This commit introduces Generate-CodepointWidthsFromUCD, a powershell
(7+) script that will parse a UCD XML database in the UAX 42 format from
https://www.unicode.org/Public/UCD/latest/ucdxml/ and generate
CodepointWidthDetector's giant width array.
By default, it will emit one UnicodeRange for every range of non-narrow
glyphs with a different Width + Emoji + Emoji Presentation class;
however, it can be run in "packing" and "full" mode.
* Packing mode: ignore the width/emoji/pres class and combine adjacent
runs that CPWD will treat the same.
* This is for optimizing the number of individual ranges emitted
into code.
* Full mode: include narrow codepoints (helpful for visualization)
It also supports overrides, provided in an XML document of the same format
as the UCD itself. Entries in the overrides files are applied after the
entire UCD is read and will replace any impacted ranges.
The output (when packing) looks like this:
```c++
// Generated by Generate-CodepointWidthsFromUCD -Pack:True -Full:False
// on 05/17/2020 02:47:55 (UTC) from Unicode 13.0.0.
// 66182 (0x10286) codepoints covered.
static constexpr std::array<UnicodeRange, 23> s_wideAndAmbiguousTable{
UnicodeRange{ 0xa1, 0xa1, CodepointWidth::Ambiguous },
UnicodeRange{ 0xa4, 0xa4, CodepointWidth::Ambiguous },
UnicodeRange{ 0xa7, 0xa8, CodepointWidth::Ambiguous },
.
.
.
UnicodeRange{ 0x1f210, 0x1f23b, CodepointWidth::Wide },
UnicodeRange{ 0x1f37e, 0x1f393, CodepointWidth::Wide },
UnicodeRange{ 0x100000, 0x10fffd, CodepointWidth::Ambiguous },
};
```
The output (when overriding) looks like this:
```c++
// Generated by Generate-CodepointWidthsFromUCD.ps1 -Pack:True -Full:False -NoOverrides:False
// on 5/22/2020 11:17:39 PM (UTC) from Unicode 13.0.0.
// 321205 (0x4E6B5) codepoints covered.
// 240 (0xF0) codepoints overridden.
static constexpr std::array<UnicodeRange, 23> s_wideAndAmbiguousTable{
UnicodeRange{ 0xa1, 0xa1, CodepointWidth::Ambiguous },
...
UnicodeRange{ 0xfe20, 0xfe2f, CodepointWidth::Narrow }, // narrow combining ligatures (split into left/right halves, which take 2 columns together)
...
UnicodeRange{ 0x100000, 0x10fffd, CodepointWidth::Ambiguous },
};
```
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