grep: add -v flag

src/grep.rs

@@ -8,6 +8,7 @@ use std::fs::{self, File};
 fn main(){
     let args: Vec<String> = env::args().collect();
     let mut pattern_and_filename: Vec<String> = Vec::new(); // 0 - pattern, 1 - name of files
+    let mut invert: bool = false;
     
     for arg in 1..args.len() {
         match args[arg].as_str() {
@@ -16,6 +17,9 @@ fn main(){
                 println!("Print lines matching a pattern");
                 return;
             },
+            "-v" => {
+                invert = true;
+            },
             arg => {
                 if args.len() < 3 {
                     println!("grep: Not enought arguments");
@@ -28,16 +32,18 @@ fn main(){
     let pattern = &pattern_and_filename[0];
     let filename = &pattern_and_filename[1];
     let contents = fs::read_to_string(&filename);
-    //contents = "".to_string();
-    for line in search(pattern.to_string(), contents.unwrap().as_str()) {
+    for line in search(pattern.to_string(), contents.unwrap().as_str(), invert) {
         println!("{}", line);
     }
 }
 
-fn search<'a>(pattern: String, contents: &'a str) -> Vec<&'a str> {
+fn search<'a>(pattern: String, contents: &'a str, invert: bool) -> Vec<&'a str> {
     let mut results = Vec::new();
     for line in contents.lines() {
-        if line.contains(&pattern) {
+        if line.contains(&pattern) && !invert {
+            results.push(line);
+        } 
+        else if !line.contains(&pattern) && invert {
             results.push(line);
         }
     }