Added AppendHTMLEscape helper function

bytesconv.go

@@ -12,6 +12,37 @@ import (
 	"unsafe"
 )
 
+// AppendHTMLEscape appends html-escaped s to dst and returns the extended dst.
+func AppendHTMLEscape(dst []byte, s string) []byte {
+	var prev int
+	var sub string
+	for i, n := 0, len(s); i < n; i++ {
+		sub = ""
+		switch s[i] {
+		case '<':
+			sub = "&lt;"
+		case '>':
+			sub = "&gt;"
+		case '"':
+			sub = "&quot;"
+		case '\'':
+			sub = "&#39;"
+		}
+		if len(sub) > 0 {
+			dst = append(dst, s[prev:i]...)
+			dst = append(dst, sub...)
+			prev = i + 1
+		}
+	}
+	return append(dst, s[prev:]...)
+}
+
+// AppendHTMLEscapeBytes appends html-escaped s to dst and returns
+// the extended dst.
+func AppendHTMLEscapeBytes(dst, s []byte) []byte {
+	return AppendHTMLEscape(dst, unsafeBytesToStr(s))
+}
+
 // AppendIPv4 appends string representation of the given ip v4 to dst
 // and returns the extended dst.
 func AppendIPv4(dst []byte, ip net.IP) []byte {

bytesconv_test.go

@@ -9,6 +9,21 @@ import (
 	"time"
 )
 
+func TestAppendHTMLEscape(t *testing.T) {
+	testAppendHTMLEscape(t, "", "")
+	testAppendHTMLEscape(t, "<", "&lt;")
+	testAppendHTMLEscape(t, "a", "a")
+	testAppendHTMLEscape(t, `><"''`, "&gt;&lt;&quot;&#39;&#39;")
+	testAppendHTMLEscape(t, "fo<b x='ss'>a</b>xxx", "fo&lt;b x=&#39;ss&#39;&gt;a&lt;/b&gt;xxx")
+}
+
+func testAppendHTMLEscape(t *testing.T, s, expectedS string) {
+	buf := AppendHTMLEscapeBytes(nil, []byte(s))
+	if string(buf) != expectedS {
+		t.Fatalf("unexpected html-escaped string %q. Expecting %q. Original string %q", buf, expectedS, s)
+	}
+}
+
 func TestParseIPv4(t *testing.T) {
 	testParseIPv4(t, "0.0.0.0", true)
 	testParseIPv4(t, "255.255.255.255", true)

bytesconv_timing_test.go

@@ -2,10 +2,43 @@ package fasthttp
 
 import (
 	"bufio"
+	"html"
 	"net"
 	"testing"
 )
 
+func BenchmarkAppendHTMLEscape(b *testing.B) {
+	sOrig := "<b>foobarbazxxxyyyzzz</b>"
+	sExpected := string(AppendHTMLEscape(nil, sOrig))
+	b.RunParallel(func(pb *testing.PB) {
+		var buf []byte
+		for pb.Next() {
+			for i := 0; i < 10; i++ {
+				buf = AppendHTMLEscape(buf[:0], sOrig)
+				if string(buf) != sExpected {
+					b.Fatalf("unexpected escaped string: %s. Expecting %s", buf, sExpected)
+				}
+			}
+		}
+	})
+}
+
+func BenchmarkHTMLEscapeString(b *testing.B) {
+	sOrig := "<b>foobarbazxxxyyyzzz</b>"
+	sExpected := html.EscapeString(sOrig)
+	b.RunParallel(func(pb *testing.PB) {
+		var s string
+		for pb.Next() {
+			for i := 0; i < 10; i++ {
+				s = html.EscapeString(sOrig)
+				if s != sExpected {
+					b.Fatalf("unexpected escaped string: %s. Expecting %s", s, sExpected)
+				}
+			}
+		}
+	})
+}
+
 func BenchmarkParseIPv4(b *testing.B) {
 	ipStr := []byte("123.145.167.189")
 	b.RunParallel(func(pb *testing.PB) {