# `Localize.Collation.ImplicitWeights`
[🔗](https://github.com/elixir-localize/localize/blob/v0.38.0/lib/localize/collation/implicit_weights.ex#L1)

Computes implicit collation elements for codepoints not in the DUCET/CLDR allkeys table.

The UCA defines an algorithm for computing implicit weights for:

* CJK Unified Ideographs (Han characters).

* Hangul syllables (decomposed algorithmically).

* Unassigned codepoints.

See UTS #10 Section 10.1 for the implicit weight computation.

# `compute`

```elixir
@spec compute(non_neg_integer()) ::
  {:hangul_decompose, [non_neg_integer()]} | [Localize.Collation.Element.t()]
```

Compute implicit collation elements for a codepoint not in the allkeys table.

### Arguments

* `cp` - an integer codepoint.

### Returns

* `{:hangul_decompose, jamo}` - for Hangul syllables.

* `[element, element]` - two implicit CEs for CJK or unassigned codepoints.

### Examples

    iex> [ce1, ce2] = Localize.Collation.ImplicitWeights.compute(0x4E00)
    iex> Localize.Collation.Element.primary(ce1) >= 0xFB40
    true
    iex> Localize.Collation.Element.secondary(ce2)
    0

# `decompose_hangul_to_jamo`

```elixir
@spec decompose_hangul_to_jamo(non_neg_integer()) :: [non_neg_integer()]
```

Decompose a Hangul syllable into its constituent jamo codepoints.

### Arguments

* `cp` - an integer codepoint for a Hangul syllable (U+AC00..U+D7A3).

### Returns

A list of 2 or 3 jamo codepoints: `[lead, vowel]` or `[lead, vowel, trail]`.

### Examples

    iex> Localize.Collation.ImplicitWeights.decompose_hangul_to_jamo(0xAC00)
    [0x1100, 0x1161]

    iex> Localize.Collation.ImplicitWeights.decompose_hangul_to_jamo(0xAC01)
    [0x1100, 0x1161, 0x11A8]

# `hangul_syllable?`

```elixir
@spec hangul_syllable?(non_neg_integer()) :: boolean()
```

Check if a codepoint is a Hangul syllable.

### Arguments

* `cp` - an integer codepoint.

### Returns

* `true` if the codepoint is a Hangul syllable.

* `false` otherwise.

### Examples

    iex> Localize.Collation.ImplicitWeights.hangul_syllable?(0xAC00)
    true

    iex> Localize.Collation.ImplicitWeights.hangul_syllable?(0x0041)
    false

# `unified_ideograph?`

```elixir
@spec unified_ideograph?(non_neg_integer()) :: boolean()
```

Check if a codepoint is a CJK Unified Ideograph.

### Arguments

* `cp` - an integer codepoint.

### Returns

* `true` if the codepoint is a CJK Unified Ideograph.

* `false` otherwise.

### Examples

    iex> Localize.Collation.ImplicitWeights.unified_ideograph?(0x4E00)
    true

    iex> Localize.Collation.ImplicitWeights.unified_ideograph?(0x0041)
    false

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*Consult [api-reference.md](api-reference.md) for complete listing*