format.go

package timezh

import "bytes"

type format struct {
	mixed      bool
	day        uint8
	dayPoint   uint8
	month      uint8
	monthPoint uint8
	pm         uint8
	pmPoint    uint8
	buf        *bytes.Buffer
}

func (f *format) init(s string) {
	f.day = 0
	f.dayPoint = 1
	f.month = 0
	f.monthPoint = 1
	f.pm = 0
	f.pmPoint = 1
	f.reset()
}

func (f *format) reset() {
	if f.buf == nil {
		f.buf = new(bytes.Buffer)
	} else {
		f.buf.Reset()
	}
}

// Format returns a textual representation of the time value formatted
// according to layout, which defines the format by showing how the reference
// time, defined to be
//	Mon Jan 2 15:04:05 -0700 MST 2006
// would be displayed if it were the value; it serves as an example of the
// desired output. The same display rules will then be applied to the time
// value.
//
// A fractional second is represented by adding a period and zeros
// to the end of the seconds section of layout string, as in "15:04:05.000"
// to format a time stamp with millisecond precision.
//
// Predefined layouts ANSIC, UnixDate, RFC3339 and others describe standard
// and convenient representations of the reference time. For more information
// about the formats and the definition of the reference time, see the
// documentation for ANSIC and the other constants defined by this package.
func (t Time) Format(layout string) string {
	t.f.mixed = false
	return t.lookup(t.Time.Format(t.formatLayout(layout)))
}

// FormatMix the difference with Format is that it can be mixed in English and Chinese.
func (t Time) FormatMix(layout string) string {
	t.f.mixed = true
	return t.lookup(t.Time.Format(t.formatLayout(layout)))
}

// FormatLayout returns a standard textual formatted layout.
// Such as
//	星期一 一月 2 下午15:04:05 -0700 MST 2006
// returns
//	Mon Jan 2 PM15:04:05 -0700 MST 2006
func FormatLayout(layout string) string {
	return new(Time).formatLayout(layout)
}

func (t *Time) formatLayout(layout string) string {
	t.f.init(layout)
	j := 0
	for i, r := range layout {
		if i < j {
			continue
		}
		switch r {
		case 'M':
			if len(layout) >= i+6 && layout[i:i+6] == "Monday" {
				j = i + 6
				if t.f.mixed {
					t.f.day <<= 1
					t.f.dayPoint <<= 1
				}
				t.f.buf.WriteString("Monday")
			} else if len(layout) >= i+3 && layout[i:i+3] == "Mon" {
				j = i + 3
				if t.f.mixed {
					t.f.day <<= 1
					t.f.dayPoint <<= 1
				}
				t.f.buf.WriteString("Mon")
			}
		case 'J':
			if len(layout) >= i+7 && layout[i:i+7] == "January" {
				j = i + 7
				if t.f.mixed {
					t.f.month <<= 1
					t.f.monthPoint <<= 1
				}
				t.f.buf.WriteString("January")
			} else if len(layout) >= i+3 && layout[i:i+3] == "Jan" {
				j = i + 3
				if t.f.mixed {
					t.f.month <<= 1
					t.f.monthPoint <<= 1
				}
				t.f.buf.WriteString("Jan")
			}
		case 'P', 'p':
			if len(layout) >= i+2 {
				if layout[i:i+2] == "PM" || layout[i:i+2] == "pm" {
					j = i + 2
					if t.f.mixed {
						t.f.pm <<= 1
						t.f.pmPoint <<= 1
					}
					t.f.buf.WriteString("PM")
				}
			}
		case '星':
			if len(layout) >= i+9 && layout[i:i+9] == "星期一" {
				j = i + 9
				if t.f.mixed {
					t.f.day = (t.f.day + 1) << 1
					t.f.dayPoint <<= 1
				}
				t.f.buf.WriteString("Monday")
			}
		case '周':
			if len(layout) >= i+6 && layout[i:i+6] == "周一" {
				j = i + 6
				if t.f.mixed {
					t.f.day = (t.f.day + 1) << 1
					t.f.dayPoint <<= 1
				}
				t.f.buf.WriteString("Mon")
			}
		case '一':
			if len(layout) >= i+6 && layout[i:i+6] == "一月" {
				j = i + 6
				if t.f.mixed {
					t.f.month = (t.f.month + 1) << 1
					t.f.monthPoint <<= 1
				}
				t.f.buf.WriteString("Jan")
			}
		case '下':
			if len(layout) >= i+6 && layout[i:i+6] == "下午" {
				j = i + 6
				if t.f.mixed {
					t.f.pm = (t.f.pm + 1) << 1
					t.f.pmPoint <<= 1
				}
				t.f.buf.WriteString("PM")
			}
		}
		if j <= i {
			t.f.buf.WriteRune(r)
		}
	}

	return t.f.buf.String()
}

// FormatValue return a Chinese textual representation of the time value formatted
// according to layout.
func FormatValue(s string) string {
	return new(Time).lookup(s)
}