Implemented function to set a field value

pkg/field/utils.go

@@ -13,3 +13,86 @@ func (f Field) Get(x, y int) int {
 func (f Field) isIn(x, y int) bool {
 	return x >= f.x && x < f.x+f.lx && y >= f.y && y < f.y+f.ly
 }
+
+func (f *Field) Set(x, y, v int) {
+	if y >= f.y {
+		if y < f.y+f.ly {
+			l := &f.lines[y-f.y]
+			if l.l == 0 {
+				// an empty line is a special case
+				l.x = x
+				l.l = 1
+				l.columns = append(l.columns, v)
+			} else if x >= l.x {
+				if x < l.x+l.l {
+					// just set the value
+					l.columns[x-l.x] = v
+				} else {
+					// append columns
+					newL := l.l + x - l.x
+					for i := l.l; i < newL-1; i++ {
+						l.columns = append(l.columns, ' ')
+					}
+					l.columns = append(l.columns, v)
+					l.l = newL
+					if f.lx < l.l-l.x {
+						f.lx = l.l - l.x
+					}
+				}
+			} else {
+				// prepend columns
+				newL := l.l + l.x - x
+				c := make([]int, newL)
+				c[0] = v
+				for i := 0; i < l.x-x; i++ {
+					c[i+1] = ' '
+				}
+				for j := 0; j < l.l; j++ {
+					c[j+l.x-x] = l.columns[j]
+				}
+				l.columns = c
+				l.x = x
+				l.l = newL
+				if f.x > x {
+					f.x = x
+					f.lx = newL
+				}
+			}
+		} else {
+			// append lines
+			newLy := y - f.y + 1
+			for i := f.ly; i < newLy-1; i++ {
+				f.lines = append(f.lines, Line{})
+			}
+			f.lines = append(f.lines, Line{x: x, l: 1, columns: []int{v}})
+			f.ly = newLy
+			if f.x > x {
+				f.lx += f.x - x
+				f.x = x
+			} else if f.lx-f.x < x {
+				f.lx = x - f.x
+			}
+		}
+	} else {
+		// prepend lines
+		newLy := f.ly + f.y - y
+		lines := make([]Line, newLy)
+		lines[0] = Line{
+			x:       x,
+			l:       1,
+			columns: []int{v},
+		}
+		for j := 0; j < f.ly; j++ {
+			lines[j+f.y-y] = f.lines[j]
+		}
+		f.lines = lines
+		f.y = y
+		f.ly = newLy
+		if f.x > x {
+			f.lx += f.x - x
+			f.x = x
+		} else if f.lx-f.x < x {
+			f.lx = x - f.x + 1
+		}
+	}
+}