
• -- Expression
• ~ Expression
• + Expression
• alignOf Expression
• sizeOf Expression

Binary Expressions

Binary expressions operate on two expressions, and are the most common kind of expression. They are used inline like regular math syntax, i.e. 1 + 1.

BinaryExpression

• ArithmeticExpression
• VectorExpression
• ConcatenationExpression
• ComparisonExpression
• LazyBooleanExpression
• TypeComparisonExpression
• SignedDifferenceExpression
• LogicalExpression
• ScopeExpression
• AssignmentExpression

Arithmetic Expressions

The arithmetic expressions are:

• Addition.
• Subtraction.
• Multiplication.
• Division quotient.
• Division remainder, also known as "modulus." Unlike C, this works on floats, too.
• Exponentation.
• Left bit-wise shift.
• Right bit-wise shift.
• Right unsigned bit-wise shift.

ArithmeticExpression

• Expression + Expression
• Expression - Expression
• Expression * Expression
• Expression / Expression
• Expression % Expression
• Expression ** Expression
• Expression << Expression
• Expression >> Expression
• Expression >>> Expression

Vector Expressions

The vector expressions are:

• Vector cross-product.
• Vector dot-product.

VectorExpression

• Expression cross Expression
• Expression dot Expression

Concatenation Expressions

Concatenation creates a string from two expressions.

The following basic types may be cast to strings through concatenation:

• Only int and uint of IntegerType
• FloatingPointType
• VectorType
• NameType
• StringLikeReferenceType except stateLabel
• ColorType
• IntegerLikeReferenceType
• NativePointerType

ConcatenationExpression

• Expression .. Expression

Comparison Expressions

The comparison expressions are:

• Less than.
• Greater than.
• Less than or equal.
• Greater than or equal.
• Equality.
• Inequality.
• Approximate equality. For strings, this is a case-insensitive comparison. For floats and vectors, this checks if the difference between the two expressions is smaller than ε.

ComparisonExpression

• Expression < Expression
• Expression > Expression
• Expression <= Expression
• Expression >= Expression
• Expression == Expression
• Expression != Expression
• Expression ~== Expression

Lazy Boolean Expressions

Lazy boolean expressions evaluate the left and right hand side expressions separately.

The first, logical and, will only evaluate the right hand side if the left hand side is true, and will evaluate to true if both expressions are true.

The second, logical or, will only evaluate the right hand side if the left hand side is false, and will evaluate to true if either expression is true.

LazyBooleanExpression

• Expression && Expression
• Expression || Expression

Type Comparison Expressions

Logical type equality. Will check if the type of the left hand side is equal to or a descendant of the right hand side.

TypeComparisonExpression

• Expression is Expression

Signed Difference Expressions

Signed difference. Will return -1 if the left hand side is lesser than the right hand side, 0 if they are equal, and 1 if the left hand side is greater than the right hand side.

SignedDifferenceExpression

• Expression <>= Expression

Logical Expressions

The logical expressions are:

• Bit-wise and.
• Bit-wise exclusive or.
• Bit-wise or.

LogicalExpression

• Expression & Expression
• Expression ^ Expression
• Expression | Expression

Scope Expressions

Not implemented. Will simply cause a compiler error.

ScopeExpression

• Expression :: Expression

Assignment Expressions

Assignment expressions are a subset of binary expressions which are never constant expressions. They assign a value to another value.

Besides the normal assignment operation, there are assignment operations for assigning the result of arithmetic expressions and logical expressions.

AssignmentExpression

• Expression = Expression
• Expression += Expression
• Expression -= Expression
• Expression *= Expression
• Expression /= Expression
• Expression %= Expression
• Expression <<= Expression
• Expression >>= Expression
• Expression >>>= Expression
• Expression |= Expression
• Expression &= Expression
• Expression ^= Expression

Ternary Expressions

The ternary expression will evaluate to the left hand side if the expression is true, or the right hand side if it is false.

TernaryExpression

Expression ? Expression : Expression