add: strings and projects

20-project-spam-masker/01-step-1/main.go

@@ -0,0 +1,54 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+/*
+✅ #1- Get and check the input
+✅ #2- Create a byte buffer and use it as the output
+✅ #3- Write input to the buffer as it is and print it
+✅ #4- Detect the link
+#5- Mask the link
+#6- Stop masking when whitespace is detected
+#7- Put a http:// prefix in front of the masked link
+*/
+
+package main
+
+import (
+	"fmt"
+	"os"
+)
+
+func main() {
+	args := os.Args[1:]
+	if len(args) != 1 {
+		fmt.Println("gimme somethin' to mask!")
+		return
+	}
+
+	const (
+		link  = "http://"
+		nlink = len(link)
+	)
+
+	var (
+		text = args[0]
+		size = len(text)
+		buf  = make([]byte, 0, size)
+	)
+
+	for i := 0; i < size; i++ {
+		buf = append(buf, text[i])
+
+		// slice the input and look for the link pattern
+		// do not slice it when it goes beyond the input text's capacity
+		if len(text[i:]) >= nlink && text[i:i+nlink] == link {
+		}
+	}
+
+	// print out the buffer as text (string)
+	fmt.Println(string(buf))
+}

20-project-spam-masker/01-step-1/spam.txt

@@ -0,0 +1,7 @@
+Hi guys, 
+
+Here is my new spammy webpage http://www.mysuperpage.com <-- This is my website!
+
+Please click on the link now!!!
+
+When you click, I will be rich, thanks!

20-project-spam-masker/02-step-2/main.go

@@ -0,0 +1,80 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+/*
+✅ #1- Get and check the input
+✅ #2- Create a byte buffer and use it as the output
+✅ #3- Write input to the buffer as it is and print it
+✅ #4- Detect the link
+✅ #5- Mask the link
+✅ #6- Stop masking when whitespace is detected
+✅ #7- Put a http:// prefix in front of the masked link
+*/
+
+package main
+
+import (
+	"fmt"
+	"os"
+)
+
+const (
+	link  = "http://"
+	nlink = len(link)
+	mask  = '*'
+)
+
+func main() {
+	args := os.Args[1:]
+	if len(args) != 1 {
+		fmt.Println("gimme somethin' to mask!")
+		return
+	}
+
+	var (
+		text = args[0]
+		size = len(text)
+		buf  = make([]byte, 0, size)
+
+		in bool
+	)
+
+	for i := 0; i < size; i++ {
+		// slice the input and look for the link pattern
+		// do not slice it when it goes beyond the input text's capacity
+		if len(text[i:]) >= nlink && text[i:i+nlink] == link {
+			// set the flag: we're in a link! -> "http://....."
+			in = true
+
+			// add the "http://" manually
+			buf = append(buf, link...)
+
+			// jump to the next character after "http://"
+			i += nlink
+		}
+
+		// get the current byte from the input
+		c := text[i]
+
+		// disable the link detection flag
+		// this will prevent masking the rest of the bytes
+		switch c {
+		case ' ', '\t', '\n': // try -> unicode.IsSpace
+			in = false
+		}
+
+		// if we're in the link detection mode (inside the link bytes)
+		// then, mask the current character
+		if in {
+			c = mask
+		}
+		buf = append(buf, c)
+	}
+
+	// print out the buffer as text (string)
+	fmt.Println(string(buf))
+}

20-project-spam-masker/02-step-2/spam.txt

@@ -0,0 +1,7 @@
+Hi guys, 
+
+Here is my new spammy webpage http://www.mysuperpage.com <-- This is my website!
+
+Please click on the link now!!!
+
+When you click, I will be rich, thanks!

20-project-spam-masker/03-step-2-no-append/main.go

@@ -0,0 +1,68 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+/*
+✅ #1- Get and check the input
+✅ #2- Create a byte buffer and use it as the output
+✅ #3- Write input to the buffer as it is and print it
+✅ #4- Detect the link
+✅ #5- Mask the link
+✅ #6- Stop masking when whitespace is detected
+✅ #7- Put a http:// prefix in front of the masked link
+*/
+
+package main
+
+import (
+	"fmt"
+	"os"
+)
+
+const (
+	link  = "http://"
+	nlink = len(link)
+	mask  = '*'
+)
+
+func main() {
+	args := os.Args[1:]
+	if len(args) != 1 {
+		fmt.Println("gimme somethin' to mask!")
+		return
+	}
+
+	var (
+		text = args[0]
+		size = len(text)
+
+		// create a byte buffer directly from the string (text)
+		buf = []byte(text)
+
+		in bool
+	)
+
+	for i := 0; i < size; i++ {
+		// no need to add an artificial http:// prefix
+		// it's already there
+		if len(text[i:]) >= nlink && text[i:i+nlink] == link {
+			in = true
+			i += nlink
+		}
+
+		switch text[i] {
+		case ' ', '\t', '\n': // try -> unicode.IsSpace
+			in = false
+		}
+
+		// when censoring mode: on
+		// directly manipulate the bytes on the buffer
+		if in {
+			buf[i] = mask
+		}
+	}
+	fmt.Println(string(buf))
+}

20-project-spam-masker/03-step-2-no-append/spam.txt

@@ -0,0 +1,7 @@
+Hi guys, 
+
+Here is my new spammy webpage http://www.mysuperpage.com <-- This is my website!
+
+Please click on the link now!!!
+
+When you click, I will be rich, thanks!

20-project-spam-masker/README.md

@@ -0,0 +1,60 @@
+# Spam Masker Challenge Tips
+
+## Rules:
+
+* You shouldn't use a standard library function.
+
+* You should only solve the challenge by manipulating the bytes directly.
+
+* Manipulate the bytes of a string using indexing, slicing, appending etc.
+
+* Be efficient: Do not use string concat (+ operator).
+	* Instead, create a new byte slice as a buffer from the given string argument.
+	* Then, manipulate it during your program.
+	* And, for once, print that buffer.
+
+* Mask only links starting with `http://`
+
+* Don't check for uppercase/lowercase letters
+
+	* The goal is learning how to manipulate bytes in strings, it's not about creating the perfect masker.
+
+	* For example: A spammer can prevent the masker like this (for now this is OK):
+
+	  ```
+      "Here's my spammy page: hTTp://youth-elixir.com"
+                               ^^
+      ```
+
+* But, you should catch this:
+
+  ```
+  INPUT:
+  Here's my spammy page: http://hehefouls.netHAHAHA see you.
+
+  OUTPUT:
+  Here's my spammy page: http://******************* see you.
+  ```
+
+## Steps:
+
+1. Check whether there's a command line argument or not. If not, quit from the program with a message.
+
+2. Create a byte buffer as big as the argument.
+
+3. Loop and detect the `http://` patterns
+
+4. Copy the input character by character to the buffer
+
+5. If you detect `http://` pattern, copy the `http://` first, then copy the `*`s instead of the original link until you see whitespace character.
+
+    For example: 
+    ```
+	INPUT:
+    Here: http://www.mylink.com Click!
+
+    OUTPUT:
+	Here: http://************** Click!
+    ```
+
+6. Print the buffer as a string