idan - add word frequency

src/main.rs

@@ -1,24 +1,33 @@
 mod testing_resources;
 
 use clap::Parser;
+use std::collections::HashMap;
 use std::fs;
 
 /// wc impl in rust
 #[derive(Parser, Debug)]
 #[command(version, about, long_about = None)]
 struct Args {
     /// Print the number of lines in each input file
-    #[arg(short = 'l')]
+    #[clap(short = 'l', conflicts_with = "should_frequency")]
     should_lines: bool,
 
     /// Print the number of bytes in each input file
-    #[arg(short = 'c')]
+    #[clap(short = 'c', conflicts_with = "should_frequency")]
     should_characters: bool,
 
     /// Print the number of words in each input file
-    #[arg(short = 'w')]
+    #[clap(short = 'w', conflicts_with = "should_frequency")]
     should_words: bool,
 
+    /// Print the n most frequent words in each input file and their count
+    #[clap(short = 'f')]
+    should_frequency: bool,
+
+    /// How many words to print when using the -f flag
+    #[clap(short = 'n', default_value_t = 10)]
+    frequency_word_count: usize,
+
     /// Paths to input files we want to `wc`. If more than one input file is
     /// specified, a line of cumulative counts for all the files is displayed
     /// on a separate line after the output for the last file.
@@ -27,11 +36,17 @@ struct Args {
 
 fn main() {
     let parsed_args = Args::parse();
+    let should_frequency = parsed_args.should_frequency;
+    let frequency_word_count = parsed_args.frequency_word_count;
     let should_words: bool;
     let should_lines: bool;
     let should_characters: bool;
     let mut should_exit_with_err: bool = false;
-    if !parsed_args.should_characters && !parsed_args.should_lines && !parsed_args.should_words {
+    if !parsed_args.should_characters
+        && !parsed_args.should_lines
+        && !parsed_args.should_words
+        && !parsed_args.should_frequency
+    {
         // Compat with wc behavior, no flags passed means all these should be on.
         should_characters = true;
         should_lines = true;
@@ -45,6 +60,7 @@ fn main() {
     let mut total_words: usize = 0;
     let mut total_lines: usize = 0;
     let mut total_characters: usize = 0;
+    let mut words_frequency: HashMap<String, usize> = HashMap::new();
     for path in parsed_args.paths.iter() {
         let file_contents = match fs::read_to_string(path) {
             Ok(x) => x,
@@ -69,6 +85,10 @@ fn main() {
             total_characters += characters_in_this_content;
             print!("{:>8}", characters_in_this_content);
         }
+        if should_frequency {
+            update_words_frequency(&file_contents, &mut words_frequency);
+            continue;
+        }
         println!(" {}", path)
     }
     // Now if more than 1 path, print total
@@ -84,6 +104,14 @@ fn main() {
         }
         println!(" total")
     }
+    if should_frequency {
+        let mut sorted_words: Vec<(&String, &usize)> = words_frequency.iter().collect();
+        sorted_words.sort_unstable_by(|(_, f1), (_, f2)| f2.cmp(f1));
+        for (word, count) in sorted_words.iter().take(frequency_word_count) {
+            println!("{} {}", count, word);
+        }
+        return;
+    }
     if should_exit_with_err {
         std::process::exit(0x00000001);
     }
@@ -106,6 +134,13 @@ fn count_words_in_content(content: &str) -> usize {
     content.split_ascii_whitespace().count()
 }
 
+fn update_words_frequency(content: &str, words_frequency: &mut HashMap<String, usize>) {
+    for word in content.split_ascii_whitespace() {
+        let count = words_frequency.entry(word.to_string()).or_insert(0);
+        *count += 1;
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use crate::testing_resources::EXAMPLE_CONTENT_EMPTY;