From eff64c563f75c50f8af0ec650e719846efff659b Mon Sep 17 00:00:00 2001
From: Russ Ross <russ@russross.com>
Date: Sat, 25 Jun 2011 15:02:46 -0600
Subject: [PATCH] reduce copying for lists

---
 block.go    | 20 +++++++++++---------
 html.go     | 52 ++++++++++++++++++++++++++++++----------------------
 latex.go    |  8 ++++++--
 markdown.go |  2 +-
 4 files changed, 48 insertions(+), 34 deletions(-)

diff --git a/block.go b/block.go
index abe627d..5ba599f 100644
--- a/block.go
+++ b/block.go
@@ -882,20 +882,22 @@ func blockOliPrefix(data []byte) int {
 
 // parse ordered or unordered list block
 func blockList(out *bytes.Buffer, rndr *render, data []byte, flags int) int {
-	var work bytes.Buffer
+	i := 0
+	work := func() bool {
+		j := 0
+		for i < len(data) {
+			j = blockListItem(out, rndr, data[i:], &flags)
+			i += j
 
-	i, j := 0, 0
-	for i < len(data) {
-		j = blockListItem(&work, rndr, data[i:], &flags)
-		i += j
-
-		if j == 0 || flags&LIST_ITEM_END_OF_LIST != 0 {
-			break
+			if j == 0 || flags&LIST_ITEM_END_OF_LIST != 0 {
+				break
+			}
 		}
+		return true
 	}
 
 	if rndr.mk.List != nil {
-		rndr.mk.List(out, work.Bytes(), flags, rndr.mk.Opaque)
+		rndr.mk.List(out, work, flags, rndr.mk.Opaque)
 	}
 	return i
 }
diff --git a/html.go b/html.go
index 2ec7997..e8543b4 100644
--- a/html.go
+++ b/html.go
@@ -123,39 +123,42 @@ func HtmlTocRenderer(flags int) *Renderer {
 func attrEscape(out *bytes.Buffer, src []byte) {
 	org := 0
 	for i, ch := range src {
-		// doing this check is a bit faster than falling into
-		// the switch statement. as the compiler improves, this
-		// should be unnecessary
-		if ch != '"' && ch != '&' && ch != '<' && ch != '>' {
-			continue
-		}
-
-		switch ch {
-		case '<':
+		// using if statements is a bit faster than a switch statement.
+		// as the compiler improves, this should be unnecessary
+		// this is only worthwhile because attrEscape is the single
+		// largest CPU user in normal use
+		if ch == '"' {
 			if i > org {
 				// copy all the normal characters since the last escape
 				out.Write(src[org:i])
 			}
 			org = i + 1
-			out.WriteString("&lt;")
-		case '>':
-			if i > org {
-				out.Write(src[org:i])
-			}
-			org = i + 1
-			out.WriteString("&gt;")
-		case '&':
+			out.WriteString("&quot;")
+			continue
+		}
+		if ch == '&' {
 			if i > org {
 				out.Write(src[org:i])
 			}
 			org = i + 1
 			out.WriteString("&amp;")
-		case '"':
+			continue
+		}
+		if ch == '<' {
 			if i > org {
 				out.Write(src[org:i])
 			}
 			org = i + 1
-			out.WriteString("&quot;")
+			out.WriteString("&lt;")
+			continue
+		}
+		if ch == '>' {
+			if i > org {
+				out.Write(src[org:i])
+			}
+			org = i + 1
+			out.WriteString("&gt;")
+			continue
 		}
 	}
 	if org < len(src) {
@@ -351,8 +354,10 @@ func htmlTableCell(out *bytes.Buffer, text []byte, align int, opaque interface{}
 	out.WriteString("</td>")
 }
 
-func htmlList(out *bytes.Buffer, text []byte, flags int, opaque interface{}) {
-	if out.Len() > 0 {
+func htmlList(out *bytes.Buffer, text func() bool, flags int, opaque interface{}) {
+	marker := out.Len()
+
+	if marker > 0 {
 		out.WriteByte('\n')
 	}
 	if flags&LIST_TYPE_ORDERED != 0 {
@@ -360,7 +365,10 @@ func htmlList(out *bytes.Buffer, text []byte, flags int, opaque interface{}) {
 	} else {
 		out.WriteString("<ul>\n")
 	}
-	out.Write(text)
+	if !text() {
+		out.Truncate(marker)
+		return
+	}
 	if flags&LIST_TYPE_ORDERED != 0 {
 		out.WriteString("</ol>\n")
 	} else {
diff --git a/latex.go b/latex.go
index 3a617a4..34f49e6 100644
--- a/latex.go
+++ b/latex.go
@@ -104,13 +104,17 @@ func latexHRule(out *bytes.Buffer, opaque interface{}) {
 	out.WriteString("\n\\HRule\n")
 }
 
-func latexList(out *bytes.Buffer, text []byte, flags int, opaque interface{}) {
+func latexList(out *bytes.Buffer, text func() bool, flags int, opaque interface{}) {
+	marker := out.Len()
 	if flags&LIST_TYPE_ORDERED != 0 {
 		out.WriteString("\n\\begin{enumerate}\n")
 	} else {
 		out.WriteString("\n\\begin{itemize}\n")
 	}
-	out.Write(text)
+	if !text() {
+		out.Truncate(marker)
+		return
+	}
 	if flags&LIST_TYPE_ORDERED != 0 {
 		out.WriteString("\n\\end{enumerate}\n")
 	} else {
diff --git a/markdown.go b/markdown.go
index 0d5c0bd..eb7a07f 100644
--- a/markdown.go
+++ b/markdown.go
@@ -101,7 +101,7 @@ type Renderer struct {
 	BlockHtml  func(out *bytes.Buffer, text []byte, opaque interface{})
 	Header     func(out *bytes.Buffer, text func() bool, level int, opaque interface{})
 	HRule      func(out *bytes.Buffer, opaque interface{})
-	List       func(out *bytes.Buffer, text []byte, flags int, opaque interface{})
+	List       func(out *bytes.Buffer, text func() bool, flags int, opaque interface{})
 	ListItem   func(out *bytes.Buffer, text []byte, flags int, opaque interface{})
 	Paragraph  func(out *bytes.Buffer, text []byte, opaque interface{})
 	Table      func(out *bytes.Buffer, header []byte, body []byte, columnData []int, opaque interface{})