Added reader interface exercises, along with rot13Exercise & image generator exercise

Author: anarchymonkey

go_basics/go.work

@@ -12,6 +12,7 @@ use (
 	./methods
 	./numeric_constants
 	./pointers
+	./reader
 	./structs
 	./typeConversionsAndInferrence
 	./variables

go_basics/reader/customImages/customImages.go

@@ -0,0 +1,34 @@
+package main
+
+import (
+	"image"
+	"image/color"
+	"math/rand"
+
+	"golang.org/x/tour/pic"
+)
+
+type MyImage struct {
+	X, Y int
+}
+
+func (img MyImage) Bounds() image.Rectangle {
+	return image.Rect(0, 0, img.X, img.Y)
+}
+
+func (img MyImage) ColorModel() color.Model {
+	return color.RGBAModel
+}
+
+func (img MyImage) At(x, y int) color.Color {
+	v := uint8(rand.Intn(255))
+	// returning Red, Green random with blue fixed
+	return color.RGBA{v, v, 255, 255}
+}
+
+func main() {
+	i := MyImage{X: 100, Y: 100}
+
+	pic.ShowImage(i)
+
+}

go_basics/reader/customImages/go.mod

@@ -0,0 +1,5 @@
+module anarchymonkey.com/go-basics/reader/customImages
+
+go 1.20
+
+require golang.org/x/tour v0.1.0

go_basics/reader/customImages/go.sum

@@ -0,0 +1,2 @@
+golang.org/x/tour v0.1.0 h1:OWzbINRoGf1wwBhKdFDpYwM88NM0d1SL/Nj6PagS6YE=
+golang.org/x/tour v0.1.0/go.mod h1:DUZC6G8mR1AXgXy73r8qt/G5RsefKIlSj6jBMc8b9Wc=

go_basics/reader/go.mod

@@ -0,0 +1,5 @@
+module anarchymonkey.com/go-basics/reader
+
+go 1.20
+
+require golang.org/x/tour v0.1.0

go_basics/reader/go.sum

@@ -0,0 +1,2 @@
+golang.org/x/tour v0.1.0 h1:OWzbINRoGf1wwBhKdFDpYwM88NM0d1SL/Nj6PagS6YE=
+golang.org/x/tour v0.1.0/go.mod h1:DUZC6G8mR1AXgXy73r8qt/G5RsefKIlSj6jBMc8b9Wc=

go_basics/reader/reader.go

@@ -0,0 +1,43 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"strings"
+
+	"golang.org/x/tour/reader"
+)
+
+// Implement a Reader type that emits an infinite stream of the ASCII character 'A'.
+
+type MyReader struct{}
+
+// Reader is an interface that contains Read method, it takes a byte stream and then recieves the reader by itself and returns the length of bytes and the error if any
+func (m MyReader) Read(b []byte) (int, error) {
+
+	for i := range b {
+		b[i] = 'A'
+	}
+
+	return len(b), nil
+}
+
+func main() {
+	r := strings.NewReader("Hey my name is Aniket!")
+	b := make([]byte, 8)
+	for {
+		lengthOfBytes, err := r.Read(b)
+		fmt.Printf("n = %v err = %v b = %v\n", lengthOfBytes, err, b)
+		fmt.Printf("b[:n] = %q\n", b[:lengthOfBytes])
+
+		if err == io.EOF {
+			break
+		}
+
+	}
+
+	// Custom reader implementation
+
+	fmt.Println("Validating the reader functionality")
+	reader.Validate(MyReader{})
+}

go_basics/reader/rot13Exercise/go.mod

@@ -0,0 +1,3 @@
+module anarchymonkey.com/go-basics/reader/rot13Exercise
+
+go 1.20

go_basics/reader/rot13Exercise/rot13Reader.go

@@ -0,0 +1,41 @@
+package main
+
+import (
+	"errors"
+	"io"
+	"os"
+	"strings"
+)
+
+/*
+	Implement a rot13Reader that implements io.Reader and reads from an io.Reader, modifying the stream by applying the rot13 substitution cipher to all alphabetical characters.
+
+The rot13Reader type is provided for you. Make it an io.Reader by implementing its Read method.
+*/
+type rot13Reader struct {
+	r io.Reader
+}
+
+func (rot *rot13Reader) Read(b []byte) (int, error) {
+	length, err := rot.r.Read(b)
+
+	if err != nil {
+		return 0, errors.New("Some error occured while reading the file")
+	}
+
+	for i := 0; i < length; i++ {
+		if (b[i] >= 'A' && b[i] <= 'M') || (b[i] >= 'a' && b[i] <= 'm') {
+			b[i] = b[i] + 13
+		} else if (b[i] >= 'N' && b[i] <= 'Z') || (b[i] >= 'n' && b[i] <= 'z') {
+			b[i] = b[i] - 13
+		}
+	}
+
+	return length, nil
+}
+
+func main() {
+	s := strings.NewReader("Lbh penpxrq gur pbqr!")
+	r := &rot13Reader{s}
+	io.Copy(os.Stdout, r)
+}