Add unicode normalization for word indexing (v0.36.10)
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- Add unicode_normalize.go with mappings for small caps and fraktur
- Map 77 decorative unicode characters to ASCII equivalents:
  - Small caps (25 chars): ᴅᴇᴀᴛʜ → death
  - Fraktur lowercase (26 chars): 𝔡𝔢𝔞𝔱𝔥 → death
  - Fraktur uppercase (26 chars): 𝔇𝔈𝔄𝔗ℌ → death
- Fix broken utf8DecodeRuneInString() that failed on multi-byte UTF-8
- Add migration v7 to rebuild word indexes with normalization
- Add comprehensive unit tests for all character mappings

Files modified:
- pkg/database/unicode_normalize.go: New - character mapping tables
- pkg/database/unicode_normalize_test.go: New - unit tests
- pkg/database/tokenize.go: Integrate normalizeRune(), fix UTF-8 decoder
- pkg/database/migrations.go: Add version 7 migration

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
This commit is contained in:
2025-12-22 18:53:30 +01:00
parent 11d1b6bfd1
commit 0addc61549
5 changed files with 439 additions and 13 deletions

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//go:build !(js && wasm)
package database
// normalizeRune maps decorative unicode characters (small caps, fraktur) back to
// their ASCII equivalents for consistent word indexing. This ensures that text
// written with decorative alphabets (e.g., "ᴅᴇᴀᴛʜ" or "𝔇𝔢𝔞𝔱𝔥") indexes the same
// as regular ASCII ("death").
//
// Character sets normalized:
// - Small Caps (used for DEATH-style text in Terry Pratchett tradition)
// - Mathematical Fraktur lowercase (𝔞-𝔷)
// - Mathematical Fraktur uppercase (𝔄-, including Letterlike Symbols block exceptions)
func normalizeRune(r rune) rune {
// Check small caps first (scattered codepoints)
if mapped, ok := smallCapsToASCII[r]; ok {
return mapped
}
// Check fraktur lowercase: U+1D51E to U+1D537 (contiguous range)
if r >= 0x1D51E && r <= 0x1D537 {
return 'a' + (r - 0x1D51E)
}
// Check fraktur uppercase main range: U+1D504 to U+1D51C (with gaps)
if r >= 0x1D504 && r <= 0x1D51C {
if mapped, ok := frakturUpperToASCII[r]; ok {
return mapped
}
}
// Check fraktur uppercase exceptions from Letterlike Symbols block
if mapped, ok := frakturLetterlikeToASCII[r]; ok {
return mapped
}
return r
}
// smallCapsToASCII maps small capital letters to lowercase ASCII.
// These are scattered across multiple Unicode blocks (IPA Extensions,
// Phonetic Extensions, Latin Extended-D).
var smallCapsToASCII = map[rune]rune{
'ᴀ': 'a', // U+1D00 LATIN LETTER SMALL CAPITAL A
'ʙ': 'b', // U+0299 LATIN LETTER SMALL CAPITAL B
'': 'c', // U+1D04 LATIN LETTER SMALL CAPITAL C
'ᴅ': 'd', // U+1D05 LATIN LETTER SMALL CAPITAL D
'ᴇ': 'e', // U+1D07 LATIN LETTER SMALL CAPITAL E
'ꜰ': 'f', // U+A730 LATIN LETTER SMALL CAPITAL F
'ɢ': 'g', // U+0262 LATIN LETTER SMALL CAPITAL G
'ʜ': 'h', // U+029C LATIN LETTER SMALL CAPITAL H
'ɪ': 'i', // U+026A LATIN LETTER SMALL CAPITAL I
'ᴊ': 'j', // U+1D0A LATIN LETTER SMALL CAPITAL J
'ᴋ': 'k', // U+1D0B LATIN LETTER SMALL CAPITAL K
'ʟ': 'l', // U+029F LATIN LETTER SMALL CAPITAL L
'ᴍ': 'm', // U+1D0D LATIN LETTER SMALL CAPITAL M
'ɴ': 'n', // U+0274 LATIN LETTER SMALL CAPITAL N
'': 'o', // U+1D0F LATIN LETTER SMALL CAPITAL O
'ᴘ': 'p', // U+1D18 LATIN LETTER SMALL CAPITAL P
'ǫ': 'q', // U+01EB LATIN SMALL LETTER O WITH OGONEK (no true small cap Q)
'ʀ': 'r', // U+0280 LATIN LETTER SMALL CAPITAL R
'': 's', // U+A731 LATIN LETTER SMALL CAPITAL S
'ᴛ': 't', // U+1D1B LATIN LETTER SMALL CAPITAL T
'': 'u', // U+1D1C LATIN LETTER SMALL CAPITAL U
'': 'v', // U+1D20 LATIN LETTER SMALL CAPITAL V
'': 'w', // U+1D21 LATIN LETTER SMALL CAPITAL W
// Note: no small cap X exists in standard use
'ʏ': 'y', // U+028F LATIN LETTER SMALL CAPITAL Y
'': 'z', // U+1D22 LATIN LETTER SMALL CAPITAL Z
}
// frakturUpperToASCII maps Mathematical Fraktur uppercase letters to lowercase ASCII.
// The main range U+1D504-U+1D51C has gaps where C, H, I, R, Z use Letterlike Symbols.
var frakturUpperToASCII = map[rune]rune{
'𝔄': 'a', // U+1D504 MATHEMATICAL FRAKTUR CAPITAL A
'𝔅': 'b', // U+1D505 MATHEMATICAL FRAKTUR CAPITAL B
// C is at U+212D (Letterlike Symbols)
'𝔇': 'd', // U+1D507 MATHEMATICAL FRAKTUR CAPITAL D
'𝔈': 'e', // U+1D508 MATHEMATICAL FRAKTUR CAPITAL E
'𝔉': 'f', // U+1D509 MATHEMATICAL FRAKTUR CAPITAL F
'𝔊': 'g', // U+1D50A MATHEMATICAL FRAKTUR CAPITAL G
// H is at U+210C (Letterlike Symbols)
// I is at U+2111 (Letterlike Symbols)
'𝔍': 'j', // U+1D50D MATHEMATICAL FRAKTUR CAPITAL J
'𝔎': 'k', // U+1D50E MATHEMATICAL FRAKTUR CAPITAL K
'𝔏': 'l', // U+1D50F MATHEMATICAL FRAKTUR CAPITAL L
'𝔐': 'm', // U+1D510 MATHEMATICAL FRAKTUR CAPITAL M
'𝔑': 'n', // U+1D511 MATHEMATICAL FRAKTUR CAPITAL N
'𝔒': 'o', // U+1D512 MATHEMATICAL FRAKTUR CAPITAL O
'𝔓': 'p', // U+1D513 MATHEMATICAL FRAKTUR CAPITAL P
'𝔔': 'q', // U+1D514 MATHEMATICAL FRAKTUR CAPITAL Q
// R is at U+211C (Letterlike Symbols)
'𝔖': 's', // U+1D516 MATHEMATICAL FRAKTUR CAPITAL S
'𝔗': 't', // U+1D517 MATHEMATICAL FRAKTUR CAPITAL T
'𝔘': 'u', // U+1D518 MATHEMATICAL FRAKTUR CAPITAL U
'𝔙': 'v', // U+1D519 MATHEMATICAL FRAKTUR CAPITAL V
'𝔚': 'w', // U+1D51A MATHEMATICAL FRAKTUR CAPITAL W
'𝔛': 'x', // U+1D51B MATHEMATICAL FRAKTUR CAPITAL X
'𝔜': 'y', // U+1D51C MATHEMATICAL FRAKTUR CAPITAL Y
// Z is at U+2128 (Letterlike Symbols)
}
// frakturLetterlikeToASCII maps the Fraktur characters that live in the
// Letterlike Symbols block (U+2100-U+214F) rather than Mathematical Alphanumeric Symbols.
var frakturLetterlikeToASCII = map[rune]rune{
'': 'c', // U+212D BLACK-LETTER CAPITAL C
'': 'h', // U+210C BLACK-LETTER CAPITAL H
'': 'i', // U+2111 BLACK-LETTER CAPITAL I
'': 'r', // U+211C BLACK-LETTER CAPITAL R
'': 'z', // U+2128 BLACK-LETTER CAPITAL Z
}
// hasDecorativeUnicode checks if text contains any small caps or fraktur characters
// that would need normalization. Used by migration to identify events needing re-indexing.
func hasDecorativeUnicode(s string) bool {
for _, r := range s {
// Check small caps
if _, ok := smallCapsToASCII[r]; ok {
return true
}
// Check fraktur lowercase range
if r >= 0x1D51E && r <= 0x1D537 {
return true
}
// Check fraktur uppercase range
if r >= 0x1D504 && r <= 0x1D51C {
return true
}
// Check letterlike symbols fraktur
if _, ok := frakturLetterlikeToASCII[r]; ok {
return true
}
}
return false
}