Added RLE parser by N.Hoffmann and incorporated it onto my gol.

rle/rle.go

@@ -0,0 +1,100 @@
+// source: https://github.com/nhoffmann/life by N.Hoffmann 2020.
+package rle
+
+import (
+	"fmt"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+type RLE struct {
+	Rule    string  // rule
+	Width   int     // x
+	Height  int     // y
+	Pattern [][]int // The actual pattern
+
+	inputLines       []string
+	headerLineIndex  int
+	patternLineIndex int
+}
+
+func Parse(input string) (RLE, error) {
+	rle := RLE{
+		inputLines: strings.Split(input, "\n"),
+	}
+
+	rle.partitionFile()
+
+	err := rle.parseComments()
+	if err != nil {
+		return RLE{}, err
+	}
+	err = rle.parseHeader()
+	if err != nil {
+		return RLE{}, err
+	}
+	err = rle.parsePattern()
+	if err != nil {
+		return RLE{}, err
+	}
+
+	return rle, nil
+}
+
+func (rle *RLE) partitionFile() error {
+	for index, line := range rle.inputLines {
+		cleanLine := removeWhitespace(line)
+		if strings.HasPrefix(cleanLine, "x=") {
+			rle.headerLineIndex = index
+			rle.patternLineIndex = index + 1
+			return nil
+		}
+	}
+
+	return fmt.Errorf("Invlaid input: Header is missing")
+}
+
+func (rle *RLE) parseComments() error {
+	return nil
+}
+
+func (rle *RLE) parseHeader() (err error) {
+	headerLine := removeWhitespace(rle.inputLines[rle.headerLineIndex])
+
+	headerElements := strings.SplitN(headerLine, ",", 3)
+
+	rle.Width, err = strconv.Atoi(strings.TrimPrefix(headerElements[0], "x="))
+	if err != nil {
+		return err
+	}
+	rle.Height, err = strconv.Atoi(strings.TrimPrefix(headerElements[1], "y="))
+	if err != nil {
+		return err
+	}
+
+	rle.Pattern = make([][]int, rle.Width)
+
+	// check wehter a rule is present, since it's optional
+	if len(headerElements) == 3 {
+		rle.Rule = strings.TrimPrefix(headerElements[2], "rule=")
+	}
+
+	return nil
+}
+
+func (rle *RLE) parsePattern() error {
+	patternString := strings.Join(rle.inputLines[rle.patternLineIndex:], "")
+
+	l := NewLexer(patternString)
+	pp := NewParser(l)
+
+	rle.Pattern = pp.ParsePattern(rle.Width, rle.Height)
+
+	return nil
+}
+
+func removeWhitespace(input string) string {
+	re := regexp.MustCompile(` *\t*\r*\n*`)
+	return re.ReplaceAllString(input, "")
+}