Select characters

UnicodeSet represents normalized Unicode ranges. It can be created from text, codepoints, ranges, or CSS unicode-range syntax.

Select characters from text

<?php

use Alto\Font\Subset\UnicodeSet;

$characters = UnicodeSet::fromText('Hello, Alto!');

Repeated characters produce one set entry. The input must be valid UTF-8.

fromText() selects the codepoints present in the input. It does not add Unicode normalization equivalents: A followed by a combining acute accent does not also select Á. A text shaper may prefer the composed character when it exists in the source font, so omitting it can change glyph selection or positioning. Include both forms when preserving that behavior matters.

Select codepoints and ranges

<?php

use Alto\Font\Subset\UnicodeRange;
use Alto\Font\Subset\UnicodeSet;

$codepoints = UnicodeSet::fromCodepoints([0x20, 0x41, 0x42]);
$ranges = UnicodeSet::fromRanges([
    UnicodeRange::between(0x30, 0x39),
    UnicodeRange::between(0x41, 0x5A),
]);
$css = UnicodeSet::fromCss('U+0020-007E, U+00A0-00FF');

Values outside U+0000-U+10FFFF, reversed ranges, and malformed CSS syntax raise InvalidUnicodeRangeException. fromText() additionally requires valid UTF-8.

Compose sets

<?php

$latin = UnicodeSet::fromCss('U+0020-024F');
$required = UnicodeSet::fromText('Alto 0123456789');
$excluded = UnicodeSet::fromText('xyz');

$combined = $latin->union($required);
$shared = $latin->intersect($required);
$filtered = $combined->without($excluded);

These operations work on normalized ranges without first expanding every codepoint.

Inspect a set

<?php

if ($filtered->contains(0x41)) {
    echo $filtered->toCss();
}

echo count($filtered);

count() returns the number of represented codepoints. isEmpty() reports whether the set contains none. Iterating over a UnicodeSet yields individual codepoints and therefore expands the selected ranges during iteration.

Pass the finished set to SubsetOptions as shown in Create a font subset.

Unicode set contract

UnicodeSet is immutable, countable, and iterable. Its factories normalize repeated or overlapping codepoints into ordered ranges.

Method	Result
`fromText(string $text)`	Select codepoints from valid UTF-8 text without adding normalization equivalents.
`fromCodepoints(iterable $codepoints)`	Select integer values from U+0000 through U+10FFFF.
`fromRanges(iterable $ranges)`	Merge overlapping or adjacent `UnicodeRange` values.
`fromCss(string $unicodeRange)`	Parse a non-empty CSS unicode-range list, including supported wildcard notation.
`union(UnicodeSet $other)`	Include values in either set.
`intersect(UnicodeSet $other)`	Include values present in both sets.
`without(UnicodeSet $other)`	Remove values present in the other set.
`contains(int $codepoint)`	Test whether one valid codepoint belongs to the set.
`toCss()`	Serialize normalized ranges as CSS unicode-range text.

UnicodeRange::single() selects one codepoint. UnicodeRange::between() uses inclusive bounds. Invalid bounds, codepoints, or CSS syntax raise InvalidUnicodeRangeException; invalid UTF-8 raises InvalidTextException.