Lexical Structure

This page defines how DQ source text is divided into tokens. For an introductory view, see Language Basics.

Source Text and Case

DQ source files use the .dq extension. Identifiers and keywords are case-sensitive. value, Value, and VALUE are different names.

An identifier starts with an ASCII letter or _ and continues with ASCII letters, decimal digits, or _. Unicode characters are allowed in text but not in identifiers.

Whitespace and Statement Boundaries

Spaces and tabs separate tokens. A newline normally terminates a statement. A semicolon may terminate a statement explicitly and is required between multiple statements on one physical line.

var x : int = 1
var y : int = 2; x += y

Newlines inside balanced parentheses, brackets, and similar expression contexts do not necessarily terminate the containing construct. Block structure is defined by statement syntax, not indentation; indentation is nevertheless the canonical style.

Comments

// starts a line comment. /* and */ delimit a block comment.

// one line

/* more than
   one line */

Comments act as whitespace and do not form part of string or character literals.

Keywords and Word Operators

Language keywords are lowercase. Contextual loop words such as to, downto, count, downcount, and step are recognized in their corresponding for forms.

Logical Boolean operators are the lowercase words and, or, and not. Integer division, remainder, and XOR use the lowercase words div, mod, and xor; other bitwise operators use &, |, ~, <<, and >>. The words is and as provide object testing and explicit casting.

Numeric Literals

Decimal and hexadecimal integer literals are supported. Floating-point literals contain a fractional part and/or exponent.

42
0xFF
3.14159
1.0e-6

A leading - is a unary operator rather than part of the literal token.

Text and Character Literals

Double quotes produce string literals, including a one-character string. Single quotes produce a wchar character literal when they contain one Unicode scalar and otherwise produce text. Escape processing applies to both forms.

var text : str = "x"
var slash : wchar = '/'
var message : str = 'hello'

Quoted literals end on the same physical line. Use escape sequences such as \n, \r, \t, \\, \", and \' for control characters and embedded delimiters. See Strings and Characters for typing and conversion rules.

Attributes and Directives

[[...]] encloses declaration attributes. A line whose first active token is # is a compiler directive. These constructs are described in Attributes, Directives, and Interoperability.