From f8f0e19982126ad0bd45a26e20cf42dc6ec8934e Mon Sep 17 00:00:00 2001
From: Gabe Cook <gabe565@gmail.com>
Date: Mon, 17 Apr 2023 11:29:16 -0500
Subject: [PATCH] Add YAML funcs: `fromYaml`, `toYaml`, `mustFromYaml`,
 `mustToYaml`

---
 defaults.go      | 29 +++++++++++++++++++++++++++++
 defaults_test.go | 26 ++++++++++++++++++++++++++
 docs/defaults.md | 18 ++++++++++++++++++
 docs/index.md    |  2 +-
 functions.go     |  4 ++++
 go.mod           |  1 +
 go.sum           |  2 ++
 7 files changed, 81 insertions(+), 1 deletion(-)

diff --git a/defaults.go b/defaults.go
index b9f97966..8efef884 100644
--- a/defaults.go
+++ b/defaults.go
@@ -7,6 +7,8 @@ import (
 	"reflect"
 	"strings"
 	"time"
+
+	"gopkg.in/yaml.v3"
 )
 
 func init() {
@@ -161,3 +163,30 @@ func ternary(vt interface{}, vf interface{}, v bool) interface{} {
 
 	return vf
 }
+
+// fromYaml decodes YAML into a structured value, ignoring errors.
+func fromYaml(v string) interface{} {
+	output, _ := mustFromYaml(v)
+	return output
+}
+
+// mustFromYaml decodes YAML into a structured value, returning errors.
+func mustFromYaml(v string) (interface{}, error) {
+	var output interface{}
+	err := yaml.Unmarshal([]byte(v), &output)
+	return output, err
+}
+
+// toYaml encodes an item into a YAML string
+func toYaml(v interface{}) string {
+	output, _ := yaml.Marshal(v)
+	return string(output)
+}
+
+func mustToYaml(v interface{}) (string, error) {
+	output, err := yaml.Marshal(v)
+	if err != nil {
+		return "", err
+	}
+	return string(output), nil
+}
diff --git a/defaults_test.go b/defaults_test.go
index a35ebf62..ee27109d 100644
--- a/defaults_test.go
+++ b/defaults_test.go
@@ -194,3 +194,29 @@ func TestTernary(t *testing.T) {
 		t.Error(err)
 	}
 }
+
+func TestFromYaml(t *testing.T) {
+	dict := map[string]interface{}{"Input": `foo: 55`}
+
+	tpl := `{{.Input | fromYaml}}`
+	expected := `map[foo:55]`
+	if err := runtv(tpl, expected, dict); err != nil {
+		t.Error(err)
+	}
+
+	tpl = `{{(.Input | fromYaml).foo}}`
+	expected = `55`
+	if err := runtv(tpl, expected, dict); err != nil {
+		t.Error(err)
+	}
+}
+
+func TestToYaml(t *testing.T) {
+	dict := map[string]interface{}{"Top": map[string]interface{}{"bool": true, "string": "test", "number": 42}}
+
+	tpl := `{{.Top | toYaml}}`
+	expected := "bool: true\nnumber: 42\nstring: test\n"
+	if err := runtv(tpl, expected, dict); err != nil {
+		t.Error(err)
+	}
+}
diff --git a/docs/defaults.md b/docs/defaults.md
index b68cd83f..333078d4 100644
--- a/docs/defaults.md
+++ b/docs/defaults.md
@@ -167,3 +167,21 @@ false | ternary "foo" "bar"
 ```
 
 The above returns `"bar"`.
+
+## fromYaml, mustFromYaml
+
+`fromYaml` decodes a YAML document into a structure. If the input cannot be decoded as YAML the function will return an empty string.
+`mustFromYaml` will return an error in case the YAML is invalid.
+
+```
+fromYaml "foo: 55"
+```
+
+## toYaml, mustToYaml
+
+The `toYaml` function encodes an item into a YAML string. If the item cannot be converted to YAML the function will return an empty string.
+`mustToYaml` will return an error in case the item cannot be encoded in YAML.
+
+```
+toYaml .Item
+```
diff --git a/docs/index.md b/docs/index.md
index 7e898fa5..066d1387 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -8,7 +8,7 @@ The Sprig library provides over 70 template functions for Go's template language
   - [Integer Slice Functions](integer_slice.md): `until`, `untilStep`
 - [Float Math Functions](mathf.md): `addf`, `maxf`, `mulf`, etc.
 - [Date Functions](date.md): `now`, `date`, etc.
-- [Defaults Functions](defaults.md): `default`, `empty`, `coalesce`, `fromJson`, `toJson`, `toPrettyJson`, `toRawJson`, `ternary`
+- [Defaults Functions](defaults.md): `default`, `empty`, `coalesce`, `fromJson`, `toJson`, `toPrettyJson`, `toRawJson`, `ternary`, `fromYaml`, `toYaml`
 - [Encoding Functions](encoding.md): `b64enc`, `b64dec`, etc.
 - [Lists and List Functions](lists.md): `list`, `first`, `uniq`, etc.
 - [Dictionaries and Dict Functions](dicts.md): `get`, `set`, `dict`, `hasKey`, `pluck`, `dig`, `deepCopy`, etc.
diff --git a/functions.go b/functions.go
index 57fcec1d..62bfac96 100644
--- a/functions.go
+++ b/functions.go
@@ -252,6 +252,10 @@ var genericMap = map[string]interface{}{
 	"mustToPrettyJson": mustToPrettyJson,
 	"mustToRawJson":    mustToRawJson,
 	"ternary":          ternary,
+	"fromYaml":         fromYaml,
+	"toYaml":           toYaml,
+	"mustFromYaml":     mustFromYaml,
+	"mustToYaml":       mustToYaml,
 	"deepCopy":         deepCopy,
 	"mustDeepCopy":     mustDeepCopy,
 
diff --git a/go.mod b/go.mod
index 494916f1..c96ec052 100644
--- a/go.mod
+++ b/go.mod
@@ -13,4 +13,5 @@ require (
 	github.com/spf13/cast v1.3.1
 	github.com/stretchr/testify v1.5.1
 	golang.org/x/crypto v0.3.0
+	gopkg.in/yaml.v3 v3.0.1
 )
diff --git a/go.sum b/go.sum
index 11a67119..8fe52150 100644
--- a/go.sum
+++ b/go.sum
@@ -59,3 +59,5 @@ gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.3.0 h1:clyUAQHOM3G0M3f5vQj7LuJrETvjVot3Z5el9nffUtU=
 gopkg.in/yaml.v2 v2.3.0/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=