--- /dev/null
+// 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 collate
+
+import (
+ "sort"
+
+ "golang.org/x/text/internal/colltab"
+ "golang.org/x/text/language"
+ "golang.org/x/text/unicode/norm"
+)
+
+// newCollator creates a new collator with default options configured.
+func newCollator(t colltab.Weighter) *Collator {
+ // Initialize a collator with default options.
+ c := &Collator{
+ options: options{
+ ignore: [colltab.NumLevels]bool{
+ colltab.Quaternary: true,
+ colltab.Identity: true,
+ },
+ f: norm.NFD,
+ t: t,
+ },
+ }
+
+ // TODO: store vt in tags or remove.
+ c.variableTop = t.Top()
+
+ return c
+}
+
+// An Option is used to change the behavior of a Collator. Options override the
+// settings passed through the locale identifier.
+type Option struct {
+ priority int
+ f func(o *options)
+}
+
+type prioritizedOptions []Option
+
+func (p prioritizedOptions) Len() int {
+ return len(p)
+}
+
+func (p prioritizedOptions) Swap(i, j int) {
+ p[i], p[j] = p[j], p[i]
+}
+
+func (p prioritizedOptions) Less(i, j int) bool {
+ return p[i].priority < p[j].priority
+}
+
+type options struct {
+ // ignore specifies which levels to ignore.
+ ignore [colltab.NumLevels]bool
+
+ // caseLevel is true if there is an additional level of case matching
+ // between the secondary and tertiary levels.
+ caseLevel bool
+
+ // backwards specifies the order of sorting at the secondary level.
+ // This option exists predominantly to support reverse sorting of accents in French.
+ backwards bool
+
+ // numeric specifies whether any sequence of decimal digits (category is Nd)
+ // is sorted at a primary level with its numeric value.
+ // For example, "A-21" < "A-123".
+ // This option is set by wrapping the main Weighter with NewNumericWeighter.
+ numeric bool
+
+ // alternate specifies an alternative handling of variables.
+ alternate alternateHandling
+
+ // variableTop is the largest primary value that is considered to be
+ // variable.
+ variableTop uint32
+
+ t colltab.Weighter
+
+ f norm.Form
+}
+
+func (o *options) setOptions(opts []Option) {
+ sort.Sort(prioritizedOptions(opts))
+ for _, x := range opts {
+ x.f(o)
+ }
+}
+
+// OptionsFromTag extracts the BCP47 collation options from the tag and
+// configures a collator accordingly. These options are set before any other
+// option.
+func OptionsFromTag(t language.Tag) Option {
+ return Option{0, func(o *options) {
+ o.setFromTag(t)
+ }}
+}
+
+func (o *options) setFromTag(t language.Tag) {
+ o.caseLevel = ldmlBool(t, o.caseLevel, "kc")
+ o.backwards = ldmlBool(t, o.backwards, "kb")
+ o.numeric = ldmlBool(t, o.numeric, "kn")
+
+ // Extract settings from the BCP47 u extension.
+ switch t.TypeForKey("ks") { // strength
+ case "level1":
+ o.ignore[colltab.Secondary] = true
+ o.ignore[colltab.Tertiary] = true
+ case "level2":
+ o.ignore[colltab.Tertiary] = true
+ case "level3", "":
+ // The default.
+ case "level4":
+ o.ignore[colltab.Quaternary] = false
+ case "identic":
+ o.ignore[colltab.Quaternary] = false
+ o.ignore[colltab.Identity] = false
+ }
+
+ switch t.TypeForKey("ka") {
+ case "shifted":
+ o.alternate = altShifted
+ // The following two types are not official BCP47, but we support them to
+ // give access to this otherwise hidden functionality. The name blanked is
+ // derived from the LDML name blanked and posix reflects the main use of
+ // the shift-trimmed option.
+ case "blanked":
+ o.alternate = altBlanked
+ case "posix":
+ o.alternate = altShiftTrimmed
+ }
+
+ // TODO: caseFirst ("kf"), reorder ("kr"), and maybe variableTop ("vt").
+
+ // Not used:
+ // - normalization ("kk", not necessary for this implementation)
+ // - hiraganaQuatenary ("kh", obsolete)
+}
+
+func ldmlBool(t language.Tag, old bool, key string) bool {
+ switch t.TypeForKey(key) {
+ case "true":
+ return true
+ case "false":
+ return false
+ default:
+ return old
+ }
+}
+
+var (
+ // IgnoreCase sets case-insensitive comparison.
+ IgnoreCase Option = ignoreCase
+ ignoreCase = Option{3, ignoreCaseF}
+
+ // IgnoreDiacritics causes diacritical marks to be ignored. ("o" == "รถ").
+ IgnoreDiacritics Option = ignoreDiacritics
+ ignoreDiacritics = Option{3, ignoreDiacriticsF}
+
+ // IgnoreWidth causes full-width characters to match their half-width
+ // equivalents.
+ IgnoreWidth Option = ignoreWidth
+ ignoreWidth = Option{2, ignoreWidthF}
+
+ // Loose sets the collator to ignore diacritics, case and width.
+ Loose Option = loose
+ loose = Option{4, looseF}
+
+ // Force ordering if strings are equivalent but not equal.
+ Force Option = force
+ force = Option{5, forceF}
+
+ // Numeric specifies that numbers should sort numerically ("2" < "12").
+ Numeric Option = numeric
+ numeric = Option{5, numericF}
+)
+
+func ignoreWidthF(o *options) {
+ o.ignore[colltab.Tertiary] = true
+ o.caseLevel = true
+}
+
+func ignoreDiacriticsF(o *options) {
+ o.ignore[colltab.Secondary] = true
+}
+
+func ignoreCaseF(o *options) {
+ o.ignore[colltab.Tertiary] = true
+ o.caseLevel = false
+}
+
+func looseF(o *options) {
+ ignoreWidthF(o)
+ ignoreDiacriticsF(o)
+ ignoreCaseF(o)
+}
+
+func forceF(o *options) {
+ o.ignore[colltab.Identity] = false
+}
+
+func numericF(o *options) { o.numeric = true }
+
+// Reorder overrides the pre-defined ordering of scripts and character sets.
+func Reorder(s ...string) Option {
+ // TODO: need fractional weights to implement this.
+ panic("TODO: implement")
+}
+
+// TODO: consider making these public again. These options cannot be fully
+// specified in BCP47, so an API interface seems warranted. Still a higher-level
+// interface would be nice (e.g. a POSIX option for enabling altShiftTrimmed)
+
+// alternateHandling identifies the various ways in which variables are handled.
+// A rune with a primary weight lower than the variable top is considered a
+// variable.
+// See https://www.unicode.org/reports/tr10/#Variable_Weighting for details.
+type alternateHandling int
+
+const (
+ // altNonIgnorable turns off special handling of variables.
+ altNonIgnorable alternateHandling = iota
+
+ // altBlanked sets variables and all subsequent primary ignorables to be
+ // ignorable at all levels. This is identical to removing all variables
+ // and subsequent primary ignorables from the input.
+ altBlanked
+
+ // altShifted sets variables to be ignorable for levels one through three and
+ // adds a fourth level based on the values of the ignored levels.
+ altShifted
+
+ // altShiftTrimmed is a slight variant of altShifted that is used to
+ // emulate POSIX.
+ altShiftTrimmed
+)
Code Review / barometer.git / blobdiff