Update vendor yaegashi/msgraph.go to v0.1.2 (2)

6 files changed, 1122 insertions, 0 deletions

diff --git a/vendor/github.com/rickb777/date/LICENSE b/vendor/github.com/rickb777/date/LICENSE
new file mode 100644
index 00000000..b0280bc6
--- /dev/null
+++ b/vendor/github.com/rickb777/date/LICENSE
@@ -0,0 +1,27 @@
+Copyright (c) 2015 The Go Authors & Rick Beton. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/vendor/github.com/rickb777/date/period/doc.go b/vendor/github.com/rickb777/date/period/doc.go
new file mode 100644
index 00000000..c8a57b4a
--- /dev/null
+++ b/vendor/github.com/rickb777/date/period/doc.go
@@ -0,0 +1,44 @@
+// Copyright 2016 Rick Beton. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package period provides functionality for periods of time using ISO-8601 conventions.
+// This deals with years, months, weeks/days, hours, minutes and seconds.
+//
+// Because of the vagaries of calendar systems, the meaning of year lengths, month lengths
+// and even day lengths depends on context. So a period is not necessarily a fixed duration
+// of time in terms of seconds.
+//
+// See https://en.wikipedia.org/wiki/ISO_8601#Durations
+//
+// Example representations:
+//
+// * "P2Y" is two years;
+//
+// * "P6M" is six months;
+//
+// * "P4D" is four days;
+//
+// * "P1W" is one week (seven days);
+//
+// * "PT3H" is three hours.
+//
+// * "PT20M" is twenty minutes.
+//
+// * "PT30S" is thirty seconds.
+//
+// These can be combined, for example:
+//
+// * "P3Y6M4W1D" is three years, 6 months, 4 weeks and one day.
+//
+// * "P2DT12H" is 2 days and 12 hours.
+//
+// Also, decimal fractions are supported to one decimal place. To comply with
+// the standard, only the last non-zero component is allowed to have a fraction.
+// For example
+//
+// * "P2.5Y" is 2.5 years.
+//
+// * "PT12M7.5S" is 12 minutes and 7.5 seconds.
+//
+package period
diff --git a/vendor/github.com/rickb777/date/period/format.go b/vendor/github.com/rickb777/date/period/format.go
new file mode 100644
index 00000000..32cb6a83
--- /dev/null
+++ b/vendor/github.com/rickb777/date/period/format.go
@@ -0,0 +1,128 @@
+// Copyright 2015 Rick Beton. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package period
+
+import (
+	"bytes"
+	"fmt"
+	"strings"
+
+	"github.com/rickb777/plural"
+)
+
+// Format converts the period to human-readable form using the default localisation.
+func (period Period) Format() string {
+	return period.FormatWithPeriodNames(PeriodYearNames, PeriodMonthNames, PeriodWeekNames, PeriodDayNames, PeriodHourNames, PeriodMinuteNames, PeriodSecondNames)
+}
+
+// FormatWithPeriodNames converts the period to human-readable form in a localisable way.
+func (period Period) FormatWithPeriodNames(yearNames, monthNames, weekNames, dayNames, hourNames, minNames, secNames plural.Plurals) string {
+	period = period.Abs()
+
+	parts := make([]string, 0)
+	parts = appendNonBlank(parts, yearNames.FormatFloat(absFloat10(period.years)))
+	parts = appendNonBlank(parts, monthNames.FormatFloat(absFloat10(period.months)))
+
+	if period.days > 0 || (period.IsZero()) {
+		if len(weekNames) > 0 {
+			weeks := period.days / 70
+			mdays := period.days % 70
+			//fmt.Printf("%v %#v - %d %d\n", period, period, weeks, mdays)
+			if weeks > 0 {
+				parts = appendNonBlank(parts, weekNames.FormatInt(int(weeks)))
+			}
+			if mdays > 0 || weeks == 0 {
+				parts = appendNonBlank(parts, dayNames.FormatFloat(absFloat10(mdays)))
+			}
+		} else {
+			parts = appendNonBlank(parts, dayNames.FormatFloat(absFloat10(period.days)))
+		}
+	}
+	parts = appendNonBlank(parts, hourNames.FormatFloat(absFloat10(period.hours)))
+	parts = appendNonBlank(parts, minNames.FormatFloat(absFloat10(period.minutes)))
+	parts = appendNonBlank(parts, secNames.FormatFloat(absFloat10(period.seconds)))
+
+	return strings.Join(parts, ", ")
+}
+
+func appendNonBlank(parts []string, s string) []string {
+	if s == "" {
+		return parts
+	}
+	return append(parts, s)
+}
+
+// PeriodDayNames provides the English default format names for the days part of the period.
+// This is a sequence of plurals where the first match is used, otherwise the last one is used.
+// The last one must include a "%v" placeholder for the number.
+var PeriodDayNames = plural.FromZero("%v days", "%v day", "%v days")
+
+// PeriodWeekNames is as for PeriodDayNames but for weeks.
+var PeriodWeekNames = plural.FromZero("", "%v week", "%v weeks")
+
+// PeriodMonthNames is as for PeriodDayNames but for months.
+var PeriodMonthNames = plural.FromZero("", "%v month", "%v months")
+
+// PeriodYearNames is as for PeriodDayNames but for years.
+var PeriodYearNames = plural.FromZero("", "%v year", "%v years")
+
+// PeriodHourNames is as for PeriodDayNames but for hours.
+var PeriodHourNames = plural.FromZero("", "%v hour", "%v hours")
+
+// PeriodMinuteNames is as for PeriodDayNames but for minutes.
+var PeriodMinuteNames = plural.FromZero("", "%v minute", "%v minutes")
+
+// PeriodSecondNames is as for PeriodDayNames but for seconds.
+var PeriodSecondNames = plural.FromZero("", "%v second", "%v seconds")
+
+// String converts the period to ISO-8601 form.
+func (period Period) String() string {
+	if period.IsZero() {
+		return "P0D"
+	}
+
+	buf := &bytes.Buffer{}
+	if period.Sign() < 0 {
+		buf.WriteByte('-')
+	}
+
+	buf.WriteByte('P')
+
+	if period.years != 0 {
+		fmt.Fprintf(buf, "%gY", absFloat10(period.years))
+	}
+	if period.months != 0 {
+		fmt.Fprintf(buf, "%gM", absFloat10(period.months))
+	}
+	if period.days != 0 {
+		if period.days%70 == 0 {
+			fmt.Fprintf(buf, "%gW", absFloat10(period.days/7))
+		} else {
+			fmt.Fprintf(buf, "%gD", absFloat10(period.days))
+		}
+	}
+	if period.hours != 0 || period.minutes != 0 || period.seconds != 0 {
+		buf.WriteByte('T')
+	}
+	if period.hours != 0 {
+		fmt.Fprintf(buf, "%gH", absFloat10(period.hours))
+	}
+	if period.minutes != 0 {
+		fmt.Fprintf(buf, "%gM", absFloat10(period.minutes))
+	}
+	if period.seconds != 0 {
+		fmt.Fprintf(buf, "%gS", absFloat10(period.seconds))
+	}
+
+	return buf.String()
+}
+
+func absFloat10(v int16) float32 {
+	f := float32(v) / 10
+	if v < 0 {
+		return -f
+	}
+	return f
+}
diff --git a/vendor/github.com/rickb777/date/period/marshal.go b/vendor/github.com/rickb777/date/period/marshal.go
new file mode 100644
index 00000000..c87ad5f6
--- /dev/null
+++ b/vendor/github.com/rickb777/date/period/marshal.go
@@ -0,0 +1,32 @@
+// 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 period
+
+// MarshalBinary implements the encoding.BinaryMarshaler interface.
+// This also provides support for gob encoding.
+func (period Period) MarshalBinary() ([]byte, error) {
+	// binary method would take more space in many cases, so we simply use text
+	return period.MarshalText()
+}
+
+// UnmarshalBinary implements the encoding.BinaryUnmarshaler interface.
+// This also provides support for gob encoding.
+func (period *Period) UnmarshalBinary(data []byte) error {
+	return period.UnmarshalText(data)
+}
+
+// MarshalText implements the encoding.TextMarshaler interface for Periods.
+func (period Period) MarshalText() ([]byte, error) {
+	return []byte(period.String()), nil
+}
+
+// UnmarshalText implements the encoding.TextUnmarshaler interface for Periods.
+func (period *Period) UnmarshalText(data []byte) (err error) {
+	u, err := Parse(string(data))
+	if err == nil {
+		*period = u
+	}
+	return err
+}
diff --git a/vendor/github.com/rickb777/date/period/parse.go b/vendor/github.com/rickb777/date/period/parse.go
new file mode 100644
index 00000000..30b3a693
--- /dev/null
+++ b/vendor/github.com/rickb777/date/period/parse.go
@@ -0,0 +1,152 @@
+// Copyright 2015 Rick Beton. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package period
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+// MustParse is as per Parse except that it panics if the string cannot be parsed.
+// This is intended for setup code; don't use it for user inputs.
+func MustParse(value string) Period {
+	d, err := Parse(value)
+	if err != nil {
+		panic(err)
+	}
+	return d
+}
+
+// Parse parses strings that specify periods using ISO-8601 rules.
+//
+// In addition, a plus or minus sign can precede the period, e.g. "-P10D"
+//
+// The value is normalised, e.g. multiple of 12 months become years so "P24M"
+// is the same as "P2Y". However, this is done without loss of precision, so
+// for example whole numbers of days do not contribute to the months tally
+// because the number of days per month is variable.
+//
+// The zero value can be represented in several ways: all of the following
+// are equivalent: "P0Y", "P0M", "P0W", "P0D", "PT0H", PT0M", PT0S", and "P0".
+// The canonical zero is "P0D".
+func Parse(period string) (Period, error) {
+	if period == "" {
+		return Period{}, fmt.Errorf("cannot parse a blank string as a period")
+	}
+
+	if period == "P0" {
+		return Period{}, nil
+	}
+
+	result := period64{}
+	pcopy := period
+	if pcopy[0] == '-' {
+		result.neg = true
+		pcopy = pcopy[1:]
+	} else if pcopy[0] == '+' {
+		pcopy = pcopy[1:]
+	}
+
+	if pcopy[0] != 'P' {
+		return Period{}, fmt.Errorf("expected 'P' period mark at the start: %s", period)
+	}
+	pcopy = pcopy[1:]
+
+	st := parseState{period, pcopy, false, nil}
+	t := strings.IndexByte(pcopy, 'T')
+	if t >= 0 {
+		st.pcopy = pcopy[t+1:]
+
+		result.hours, st = parseField(st, 'H')
+		if st.err != nil {
+			return Period{}, fmt.Errorf("expected a number before the 'H' marker: %s", period)
+		}
+
+		result.minutes, st = parseField(st, 'M')
+		if st.err != nil {
+			return Period{}, fmt.Errorf("expected a number before the 'M' marker: %s", period)
+		}
+
+		result.seconds, st = parseField(st, 'S')
+		if st.err != nil {
+			return Period{}, fmt.Errorf("expected a number before the 'S' marker: %s", period)
+		}
+
+		st.pcopy = pcopy[:t]
+	}
+
+	result.years, st = parseField(st, 'Y')
+	if st.err != nil {
+		return Period{}, fmt.Errorf("expected a number before the 'Y' marker: %s", period)
+	}
+
+	result.months, st = parseField(st, 'M')
+	if st.err != nil {
+		return Period{}, fmt.Errorf("expected a number before the 'M' marker: %s", period)
+	}
+
+	weeks, st := parseField(st, 'W')
+	if st.err != nil {
+		return Period{}, fmt.Errorf("expected a number before the 'W' marker: %s", period)
+	}
+
+	days, st := parseField(st, 'D')
+	if st.err != nil {
+		return Period{}, fmt.Errorf("expected a number before the 'D' marker: %s", period)
+	}
+
+	result.days = weeks*7 + days
+	//fmt.Printf("%#v\n", st)
+
+	if !st.ok {
+		return Period{}, fmt.Errorf("expected 'Y', 'M', 'W', 'D', 'H', 'M', or 'S' marker: %s", period)
+	}
+
+	return result.normalise64(true).toPeriod(), nil
+}
+
+type parseState struct {
+	period, pcopy string
+	ok            bool
+	err           error
+}
+
+func parseField(st parseState, mark byte) (int64, parseState) {
+	//fmt.Printf("%c %#v\n", mark, st)
+	r := int64(0)
+	m := strings.IndexByte(st.pcopy, mark)
+	if m > 0 {
+		r, st.err = parseDecimalFixedPoint(st.pcopy[:m], st.period)
+		if st.err != nil {
+			return 0, st
+		}
+		st.pcopy = st.pcopy[m+1:]
+		st.ok = true
+	}
+	return r, st
+}
+
+// Fixed-point three decimal places
+func parseDecimalFixedPoint(s, original string) (int64, error) {
+	//was := s
+	dec := strings.IndexByte(s, '.')
+	if dec < 0 {
+		dec = strings.IndexByte(s, ',')
+	}
+
+	if dec >= 0 {
+		dp := len(s) - dec
+		if dp > 1 {
+			s = s[:dec] + s[dec+1:dec+2]
+		} else {
+			s = s[:dec] + s[dec+1:] + "0"
+		}
+	} else {
+		s = s + "0"
+	}
+
+	return strconv.ParseInt(s, 10, 64)
+}
diff --git a/vendor/github.com/rickb777/date/period/period.go b/vendor/github.com/rickb777/date/period/period.go
new file mode 100644
index 00000000..604dbfc1
--- /dev/null
+++ b/vendor/github.com/rickb777/date/period/period.go
@@ -0,0 +1,739 @@
+// Copyright 2015 Rick Beton. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package period
+
+import (
+	"fmt"
+	"time"
+)
+
+const daysPerYearE4 int64 = 3652425   // 365.2425 days by the Gregorian rule
+const daysPerMonthE4 int64 = 304375   // 30.4375 days per month
+const daysPerMonthE6 int64 = 30436875 // 30.436875 days per month
+
+const oneE4 int64 = 10000
+const oneE5 int64 = 100000
+const oneE6 int64 = 1000000
+const oneE7 int64 = 10000000
+
+const hundredMs = 100 * time.Millisecond
+
+// reminder: int64 overflow is after 9,223,372,036,854,775,807 (math.MaxInt64)
+
+// Period holds a period of time and provides conversion to/from ISO-8601 representations.
+// Therefore there are six fields: years, months, days, hours, minutes, and seconds.
+//
+// In the ISO representation, decimal fractions are supported, although only the last non-zero
+// component is allowed to have a fraction according to the Standard. For example "P2.5Y"
+// is 2.5 years.
+//
+// However, in this implementation, the precision is limited to one decimal place only, by
+// means of integers with fixed point arithmetic. (This avoids using float32 in the struct,
+// so there are no problems testing equality using ==.)
+//
+// The implementation limits the range of possible values to ± 2^16 / 10 in each field.
+// Note in particular that the range of years is limited to approximately ± 3276.
+//
+// The concept of weeks exists in string representations of periods, but otherwise weeks
+// are unimportant. The period contains a number of days from which the number of weeks can
+// be calculated when needed.
+//
+// Note that although fractional weeks can be parsed, they will never be returned via String().
+// This is because the number of weeks is always inferred from the number of days.
+//
+type Period struct {
+	years, months, days, hours, minutes, seconds int16
+}
+
+// NewYMD creates a simple period without any fractional parts. The fields are initialised verbatim
+// without any normalisation; e.g. 12 months will not become 1 year. Use the Normalise method if you
+// need to.
+//
+// All the parameters must have the same sign (otherwise a panic occurs).
+func NewYMD(years, months, days int) Period {
+	return New(years, months, days, 0, 0, 0)
+}
+
+// NewHMS creates a simple period without any fractional parts. The fields are initialised verbatim
+// without any normalisation; e.g. 120 seconds will not become 2 minutes. Use the Normalise method
+// if you need to.
+//
+// All the parameters must have the same sign (otherwise a panic occurs).
+func NewHMS(hours, minutes, seconds int) Period {
+	return New(0, 0, 0, hours, minutes, seconds)
+}
+
+// New creates a simple period without any fractional parts. The fields are initialised verbatim
+// without any normalisation; e.g. 120 seconds will not become 2 minutes. Use the Normalise method
+// if you need to.
+//
+// All the parameters must have the same sign (otherwise a panic occurs).
+func New(years, months, days, hours, minutes, seconds int) Period {
+	if (years >= 0 && months >= 0 && days >= 0 && hours >= 0 && minutes >= 0 && seconds >= 0) ||
+		(years <= 0 && months <= 0 && days <= 0 && hours <= 0 && minutes <= 0 && seconds <= 0) {
+		return Period{
+			int16(years) * 10, int16(months) * 10, int16(days) * 10,
+			int16(hours) * 10, int16(minutes) * 10, int16(seconds) * 10,
+		}
+	}
+	panic(fmt.Sprintf("Periods must have homogeneous signs; got P%dY%dM%dDT%dH%dM%dS",
+		years, months, days, hours, minutes, seconds))
+}
+
+// TODO NewFloat
+
+// NewOf converts a time duration to a Period, and also indicates whether the conversion is precise.
+// Any time duration that spans more than ± 3276 hours will be approximated by assuming that there
+// are 24 hours per day, 30.4375 per month and 365.2425 days per year.
+func NewOf(duration time.Duration) (p Period, precise bool) {
+	var sign int16 = 1
+	d := duration
+	if duration < 0 {
+		sign = -1
+		d = -duration
+	}
+
+	sign10 := sign * 10
+
+	totalHours := int64(d / time.Hour)
+
+	// check for 16-bit overflow - occurs near the 4.5 month mark
+	if totalHours < 3277 {
+		// simple HMS case
+		minutes := d % time.Hour / time.Minute
+		seconds := d % time.Minute / hundredMs
+		return Period{0, 0, 0, sign10 * int16(totalHours), sign10 * int16(minutes), sign * int16(seconds)}, true
+	}
+
+	totalDays := totalHours / 24 // ignoring daylight savings adjustments
+
+	if totalDays < 3277 {
+		hours := totalHours - totalDays*24
+		minutes := d % time.Hour / time.Minute
+		seconds := d % time.Minute / hundredMs
+		return Period{0, 0, sign10 * int16(totalDays), sign10 * int16(hours), sign10 * int16(minutes), sign * int16(seconds)}, false
+	}
+
+	// TODO it is uncertain whether this is too imprecise and should be improved
+	years := (oneE4 * totalDays) / daysPerYearE4
+	months := ((oneE4 * totalDays) / daysPerMonthE4) - (12 * years)
+	hours := totalHours - totalDays*24
+	totalDays = ((totalDays * oneE4) - (daysPerMonthE4 * months) - (daysPerYearE4 * years)) / oneE4
+	return Period{sign10 * int16(years), sign10 * int16(months), sign10 * int16(totalDays), sign10 * int16(hours), 0, 0}, false
+}
+
+// Between converts the span between two times to a period. Based on the Gregorian conversion
+// algorithms of `time.Time`, the resultant period is precise.
+//
+// The result is not normalised; for time differences less than 3276 days, it will contain zero in the
+// years and months fields but the number of days may be up to 3275; this reduces errors arising from
+// the variable lengths of months. For larger time differences, greater than 3276 days, the months and
+// years fields are used as well.
+//
+// Remember that the resultant period does not retain any knowledge of the calendar, so any subsequent
+// computations applied to the period can only be precise if they concern either the date (year, month,
+// day) part, or the clock (hour, minute, second) part, but not both.
+func Between(t1, t2 time.Time) (p Period) {
+	if t1.Location() != t2.Location() {
+		t2 = t2.In(t1.Location())
+	}
+
+	sign := 1
+	if t2.Before(t1) {
+		t1, t2, sign = t2, t1, -1
+	}
+
+	year, month, day, hour, min, sec, hundredth := daysDiff(t1, t2)
+
+	if sign < 0 {
+		p = New(-year, -month, -day, -hour, -min, -sec)
+		p.seconds -= int16(hundredth)
+	} else {
+		p = New(year, month, day, hour, min, sec)
+		p.seconds += int16(hundredth)
+	}
+	return
+}
+
+func daysDiff(t1, t2 time.Time) (year, month, day, hour, min, sec, hundredth int) {
+	duration := t2.Sub(t1)
+
+	hh1, mm1, ss1 := t1.Clock()
+	hh2, mm2, ss2 := t2.Clock()
+
+	day = int(duration / (24 * time.Hour))
+
+	hour = int(hh2 - hh1)
+	min = int(mm2 - mm1)
+	sec = int(ss2 - ss1)
+	hundredth = (t2.Nanosecond() - t1.Nanosecond()) / 100000000
+
+	// Normalize negative values
+	if sec < 0 {
+		sec += 60
+		min--
+	}
+
+	if min < 0 {
+		min += 60
+		hour--
+	}
+
+	if hour < 0 {
+		hour += 24
+		// no need to reduce day - it's calculated differently.
+	}
+
+	// test 16bit storage limit (with 1 fixed decimal place)
+	if day > 3276 {
+		y1, m1, d1 := t1.Date()
+		y2, m2, d2 := t2.Date()
+		year = y2 - y1
+		month = int(m2 - m1)
+		day = d2 - d1
+	}
+
+	return
+}
+
+// IsZero returns true if applied to a zero-length period.
+func (period Period) IsZero() bool {
+	return period == Period{}
+}
+
+// IsPositive returns true if any field is greater than zero. By design, this also implies that
+// all the other fields are greater than or equal to zero.
+func (period Period) IsPositive() bool {
+	return period.years > 0 || period.months > 0 || period.days > 0 ||
+		period.hours > 0 || period.minutes > 0 || period.seconds > 0
+}
+
+// IsNegative returns true if any field is negative. By design, this also implies that
+// all the other fields are negative or zero.
+func (period Period) IsNegative() bool {
+	return period.years < 0 || period.months < 0 || period.days < 0 ||
+		period.hours < 0 || period.minutes < 0 || period.seconds < 0
+}
+
+// Sign returns +1 for positive periods and -1 for negative periods. If the period is zero, it returns zero.
+func (period Period) Sign() int {
+	if period.IsZero() {
+		return 0
+	}
+	if period.IsNegative() {
+		return -1
+	}
+	return 1
+}
+
+// OnlyYMD returns a new Period with only the year, month and day fields. The hour,
+// minute and second fields are zeroed.
+func (period Period) OnlyYMD() Period {
+	return Period{period.years, period.months, period.days, 0, 0, 0}
+}
+
+// OnlyHMS returns a new Period with only the hour, minute and second fields. The year,
+// month and day fields are zeroed.
+func (period Period) OnlyHMS() Period {
+	return Period{0, 0, 0, period.hours, period.minutes, period.seconds}
+}
+
+// Abs converts a negative period to a positive one.
+func (period Period) Abs() Period {
+	return Period{absInt16(period.years), absInt16(period.months), absInt16(period.days),
+		absInt16(period.hours), absInt16(period.minutes), absInt16(period.seconds)}
+}
+
+func absInt16(v int16) int16 {
+	if v < 0 {
+		return -v
+	}
+	return v
+}
+
+// Negate changes the sign of the period.
+func (period Period) Negate() Period {
+	return Period{-period.years, -period.months, -period.days, -period.hours, -period.minutes, -period.seconds}
+}
+
+// Add adds two periods together. Use this method along with Negate in order to subtract periods.
+//
+// The result is not normalised and may overflow arithmetically (to make this unlikely, use Normalise on
+// the inputs before adding them).
+func (period Period) Add(that Period) Period {
+	return Period{
+		period.years + that.years,
+		period.months + that.months,
+		period.days + that.days,
+		period.hours + that.hours,
+		period.minutes + that.minutes,
+		period.seconds + that.seconds,
+	}
+}
+
+// Scale a period by a multiplication factor. Obviously, this can both enlarge and shrink it,
+// and change the sign if negative. The result is normalised.
+//
+// Bear in mind that the internal representation is limited by fixed-point arithmetic with one
+// decimal place; each field is only int16.
+//
+// Known issue: scaling by a large reduction factor (i.e. much less than one) doesn't work properly.
+func (period Period) Scale(factor float32) Period {
+
+	if -0.5 < factor && factor < 0.5 {
+		d, pr1 := period.Duration()
+		mul := float64(d) * float64(factor)
+		p2, pr2 := NewOf(time.Duration(mul))
+		return p2.Normalise(pr1 && pr2)
+	}
+
+	y := int64(float32(period.years) * factor)
+	m := int64(float32(period.months) * factor)
+	d := int64(float32(period.days) * factor)
+	hh := int64(float32(period.hours) * factor)
+	mm := int64(float32(period.minutes) * factor)
+	ss := int64(float32(period.seconds) * factor)
+
+	return (&period64{y, m, d, hh, mm, ss, false}).normalise64(true).toPeriod()
+}
+
+// Years gets the whole number of years in the period.
+// The result is the number of years and does not include any other field.
+func (period Period) Years() int {
+	return int(period.YearsFloat())
+}
+
+// YearsFloat gets the number of years in the period, including a fraction if any is present.
+// The result is the number of years and does not include any other field.
+func (period Period) YearsFloat() float32 {
+	return float32(period.years) / 10
+}
+
+// Months gets the whole number of months in the period.
+// The result is the number of months and does not include any other field.
+//
+// Note that after normalisation, whole multiple of 12 months are added to
+// the number of years, so the number of months will be reduced correspondingly.
+func (period Period) Months() int {
+	return int(period.MonthsFloat())
+}
+
+// MonthsFloat gets the number of months in the period.
+// The result is the number of months and does not include any other field.
+//
+// Note that after normalisation, whole multiple of 12 months are added to
+// the number of years, so the number of months will be reduced correspondingly.
+func (period Period) MonthsFloat() float32 {
+	return float32(period.months) / 10
+}
+
+// Days gets the whole number of days in the period. This includes the implied
+// number of weeks but does not include any other field.
+func (period Period) Days() int {
+	return int(period.DaysFloat())
+}
+
+// DaysFloat gets the number of days in the period. This includes the implied
+// number of weeks but does not include any other field.
+func (period Period) DaysFloat() float32 {
+	return float32(period.days) / 10
+}
+
+// Weeks calculates the number of whole weeks from the number of days. If the result
+// would contain a fraction, it is truncated.
+// The result is the number of weeks and does not include any other field.
+//
+// Note that weeks are synthetic: they are internally represented using days.
+// See ModuloDays(), which returns the number of days excluding whole weeks.
+func (period Period) Weeks() int {
+	return int(period.days) / 70
+}
+
+// WeeksFloat calculates the number of weeks from the number of days.
+// The result is the number of weeks and does not include any other field.
+func (period Period) WeeksFloat() float32 {
+	return float32(period.days) / 70
+}
+
+// ModuloDays calculates the whole number of days remaining after the whole number of weeks
+// has been excluded.
+func (period Period) ModuloDays() int {
+	days := absInt16(period.days) % 70
+	f := int(days / 10)
+	if period.days < 0 {
+		return -f
+	}
+	return f
+}
+
+// Hours gets the whole number of hours in the period.
+// The result is the number of hours and does not include any other field.
+func (period Period) Hours() int {
+	return int(period.HoursFloat())
+}
+
+// HoursFloat gets the number of hours in the period.
+// The result is the number of hours and does not include any other field.
+func (period Period) HoursFloat() float32 {
+	return float32(period.hours) / 10
+}
+
+// Minutes gets the whole number of minutes in the period.
+// The result is the number of minutes and does not include any other field.
+//
+// Note that after normalisation, whole multiple of 60 minutes are added to
+// the number of hours, so the number of minutes will be reduced correspondingly.
+func (period Period) Minutes() int {
+	return int(period.MinutesFloat())
+}
+
+// MinutesFloat gets the number of minutes in the period.
+// The result is the number of minutes and does not include any other field.
+//
+// Note that after normalisation, whole multiple of 60 minutes are added to
+// the number of hours, so the number of minutes will be reduced correspondingly.
+func (period Period) MinutesFloat() float32 {
+	return float32(period.minutes) / 10
+}
+
+// Seconds gets the whole number of seconds in the period.
+// The result is the number of seconds and does not include any other field.
+//
+// Note that after normalisation, whole multiple of 60 seconds are added to
+// the number of minutes, so the number of seconds will be reduced correspondingly.
+func (period Period) Seconds() int {
+	return int(period.SecondsFloat())
+}
+
+// SecondsFloat gets the number of seconds in the period.
+// The result is the number of seconds and does not include any other field.
+//
+// Note that after normalisation, whole multiple of 60 seconds are added to
+// the number of minutes, so the number of seconds will be reduced correspondingly.
+func (period Period) SecondsFloat() float32 {
+	return float32(period.seconds) / 10
+}
+
+// AddTo adds the period to a time, returning the result.
+// A flag is also returned that is true when the conversion was precise and false otherwise.
+//
+// When the period specifies hours, minutes and seconds only, the result is precise.
+// Also, when the period specifies whole years, months and days (i.e. without fractions), the
+// result is precise. However, when years, months or days contains fractions, the result
+// is only an approximation (it assumes that all days are 24 hours and every year is 365.2425 days).
+func (period Period) AddTo(t time.Time) (time.Time, bool) {
+	wholeYears := (period.years % 10) == 0
+	wholeMonths := (period.months % 10) == 0
+	wholeDays := (period.days % 10) == 0
+
+	if wholeYears && wholeMonths && wholeDays {
+		// in this case, time.AddDate provides an exact solution
+		stE3 := totalSecondsE3(period)
+		t1 := t.AddDate(int(period.years/10), int(period.months/10), int(period.days/10))
+		return t1.Add(stE3 * time.Millisecond), true
+	}
+
+	d, precise := period.Duration()
+	return t.Add(d), precise
+}
+
+// DurationApprox converts a period to the equivalent duration in nanoseconds.
+// When the period specifies hours, minutes and seconds only, the result is precise.
+// however, when the period specifies years, months and days, it is impossible to be precise
+// because the result may depend on knowing date and timezone information, so the duration
+// is estimated on the basis of a year being 365.2425 days and a month being
+// 1/12 of a that; days are all assumed to be 24 hours long.
+func (period Period) DurationApprox() time.Duration {
+	d, _ := period.Duration()
+	return d
+}
+
+// Duration converts a period to the equivalent duration in nanoseconds.
+// A flag is also returned that is true when the conversion was precise and false otherwise.
+//
+// When the period specifies hours, minutes and seconds only, the result is precise.
+// however, when the period specifies years, months and days, it is impossible to be precise
+// because the result may depend on knowing date and timezone information, so the duration
+// is estimated on the basis of a year being 365.2425 days and a month being
+// 1/12 of a that; days are all assumed to be 24 hours long.
+func (period Period) Duration() (time.Duration, bool) {
+	// remember that the fields are all fixed-point 1E1
+	tdE6 := time.Duration(totalDaysApproxE7(period) * 8640)
+	stE3 := totalSecondsE3(period)
+	return tdE6*time.Microsecond + stE3*time.Millisecond, tdE6 == 0
+}
+
+func totalSecondsE3(period Period) time.Duration {
+	// remember that the fields are all fixed-point 1E1
+	// and these are divided by 1E1
+	hhE3 := time.Duration(period.hours) * 360000
+	mmE3 := time.Duration(period.minutes) * 6000
+	ssE3 := time.Duration(period.seconds) * 100
+	return hhE3 + mmE3 + ssE3
+}
+
+func totalDaysApproxE7(period Period) int64 {
+	// remember that the fields are all fixed-point 1E1
+	ydE6 := int64(period.years) * (daysPerYearE4 * 100)
+	mdE6 := int64(period.months) * daysPerMonthE6
+	ddE6 := int64(period.days) * oneE6
+	return ydE6 + mdE6 + ddE6
+}
+
+// TotalDaysApprox gets the approximate total number of days in the period. The approximation assumes
+// a year is 365.2425 days and a month is 1/12 of that. Whole multiples of 24 hours are also included
+// in the calculation.
+func (period Period) TotalDaysApprox() int {
+	pn := period.Normalise(false)
+	tdE6 := totalDaysApproxE7(pn)
+	hE6 := (int64(pn.hours) * oneE6) / 24
+	return int((tdE6 + hE6) / oneE7)
+}
+
+// TotalMonthsApprox gets the approximate total number of months in the period. The days component
+// is included by approximation, assuming a year is 365.2425 days and a month is 1/12 of that.
+// Whole multiples of 24 hours are also included in the calculation.
+func (period Period) TotalMonthsApprox() int {
+	pn := period.Normalise(false)
+	mE1 := int64(pn.years)*12 + int64(pn.months)
+	hE1 := int64(pn.hours) / 24
+	dE1 := ((int64(pn.days) + hE1) * oneE6) / daysPerMonthE6
+	return int((mE1 + dE1) / 10)
+}
+
+// Normalise attempts to simplify the fields. It operates in either precise or imprecise mode.
+//
+// Because the number of hours per day is imprecise (due to daylight savings etc), and because
+// the number of days per month is variable in the Gregorian calendar, there is a reluctance
+// to transfer time too or from the days element. To give control over this, there are two modes.
+//
+// In precise mode:
+// Multiples of 60 seconds become minutes.
+// Multiples of 60 minutes become hours.
+// Multiples of 12 months become years.
+//
+// Additionally, in imprecise mode:
+// Multiples of 24 hours become days.
+// Multiples of approx. 30.4 days become months.
+//
+// Note that leap seconds are disregarded: every minute is assumed to have 60 seconds.
+func (period Period) Normalise(precise bool) Period {
+	const limit = 32670 - (32670 / 60)
+
+	// can we use a quicker algorithm for HHMMSS with int16 arithmetic?
+	if period.years == 0 && period.months == 0 &&
+		(!precise || period.days == 0) &&
+		period.hours > -limit && period.hours < limit {
+
+		return period.normaliseHHMMSS(precise)
+	}
+
+	// can we use a quicker algorithm for YYMM with int16 arithmetic?
+	if (period.years != 0 || period.months != 0) && //period.months%10 == 0 &&
+		period.days == 0 && period.hours == 0 && period.minutes == 0 && period.seconds == 0 {
+
+		return period.normaliseYYMM()
+	}
+
+	// do things the no-nonsense way using int64 arithmetic
+	return period.toPeriod64().normalise64(precise).toPeriod()
+}
+
+func (period Period) normaliseHHMMSS(precise bool) Period {
+	s := period.Sign()
+	ap := period.Abs()
+
+	// remember that the fields are all fixed-point 1E1
+	ap.minutes += (ap.seconds / 600) * 10
+	ap.seconds = ap.seconds % 600
+
+	ap.hours += (ap.minutes / 600) * 10
+	ap.minutes = ap.minutes % 600
+
+	// up to 36 hours stays as hours
+	if !precise && ap.hours > 360 {
+		ap.days += (ap.hours / 240) * 10
+		ap.hours = ap.hours % 240
+	}
+
+	d10 := ap.days % 10
+	if d10 != 0 && (ap.hours != 0 || ap.minutes != 0 || ap.seconds != 0) {
+		ap.hours += d10 * 24
+		ap.days -= d10
+	}
+
+	hh10 := ap.hours % 10
+	if hh10 != 0 {
+		ap.minutes += hh10 * 60
+		ap.hours -= hh10
+	}
+
+	mm10 := ap.minutes % 10
+	if mm10 != 0 {
+		ap.seconds += mm10 * 60
+		ap.minutes -= mm10
+	}
+
+	if s < 0 {
+		return ap.Negate()
+	}
+	return ap
+}
+
+func (period Period) normaliseYYMM() Period {
+	s := period.Sign()
+	ap := period.Abs()
+
+	// remember that the fields are all fixed-point 1E1
+	if ap.months > 129 {
+		ap.years += (ap.months / 120) * 10
+		ap.months = ap.months % 120
+	}
+
+	y10 := ap.years % 10
+	if y10 != 0 && (ap.years < 10 || ap.months != 0) {
+		ap.months += y10 * 12
+		ap.years -= y10
+	}
+
+	if s < 0 {
+		return ap.Negate()
+	}
+	return ap
+}
+
+//-------------------------------------------------------------------------------------------------
+
+// used for stages in arithmetic
+type period64 struct {
+	years, months, days, hours, minutes, seconds int64
+	neg                                          bool
+}
+
+func (period Period) toPeriod64() *period64 {
+	return &period64{
+		int64(period.years), int64(period.months), int64(period.days),
+		int64(period.hours), int64(period.minutes), int64(period.seconds),
+		false,
+	}
+}
+
+func (p *period64) toPeriod() Period {
+	if p.neg {
+		return Period{
+			int16(-p.years), int16(-p.months), int16(-p.days),
+			int16(-p.hours), int16(-p.minutes), int16(-p.seconds),
+		}
+	}
+
+	return Period{
+		int16(p.years), int16(p.months), int16(p.days),
+		int16(p.hours), int16(p.minutes), int16(p.seconds),
+	}
+}
+
+func (p *period64) normalise64(precise bool) *period64 {
+	return p.abs().rippleUp(precise).moveFractionToRight()
+}
+
+func (p *period64) abs() *period64 {
+
+	if !p.neg {
+		if p.years < 0 {
+			p.years = -p.years
+			p.neg = true
+		}
+
+		if p.months < 0 {
+			p.months = -p.months
+			p.neg = true
+		}
+
+		if p.days < 0 {
+			p.days = -p.days
+			p.neg = true
+		}
+
+		if p.hours < 0 {
+			p.hours = -p.hours
+			p.neg = true
+		}
+
+		if p.minutes < 0 {
+			p.minutes = -p.minutes
+			p.neg = true
+		}
+
+		if p.seconds < 0 {
+			p.seconds = -p.seconds
+			p.neg = true
+		}
+	}
+	return p
+}
+
+func (p *period64) rippleUp(precise bool) *period64 {
+	// remember that the fields are all fixed-point 1E1
+
+	p.minutes = p.minutes + (p.seconds/600)*10
+	p.seconds = p.seconds % 600
+
+	p.hours = p.hours + (p.minutes/600)*10
+	p.minutes = p.minutes % 600
+
+	// 32670-(32670/60)-(32670/3600) = 32760 - 546 - 9.1 = 32204.9
+	if !precise || p.hours > 32204 {
+		p.days += (p.hours / 240) * 10
+		p.hours = p.hours % 240
+	}
+
+	if !precise || p.days > 32760 {
+		dE6 := p.days * oneE6
+		p.months += dE6 / daysPerMonthE6
+		p.days = (dE6 % daysPerMonthE6) / oneE6
+	}
+
+	p.years = p.years + (p.months/120)*10
+	p.months = p.months % 120
+
+	return p
+}
+
+// moveFractionToRight applies the rule that only the smallest field is permitted to have a decimal fraction.
+func (p *period64) moveFractionToRight() *period64 {
+	// remember that the fields are all fixed-point 1E1
+
+	y10 := p.years % 10
+	if y10 != 0 && (p.months != 0 || p.days != 0 || p.hours != 0 || p.minutes != 0 || p.seconds != 0) {
+		p.months += y10 * 12
+		p.years = (p.years / 10) * 10
+	}
+
+	m10 := p.months % 10
+	if m10 != 0 && (p.days != 0 || p.hours != 0 || p.minutes != 0 || p.seconds != 0) {
+		p.days += (m10 * daysPerMonthE6) / oneE6
+		p.months = (p.months / 10) * 10
+	}
+
+	d10 := p.days % 10
+	if d10 != 0 && (p.hours != 0 || p.minutes != 0 || p.seconds != 0) {
+		p.hours += d10 * 24
+		p.days = (p.days / 10) * 10
+	}
+
+	hh10 := p.hours % 10
+	if hh10 != 0 && (p.minutes != 0 || p.seconds != 0) {
+		p.minutes += hh10 * 60
+		p.hours = (p.hours / 10) * 10
+	}
+
+	mm10 := p.minutes % 10
+	if mm10 != 0 && p.seconds != 0 {
+		p.seconds += mm10 * 60
+		p.minutes = (p.minutes / 10) * 10
+	}
+
+	return p
+}