mirror of
https://github.com/ergochat/ergo.git
synced 2024-11-25 13:29:27 +01:00
83 lines
2.9 KiB
Go
83 lines
2.9 KiB
Go
// Copyright 2015 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package cases
|
|
|
|
func (c info) cccVal() info {
|
|
if c&exceptionBit != 0 {
|
|
return info(exceptions[c>>exceptionShift]) & cccMask
|
|
}
|
|
return c & cccMask
|
|
}
|
|
|
|
func (c info) cccType() info {
|
|
ccc := c.cccVal()
|
|
if ccc <= cccZero {
|
|
return cccZero
|
|
}
|
|
return ccc
|
|
}
|
|
|
|
// TODO: Implement full Unicode breaking algorithm:
|
|
// 1) Implement breaking in separate package.
|
|
// 2) Use the breaker here.
|
|
// 3) Compare table size and performance of using the more generic breaker.
|
|
//
|
|
// Note that we can extend the current algorithm to be much more accurate. This
|
|
// only makes sense, though, if the performance and/or space penalty of using
|
|
// the generic breaker is big. Extra data will only be needed for non-cased
|
|
// runes, which means there are sufficient bits left in the caseType.
|
|
// ICU prohibits breaking in such cases as well.
|
|
|
|
// For the purpose of title casing we use an approximation of the Unicode Word
|
|
// Breaking algorithm defined in Annex #29:
|
|
// https://www.unicode.org/reports/tr29/#Default_Grapheme_Cluster_Table.
|
|
//
|
|
// For our approximation, we group the Word Break types into the following
|
|
// categories, with associated rules:
|
|
//
|
|
// 1) Letter:
|
|
// ALetter, Hebrew_Letter, Numeric, ExtendNumLet, Extend, Format_FE, ZWJ.
|
|
// Rule: Never break between consecutive runes of this category.
|
|
//
|
|
// 2) Mid:
|
|
// MidLetter, MidNumLet, Single_Quote.
|
|
// (Cf. case-ignorable: MidLetter, MidNumLet, Single_Quote or cat is Mn,
|
|
// Me, Cf, Lm or Sk).
|
|
// Rule: Don't break between Letter and Mid, but break between two Mids.
|
|
//
|
|
// 3) Break:
|
|
// Any other category: NewLine, MidNum, CR, LF, Double_Quote, Katakana, and
|
|
// Other.
|
|
// These categories should always result in a break between two cased letters.
|
|
// Rule: Always break.
|
|
//
|
|
// Note 1: the Katakana and MidNum categories can, in esoteric cases, result in
|
|
// preventing a break between two cased letters. For now we will ignore this
|
|
// (e.g. [ALetter] [ExtendNumLet] [Katakana] [ExtendNumLet] [ALetter] and
|
|
// [ALetter] [Numeric] [MidNum] [Numeric] [ALetter].)
|
|
//
|
|
// Note 2: the rule for Mid is very approximate, but works in most cases. To
|
|
// improve, we could store the categories in the trie value and use a FA to
|
|
// manage breaks. See TODO comment above.
|
|
//
|
|
// Note 3: according to the spec, it is possible for the Extend category to
|
|
// introduce breaks between other categories grouped in Letter. However, this
|
|
// is undesirable for our purposes. ICU prevents breaks in such cases as well.
|
|
|
|
// isBreak returns whether this rune should introduce a break.
|
|
func (c info) isBreak() bool {
|
|
return c.cccVal() == cccBreak
|
|
}
|
|
|
|
// isLetter returns whether the rune is of break type ALetter, Hebrew_Letter,
|
|
// Numeric, ExtendNumLet, or Extend.
|
|
func (c info) isLetter() bool {
|
|
ccc := c.cccVal()
|
|
if ccc == cccZero {
|
|
return !c.isCaseIgnorable()
|
|
}
|
|
return ccc != cccBreak
|
|
}
|