Adding new indent function

Signed-off-by: Dave Henderson <dhenderson@gmail.com>

5 files changed, 59 insertions, 0 deletions

diff --git a/README.md b/README.md
index 39a60bcf..92b8085f 100644
--- a/README.md
+++ b/README.md
@@ -52,6 +52,7 @@ Gomplate is an alternative that will let you process templates which also includ
 		- [`trim`](#trim)
 		- [`urlParse`](#urlparse)
 		- [`has`](#has)
+		- [`indent`](#indent)
 		- [`json`](#json)
 		- [`jsonArray`](#jsonarray)
 		- [`yaml`](#yaml)
@@ -459,6 +460,27 @@ $ gomplate -d vault:///secret/foo < input.tmpl
 The secret is 'foo: bar'
 ```
 
+#### `indent`
+
+Indents a given string with the given indentation pattern. If the input string has multiple lines, each line will be indented.
+
+##### Example
+
+This function can be especially useful when adding YAML snippets into other YAML documents, where indentation is important:
+
+_`input.tmpl`:_
+```
+foo:
+{{ `{"bar": {"baz": 2}}` | json | toYAML | indent "  " }}
+```
+
+```console
+$ gomplate -f input.tmpl
+foo:
+  bar:
+    baz: 2
+```
+
 #### `json`
 
 Converts a JSON string into an object. Only works for JSON Objects (not Arrays or other valid JSON types). This can be used to access properties of JSON objects.
diff --git a/gomplate.go b/gomplate.go
index eb778ea4..28e623ab 100644
--- a/gomplate.go
+++ b/gomplate.go
@@ -53,6 +53,7 @@ func NewGomplate(data *Data, leftDelim, rightDelim string) *Gomplate {
 			"yaml":             typeconv.YAML,
 			"yamlArray":        typeconv.YAMLArray,
 			"slice":            typeconv.Slice,
+			"indent":           typeconv.indent,
 			"join":             typeconv.Join,
 			"toJSON":           typeconv.ToJSON,
 			"toJSONPretty":     typeconv.toJSONPretty,
diff --git a/test/integration/typeconv_funcs.bats b/test/integration/typeconv_funcs.bats
index c080a2ad..14921117 100644
--- a/test/integration/typeconv_funcs.bats
+++ b/test/integration/typeconv_funcs.bats
@@ -29,3 +29,11 @@ function teardown () {
 \"hello\": \"world\"
 }" ]]
 }
+
+@test "indent" {
+  gomplate -i '{{ indent "   " "hello world" }}{{ "hello\nmultiline\nworld" | indent " " }}'
+  [ "$status" -eq 0 ]
+  [[ "${output}" == "   hello world hello
+ multiline
+ world" ]]
+}
diff --git a/typeconv.go b/typeconv.go
index fb8c0e5f..76739b3f 100644
--- a/typeconv.go
+++ b/typeconv.go
@@ -99,6 +99,21 @@ func (t *TypeConv) Slice(args ...interface{}) []interface{} {
 	return args
 }
 
+// Indent - indent each line of the string with the given indent string
+func (t *TypeConv) indent(indent, s string) string {
+	var res []byte
+	bol := true
+	for i := 0; i < len(s); i++ {
+		c := s[i]
+		if bol && c != '\n' {
+			res = append(res, indent...)
+		}
+		res = append(res, c)
+		bol = c == '\n'
+	}
+	return string(res)
+}
+
 // Join concatenates the elements of a to create a single string.
 // The separator string sep is placed between elements in the resulting string.
 //
diff --git a/typeconv_test.go b/typeconv_test.go
index ae2424ce..85620b7c 100644
--- a/typeconv_test.go
+++ b/typeconv_test.go
@@ -169,3 +169,16 @@ func TestHas(t *testing.T) {
 	assert.False(t, ty.Has(in, "bar"))
 	assert.True(t, ty.Has(in["baz"], "qux"))
 }
+
+func TestIndent(t *testing.T) {
+	ty := new(TypeConv)
+	actual := "hello\nworld\n!"
+	expected := "  hello\n  world\n  !"
+	assert.Equal(t, expected, ty.indent("  ", actual))
+
+	assert.Equal(t, "\n", ty.indent("  ", "\n"))
+
+	assert.Equal(t, "  foo\n", ty.indent("  ", "foo\n"))
+
+	assert.Equal(t, "   foo", ty.indent("   ", "foo"))
+}