Break util func into a new file

cmd/mungedocs/util.go

@@ -0,0 +1,67 @@
+/*
+Copyright 2015 The Kubernetes Authors All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"strings"
+)
+
+// Replaces the text between matching "beginMark" and "endMark" within "document" with "insertThis".
+//
+// Delimiters should occupy own line.
+// Returns copy of document with modifications.
+func updateMacroBlock(document []byte, beginMark, endMark, insertThis string) ([]byte, error) {
+	var buffer bytes.Buffer
+	lines := strings.Split(string(document), "\n")
+	// Skip trailing empty string from Split-ing
+	if len(lines) > 0 && lines[len(lines)-1] == "" {
+		lines = lines[:len(lines)-1]
+	}
+	betweenBeginAndEnd := false
+	for _, line := range lines {
+		trimmedLine := strings.Trim(line, " \n")
+		if trimmedLine == beginMark {
+			if betweenBeginAndEnd {
+				return nil, fmt.Errorf("found second begin mark while updating macro blocks")
+			}
+			betweenBeginAndEnd = true
+			buffer.WriteString(line)
+			buffer.WriteString("\n")
+		} else if trimmedLine == endMark {
+			if !betweenBeginAndEnd {
+				return nil, fmt.Errorf("found end mark without being mark while updating macro blocks")
+			}
+			buffer.WriteString(insertThis)
+			// Extra newline avoids github markdown bug where comment ends up on same line as last bullet.
+			buffer.WriteString("\n")
+			buffer.WriteString(line)
+			buffer.WriteString("\n")
+			betweenBeginAndEnd = false
+		} else {
+			if !betweenBeginAndEnd {
+				buffer.WriteString(line)
+				buffer.WriteString("\n")
+			}
+		}
+	}
+	if betweenBeginAndEnd {
+		return nil, fmt.Errorf("never found closing end mark while updating macro blocks")
+	}
+	return buffer.Bytes(), nil
+}