truncatesentences_html-filter added.

filters.go

@@ -1,10 +1,13 @@
 package pongo2addons
 
 import (
+	"bytes"
 	"errors"
-	"time"
+	"fmt"
 	"regexp"
 	"strings"
+	"time"
+	"unicode/utf8"
 
 	"github.com/flosch/pongo2"
 
@@ -18,6 +21,7 @@ func init() {
 	pongo2.RegisterFilter("slugify", filterSlugify)
 	pongo2.RegisterFilter("filesizeformat", filterFilesizeformat)
 	pongo2.RegisterFilter("truncatesentences", filterTruncatesentences)
+	pongo2.RegisterFilter("truncatesentences_html", filterTruncatesentencesHtml)
 
 	// Markup
 	pongo2.RegisterFilter("markdown", filterMarkdown)
@@ -54,6 +58,166 @@ func filterTruncatesentences(in *pongo2.Value, param *pongo2.Value) (*pongo2.Val
 	return pongo2.AsValue(strings.TrimSpace(strings.Join(sentencens[:min(count, len(sentencens))], ""))), nil
 }
 
+// Taken from pongo2/filters_builtin.go
+func filterTruncateHtmlHelper(value string, new_output *bytes.Buffer, cond func() bool, fn func(c rune, s int, idx int) int, finalize func()) {
+	vLen := len(value)
+	tag_stack := make([]string, 0)
+	idx := 0
+
+	for idx < vLen && !cond() {
+		c, s := utf8.DecodeRuneInString(value[idx:])
+		if c == utf8.RuneError {
+			idx += s
+			continue
+		}
+
+		if c == '<' {
+			new_output.WriteRune(c)
+			idx += s // consume "<"
+
+			if idx+1 < vLen {
+				if value[idx] == '/' {
+					// Close tag
+
+					new_output.WriteString("/")
+
+					tag := ""
+					idx += 1 // consume "/"
+
+					for idx < vLen {
+						c2, size2 := utf8.DecodeRuneInString(value[idx:])
+						if c2 == utf8.RuneError {
+							idx += size2
+							continue
+						}
+
+						// End of tag found
+						if c2 == '>' {
+							idx++ // consume ">"
+							break
+						}
+						tag += string(c2)
+						idx += size2
+					}
+
+					if len(tag_stack) > 0 {
+						// Ideally, the close tag is TOP of tag stack
+						// In malformed HTML, it must not be, so iterate through the stack and remove the tag
+						for i := len(tag_stack) - 1; i >= 0; i-- {
+							if tag_stack[i] == tag {
+								// Found the tag
+								tag_stack[i] = tag_stack[len(tag_stack)-1]
+								tag_stack = tag_stack[:len(tag_stack)-1]
+								break
+							}
+						}
+					}
+
+					new_output.WriteString(tag)
+					new_output.WriteString(">")
+				} else {
+					// Open tag
+
+					tag := ""
+
+					params := false
+					for idx < vLen {
+						c2, size2 := utf8.DecodeRuneInString(value[idx:])
+						if c2 == utf8.RuneError {
+							idx += size2
+							continue
+						}
+
+						new_output.WriteRune(c2)
+
+						// End of tag found
+						if c2 == '>' {
+							idx++ // consume ">"
+							break
+						}
+
+						if !params {
+							if c2 == ' ' {
+								params = true
+							} else {
+								tag += string(c2)
+							}
+						}
+
+						idx += size2
+					}
+
+					// Add tag to stack
+					tag_stack = append(tag_stack, tag)
+				}
+			}
+		} else {
+			idx = fn(c, s, idx)
+		}
+	}
+
+	finalize()
+
+	for i := len(tag_stack) - 1; i >= 0; i-- {
+		tag := tag_stack[i]
+		// Close everything from the regular tag stack
+		new_output.WriteString(fmt.Sprintf("</%s>", tag))
+	}
+}
+
+func filterTruncatesentencesHtml(in *pongo2.Value, param *pongo2.Value) (*pongo2.Value, error) {
+	count := param.Integer()
+	if count <= 0 {
+		return pongo2.AsValue(""), nil
+	}
+
+	value := in.String()
+	newLen := max(param.Integer(), 0)
+
+	new_output := bytes.NewBuffer(nil)
+
+	sentencefilter := 0
+
+	filterTruncateHtmlHelper(value, new_output, func() bool {
+		return sentencefilter >= newLen
+	}, func(_ rune, _ int, idx int) int {
+		// Get next word
+		word_found := false
+
+		for idx < len(value) {
+			c2, size2 := utf8.DecodeRuneInString(value[idx:])
+			if c2 == utf8.RuneError {
+				idx += size2
+				continue
+			}
+
+			if c2 == '<' {
+				// HTML tag start, don't consume it
+				return idx
+			}
+
+			new_output.WriteRune(c2)
+			idx += size2
+
+			if (c2 == '.' && !(idx+1 < len(value) && value[idx+1] >= '0' && value[idx+1] <= '9')) ||
+				c2 == '!' || c2 == '?' || c2 == '\n' {
+				// Sentence ends here, stop capturing it now
+				break
+			} else {
+				word_found = true
+			}
+		}
+
+		if word_found {
+			sentencefilter++
+		}
+
+		return idx
+	}, func() {})
+
+	return pongo2.AsValue(new_output.String()), nil
+}
+
 func filterTimeuntilTimesince(in *pongo2.Value, param *pongo2.Value) (*pongo2.Value, error) {
 	basetime, is_time := in.Interface().(time.Time)
 	if !is_time {