Initial commit

16-strings-revisited/05-masker-solution/main.go

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+// 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 buffer with a sufficient size
+#3- Write input to the buffer as it is and print it
+#4- Detect the link
+#5- Mask the link
+#6- Detect white spaces and disable the masking
+#7- Write http:// to the buffer, just before the link
+*/
+
+package main
+
+import (
+	"fmt"
+	"os"
+)
+
+const (
+	link = "http://"
+	mask = '*'
+)
+
+func main() {
+	args := os.Args[1:]
+	if len(args) != 1 {
+		fmt.Println("gimme somethin' to censor!")
+		return
+	}
+
+	var (
+		text = args[0]
+		size = len(text)
+
+		// create a sufficient buffer for the output
+		//
+		// and adjust its slice pointer to the first element
+		//   of the backing array! -> make(..., 0, ...)
+		buf = make([]byte, 0, size)
+
+		in bool
+	)
+
+	for i := 0; i < size; i++ {
+		nlink := len(link)
+
+		// 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 {
+			// jump to the next character after "http://"
+			i += nlink
+
+			// set the flag: we're in a link! -> "http://....."
+			in = true
+
+			// add the "http://" manually
+			buf = append(buf, link...)
+		}
+
+		// 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
+		}
+
+		// add the current character to the buffer
+		buf = append(buf, c)
+	}
+
+	// print out the buffer as text (string)
+	fmt.Println(string(buf))
+}