truncatesentences-filter added.

README.md

@@ -23,6 +23,7 @@ All additional filters/tags will be registered automatically.
   - Regulars
      - **[filesizeformat](https://docs.djangoproject.com/en/dev/ref/templates/builtins/#filesizeformat)** (human-readable filesize; takes bytes as input)
      - **[slugify](https://docs.djangoproject.com/en/dev/ref/templates/builtins/#slugify)** (creates a slug for a given input)
+     - **truncatesentences** (returns the first X sentences [like truncatechars/truncatewords]; please provide X as a parameter)
 
   - Markup
      - **markdown** (parses markdown text and outputs HTML; **hint**: use the **safe**-filter to make the output not being escaped)

filters.go

@@ -3,6 +3,8 @@ package pongo2addons
 import (
 	"errors"
 	"time"
+	"regexp"
+	"strings"
 
 	"github.com/flosch/pongo2"
 
@@ -12,9 +14,15 @@ import (
 )
 
 func init() {
-	pongo2.RegisterFilter("markdown", filterMarkdown)
+	// Regulars
 	pongo2.RegisterFilter("slugify", filterSlugify)
 	pongo2.RegisterFilter("filesizeformat", filterFilesizeformat)
+	pongo2.RegisterFilter("truncatesentences", filterTruncatesentences)
+
+	// Markup
+	pongo2.RegisterFilter("markdown", filterMarkdown)
+
+	// Humanize
 	pongo2.RegisterFilter("timeuntil", filterTimeuntilTimesince)
 	pongo2.RegisterFilter("timesince", filterTimeuntilTimesince)
 	pongo2.RegisterFilter("naturaltime", filterTimeuntilTimesince)
@@ -35,6 +43,17 @@ func filterFilesizeformat(in *pongo2.Value, param *pongo2.Value) (*pongo2.Value,
 	return pongo2.AsValue(humanize.IBytes(uint64(in.Integer()))), nil
 }
 
+var filterTruncatesentencesRe = regexp.MustCompile(`(?U:.*[\w]{3,}.*([\d][\.!?][\D]|[\D][\.!?][\s]|[\n$]))`)
+
+func filterTruncatesentences(in *pongo2.Value, param *pongo2.Value) (*pongo2.Value, error) {
+	count := param.Integer()
+	if count <= 0 {
+		return pongo2.AsValue(""), nil
+	}
+	sentencens := filterTruncatesentencesRe.FindAllString(strings.TrimSpace(in.String()), -1)
+	return pongo2.AsValue(strings.TrimSpace(strings.Join(sentencens[:min(count, len(sentencens))], ""))), nil
+}
+
 func filterTimeuntilTimesince(in *pongo2.Value, param *pongo2.Value) (*pongo2.Value, error) {
 	basetime, is_time := in.Interface().(time.Time)
 	if !is_time {

filters_test.go

@@ -18,6 +18,9 @@ type TestSuite1 struct{}
 
 var _ = Suite(&TestSuite1{})
 
+// Taken from http://www.florian-schlachter.de/post/pongo2-10-rc1/
+const demoText = `This is a first sentencen with a 4.50 number. The second one is even more fun! Isn't it? Last sentence, okay.`
+
 func (s *TestSuite1) TestFilters(c *C) {
 	// Markdown
 	c.Assert(pongo2.RenderTemplateString("{{ \"**test**\"|markdown|safe }}", nil), Equals, "<p><strong>test</strong></p>\n")
@@ -70,4 +73,8 @@ func (s *TestSuite1) TestFilters(c *C) {
 	// Ordinal
 	c.Assert(pongo2.RenderTemplateString("{{ 1|ordinal }} {{ 2|ordinal }} {{ 3|ordinal }} {{ 18241|ordinal }}", nil),
 		Equals, "1st 2nd 3rd 18241st")
+
+	// Truncatesentences
+	c.Assert(pongo2.RenderTemplateString("{{ text|truncatesentences:3|safe }}", pongo2.Context{"text": demoText}),
+		Equals, "This is a first sentencen with a 4.50 number. The second one is even more fun! Isn't it?")
 }

helpers.go

@@ -0,0 +1,15 @@
+package pongo2addons
+
+func max(a, b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}
+
+func min(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}