Prevent an importer from importing the same page more than once

importer.go

@@ -7,12 +7,13 @@ import (
 
 // The Importer class to be used by a pdf generation library
 type Importer struct {
-	sourceFile string
-	readers    map[string]*PdfReader
-	writers    map[string]*PdfWriter
-	tplMap     map[int]*TplInfo
-	tplN       int
-	writer     *PdfWriter
+	sourceFile    string
+	readers       map[string]*PdfReader
+	writers       map[string]*PdfWriter
+	tplMap        map[int]*TplInfo
+	tplN          int
+	writer        *PdfWriter
+	importedPages map[string]int
 }
 
 type TplInfo struct {
@@ -57,6 +58,7 @@ func (this *Importer) init() {
 	this.writers = make(map[string]*PdfWriter, 0)
 	this.tplMap = make(map[int]*TplInfo, 0)
 	this.writer, _ = NewPdfWriter("")
+	this.importedPages = make(map[string]int, 0)
 }
 
 func (this *Importer) SetSourceFile(f string) {
@@ -129,6 +131,12 @@ func (this *Importer) GetPageSizes() map[int]map[string]map[string]float64 {
 }
 
 func (this *Importer) ImportPage(pageno int, box string) int {
+	// If page has already been imported, return existing tplN
+	pageNameNumber := fmt.Sprintf("%s-%04d", this.sourceFile, pageno)
+	if _, ok := this.importedPages[pageNameNumber]; ok {
+		return this.importedPages[pageNameNumber]
+	}
+
 	res, err := this.GetWriter().ImportPage(this.GetReader(), pageno, box)
 	if err != nil {
 		panic(err)
@@ -143,6 +151,9 @@ func (this *Importer) ImportPage(pageno int, box string) int {
 	// Increment template id
 	this.tplN++
 
+	// Cache imported page tplN
+	this.importedPages[pageNameNumber] = tplN
+
 	return tplN
 }