Erbui Lexical Structure

This document describes what sequence of characters form valid tokens of the language.

Whitespace and Comments

Whitespace allows to separate tokens in the source file.

Comments are treated as whitespace by the transpiler. Single line comments begin with // and continue until a line feed (0x0a) or carriage return (0x0d). Multiline comments begin with /* and end with */. They can’t be nested.

Identifiers

Identifiers begin with an uppercase or lowercase letter A through Z. After the first character, digits or underscore (_) are also allowed.

Identifiers represent tokens of some kind of entity. They are names with implicitly defined semantic:

Either a semantic that the developer will define, such as a control name,
Or a dynamic property of the language, interpreted at configuration time, such as a board name.

The following are examples of identifiers:

control myGreatControl { ... }
board kivu12

In the above examples, myGreatControl and kivu12 are identifiers.

Keywords

Unlike identifiers, keywords are predefined list of characters built into the language. In erbui, they can be seen as directives, and each directive can be seen either like a definition of something in the physical world, or a property of that thing in the physical world.

The following are examples of keywords:

module
control
width
aluminum
black

Symbols

Symbols are predefined list of ponctuation characters built into the language.

The following are examples of symbols:

{ }
,

Literals

A literal is the source code representation of a value of a type, such as a number or string.

The following are examples of literals:

12mm
2hp
"some text"
90°

Literals in erbui define a type implicitly.

Distance literals

Distance literals represent float-point values that can be interpreted as distances in the physical world. As such, distance literals comes with a unit.

Supported units are SI units mm or cm, as well as hp which represents exactly 5.08mm. The hp unit is the standard in Eurorack, and represents 0.2 inch in the imperial system, used a lot in electronics, yet defined in SI metrics units (as exactly 5.08mm).

The following are examples of distance literals:

12mm
10cm
2hp

Rotation literals

Rotation literals represent a specific set of integer values that can be interpreted as angles in the physical world. As such, rotation literals comes with a unit.

Supported units are only degrees (°) based. The base degree follows axis orientation and is therefore clockwise. The units can specify explicit orientation with proper suffix, ccw for counterclokwise, and cw for clockwise.

Finally only a specific set of rotations are supported, usually multiples of 90. See each control reference for supported rotation, if any.

The following are examples of rotation literals:

90°
90°ccw
180°cw

String Literals

A string literal is a sequence of characters surrounded by quotation marks. A string literal is surrounded by double quotation marks and has the following form:

"characters"

String literals do not support any escaping sequence. They are a sequence of ASCII-7 characters of whatever the underlying rendering font can support when converting a stream of character into glyphs.

The following are examples of string literals:

"Hello, world!"
"FREQ"

Path Literals

A path literal is a sequence of characters surrounded by quotation marks. A path literal is surrounded by double quotation marks and has the following form:

"characters"

Path literals do not support any escaping sequence. They are a sequence of ASCII-7 characters.

The following are examples of path literals:

"relative/path/to/my_file.svg"
"../shared/design.svg"