Enum Tag 

#[repr(u8)]
pub enum Tag {
    Fallback = 0,
    LongPrimary = 1,
    LongSecondary = 2,
    Reserved3 = 3,
    LatinExpansion = 4,
    Expansion32 = 5,
    Expansion = 6,
    BuilderData = 7,
    Prefix = 8,
    Contraction = 9,
    Digit = 10,
    LongPrimaryForReorderable = 11,
    Hangul = 12,
    ExpansionForReorderable = 13,
    Offset = 14,
    Implicit = 15,
}

Special-CE32 tags, from bits 3..0 of a special 32-bit CE. Bits 31..8 are available for tag-specific data. Bits 5..4: Reserved. May be used in the future to indicate lccc!=0 and tccc!=0.

Variants

Fallback = 0

Fall back to the base collator. This is the tag value in SPECIAL_CE32_LOW_BYTE and FALLBACK_CE32. Bits 31..8: Unused, 0.

LongPrimary = 1

Long-primary CE with COMMON_SEC_AND_TER_CE.

When this occurs directly in the trie (not behind an further lookup like Expansion32) and we know we haven’t loaded old-format data, this further signals that the canonical combining class of the character is zero. See also [LongPrimaryForReorderable].

Bits 31..8: Three-byte primary.

LongSecondary = 2

Long-secondary CE with zero primary. Bits 31..16: Secondary weight. Bits 15.. 8: Tertiary weight.

Reserved3 = 3

Unused. May be used in the future for single-byte secondary CEs (SHORT_SECONDARY_TAG), storing the secondary in bits 31..24, the ccc in bits 23..16, and the tertiary in bits 15..8.

LatinExpansion = 4

Latin mini expansions of two simple CEs [pp, 05, tt] [00, ss, 05]. Bits 31..24: Single-byte primary weight pp of the first CE. Bits 23..16: Tertiary weight tt of the first CE. Bits 15.. 8: Secondary weight ss of the second CE. Unused by ICU4X, may get repurposed for jamo expansions is Korean search.

Expansion32 = 5

Points to one or more simple/long-primary/long-secondary 32-bit CE32s. Bits 31..13: Index into uint32_t table. Bits 12.. 8: Length=1..31.

Expansion = 6

Points to one or more 64-bit CEs.

When this occurs directly in the trie (not behind an further lookup like Expansion32) and we know we haven’t loaded old-format data, this further signals that the canonical combining class of the character is zero. See also [ExpansionForReorderable].

Bits 31..13: Index into CE table. Bits 12.. 8: Length=1..31.

BuilderData = 7

Builder data, used only in the CollationDataBuilder, not in runtime data.

If bit 8 is 0: Builder context, points to a list of context-sensitive mappings. Bits 31..13: Index to the builder’s list of ConditionalCE32 for this character. Bits 12.. 9: Unused, 0.

If bit 8 is 1 (IS_BUILDER_JAMO_CE32): Builder-only jamoCE32 value. The builder fetches the Jamo CE32 from the trie. Bits 31..13: Jamo code point. Bits 12.. 9: Unused, 0.

Prefix = 8

Points to prefix trie. Bits 31..13: Index into prefix/contraction data. Bits 12.. 8: Unused, 0.

Contraction = 9

Points to contraction data. Bits 31..13: Index into prefix/contraction data. Bits 12..11: Unused, 0. Bit 10: CONTRACT_TRAILING_CCC flag. Bit 9: CONTRACT_NEXT_CCC flag. Bit 8: CONTRACT_SINGLE_CP_NO_MATCH flag.

Digit = 10

Decimal digit. Bits 31..13: Index into uint32_t table for non-numeric-collation CE32. Bit 12: Unused, 0. Bits 11.. 8: Digit value 0..9.

LongPrimaryForReorderable = 11

The same as LongPrimary but if ccc!=0.

In ICU4C, this is U0000_TAG, which is not used by ICU4X: Tag for U+0000, for moving the NUL-termination handling from the regular fastpath into specials-handling code. Bits 31..8: Unused, 0.

Hangul = 12

Tag for a Hangul syllable. Bits 31..9: Unused, 0. Bit 8: HANGUL_NO_SPECIAL_JAMO flag. Not used by ICU4X, may get reused for compressing Hanja expansions.

ExpansionForReorderable = 13

The same as Expansion but if ccc!=0.

In ICU4C, this is LEAD_SURROGATE_TAG, which is not used by ICU4X: Optional optimization for UTF-16 string processing. Bits 31..10: Unused, 0. 9.. 8: =0: All associated supplementary code points are unassigned-implicit. =1: All associated supplementary code points fall back to the base data. else: (Normally 2) Look up the data for the supplementary code point.

Offset = 14

Tag for CEs with primary weights in code point order. Bits 31..13: Index into CE table, for one data “CE”. Bits 12.. 8: Unused, 0.

This data “CE” has the following bit fields: Bits 63..32: Three-byte primary pppppp00. 31.. 8: Start/base code point of the in-order range. 7: Flag isCompressible primary. 6.. 0: Per-code point primary-weight increment.

Implicit = 15

Implicit CE tag. Compute an unassigned-implicit CE. All bits are set (UNASSIGNED_CE32=0xffffffff).

Trait Implementations

impl Debug for Tag

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for Tag

impl PartialEq for Tag

fn eq(&self, other: &Tag) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Tag