add Go lang examples

README.md

@@ -51,6 +51,24 @@ How to run:
     ./compile-source-code.sh
     ./download
 
+Go language
+-----------
+
+Go examples based on: https://golang.org/
+
+### 01-hello ###
+
+How to run:
+
+    cd 01-hello
+    go run hello.go
+    
+### 02-conway ###
+
+How to run
+
+    cd 02-conway
+    go run conway.go    
 
 GTK+
 ----

golang/01-hello/hello.go

@@ -0,0 +1,8 @@
+package main
+
+import "fmt"
+
+func main() {
+    fmt.Println("Hello, 世界")
+}
+

golang/02-conway/conway.go

@@ -0,0 +1,115 @@
+// An implementation of Conway's Game of Life.
+package main
+
+import (
+    "bytes"
+    "fmt"
+    "math/rand"
+    "time"
+)
+
+// Field represents a two-dimensional field of cells.
+type Field struct {
+    s    [][]bool
+    w, h int
+}
+
+// NewField returns an empty field of the specified width and height.
+func NewField(w, h int) *Field {
+    s := make([][]bool, h)
+    for i := range s {
+        s[i] = make([]bool, w)
+    }
+    return &Field{s: s, w: w, h: h}
+}
+
+// Set sets the state of the specified cell to the given value.
+func (f *Field) Set(x, y int, b bool) {
+    f.s[y][x] = b
+}
+
+// Alive reports whether the specified cell is alive.
+// If the x or y coordinates are outside the field boundaries they are wrapped
+// toroidally. For instance, an x value of -1 is treated as width-1.
+func (f *Field) Alive(x, y int) bool {
+    x += f.w
+    x %= f.w
+    y += f.h
+    y %= f.h
+    return f.s[y][x]
+}
+
+// Next returns the state of the specified cell at the next time step.
+func (f *Field) Next(x, y int) bool {
+    // Count the adjacent cells that are alive.
+    alive := 0
+    for i := -1; i <= 1; i++ {
+        for j := -1; j <= 1; j++ {
+            if (j != 0 || i != 0) && f.Alive(x+i, y+j) {
+                alive++
+            }
+        }
+    }
+    // Return next state according to the game rules:
+    //   exactly 3 neighbors: on,
+    //   exactly 2 neighbors: maintain current state,
+    //   otherwise: off.
+    return alive == 3 || alive == 2 && f.Alive(x, y)
+}
+
+// Life stores the state of a round of Conway's Game of Life.
+type Life struct {
+    a, b *Field
+    w, h int
+}
+
+// NewLife returns a new Life game state with a random initial state.
+func NewLife(w, h int) *Life {
+    a := NewField(w, h)
+    for i := 0; i < (w * h / 4); i++ {
+        a.Set(rand.Intn(w), rand.Intn(h), true)
+    }
+    return &Life{
+        a: a, b: NewField(w, h),
+        w: w, h: h,
+    }
+}
+
+// Step advances the game by one instant, recomputing and updating all cells.
+func (l *Life) Step() {
+    // Update the state of the next field (b) from the current field (a).
+    for y := 0; y < l.h; y++ {
+        for x := 0; x < l.w; x++ {
+            l.b.Set(x, y, l.a.Next(x, y))
+        }
+    }
+    // Swap fields a and b.
+    l.a, l.b = l.b, l.a
+}
+
+// String returns the game board as a string.
+func (l *Life) String() string {
+    var buf bytes.Buffer
+    for y := 0; y < l.h; y++ {
+        for x := 0; x < l.w; x++ {
+            b := byte(' ')
+            if l.a.Alive(x, y) {
+                b = '*'
+            }
+            buf.WriteByte(b)
+        }
+        buf.WriteByte('\n')
+    }
+    return buf.String()
+}
+
+func main() {
+    l := NewLife(40, 15)
+    for i := 0; i < 300; i++ {
+        l.Step()
+        fmt.Print("\x0c", l) // Clear screen and print field.
+        time.Sleep(time.Second / 30)
+    }
+}
+
+