6.25 Characters

8.14.0.2

6.25 Characters🔗ℹ

A character is Unicode code point.

Characters are comparable, which means that generic operations like < and > work on characters.

The . operator can be used on a character expression as equivalent to calling Char functions:

ch.to_int()
is
Char.to_int(ch)
ch.upcase()
is
Char.upcase(ch)
ch.downcase()
is
Char.downcase(ch)
ch.foldcase()
is
Char.foldcase(ch)
ch.titlecase()
is
Char.titlecase(ch)
ch.is_alphabetic()
is
Char.is_alphabetic(ch)
ch.is_lowercase()
is
Char.is_lowercase(ch)
ch.is_uppercase()
is
Char.is_uppercase(ch)
ch.is_titlecase()
is
Char.is_titlecase(ch)
ch.is_numeric()
is
Char.is_numeric(ch)
ch.is_symbolic()
is
Char.is_symbolic(ch)
ch.is_punctuation()
is
Char.is_punctuation(ch)
ch.is_graphic()
is
Char.is_graphic(ch)
ch.is_whitespace()
is
Char.is_whitespace(ch)
ch.is_blank()
is
Char.is_blank(ch)
ch.is_extended_pictographic()
is
Char.is_extended_pictographic(ch)
ch.general_category()
is
Char.general_category(ch)
ch.grapheme_break_property()
is
Char.grapheme_break_property(ch)
ch.grapheme_step(state)
is
Char.grapheme_step(ch, state)

annotation

Char

Matches characters.

function

fun Char.to_int(ch :: Char) :: NonnegInt

Returns the Unicode value of a character.

function

fun Char.from_int(i :: NonnegInt) :: Char

Returns the character corresponding to a Unicode value. The given i must be in the range 0x0 to 0x10FFFF, (inclusive), and not in the range 0xD800 to 0xDFFF (inclusive).

function

fun Char.upcase(ch :: Char) :: Char

function

fun Char.downcase(ch :: Char) :: Char

function

fun Char.foldcase(ch :: Char) :: Char

function

fun Char.titlecase(ch :: Char) :: Char

Unicode case conversions.

function

fun Char.is_alphabetic(ch :: Char) :: Boolean

function

fun Char.is_lowercase(ch :: Char) :: Boolean

function

fun Char.is_uppercase(ch :: Char) :: Boolean

function

fun Char.is_titlecase(ch :: Char) :: Boolean

function

fun Char.is_numeric(ch :: Char) :: Boolean

function

fun Char.is_symbolic(ch :: Char) :: Boolean

function

fun Char.is_punctuation(ch :: Char) :: Boolean

function

fun Char.is_graphic(ch :: Char) :: Boolean

function

fun Char.is_whitespace(ch :: Char) :: Boolean

function

fun Char.is_blank(ch :: Char) :: Boolean

function

fun Char.is_extended_pictographic(ch :: Char) :: Boolean

function

fun Char.general_category(ch :: Char) :: Symbol

function

fun Char.grapheme_break_property(ch :: Char) :: Symbol

Character Unicode classifications:

alphabetic: Unicode “Alphabetic” property
lowercase: Unicode “Lowercase” property
uppercase: Unicode “Uppercase” property
titlecase: Unicode general category Lt
numeric: Unicode “Numeric_Type” property other than None
symbolic: Unicode general category Sm, Sc, Sk, or So
punctuation: Unicode general category Pc, Pd, Ps, Pe, Pi, Pf, or Po
graphic: alphabetic, numeric, symbolic, punctionation, or Unicode general category is Ll, Lm, Lo, Lt, Lu, Nd, Nl, No, Mn, Mc, or Me
whitespace: Unicode “White_Space” property
blank (horizontal whitespace): Unicode general category is Zs or the Tab character
ISO control: Unicode value between 0x0 and 0x1F (inclusive) or between 0x7F and 0x9F (inclusive)
extended pictographic: Unicode “Extended_Pictographic” property
general category: #'lu, #'ll, #'lt, #'lm, #'lo, #'mn, #'mc, #'me, #'nd, #'nl, #'no, #'ps, #'pe, #'pi, #'pf, #'pd, #'pc, #'po, #'sc, #'sm, #'sk, #'so, #'zs, #'zp, #'zl, #'cc, #'cf, #'cs, #'co, or #'cn.
grapheme break property: #'Other, #'CR, #'LF, #'Control, #'Extend, #'ZWJ, #'Regional_Indicator, #'Prepend, #'SpacingMark, #'L, #'V, #'T, #'LV, or #'LVT

function

fun Char.grapheme_step(ch :: Char, state :: Int)

:: (Boolean, Int)

Encodes a state machine for Unicode’s grapheme-cluster specification on a sequence of code points. It accepts a character for the next code point in a sequence, and it returns two values: whether a (single) grapheme cluster has terminated since the most recently reported termination (or the start of the stream), and a new state to be used with Char.grapheme_step and the next character.

A value of 0 for state represents the initial state or a state where no characters are pending toward a new boundary. Thus, if a sequence of characters is exhausted and accumulated state is not 0, then the end of the stream creates one last grapheme-cluster boundary. When Char.grapheme_step produces a true value as its first result and a non-0 value as its second result, then the given ch must be the only character pending toward the next grapheme cluster (by the rules of Unicode grapheme clustering).

The Char.grapheme_step procedure will produce a result for any fixnum state, but the meaning of a non-0 state is specified only in that providing such a state produced by Char.grapheme_step in another call to Char.grapheme_step continues detecting grapheme-cluster boundaries in the sequence.

annotation

CharCI

A veneer for a character that redirects comparable operations like < and > to case-insensitive comparisons, equivalent to using Char.foldcase on each character before comparing.

As always for a veneer, CharCI works only in static mode (see use_static) to help ensure that it has the intended effect.

> "a"[0] < "B"[0]
#false
> ("a"[0] :: CharCI) < ("B"[0] :: CharCI)
#true

1	Rhombus Essentials
2	Collections and Iteration
3	Syntax Objects and Macros
4	Classes and Interfaces
5	Static Information and Binding
6	Core Reference
7	Meta and Macros Reference
8	Rhombus Static by Default
9	Libraries
10	Naming Conventions

6.1	General Forms
6.2	Definitions
6.3	Namespaces
6.4	Import
6.5	Export
6.6	Functions
6.7	Operators
6.8	Classes and Interfaces
6.9	Veneers
6.10	Mutable Variables and Assignment
6.11	Repetitions
6.12	Block
6.13	Conditionals
6.14	Matching
6.15	Iteration
6.16	Recursion
6.17	Context Parameters
6.18	Exceptions
6.19	Continuations
6.20	Implicit Forms
6.21	Static and Dynamic Lookup
6.22	Modules and Submodules
6.23	Booleans
6.24	Numbers
6.25	Characters
6.26	Strings
6.27	Keywords
6.28	Symbols
6.29	Byte Strings
6.30	Lists
6.31	Pairs and Pair Lists
6.32	Mutable Lists
6.33	Arrays
6.34	Maps
6.35	Sets
6.36	Boxes
6.37	Ranges
6.38	Indexables
6.39	Listables
6.40	Sequences
6.41	Appendables
6.42	Comparables
6.43	Paths
6.44	Source Locations
6.45	Void
6.46	Equality
6.47	Dot
6.48	Multiple Values
6.49	Annotations
6.50	Enumerations
6.51	String Formatting
6.52	Input and Output
6.53	Eval
6.54	Syntax Objects
6.55	Syntax Classes
6.56	Simple Expression Macros
6.57	Unit Testing

ch.to_int()	is	Char.to_int(ch)
ch.upcase()	is	Char.upcase(ch)
ch.downcase()	is	Char.downcase(ch)
ch.foldcase()	is	Char.foldcase(ch)
ch.titlecase()	is	Char.titlecase(ch)
ch.is_alphabetic()	is	Char.is_alphabetic(ch)
ch.is_lowercase()	is	Char.is_lowercase(ch)
ch.is_uppercase()	is	Char.is_uppercase(ch)
ch.is_titlecase()	is	Char.is_titlecase(ch)
ch.is_numeric()	is	Char.is_numeric(ch)
ch.is_symbolic()	is	Char.is_symbolic(ch)
ch.is_punctuation()	is	Char.is_punctuation(ch)
ch.is_graphic()	is	Char.is_graphic(ch)
ch.is_whitespace()	is	Char.is_whitespace(ch)
ch.is_blank()	is	Char.is_blank(ch)
ch.is_extended_pictographic()	is	Char.is_extended_pictographic(ch)
ch.general_category()	is	Char.general_category(ch)
ch.grapheme_break_property()	is	Char.grapheme_break_property(ch)
ch.grapheme_step(state)	is	Char.grapheme_step(ch, state)