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// Copyright 2016 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 currency
import (
"sort"
"time"
"golang.org/x/text/language"
)
// QueryIter represents a set of Units. The default set includes all Units that
// are currently in use as legal tender in any Region.
type QueryIter interface {
// Next returns true if there is a next element available.
// It must be called before any of the other methods are called.
Next() bool
// Unit returns the unit of the current iteration.
Unit() Unit
// Region returns the Region for the current iteration.
Region() language.Region
// From returns the date from which the unit was used in the region.
// It returns false if this date is unknown.
From() (time.Time, bool)
// To returns the date up till which the unit was used in the region.
// It returns false if this date is unknown or if the unit is still in use.
To() (time.Time, bool)
// IsTender reports whether the unit is a legal tender in the region during
// the specified date range.
IsTender() bool
}
// Query represents a set of Units. The default set includes all Units that are
// currently in use as legal tender in any Region.
func Query(options ...QueryOption) QueryIter {
it := &iter{
end: len(regionData),
date: 0xFFFFFFFF,
}
for _, fn := range options {
fn(it)
}
return it
}
// NonTender returns a new query that also includes matching Units that are not
// legal tender.
var NonTender QueryOption = nonTender
func nonTender(i *iter) {
i.nonTender = true
}
// Historical selects the units for all dates.
var Historical QueryOption = historical
func historical(i *iter) {
i.date = hist
}
// A QueryOption can be used to change the set of unit information returned by
// a query.
type QueryOption func(*iter)
// Date queries the units that were in use at the given point in history.
func Date(t time.Time) QueryOption {
d := toDate(t)
return func(i *iter) {
i.date = d
}
}
// Region limits the query to only return entries for the given region.
func Region(r language.Region) QueryOption {
p, end := len(regionData), len(regionData)
x := regionToCode(r)
i := sort.Search(len(regionData), func(i int) bool {
return regionData[i].region >= x
})
if i < len(regionData) && regionData[i].region == x {
p = i
for i++; i < len(regionData) && regionData[i].region == x; i++ {
}
end = i
}
return func(i *iter) {
i.p, i.end = p, end
}
}
const (
hist = 0x00
now = 0xFFFFFFFF
)
type iter struct {
*regionInfo
p, end int
date uint32
nonTender bool
}
func (i *iter) Next() bool {
for ; i.p < i.end; i.p++ {
i.regionInfo = ®ionData[i.p]
if !i.nonTender && !i.IsTender() {
continue
}
if i.date == hist || (i.from <= i.date && (i.to == 0 || i.date <= i.to)) {
i.p++
return true
}
}
return false
}
func (r *regionInfo) Region() language.Region {
// TODO: this could be much faster.
var buf [2]byte
buf[0] = uint8(r.region >> 8)
buf[1] = uint8(r.region)
return language.MustParseRegion(string(buf[:]))
}
func (r *regionInfo) Unit() Unit {
return Unit{r.code &^ nonTenderBit}
}
func (r *regionInfo) IsTender() bool {
return r.code&nonTenderBit == 0
}
func (r *regionInfo) From() (time.Time, bool) {
if r.from == 0 {
return time.Time{}, false
}
return fromDate(r.from), true
}
func (r *regionInfo) To() (time.Time, bool) {
if r.to == 0 {
return time.Time{}, false
}
return fromDate(r.to), true
}
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