/
Timestamp.go
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/
Timestamp.go
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// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Code generated by the FlatBuffers compiler. DO NOT EDIT.
package flatbuf
import (
flatbuffers "github.com/google/flatbuffers/go"
)
/// Timestamp is a 64-bit signed integer representing an elapsed time since a
/// fixed epoch, stored in either of four units: seconds, milliseconds,
/// microseconds or nanoseconds, and is optionally annotated with a timezone.
///
/// Timestamp values do not include any leap seconds (in other words, all
/// days are considered 86400 seconds long).
///
/// Timestamps with a non-empty timezone
/// ------------------------------------
///
/// If a Timestamp column has a non-empty timezone value, its epoch is
/// 1970-01-01 00:00:00 (January 1st 1970, midnight) in the *UTC* timezone
/// (the Unix epoch), regardless of the Timestamp's own timezone.
///
/// Therefore, timestamp values with a non-empty timezone correspond to
/// physical points in time together with some additional information about
/// how the data was obtained and/or how to display it (the timezone).
///
/// For example, the timestamp value 0 with the timezone string "Europe/Paris"
/// corresponds to "January 1st 1970, 00h00" in the UTC timezone, but the
/// application may prefer to display it as "January 1st 1970, 01h00" in
/// the Europe/Paris timezone (which is the same physical point in time).
///
/// One consequence is that timestamp values with a non-empty timezone
/// can be compared and ordered directly, since they all share the same
/// well-known point of reference (the Unix epoch).
///
/// Timestamps with an unset / empty timezone
/// -----------------------------------------
///
/// If a Timestamp column has no timezone value, its epoch is
/// 1970-01-01 00:00:00 (January 1st 1970, midnight) in an *unknown* timezone.
///
/// Therefore, timestamp values without a timezone cannot be meaningfully
/// interpreted as physical points in time, but only as calendar / clock
/// indications ("wall clock time") in an unspecified timezone.
///
/// For example, the timestamp value 0 with an empty timezone string
/// corresponds to "January 1st 1970, 00h00" in an unknown timezone: there
/// is not enough information to interpret it as a well-defined physical
/// point in time.
///
/// One consequence is that timestamp values without a timezone cannot
/// be reliably compared or ordered, since they may have different points of
/// reference. In particular, it is *not* possible to interpret an unset
/// or empty timezone as the same as "UTC".
///
/// Conversion between timezones
/// ----------------------------
///
/// If a Timestamp column has a non-empty timezone, changing the timezone
/// to a different non-empty value is a metadata-only operation:
/// the timestamp values need not change as their point of reference remains
/// the same (the Unix epoch).
///
/// However, if a Timestamp column has no timezone value, changing it to a
/// non-empty value requires to think about the desired semantics.
/// One possibility is to assume that the original timestamp values are
/// relative to the epoch of the timezone being set; timestamp values should
/// then adjusted to the Unix epoch (for example, changing the timezone from
/// empty to "Europe/Paris" would require converting the timestamp values
/// from "Europe/Paris" to "UTC", which seems counter-intuitive but is
/// nevertheless correct).
///
/// Guidelines for encoding data from external libraries
/// ----------------------------------------------------
///
/// Date & time libraries often have multiple different data types for temporal
/// data. In order to ease interoperability between different implementations the
/// Arrow project has some recommendations for encoding these types into a Timestamp
/// column.
///
/// An "instant" represents a physical point in time that has no relevant timezone
/// (for example, astronomical data). To encode an instant, use a Timestamp with
/// the timezone string set to "UTC", and make sure the Timestamp values
/// are relative to the UTC epoch (January 1st 1970, midnight).
///
/// A "zoned date-time" represents a physical point in time annotated with an
/// informative timezone (for example, the timezone in which the data was
/// recorded). To encode a zoned date-time, use a Timestamp with the timezone
/// string set to the name of the timezone, and make sure the Timestamp values
/// are relative to the UTC epoch (January 1st 1970, midnight).
///
/// (There is some ambiguity between an instant and a zoned date-time with the
/// UTC timezone. Both of these are stored the same in Arrow. Typically,
/// this distinction does not matter. If it does, then an application should
/// use custom metadata or an extension type to distinguish between the two cases.)
///
/// An "offset date-time" represents a physical point in time combined with an
/// explicit offset from UTC. To encode an offset date-time, use a Timestamp
/// with the timezone string set to the numeric timezone offset string
/// (e.g. "+03:00"), and make sure the Timestamp values are relative to
/// the UTC epoch (January 1st 1970, midnight).
///
/// A "naive date-time" (also called "local date-time" in some libraries)
/// represents a wall clock time combined with a calendar date, but with
/// no indication of how to map this information to a physical point in time.
/// Naive date-times must be handled with care because of this missing
/// information, and also because daylight saving time (DST) may make
/// some values ambiguous or nonexistent. A naive date-time may be
/// stored as a struct with Date and Time fields. However, it may also be
/// encoded into a Timestamp column with an empty timezone. The timestamp
/// values should be computed "as if" the timezone of the date-time values
/// was UTC; for example, the naive date-time "January 1st 1970, 00h00" would
/// be encoded as timestamp value 0.
type Timestamp struct {
_tab flatbuffers.Table
}
func GetRootAsTimestamp(buf []byte, offset flatbuffers.UOffsetT) *Timestamp {
n := flatbuffers.GetUOffsetT(buf[offset:])
x := &Timestamp{}
x.Init(buf, n+offset)
return x
}
func (rcv *Timestamp) Init(buf []byte, i flatbuffers.UOffsetT) {
rcv._tab.Bytes = buf
rcv._tab.Pos = i
}
func (rcv *Timestamp) Table() flatbuffers.Table {
return rcv._tab
}
func (rcv *Timestamp) Unit() TimeUnit {
o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
if o != 0 {
return TimeUnit(rcv._tab.GetInt16(o + rcv._tab.Pos))
}
return 0
}
func (rcv *Timestamp) MutateUnit(n TimeUnit) bool {
return rcv._tab.MutateInt16Slot(4, int16(n))
}
/// The timezone is an optional string indicating the name of a timezone,
/// one of:
///
/// * As used in the Olson timezone database (the "tz database" or
/// "tzdata"), such as "America/New_York".
/// * An absolute timezone offset of the form "+XX:XX" or "-XX:XX",
/// such as "+07:30".
///
/// Whether a timezone string is present indicates different semantics about
/// the data (see above).
func (rcv *Timestamp) Timezone() []byte {
o := flatbuffers.UOffsetT(rcv._tab.Offset(6))
if o != 0 {
return rcv._tab.ByteVector(o + rcv._tab.Pos)
}
return nil
}
/// The timezone is an optional string indicating the name of a timezone,
/// one of:
///
/// * As used in the Olson timezone database (the "tz database" or
/// "tzdata"), such as "America/New_York".
/// * An absolute timezone offset of the form "+XX:XX" or "-XX:XX",
/// such as "+07:30".
///
/// Whether a timezone string is present indicates different semantics about
/// the data (see above).
func TimestampStart(builder *flatbuffers.Builder) {
builder.StartObject(2)
}
func TimestampAddUnit(builder *flatbuffers.Builder, unit TimeUnit) {
builder.PrependInt16Slot(0, int16(unit), 0)
}
func TimestampAddTimezone(builder *flatbuffers.Builder, timezone flatbuffers.UOffsetT) {
builder.PrependUOffsetTSlot(1, flatbuffers.UOffsetT(timezone), 0)
}
func TimestampEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
return builder.EndObject()
}