From 441edd4c01e158275039db882bf6b18d6f3fba8d Mon Sep 17 00:00:00 2001
From: Dave Henderson <dhenderson@gmail.com>
Date: Thu, 19 Apr 2018 01:06:33 -0400
Subject: Adding time.Since and time.Until wrappers

Signed-off-by: Dave Henderson <dhenderson@gmail.com>
---
 docs/content/functions/time.md | 54 ++++++++++++++++++++++++++++++++++++++++++
 funcs/time.go                  | 10 ++++++++
 2 files changed, 64 insertions(+)

diff --git a/docs/content/functions/time.md b/docs/content/functions/time.md
index 902f3d78..54af2f47 100644
--- a/docs/content/functions/time.md
+++ b/docs/content/functions/time.md
@@ -212,6 +212,30 @@ $ gomplate -i '{{ (time.ParseInLocation time.Kitchen "Africa/Luanda" "6:00AM").F
 06:00 LMT
 ```
 
+## `time.Since`
+
+Returns the time elapsed since a given time. This wraps [`time.Since`](https://golang.org/pkg/time/#Since).
+
+It is shorthand for `time.Now.Sub t`.
+
+### Usage
+```go
+time.Since t
+```
+
+### Arguments
+
+| name   | description |
+|--------|-------------|
+| `t`    | the `Time` to calculate since |
+
+### Examples
+
+```console
+$ gomplate -i '{{ $t := time.Parse time.RFC3339 "1970-01-01T00:00:00Z" }}time since the epoch: {{ time.Since $t }}'
+time since the epoch: 423365h0m24.353828924s
+```
+
 ## `time.Unix`
 
 Returns the local `Time` corresponding to the given Unix time, in seconds since
@@ -237,6 +261,36 @@ $ gomplate -i '{{ (time.Unix "123456.789").UTC.Format time.StampMilli}}'
 Jan  2 10:17:36.789
 ```
 
+## `time.Until`
+
+Returns the duration until a given time. This wraps [`time.Until`](https://golang.org/pkg/time/#Until).
+
+It is shorthand for `$t.Sub time.Now`.
+
+### Usage
+```go
+time.Until t
+```
+
+### Arguments
+
+| name   | description |
+|--------|-------------|
+| `t`    | the `Time` to calculate until |
+
+### Examples
+
+```console
+$ gomplate -i '{{ $t := time.Parse time.RFC3339 "2020-01-01T00:00:00Z" }}only {{ time.Until $t }} to go...'
+only 14922h56m46.578625891s to go...
+```
+
+Or, less precise:
+```console
+$ bin/gomplate -i '{{ $t := time.Parse time.RFC3339 "2020-01-01T00:00:00Z" }}only {{ (time.Until $t).Round (time.Hour 1) }} to go...'
+only 14923h0m0s to go...
+```
+
 ## `time.ZoneName`
 
 Return the local system's time zone's name.
diff --git a/funcs/time.go b/funcs/time.go
index 111b0b23..d1030cab 100644
--- a/funcs/time.go
+++ b/funcs/time.go
@@ -143,6 +143,16 @@ func (f *TimeFuncs) ParseDuration(n interface{}) (gotime.Duration, error) {
 	return gotime.ParseDuration(conv.ToString(n))
 }
 
+// Since -
+func (f *TimeFuncs) Since(n gotime.Time) gotime.Duration {
+	return gotime.Since(n)
+}
+
+// Until -
+func (f *TimeFuncs) Until(n gotime.Time) gotime.Duration {
+	return gotime.Until(n)
+}
+
 // convert a number input to a pair of int64s, representing the integer portion and the decimal remainder
 // this can handle a string as well as any integer or float type
 // precision is at the "nano" level (i.e. 1e+9)
-- 
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