Written the first version of a text reader, with

tests

io/reader/text.go

@@ -0,0 +1,125 @@
+package reader
+
+import (
+	"bufio"
+	"fmt"
+	"maze-solver/maze"
+	"os"
+)
+
+type TextReader struct {
+	PathChar, WallChar byte
+}
+
+func (r *TextReader) Read(filename string) (*maze.Maze, error) {
+	nodesByCoord := make(map[maze.Coordinates]*maze.Node)
+	var lines []string
+
+	ret := &maze.Maze{}
+
+	if _, err := os.Stat(filename); err != nil {
+		return nil, err
+	}
+
+	file, err := os.Open(filename)
+	if err != nil {
+		return nil, err
+	}
+
+	scanner := bufio.NewScanner(file)
+	scanner.Split(bufio.ScanLines)
+
+	y := 0
+	var line string
+	for scanner.Scan() {
+		line = scanner.Text()
+
+		if len(lines) == 0 {
+			lines = make([]string, 0, len(line))
+		}
+
+		for x := 1; x < len(line)-1; x++ {
+			char := line[x]
+			var left_char, right_char, above_char byte
+
+			if y > 0 {
+				left_char = line[x-1]
+				right_char = line[x+1]
+				above_char = lines[y-1][x]
+			}
+
+			// Parse first line to get entrance
+			if y == 0 && char == r.PathChar {
+				coords := maze.Coordinates{X: x, Y: y}
+				node := maze.NewNode(coords)
+				ret.Nodes = append(ret.Nodes, node)
+				nodesByCoord[coords] = node
+				continue
+			}
+
+			// Parse middle of the maze
+			if y > 0 && char == r.PathChar &&
+				(left_char == r.WallChar && right_char == r.PathChar ||
+					left_char == r.PathChar && right_char == r.WallChar ||
+					above_char == r.PathChar && (left_char == r.PathChar || right_char == r.PathChar)) {
+				coords := maze.Coordinates{X: x, Y: y}
+				node := maze.NewNode(coords)
+				ret.Nodes = append(ret.Nodes, node)
+				nodesByCoord[coords] = node
+
+				r.lookupNeighbourAbove(&lines, node, &nodesByCoord)
+				if left_char == r.PathChar && right_char == r.WallChar ||
+					above_char == r.PathChar && (left_char == r.PathChar || right_char == r.PathChar) {
+					r.lookupNeighbourLeft(&line, node, &nodesByCoord)
+				}
+			}
+		}
+		lines = append(lines, line)
+		y++
+	}
+	y--
+	// Parse last line to get exit
+	for x, rune := range line {
+		char := byte(rune)
+		if char == r.PathChar {
+			fmt.Printf("last line number: %v\n", y)
+			coords := maze.Coordinates{X: x, Y: y}
+			node := maze.NewNode(coords)
+			r.lookupNeighbourAbove(&lines, node, &nodesByCoord)
+			ret.Nodes = append(ret.Nodes, node)
+			break
+		}
+	}
+
+	return ret, nil
+}
+
+func (r *TextReader) lookupNeighbourAbove(lines *[]string, node *maze.Node, nodesByCoord *map[maze.Coordinates]*maze.Node) {
+	for y := node.Coords.Y - 1; y >= 0; y-- {
+		if (*lines)[y][node.Coords.X] == r.WallChar {
+			break
+		}
+
+		neighbour, ok := (*nodesByCoord)[maze.Coordinates{X: node.Coords.X, Y: y}]
+		if ok {
+			node.Up = neighbour
+			neighbour.Down = node
+		}
+	}
+}
+
+func (r *TextReader) lookupNeighbourLeft(line *string, node *maze.Node, nodesByCoord *map[maze.Coordinates]*maze.Node) {
+	for x := node.Coords.X - 1; x > 0; x-- {
+		if (*line)[x] == r.WallChar {
+			panic(fmt.Sprintf("Found no node before wall while looking to the left at neighbours of node %v", node))
+		}
+
+		neighbour, ok := (*nodesByCoord)[maze.Coordinates{X: x, Y: node.Coords.Y}]
+		if ok {
+			node.Left = neighbour
+			fmt.Printf("Setting left of %v to %v\n", node.Coords, neighbour.Coords)
+			neighbour.Right = node
+			break
+		}
+	}
+}