Change SummaryLength to be configurable (#3924)

Move SummaryLength into the ContentSpec struct and refactor the
relevant summary functions to be methods of ContentSpec. The new
summaryLength struct member is configurable by the summaryLength config
value, and the default remains 70. Also updates hugolib/page to use the
refactored methods.

Resolves #3734

docs/content/getting-started/configuration.md

@@ -111,6 +111,8 @@ googleAnalytics:            ""
 # if true, auto-detect Chinese/Japanese/Korean Languages in the content. (.Summary and .WordCount can work properly in CJKLanguage)
 hasCJKLanguage:             false
 languageCode:               ""
+# the length of text to show in a .Summary
+summaryLength:              70
 layoutDir:                  "layouts"
 # Enable Logging
 log:                        false
@@ -252,6 +254,8 @@ googleAnalytics =             ""
 # if true, auto-detect Chinese/Japanese/Korean Languages in the content. (.Summary and .WordCount can work properly in CJKLanguage)
 hasCJKLanguage =              false
 languageCode =                ""
+# the length of text to show in a .Summary
+summaryLength:              70
 layoutDir =                   "layouts"
 # Enable Logging
 log =                         false

helpers/content.go

@@ -36,9 +36,6 @@ import (
 	"strings"
 )
 
-// SummaryLength is the length of the summary that Hugo extracts from a content.
-var SummaryLength = 70
-
 // SummaryDivider denotes where content summarization should end. The default is "<!--more-->".
 var SummaryDivider = []byte("<!--more-->")
 
@@ -47,6 +44,8 @@ type ContentSpec struct {
 	blackfriday                map[string]interface{}
 	footnoteAnchorPrefix       string
 	footnoteReturnLinkContents string
+	// SummaryLength is the length of the summary that Hugo extracts from a content.
+	summaryLength int
 
 	Highlight            func(code, lang, optsStr string) (string, error)
 	defatultPygmentsOpts map[string]string
@@ -61,6 +60,7 @@ func NewContentSpec(cfg config.Provider) (*ContentSpec, error) {
 		blackfriday:                cfg.GetStringMap("blackfriday"),
 		footnoteAnchorPrefix:       cfg.GetString("footnoteAnchorPrefix"),
 		footnoteReturnLinkContents: cfg.GetString("footnoteReturnLinkContents"),
+		summaryLength:              cfg.GetInt("summaryLength"),
 
 		cfg: cfg,
 	}
@@ -480,20 +480,20 @@ func totalWordsOld(s string) int {
 }
 
 // TruncateWordsByRune truncates words by runes.
-func TruncateWordsByRune(words []string, max int) (string, bool) {
+func (c *ContentSpec) TruncateWordsByRune(words []string) (string, bool) {
 	count := 0
 	for index, word := range words {
-		if count >= max {
+		if count >= c.summaryLength {
 			return strings.Join(words[:index], " "), true
 		}
 		runeCount := utf8.RuneCountInString(word)
 		if len(word) == runeCount {
 			count++
-		} else if count+runeCount < max {
+		} else if count+runeCount < c.summaryLength {
 			count += runeCount
 		} else {
 			for ri := range word {
-				if count >= max {
+				if count >= c.summaryLength {
 					truncatedWords := append(words[:index], word[:ri])
 					return strings.Join(truncatedWords, " "), true
 				}
@@ -507,8 +507,7 @@ func TruncateWordsByRune(words []string, max int) (string, bool) {
 
 // TruncateWordsToWholeSentence takes content and truncates to whole sentence
 // limited by max number of words. It also returns whether it is truncated.
-func TruncateWordsToWholeSentence(s string, max int) (string, bool) {
+func (c *ContentSpec) TruncateWordsToWholeSentence(s string) (string, bool) {
-
 	var (
 		wordCount     = 0
 		lastWordIndex = -1
@@ -519,7 +518,7 @@ func TruncateWordsToWholeSentence(s string, max int) (string, bool) {
 			wordCount++
 			lastWordIndex = i
 
-			if wordCount >= max {
+			if wordCount >= c.summaryLength {
 				break
 			}
 
@@ -551,24 +550,24 @@ func isEndOfSentence(r rune) bool {
 }
 
 // Kept only for benchmark.
-func truncateWordsToWholeSentenceOld(content string, max int) (string, bool) {
+func (c *ContentSpec) truncateWordsToWholeSentenceOld(content string) (string, bool) {
 	words := strings.Fields(content)
 
-	if max >= len(words) {
+	if c.summaryLength >= len(words) {
 		return strings.Join(words, " "), false
 	}
 
-	for counter, word := range words[max:] {
+	for counter, word := range words[c.summaryLength:] {
 		if strings.HasSuffix(word, ".") ||
 			strings.HasSuffix(word, "?") ||
 			strings.HasSuffix(word, ".\"") ||
 			strings.HasSuffix(word, "!") {
-			upper := max + counter + 1
+			upper := c.summaryLength + counter + 1
 			return strings.Join(words[:upper], " "), (upper < len(words))
 		}
 	}
 
-	return strings.Join(words[:max], " "), true
+	return strings.Join(words[:c.summaryLength], " "), true
 }
 
 func getAsciidocExecPath() string {

helpers/content_test.go

@@ -76,20 +76,23 @@ func TestBytesToHTML(t *testing.T) {
 var benchmarkTruncateString = strings.Repeat("This is a sentence about nothing.", 20)
 
 func BenchmarkTestTruncateWordsToWholeSentence(b *testing.B) {
+	c := newTestContentSpec()
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
-		TruncateWordsToWholeSentence(benchmarkTruncateString, SummaryLength)
+		c.TruncateWordsToWholeSentence(benchmarkTruncateString)
 	}
 }
 
 func BenchmarkTestTruncateWordsToWholeSentenceOld(b *testing.B) {
+	c := newTestContentSpec()
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
-		truncateWordsToWholeSentenceOld(benchmarkTruncateString, SummaryLength)
+		c.truncateWordsToWholeSentenceOld(benchmarkTruncateString)
 	}
 }
 
 func TestTruncateWordsToWholeSentence(t *testing.T) {
+	c := newTestContentSpec()
 	type test struct {
 		input, expected string
 		max             int
@@ -104,9 +107,11 @@ func TestTruncateWordsToWholeSentence(t *testing.T) {
 		{"To be. Or not to be. That's the question.", "To be.", 1, true},
 		{" \nThis is not a sentence\nAnd this is another", "This is not a sentence", 4, true},
 		{"", "", 10, false},
+		{"This... is a more difficult test?", "This... is a more difficult test?", 1, false},
 	}
 	for i, d := range data {
-		output, truncated := TruncateWordsToWholeSentence(d.input, d.max)
+		c.summaryLength = d.max
+		output, truncated := c.TruncateWordsToWholeSentence(d.input)
 		if d.expected != output {
 			t.Errorf("Test %d failed. Expected %q got %q", i, d.expected, output)
 		}
@@ -118,6 +123,7 @@ func TestTruncateWordsToWholeSentence(t *testing.T) {
 }
 
 func TestTruncateWordsByRune(t *testing.T) {
+	c := newTestContentSpec()
 	type test struct {
 		input, expected string
 		max             int
@@ -139,7 +145,8 @@ func TestTruncateWordsByRune(t *testing.T) {
 		{" \nThis is    not a sentence\n ", "This is not", 3, true},
 	}
 	for i, d := range data {
-		output, truncated := TruncateWordsByRune(strings.Fields(d.input), d.max)
+		c.summaryLength = d.max
+		output, truncated := c.TruncateWordsByRune(strings.Fields(d.input))
 		if d.expected != output {
 			t.Errorf("Test %d failed. Expected %q got %q", i, d.expected, output)
 		}

hugolib/config.go

@@ -135,6 +135,7 @@ func loadDefaultSettingsFor(v *viper.Viper) error {
 	v.SetDefault("newContentEditor", "")
 	v.SetDefault("paginate", 10)
 	v.SetDefault("paginatePath", "page")
+	v.SetDefault("summaryLength", 70)
 	v.SetDefault("blackfriday", c.NewBlackfriday())
 	v.SetDefault("rSSUri", "index.xml")
 	v.SetDefault("rssLimit", -1)

hugolib/page.go

@@ -677,9 +677,9 @@ func (p *Page) setAutoSummary() error {
 	var summary string
 	var truncated bool
 	if p.isCJKLanguage {
-		summary, truncated = helpers.TruncateWordsByRune(p.PlainWords(), helpers.SummaryLength)
+		summary, truncated = p.s.ContentSpec.TruncateWordsByRune(p.PlainWords())
 	} else {
-		summary, truncated = helpers.TruncateWordsToWholeSentence(p.Plain(), helpers.SummaryLength)
+		summary, truncated = p.s.ContentSpec.TruncateWordsToWholeSentence(p.Plain())
 	}
 	p.Summary = template.HTML(summary)
 	p.Truncated = truncated