Adding strings.RuneCount function

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

1 files changed, 23 insertions, 0 deletions

diff --git a/docs-src/content/functions/strings.yml b/docs-src/content/functions/strings.yml
index 9dbc886f..b3062dc4 100644
--- a/docs-src/content/functions/strings.yml
+++ b/docs-src/content/functions/strings.yml
@@ -479,6 +479,29 @@ funcs:
         http://example.com/a/very/long/url
         which should not be
         broken
+  - name: strings.RuneCount
+    description: |
+      Return the number of _runes_ (Unicode code-points) contained within the
+      input. This is similar to the built-in `len` function, but `len` counts
+      the length in _bytes_. The length of an input containing multi-byte
+      code-points should therefore be measured with `strings.RuneCount`.
+
+      Inputs will first be converted to strings, and multiple inputs are
+      concatenated.
+
+      This wraps Go's [`utf8.RuneCountInString`](https://golang.org/pkg/unicode/utf8/#RuneCountInString)
+      function.
+    pipeline: true
+    arguments:
+      - name: input
+        required: true
+        description: the input(s) to measure
+    examples:
+      - |
+        $ gomplate -i '{{ range (slice "\u03a9" "\u0030" "\u1430") }}{{ printf "%s is %d bytes and %d runes\n" . (len .) (strings.RuneCount .) }}{{ end }}'
+        Ω is 2 bytes and 1 runes
+        0 is 1 bytes and 1 runes
+        ᐰ is 3 bytes and 1 runes
   - name: contains
     description: |
       **See [`strings.Contains`](#strings-contains) for a pipeline-compatible version**