mirror of
https://github.com/Luzifer/ansible-role-version.git
synced 2024-12-24 19:41:20 +00:00
236 lines
7 KiB
Go
236 lines
7 KiB
Go
// Copyright 2014 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 colltab
|
||
|
||
import (
|
||
"unicode"
|
||
"unicode/utf8"
|
||
)
|
||
|
||
// NewNumericWeighter wraps w to replace individual digits to sort based on their
|
||
// numeric value.
|
||
//
|
||
// Weighter w must have a free primary weight after the primary weight for 9.
|
||
// If this is not the case, numeric value will sort at the same primary level
|
||
// as the first primary sorting after 9.
|
||
func NewNumericWeighter(w Weighter) Weighter {
|
||
getElem := func(s string) Elem {
|
||
elems, _ := w.AppendNextString(nil, s)
|
||
return elems[0]
|
||
}
|
||
nine := getElem("9")
|
||
|
||
// Numbers should order before zero, but the DUCET has no room for this.
|
||
// TODO: move before zero once we use fractional collation elements.
|
||
ns, _ := MakeElem(nine.Primary()+1, nine.Secondary(), int(nine.Tertiary()), 0)
|
||
|
||
return &numericWeighter{
|
||
Weighter: w,
|
||
|
||
// We assume that w sorts digits of different kinds in order of numeric
|
||
// value and that the tertiary weight order is preserved.
|
||
//
|
||
// TODO: evaluate whether it is worth basing the ranges on the Elem
|
||
// encoding itself once the move to fractional weights is complete.
|
||
zero: getElem("0"),
|
||
zeroSpecialLo: getElem("０"), // U+FF10 FULLWIDTH DIGIT ZERO
|
||
zeroSpecialHi: getElem("₀"), // U+2080 SUBSCRIPT ZERO
|
||
nine: nine,
|
||
nineSpecialHi: getElem("₉"), // U+2089 SUBSCRIPT NINE
|
||
numberStart: ns,
|
||
}
|
||
}
|
||
|
||
// A numericWeighter translates a stream of digits into a stream of weights
|
||
// representing the numeric value.
|
||
type numericWeighter struct {
|
||
Weighter
|
||
|
||
// The Elems below all demarcate boundaries of specific ranges. With the
|
||
// current element encoding digits are in two ranges: normal (default
|
||
// tertiary value) and special. For most languages, digits have collation
|
||
// elements in the normal range.
|
||
//
|
||
// Note: the range tests are very specific for the element encoding used by
|
||
// this implementation. The tests in collate_test.go are designed to fail
|
||
// if this code is not updated when an encoding has changed.
|
||
|
||
zero Elem // normal digit zero
|
||
zeroSpecialLo Elem // special digit zero, low tertiary value
|
||
zeroSpecialHi Elem // special digit zero, high tertiary value
|
||
nine Elem // normal digit nine
|
||
nineSpecialHi Elem // special digit nine
|
||
numberStart Elem
|
||
}
|
||
|
||
// AppendNext calls the namesake of the underlying weigher, but replaces single
|
||
// digits with weights representing their value.
|
||
func (nw *numericWeighter) AppendNext(buf []Elem, s []byte) (ce []Elem, n int) {
|
||
ce, n = nw.Weighter.AppendNext(buf, s)
|
||
nc := numberConverter{
|
||
elems: buf,
|
||
w: nw,
|
||
b: s,
|
||
}
|
||
isZero, ok := nc.checkNextDigit(ce)
|
||
if !ok {
|
||
return ce, n
|
||
}
|
||
// ce might have been grown already, so take it instead of buf.
|
||
nc.init(ce, len(buf), isZero)
|
||
for n < len(s) {
|
||
ce, sz := nw.Weighter.AppendNext(nc.elems, s[n:])
|
||
nc.b = s
|
||
n += sz
|
||
if !nc.update(ce) {
|
||
break
|
||
}
|
||
}
|
||
return nc.result(), n
|
||
}
|
||
|
||
// AppendNextString calls the namesake of the underlying weigher, but replaces
|
||
// single digits with weights representing their value.
|
||
func (nw *numericWeighter) AppendNextString(buf []Elem, s string) (ce []Elem, n int) {
|
||
ce, n = nw.Weighter.AppendNextString(buf, s)
|
||
nc := numberConverter{
|
||
elems: buf,
|
||
w: nw,
|
||
s: s,
|
||
}
|
||
isZero, ok := nc.checkNextDigit(ce)
|
||
if !ok {
|
||
return ce, n
|
||
}
|
||
nc.init(ce, len(buf), isZero)
|
||
for n < len(s) {
|
||
ce, sz := nw.Weighter.AppendNextString(nc.elems, s[n:])
|
||
nc.s = s
|
||
n += sz
|
||
if !nc.update(ce) {
|
||
break
|
||
}
|
||
}
|
||
return nc.result(), n
|
||
}
|
||
|
||
type numberConverter struct {
|
||
w *numericWeighter
|
||
|
||
elems []Elem
|
||
nDigits int
|
||
lenIndex int
|
||
|
||
s string // set if the input was of type string
|
||
b []byte // set if the input was of type []byte
|
||
}
|
||
|
||
// init completes initialization of a numberConverter and prepares it for adding
|
||
// more digits. elems is assumed to have a digit starting at oldLen.
|
||
func (nc *numberConverter) init(elems []Elem, oldLen int, isZero bool) {
|
||
// Insert a marker indicating the start of a number and and a placeholder
|
||
// for the number of digits.
|
||
if isZero {
|
||
elems = append(elems[:oldLen], nc.w.numberStart, 0)
|
||
} else {
|
||
elems = append(elems, 0, 0)
|
||
copy(elems[oldLen+2:], elems[oldLen:])
|
||
elems[oldLen] = nc.w.numberStart
|
||
elems[oldLen+1] = 0
|
||
|
||
nc.nDigits = 1
|
||
}
|
||
nc.elems = elems
|
||
nc.lenIndex = oldLen + 1
|
||
}
|
||
|
||
// checkNextDigit reports whether bufNew adds a single digit relative to the old
|
||
// buffer. If it does, it also reports whether this digit is zero.
|
||
func (nc *numberConverter) checkNextDigit(bufNew []Elem) (isZero, ok bool) {
|
||
if len(nc.elems) >= len(bufNew) {
|
||
return false, false
|
||
}
|
||
e := bufNew[len(nc.elems)]
|
||
if e < nc.w.zeroSpecialLo || nc.w.nine < e {
|
||
// Not a number.
|
||
return false, false
|
||
}
|
||
if e < nc.w.zero {
|
||
if e > nc.w.nineSpecialHi {
|
||
// Not a number.
|
||
return false, false
|
||
}
|
||
if !nc.isDigit() {
|
||
return false, false
|
||
}
|
||
isZero = e <= nc.w.zeroSpecialHi
|
||
} else {
|
||
// This is the common case if we encounter a digit.
|
||
isZero = e == nc.w.zero
|
||
}
|
||
// Test the remaining added collation elements have a zero primary value.
|
||
if n := len(bufNew) - len(nc.elems); n > 1 {
|
||
for i := len(nc.elems) + 1; i < len(bufNew); i++ {
|
||
if bufNew[i].Primary() != 0 {
|
||
return false, false
|
||
}
|
||
}
|
||
// In some rare cases, collation elements will encode runes in
|
||
// unicode.No as a digit. For example Ethiopic digits (U+1369 - U+1371)
|
||
// are not in Nd. Also some digits that clearly belong in unicode.No,
|
||
// like U+0C78 TELUGU FRACTION DIGIT ZERO FOR ODD POWERS OF FOUR, have
|
||
// collation elements indistinguishable from normal digits.
|
||
// Unfortunately, this means we need to make this check for nearly all
|
||
// non-Latin digits.
|
||
//
|
||
// TODO: check the performance impact and find something better if it is
|
||
// an issue.
|
||
if !nc.isDigit() {
|
||
return false, false
|
||
}
|
||
}
|
||
return isZero, true
|
||
}
|
||
|
||
func (nc *numberConverter) isDigit() bool {
|
||
if nc.b != nil {
|
||
r, _ := utf8.DecodeRune(nc.b)
|
||
return unicode.In(r, unicode.Nd)
|
||
}
|
||
r, _ := utf8.DecodeRuneInString(nc.s)
|
||
return unicode.In(r, unicode.Nd)
|
||
}
|
||
|
||
// We currently support a maximum of about 2M digits (the number of primary
|
||
// values). Such numbers will compare correctly against small numbers, but their
|
||
// comparison against other large numbers is undefined.
|
||
//
|
||
// TODO: define a proper fallback, such as comparing large numbers textually or
|
||
// actually allowing numbers of unlimited length.
|
||
//
|
||
// TODO: cap this to a lower number (like 100) and maybe allow a larger number
|
||
// in an option?
|
||
const maxDigits = 1<<maxPrimaryBits - 1
|
||
|
||
func (nc *numberConverter) update(elems []Elem) bool {
|
||
isZero, ok := nc.checkNextDigit(elems)
|
||
if nc.nDigits == 0 && isZero {
|
||
return true
|
||
}
|
||
nc.elems = elems
|
||
if !ok {
|
||
return false
|
||
}
|
||
nc.nDigits++
|
||
return nc.nDigits < maxDigits
|
||
}
|
||
|
||
// result fills in the length element for the digit sequence and returns the
|
||
// completed collation elements.
|
||
func (nc *numberConverter) result() []Elem {
|
||
e, _ := MakeElem(nc.nDigits, defaultSecondary, defaultTertiary, 0)
|
||
nc.elems[nc.lenIndex] = e
|
||
return nc.elems
|
||
}
|