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// Copyright 2012 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 build
import (
"fmt"
"log"
"sort"
"strings"
"unicode"
"golang.org/x/text/internal/colltab"
"golang.org/x/text/unicode/norm"
)
type logicalAnchor int
const (
firstAnchor logicalAnchor = -1
noAnchor = 0
lastAnchor = 1
)
// entry is used to keep track of a single entry in the collation element table
// during building. Examples of entries can be found in the Default Unicode
// Collation Element Table.
// See https://www.unicode.org/Public/UCA/6.0.0/allkeys.txt.
type entry struct {
str string // same as string(runes)
runes []rune
elems []rawCE // the collation elements
extend string // weights of extend to be appended to elems
before bool // weights relative to next instead of previous.
lock bool // entry is used in extension and can no longer be moved.
// prev, next, and level are used to keep track of tailorings.
prev, next *entry
level colltab.Level // next differs at this level
skipRemove bool // do not unlink when removed
decompose bool // can use NFKD decomposition to generate elems
exclude bool // do not include in table
implicit bool // derived, is not included in the list
modified bool // entry was modified in tailoring
logical logicalAnchor
expansionIndex int // used to store index into expansion table
contractionHandle ctHandle
contractionIndex int // index into contraction elements
}
func (e *entry) String() string {
return fmt.Sprintf("%X (%q) -> %X (ch:%x; ci:%d, ei:%d)",
e.runes, e.str, e.elems, e.contractionHandle, e.contractionIndex, e.expansionIndex)
}
func (e *entry) skip() bool {
return e.contraction()
}
func (e *entry) expansion() bool {
return !e.decompose && len(e.elems) > 1
}
func (e *entry) contraction() bool {
return len(e.runes) > 1
}
func (e *entry) contractionStarter() bool {
return e.contractionHandle.n != 0
}
// nextIndexed gets the next entry that needs to be stored in the table.
// It returns the entry and the collation level at which the next entry differs
// from the current entry.
// Entries that can be explicitly derived and logical reset positions are
// examples of entries that will not be indexed.
func (e *entry) nextIndexed() (*entry, colltab.Level) {
level := e.level
for e = e.next; e != nil && (e.exclude || len(e.elems) == 0); e = e.next {
if e.level < level {
level = e.level
}
}
return e, level
}
// remove unlinks entry e from the sorted chain and clears the collation
// elements. e may not be at the front or end of the list. This should always
// be the case, as the front and end of the list are always logical anchors,
// which may not be removed.
func (e *entry) remove() {
if e.logical != noAnchor {
log.Fatalf("may not remove anchor %q", e.str)
}
// TODO: need to set e.prev.level to e.level if e.level is smaller?
e.elems = nil
if !e.skipRemove {
if e.prev != nil {
e.prev.next = e.next
}
if e.next != nil {
e.next.prev = e.prev
}
}
e.skipRemove = false
}
// insertAfter inserts n after e.
func (e *entry) insertAfter(n *entry) {
if e == n {
panic("e == anchor")
}
if e == nil {
panic("unexpected nil anchor")
}
n.remove()
n.decompose = false // redo decomposition test
n.next = e.next
n.prev = e
if e.next != nil {
e.next.prev = n
}
e.next = n
}
// insertBefore inserts n before e.
func (e *entry) insertBefore(n *entry) {
if e == n {
panic("e == anchor")
}
if e == nil {
panic("unexpected nil anchor")
}
n.remove()
n.decompose = false // redo decomposition test
n.prev = e.prev
n.next = e
if e.prev != nil {
e.prev.next = n
}
e.prev = n
}
func (e *entry) encodeBase() (ce uint32, err error) {
switch {
case e.expansion():
ce, err = makeExpandIndex(e.expansionIndex)
default:
if e.decompose {
log.Fatal("decompose should be handled elsewhere")
}
ce, err = makeCE(e.elems[0])
}
return
}
func (e *entry) encode() (ce uint32, err error) {
if e.skip() {
log.Fatal("cannot build colElem for entry that should be skipped")
}
switch {
case e.decompose:
t1 := e.elems[0].w[2]
t2 := 0
if len(e.elems) > 1 {
t2 = e.elems[1].w[2]
}
ce, err = makeDecompose(t1, t2)
case e.contractionStarter():
ce, err = makeContractIndex(e.contractionHandle, e.contractionIndex)
default:
if len(e.runes) > 1 {
log.Fatal("colElem: contractions are handled in contraction trie")
}
ce, err = e.encodeBase()
}
return
}
// entryLess returns true if a sorts before b and false otherwise.
func entryLess(a, b *entry) bool {
if res, _ := compareWeights(a.elems, b.elems); res != 0 {
return res == -1
}
if a.logical != noAnchor {
return a.logical == firstAnchor
}
if b.logical != noAnchor {
return b.logical == lastAnchor
}
return a.str < b.str
}
type sortedEntries []*entry
func (s sortedEntries) Len() int {
return len(s)
}
func (s sortedEntries) Swap(i, j int) {
s[i], s[j] = s[j], s[i]
}
func (s sortedEntries) Less(i, j int) bool {
return entryLess(s[i], s[j])
}
type ordering struct {
id string
entryMap map[string]*entry
ordered []*entry
handle *trieHandle
}
// insert inserts e into both entryMap and ordered.
// Note that insert simply appends e to ordered. To reattain a sorted
// order, o.sort() should be called.
func (o *ordering) insert(e *entry) {
if e.logical == noAnchor {
o.entryMap[e.str] = e
} else {
// Use key format as used in UCA rules.
o.entryMap[fmt.Sprintf("[%s]", e.str)] = e
// Also add index entry for XML format.
o.entryMap[fmt.Sprintf("<%s/>", strings.Replace(e.str, " ", "_", -1))] = e
}
o.ordered = append(o.ordered, e)
}
// newEntry creates a new entry for the given info and inserts it into
// the index.
func (o *ordering) newEntry(s string, ces []rawCE) *entry {
e := &entry{
runes: []rune(s),
elems: ces,
str: s,
}
o.insert(e)
return e
}
// find looks up and returns the entry for the given string.
// It returns nil if str is not in the index and if an implicit value
// cannot be derived, that is, if str represents more than one rune.
func (o *ordering) find(str string) *entry {
e := o.entryMap[str]
if e == nil {
r := []rune(str)
if len(r) == 1 {
const (
firstHangul = 0xAC00
lastHangul = 0xD7A3
)
if r[0] >= firstHangul && r[0] <= lastHangul {
ce := []rawCE{}
nfd := norm.NFD.String(str)
for _, r := range nfd {
ce = append(ce, o.find(string(r)).elems...)
}
e = o.newEntry(nfd, ce)
} else {
e = o.newEntry(string(r[0]), []rawCE{
{w: []int{
implicitPrimary(r[0]),
defaultSecondary,
defaultTertiary,
int(r[0]),
},
},
})
e.modified = true
}
e.exclude = true // do not index implicits
}
}
return e
}
// makeRootOrdering returns a newly initialized ordering value and populates
// it with a set of logical reset points that can be used as anchors.
// The anchors first_tertiary_ignorable and __END__ will always sort at
// the beginning and end, respectively. This means that prev and next are non-nil
// for any indexed entry.
func makeRootOrdering() ordering {
const max = unicode.MaxRune
o := ordering{
entryMap: make(map[string]*entry),
}
insert := func(typ logicalAnchor, s string, ce []int) {
e := &entry{
elems: []rawCE{{w: ce}},
str: s,
exclude: true,
logical: typ,
}
o.insert(e)
}
insert(firstAnchor, "first tertiary ignorable", []int{0, 0, 0, 0})
insert(lastAnchor, "last tertiary ignorable", []int{0, 0, 0, max})
insert(lastAnchor, "last primary ignorable", []int{0, defaultSecondary, defaultTertiary, max})
insert(lastAnchor, "last non ignorable", []int{maxPrimary, defaultSecondary, defaultTertiary, max})
insert(lastAnchor, "__END__", []int{1 << maxPrimaryBits, defaultSecondary, defaultTertiary, max})
return o
}
// patchForInsert eliminates entries from the list with more than one collation element.
// The next and prev fields of the eliminated entries still point to appropriate
// values in the newly created list.
// It requires that sort has been called.
func (o *ordering) patchForInsert() {
for i := 0; i < len(o.ordered)-1; {
e := o.ordered[i]
lev := e.level
n := e.next
for ; n != nil && len(n.elems) > 1; n = n.next {
if n.level < lev {
lev = n.level
}
n.skipRemove = true
}
for ; o.ordered[i] != n; i++ {
o.ordered[i].level = lev
o.ordered[i].next = n
o.ordered[i+1].prev = e
}
}
}
// clone copies all ordering of es into a new ordering value.
func (o *ordering) clone() *ordering {
o.sort()
oo := ordering{
entryMap: make(map[string]*entry),
}
for _, e := range o.ordered {
ne := &entry{
runes: e.runes,
elems: e.elems,
str: e.str,
decompose: e.decompose,
exclude: e.exclude,
logical: e.logical,
}
oo.insert(ne)
}
oo.sort() // link all ordering.
oo.patchForInsert()
return &oo
}
// front returns the first entry to be indexed.
// It assumes that sort() has been called.
func (o *ordering) front() *entry {
e := o.ordered[0]
if e.prev != nil {
log.Panicf("unexpected first entry: %v", e)
}
// The first entry is always a logical position, which should not be indexed.
e, _ = e.nextIndexed()
return e
}
// sort sorts all ordering based on their collation elements and initializes
// the prev, next, and level fields accordingly.
func (o *ordering) sort() {
sort.Sort(sortedEntries(o.ordered))
l := o.ordered
for i := 1; i < len(l); i++ {
k := i - 1
l[k].next = l[i]
_, l[k].level = compareWeights(l[k].elems, l[i].elems)
l[i].prev = l[k]
}
}
// genColElems generates a collation element array from the runes in str. This
// assumes that all collation elements have already been added to the Builder.
func (o *ordering) genColElems(str string) []rawCE {
elems := []rawCE{}
for _, r := range []rune(str) {
for _, ce := range o.find(string(r)).elems {
if ce.w[0] != 0 || ce.w[1] != 0 || ce.w[2] != 0 {
elems = append(elems, ce)
}
}
}
return elems
}