quantities.runtime.parsing

This module defines functions to parse units and quantities.

The text input is parsed according to the following grammar. For example:

Prefixes and unit symbols must be joined:

"1 mm" = 1 millimeter

"1 m m" = 1 square meter

Standalone units are preferred over prefixed ones:

"1 cd" = 1 candela, not 1 centiday

Powers of units:

"1 m^2"

"1 m^-1/2" (rational exponent)

"1 m²" (superscript integer)

Multiplication of to units:

"1 N m" (whitespace)

"1 N . m"

"1 N ⋅ m" (centered dot)

"1 N * m"

"1 N × m" (times sign)

Division of to units:

"1 mol / s"

"1 mol ÷ s"

Grouping of units with parentheses:

"1 kg/(m.s^2)" = 1 kg m⁻¹ s⁻²

Grammar: (whitespace not significant)

Quantity:

Units

Number Units

Number:

Numeric value parsed by std.conv.parse!double

Units:

Unit

Unit Units

Unit Operator Units

Operator:

*

.

⋅

×

/

÷

Unit:

Base

Base ^ Integer

Base ^ Rational

Base SupInteger

Base:

Symbol

Prefix Symbol

( Units )

Symbol:

The symbol of a valid unit

Prefix:

The symbol of a valid prefix

Rational:

Integer / Integer

Integer:

Integer value parsed by std.conv.parse!int

SupInteger:

Superscript version of Integer