Allows opening files using full path on Windows (#1126)

* Now can open Windows full-path from command line arg

Example that now works: micro.exe D:\myfile.txt

* Now correctly retrieves the path from the input path string. Except for single-letter filenames

* Fixed line/cols, need to make the code prettier

* Fixed path matching with regex by @Pariador

* Fixed not stripping the line/col args from file path

* Added tests for ParseCursorLocation

cmd/micro/util.go

@@ -12,6 +12,7 @@ import (
 	"unicode/utf8"
 
 	"github.com/mattn/go-runewidth"
+	"regexp"
 )
 
 // Util.go is a collection of utility functions that are used throughout
@@ -356,11 +357,43 @@ func ReplaceHome(path string) string {
 	return strings.Replace(path, homeString, home, 1)
 }
 
-// GetPath returns a filename without everything following a `:`
+// GetPathAndCursorPosition returns a filename without everything following a `:`
 // This is used for opening files like util.go:10:5 to specify a line and column
-func GetPath(path string) string {
-	if strings.Contains(path, ":") {
-		path = strings.Split(path, ":")[0]
+// Special cases like Windows Absolute path (C:\myfile.txt:10:5) are handled correctly.
+func GetPathAndCursorPosition(path string) (string, []string) {
+	re := regexp.MustCompile(`([\s\S]+?)(?::(\d+))(?::(\d+))?`)
+	match := re.FindStringSubmatch(path)
+	// no lines/columns were specified in the path, return just the path with cursor at 0, 0
+	if len(match) == 0 {
+		return path, []string{"0", "0"}
+	} else if match[len(match)-1] != "" {
+		// if the last capture group match isn't empty then both line and column were provided
+		return match[1], match[2:]
 	}
-	return path
+	// if it was empty, then only a line was provided, so default to column 0
+	return match[1], []string{match[2], "0"}
+}
+
+func ParseCursorLocation(cursorPositions []string) (Loc, error) {
+	startpos := Loc{0, 0}
+	var err error
+
+	// if no positions are available exit early
+	if len(cursorPositions) == 0 {
+		return startpos, err
+	}
+
+	startpos.Y, err = strconv.Atoi(cursorPositions[0])
+	if err != nil {
+		messenger.Error("Error parsing cursor position: ", err)
+	} else {
+		if len(cursorPositions) > 1 {
+			startpos.X, err = strconv.Atoi(cursorPositions[1])
+			if err != nil {
+				messenger.Error("Error parsing cursor position: ", err)
+			}
+		}
+	}
+
+	return startpos, err
 }