improve parsing of desktop entries.

- speed up parsing by not creating nearly as many strings.
- fix basic whitespace handling. fixes #4

goos: linux
goarch: amd64
pkg: github.com/nwg-piotr/nwg-drawer
cpu: AMD Ryzen 7 1800X Eight-Core Processor
BenchmarkDesktopEntryParserOld-16    	   10000	    146094 ns/op
BenchmarkDesktopEntryParser-16       	   26097	     43303 ns/op
PASS
ok  	github.com/nwg-piotr/nwg-drawer	3.090s

main.go

@@ -59,6 +59,7 @@ type desktopEntry struct {
 	CommentLoc string
 	Icon       string
 	Exec       string
+	Category   string
 	Terminal   bool
 	NoDisplay  bool
 }

tools.go

@@ -350,103 +350,28 @@ func setUpCategories() {
 
 func parseDesktopFiles(desktopFiles []string) string {
 	id2entry = make(map[string]desktopEntry)
-	var added []string
 	skipped := 0
 	hidden := 0
 	for _, file := range desktopFiles {
-		lines, err := loadTextFile(file)
+		id := filepath.Base(file)
-		if err == nil {
+		if _, ok := id2entry[id]; ok {
-			parts := strings.Split(file, "/")
+			skipped++
-			desktopID := parts[len(parts)-1]
+			continue
-			name := ""
-			nameLoc := ""
-			comment := ""
-			commentLoc := ""
-			icon := ""
-			exec := ""
-			terminal := false
-			noDisplay := false
-
-			categories := ""
-
-			for _, l := range lines {
-				if strings.HasPrefix(l, "[") && l != "[Desktop Entry]" {
-					break
-				}
-				if strings.HasPrefix(l, "Name=") {
-					name = strings.Split(l, "=")[1]
-					continue
-				}
-				if strings.HasPrefix(l, fmt.Sprintf("Name[%s]=", strings.Split(*lang, "_")[0])) {
-					nameLoc = strings.Split(l, "=")[1]
-					continue
-				}
-				if strings.HasPrefix(l, "Comment=") {
-					comment = strings.Split(l, "=")[1]
-					continue
-				}
-				if strings.HasPrefix(l, fmt.Sprintf("Comment[%s]=", strings.Split(*lang, "_")[0])) {
-					commentLoc = strings.Split(l, "=")[1]
-					continue
-				}
-				if strings.HasPrefix(l, "Icon=") {
-					icon = strings.Split(l, "=")[1]
-					continue
-				}
-				if strings.HasPrefix(l, "Exec=") {
-					exec = strings.Split(l, "Exec=")[1]
-					disallowed := [2]string{"\"", "'"}
-					for _, char := range disallowed {
-						exec = strings.Replace(exec, char, "", -1)
-					}
-					continue
-				}
-				if strings.HasPrefix(l, "Categories=") {
-					categories = strings.Split(l, "Categories=")[1]
-					continue
-				}
-				if l == "Terminal=true" {
-					terminal = true
-					continue
-				}
-				if l == "NoDisplay=true" {
-					noDisplay = true
-					hidden++
-					continue
-				}
-			}
-
-			// if name[ln] not found, let's try to find name[ln_LN]
-			if nameLoc == "" {
-				nameLoc = name
-			}
-			if commentLoc == "" {
-				commentLoc = comment
-			}
-
-			if !isIn(added, desktopID) {
-				added = append(added, desktopID)
-
-				var entry desktopEntry
-				entry.DesktopID = desktopID
-				entry.Name = name
-				entry.NameLoc = nameLoc
-				entry.Comment = comment
-				entry.CommentLoc = commentLoc
-				entry.Icon = icon
-				entry.Exec = exec
-				entry.Terminal = terminal
-				entry.NoDisplay = noDisplay
-				desktopEntries = append(desktopEntries, entry)
-
-				id2entry[entry.DesktopID] = entry
-
-				assignToLists(entry.DesktopID, categories)
-
-			} else {
-				skipped++
-			}
 		}
+
+		entry, err := parseDesktopEntryFile(id, file)
+		if err != nil {
+			continue
+		}
+
+		if entry.NoDisplay {
+			hidden++
+			continue
+		}
+
+		id2entry[entry.DesktopID] = entry
+		desktopEntries = append(desktopEntries, entry)
+		assignToLists(entry.DesktopID, entry.Category)
 	}
 	sort.Slice(desktopEntries, func(i, j int) bool {
 		return desktopEntries[i].NameLoc < desktopEntries[j].NameLoc

xdgdesktop_parser.go

@@ -0,0 +1,166 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+	"strconv"
+	"strings"
+)
+
+func parseDesktopEntryFileDeprecated(id string, path string) (entry desktopEntry, err error) {
+	lines, err := loadTextFile(path)
+	if err != nil {
+		return entry, err
+	}
+
+	return parseDesktopEntryDeprecated(id, lines)
+}
+
+func parseDesktopEntryDeprecated(id string, lines []string) (entry desktopEntry, err error) {
+	desktopID := id
+	name := ""
+	nameLoc := ""
+	comment := ""
+	commentLoc := ""
+	icon := ""
+	exec := ""
+	categories := ""
+	terminal := false
+	noDisplay := false
+
+	for _, l := range lines {
+		if strings.HasPrefix(l, "[") && l != "[Desktop Entry]" {
+			break
+		}
+		if strings.HasPrefix(l, "Name=") {
+			name = strings.Split(l, "=")[1]
+			continue
+		}
+		if strings.HasPrefix(l, fmt.Sprintf("Name[%s]=", strings.Split(*lang, "_")[0])) {
+			nameLoc = strings.Split(l, "=")[1]
+			continue
+		}
+		if strings.HasPrefix(l, "Comment=") {
+			comment = strings.Split(l, "=")[1]
+			continue
+		}
+		if strings.HasPrefix(l, fmt.Sprintf("Comment[%s]=", strings.Split(*lang, "_")[0])) {
+			commentLoc = strings.Split(l, "=")[1]
+			continue
+		}
+		if strings.HasPrefix(l, "Icon=") {
+			icon = strings.Split(l, "=")[1]
+			continue
+		}
+		if strings.HasPrefix(l, "Exec=") {
+			exec = strings.Split(l, "Exec=")[1]
+			disallowed := [2]string{"\"", "'"}
+			for _, char := range disallowed {
+				exec = strings.Replace(exec, char, "", -1)
+			}
+			continue
+		}
+		if strings.HasPrefix(l, "Categories=") {
+			categories = strings.Split(l, "Categories=")[1]
+			continue
+		}
+		if l == "Terminal=true" {
+			terminal = true
+			continue
+		}
+		if l == "NoDisplay=true" {
+			noDisplay = true
+			continue
+		}
+	}
+
+	// if name[ln] not found, let's try to find name[ln_LN]
+	if nameLoc == "" {
+		nameLoc = name
+	}
+	if commentLoc == "" {
+		commentLoc = comment
+	}
+
+	entry.DesktopID = desktopID
+	entry.Name = name
+	entry.NameLoc = nameLoc
+	entry.Comment = comment
+	entry.CommentLoc = commentLoc
+	entry.Icon = icon
+	entry.Exec = exec
+	entry.Terminal = terminal
+	entry.NoDisplay = noDisplay
+	entry.Category = categories
+	return entry, nil
+}
+
+func parseDesktopEntryFile(id string, path string) (e desktopEntry, err error) {
+	o, err := os.Open(path)
+	if err != nil {
+		return e, err
+	}
+	defer o.Close()
+
+	return parseDesktopEntry(id, o)
+}
+
+func parseDesktopEntry(id string, in io.Reader) (entry desktopEntry, err error) {
+	cleanexec := strings.NewReplacer("\"", "", "'", "")
+	entry.DesktopID = id
+	localizedName := fmt.Sprintf("Name[%s]", strings.Split(*lang, "_")[0])
+	localizedComment := fmt.Sprintf("Comment[%s]", strings.Split(*lang, "_")[0])
+	scanner := bufio.NewScanner(in)
+	scanner.Split(bufio.ScanLines)
+
+	for scanner.Scan() {
+		l := scanner.Text()
+		if strings.HasPrefix(l, "[") && l != "[Desktop Entry]" {
+			break
+		}
+
+		name, value := parseKeypair(l)
+		if value == "" {
+			continue
+		}
+
+		switch name {
+		case "Name":
+			entry.Name = value
+		case localizedName:
+			entry.NameLoc = value
+		case "Comment":
+			entry.Comment = value
+		case localizedComment:
+			entry.CommentLoc = value
+		case "Icon":
+			entry.Icon = value
+		case "Categories":
+			entry.Category = value
+		case "Terminal":
+			entry.Terminal, _ = strconv.ParseBool(value)
+		case "NoDisplay":
+			entry.NoDisplay, _ = strconv.ParseBool(value)
+		case "Exec":
+			entry.Exec = cleanexec.Replace(value)
+		}
+	}
+
+	// if name[ln] not found, let's try to find name[ln_LN]
+	if entry.NameLoc == "" {
+		entry.NameLoc = entry.Name
+	}
+	if entry.CommentLoc == "" {
+		entry.CommentLoc = entry.Comment
+	}
+	return entry, err
+}
+
+func parseKeypair(s string) (string, string) {
+	if idx := strings.IndexRune(s, '='); idx > 0 {
+		return strings.TrimSpace(s[:idx]), strings.TrimSpace(s[idx+1:])
+	}
+	return s, ""
+}

xdgdesktop_parser_test.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+	"strings"
+	"testing"
+)
+
+var result desktopEntry
+
+func BenchmarkDesktopEntryParserOld(b *testing.B) {
+	var entry desktopEntry
+	for n := 0; n < b.N; n++ {
+		entry, _ = parseDesktopEntryFileDeprecated("id", "./desktop-directories/game.directory")
+	}
+	result = entry
+}
+
+func BenchmarkDesktopEntryParser(b *testing.B) {
+	var entry desktopEntry
+	for n := 0; n < b.N; n++ {
+		entry, _ = parseDesktopEntryFile("id", "./desktop-directories/game.directory")
+	}
+	result = entry
+}
+
+func TestWhitespaceHandling(t *testing.T) {
+	const whitespace = `[Desktop Entry]
+	Categories = Debugger; Development; Git; IDE; Programming; TextEditor; 
+	Comment = Editor for building and debugging modern web and cloud applications
+	Exec = bash -c "code-insiders ~/Workspaces/Linux/Flutter.code-workspace"
+	GenericName = Text Editor
+	Icon = vscode-flutter
+	Keywords = editor; IDE; plaintext; text; write; 
+	MimeType = application/x-shellscript; inode/directory; text/english; text/plain; text/x-c; text/x-c++; text/x-c++hdr; text/x-c++src; text/x-chdr; text/x-csrc; text/x-java; text/x-makefile; text/x-moc; text/x-pascal; text/x-tcl; text/x-tex; 
+	Name = VSCode Insiders with Flutter
+	Name[pt] = VSCode Insiders com Flutter
+	StartupNotify = true
+	StartupWMClass = code - insiders
+	Terminal = false
+	NoDisplay = false
+	Type = Application
+	Version = 1.0`
+
+	// entry, err := parseDesktopEntryDeprecated("id", strings.Split(whitespace, "\n"))
+	*lang = "pt"
+	entry, err := parseDesktopEntry("id", strings.NewReader(whitespace))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if entry.Name != "VSCode Insiders with Flutter" {
+		t.Error("failed to parse desktop entry name")
+	}
+
+	if entry.NameLoc != "VSCode Insiders com Flutter" {
+		t.Error("failed to parse localized name")
+	}
+
+	if entry.NoDisplay {
+		t.Error("failed to parse desktop entry no display")
+	}
+}