feat: add yaml to/from functions

In the same vein of Masterminds#223, add YAML conversion functions. Fixes Masterminds#358.

defaults.go

@@ -3,6 +3,7 @@ package sprig
 import (
 	"bytes"
 	"encoding/json"
+	"gopkg.in/yaml.v2"
 	"math/rand"
 	"reflect"
 	"strings"
@@ -153,6 +154,34 @@ func mustToRawJson(v interface{}) (string, error) {
 	return strings.TrimSuffix(buf.String(), "\n"), nil
 }
 
+// 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, _ := mustToYaml(v)
+	return string(output)
+}
+
+// toYaml encodes an item into a YAML string, returning errors
+func mustToYaml(v interface{}) (string, error) {
+	output, err := yaml.Marshal(v)
+	if err != nil {
+		return "", err
+	}
+	return string(output), nil
+}
+
 // ternary returns the first value if the last value is true, otherwise returns the second value.
 func ternary(vt interface{}, vf interface{}, v bool) interface{} {
 	if v {

defaults_test.go

@@ -150,6 +150,35 @@ func TestToJson(t *testing.T) {
 	}
 }
 
+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
+number: 42
+string: test
+`
+	if err := runtv(tpl, expected, dict); err != nil {
+		t.Error(err)
+	}
+}
+
 func TestToPrettyJson(t *testing.T) {
 	dict := map[string]interface{}{"Top": map[string]interface{}{"bool": true, "string": "test", "number": 42}}
 	tpl := `{{.Top | toPrettyJson}}`

docs/defaults.md

@@ -134,6 +134,26 @@ toRawJson .Item
 
 The above returns unescaped JSON string representation of `.Item`.
 
+## 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
+```
+
+The above returns YAML string representation of `.Item`.
+
 ## ternary
 
 The `ternary` function takes two values, and a test value. If the test value is

functions.go

@@ -22,8 +22,7 @@ import (
 //
 // Use this to pass the functions into the template engine:
 //
-// 	tpl := template.New("foo").Funcs(sprig.FuncMap()))
-//
+//	tpl := template.New("foo").Funcs(sprig.FuncMap()))
 func FuncMap() template.FuncMap {
 	return HtmlFuncMap()
 }
@@ -251,6 +250,10 @@ var genericMap = map[string]interface{}{
 	"mustToJson":       mustToJson,
 	"mustToPrettyJson": mustToPrettyJson,
 	"mustToRawJson":    mustToRawJson,
+	"fromYaml":         fromYaml,
+	"toYaml":           toYaml,
+	"mustFromYaml":     mustFromYaml,
+	"mustToYaml":       mustToYaml,
 	"ternary":          ternary,
 	"deepCopy":         deepCopy,
 	"mustDeepCopy":     mustDeepCopy,
@@ -336,20 +339,20 @@ var genericMap = map[string]interface{}{
 	"mustChunk":   mustChunk,
 
 	// Crypto:
-	"bcrypt":            bcrypt,
-	"htpasswd":          htpasswd,
-	"genPrivateKey":     generatePrivateKey,
-	"derivePassword":    derivePassword,
-	"buildCustomCert":   buildCustomCertificate,
-	"genCA":             generateCertificateAuthority,
-	"genCAWithKey":      generateCertificateAuthorityWithPEMKey,
-	"genSelfSignedCert": generateSelfSignedCertificate,
+	"bcrypt":                   bcrypt,
+	"htpasswd":                 htpasswd,
+	"genPrivateKey":            generatePrivateKey,
+	"derivePassword":           derivePassword,
+	"buildCustomCert":          buildCustomCertificate,
+	"genCA":                    generateCertificateAuthority,
+	"genCAWithKey":             generateCertificateAuthorityWithPEMKey,
+	"genSelfSignedCert":        generateSelfSignedCertificate,
 	"genSelfSignedCertWithKey": generateSelfSignedCertificateWithPEMKey,
-	"genSignedCert":     generateSignedCertificate,
-	"genSignedCertWithKey": generateSignedCertificateWithPEMKey,
-	"encryptAES":        encryptAES,
-	"decryptAES":        decryptAES,
-	"randBytes":         randBytes,
+	"genSignedCert":            generateSignedCertificate,
+	"genSignedCertWithKey":     generateSignedCertificateWithPEMKey,
+	"encryptAES":               encryptAES,
+	"decryptAES":               decryptAES,
+	"randBytes":                randBytes,
 
 	// UUIDs:
 	"uuidv4": uuidv4,

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.v2 v2.3.0
 )