Add hasPrefix(prefix,s) and hasSuffix(suffix,s)

Author: md5

README.md

@@ -114,6 +114,8 @@ Within those templates, the object emitted by docker-gen will have [this structu
 * *`groupBy $containers $fieldPath`*: Groups an array of `RuntimeContainer` instances based on the values of a field path expression `$fieldPath`. A field path expression is a dot-delimited list of map keys or struct member names specifying the path from container to a nested value, which must be a string. Returns a map from the value of the field path expression to an array of containers having that value. Containers that do not have a value for the field path in question are omitted.
 * *`groupByKeys $containers $fieldPath`*: Returns the same as `groupBy` but only returns the keys of the map.
 * *`groupByMulti $containers $fieldPath $sep`*: Like `groupBy`, but the string value specified by `$fieldPath` is first split by `$sep` into a list of strings. A container whose `$fieldPath` value contains a list of strings will show up in the map output under each of those strings.
+* *`hasPrefix $prefix $string`*: Returns whether `$prefix` is a prefix of `$string`.
+* *`hasSuffix $suffix $string`*: Returns whether `$suffix` is a suffix of `$string`.
 * *`split $string $sep`*: Splits `$string` into a slice of substrings delimited by `$sep`. Alias for [`strings.Split`](http://golang.org/pkg/strings/#Split)
 * *`replace $string $old $new $count`*: Replaces up to `$count` occurences of `$old` with `$new` in `$string`. Alias for [`strings.Replace`](http://golang.org/pkg/strings/#Replace)
 * *`dict $key $value ...`*: Creates a map from a list of pairs. Each `$key` value must be a `string`, but the `$value` can be any type (or `nil`). Useful for passing more than one value as a pipeline context to subtemplates.

template.go

@@ -65,6 +65,16 @@ func groupByKeys(entries []*RuntimeContainer, key string) []string {
 	return ret
 }
 
+// hasPrefix returns whether a given string is a prefix of another string
+func hasPrefix(prefix, s string) bool {
+	return strings.HasPrefix(s, prefix)
+}
+
+// hasSuffix returns whether a given string is a suffix of another string
+func hasSuffix(suffix, s string) bool {
+	return strings.HasSuffix(s, suffix)
+}
+
 func contains(item map[string]string, key string) bool {
 	if _, ok := item[key]; ok {
 		return true
@@ -170,6 +180,8 @@ func generateFile(config Config, containers Context) bool {
 		"groupBy":      groupBy,
 		"groupByMulti": groupByMulti,
 		"groupByKeys":  groupByKeys,
+		"hasPrefix":    hasPrefix,
+		"hasSuffix":    hasSuffix,
 		"split":        strings.Split,
 		"replace":      strings.Replace,
 		"dict":         dict,

template_test.go

@@ -104,6 +104,22 @@ func TestGroupByMulti(t *testing.T) {
 	}
 }
 
+func TestHasPrefix(t *testing.T) {
+	const prefix = "tcp://"
+	const str = "tcp://127.0.0.1:2375"
+	if !hasPrefix(prefix, str) {
+		t.Fatalf("expected %s to have prefix %s", str, prefix)
+	}
+}
+
+func TestHasSuffix(t *testing.T) {
+	const suffix = ".local"
+	const str = "myhost.local"
+	if !hasSuffix(suffix, str) {
+		t.Fatalf("expected %s to have suffix %s", str, suffix)
+	}
+}
+
 func TestDict(t *testing.T) {
 	containers := []*RuntimeContainer{
 		&RuntimeContainer{