refactor using Enum

src/line.rs

@@ -1,100 +1,51 @@
 use std::fmt;
 use std::fmt::Formatter;
-use std::ops::Deref;
 
-pub trait Line: fmt::Display {
-    fn is_differing(&self) -> bool;
-}
-
-/// Line represents a non-differing line.
-pub(crate) struct MatchedLine {
-    line_number: i32,
-    line: String,
-}
-
-impl MatchedLine {
-    /// Constructs a new Line instance
-    pub fn new(line_number: i32, line: String) -> MatchedLine {
-        MatchedLine { line_number, line }
-    }
-
-    /// get_line returns the line.
-    pub fn get_line(&self) -> &String {
-        &self.line
-    }
-}
-
-impl fmt::Display for MatchedLine {
-    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
-        write!(f, r#"{}. {}"#, self.line_number, self.get_line(),)
-            .expect("Failed to write MatchedLine");
-        writeln!(f)
-    }
-}
-
-impl Line for MatchedLine {
-    fn is_differing(&self) -> bool {
-       false
-    }
-}
-
-/// A line difference is represented by the Difference struct.
 #[derive(Debug)]
-pub(crate) struct DifferingLine {
-    line_number: i32,
-    missing_line_indicator: String,
-    left_line: String,
-    right_line: String,
+pub(crate) struct MissingLineIndicator {
+    pub value: String
 }
 
-impl DifferingLine {
-    /// Constructs a new difference instance.
-    pub fn new(line_number: i32, left_line: String, right_line: String) -> DifferingLine {
-        DifferingLine {
-            line_number,
-            missing_line_indicator: String::from("<missing line>"),
-            left_line: left_line.into(),
-            right_line: right_line.into(),
+impl Default for MissingLineIndicator {
+    fn default() -> Self {
+        MissingLineIndicator{
+            value: String::from("<missing line>")
         }
     }
-
-    /// Returns the left line of the difference.
-    #[allow(dead_code)]
-    pub fn left_line(&self) -> &String {
-        if self.left_line.deref() == "" {
-            return &self.missing_line_indicator;
-        }
-        &self.left_line
-    }
-
-    /// Returns the right line of the difference.
-    #[allow(dead_code)]
-    pub fn right_line(&self) -> &String {
-        if self.right_line.deref() == "" {
-            return &self.missing_line_indicator;
-        }
-        &self.right_line
-    }
 }
 
-impl fmt::Display for DifferingLine {
+/// The line enum models a file line.
+pub(crate) enum Line {
+    /// MatchedLine represents a line that matches when comparing the files.
+    ///
+    /// MatchedLine(line_number, line)
+    MatchedLine(i32, String),
+    /// DifferingLine represents a line that does not match its counterpart line.
+    ///
+    /// DifferingLine(line_number, left_line, right_line)
+    DifferingLine(i32, String, String),
+}
+
+impl fmt::Display for Line {
     fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
-        write!(
-            f,
-            r#"  - {}
-{}. ----
-  + {}"#,
-            self.left_line(),
-            self.line_number,
-            self.right_line()
-        )
-        .expect("Failed to write DifferingLines");
-        writeln!(f)
-    }
-}
-
-impl Line for DifferingLine {
-    fn is_differing(&self) -> bool {
-        true
+        match self {
+            Line::MatchedLine(line_number, line) => {
+                write!(f, r#"{}. {}"#, line_number, line,).expect("Failed to write MatchedLine");
+                writeln!(f)
+            }
+            Line::DifferingLine(line_number, left_line, right_line) => {
+                write!(
+                    f,
+                    r#" - {left_line}
+{line_number}. ----
+ + {right_line}"#,
+                    left_line = left_line,
+                    line_number = line_number,
+                    right_line = right_line
+                )
+                .expect("Failed to write DifferingLines");
+                writeln!(f)
+            }
+        }
     }
 }

src/main.rs

@@ -1,27 +1,27 @@
-use crate::line::{DifferingLine, Line, MatchedLine};
+use crate::line::{Line, MissingLineIndicator};
 use itertools::Itertools;
 use std::fs::read_to_string;
-use std::ops::Deref;
 
 mod line;
 
 /// Gets the lines of two given texts
 ///
-/// It returns a [`Vec<Box<dyn Line>>`]
-fn get_lines(left_text: &String, right_text: &String) -> Vec<Box<dyn Line>> {
+/// It returns a [`Vec<Box<Line>>`]
+fn get_lines(left_text: &String, right_text: &String) -> Vec<Line> {
     left_text
         .lines()
         .map(String::from)
         .zip_longest(right_text.lines().map(String::from))
         .enumerate()
-        .map(|(line, item)| -> Box<dyn Line> {
-            let left = item.clone().left().unwrap_or(String::from(""));
-            let right = item.right().unwrap_or(String::from(""));
+        .map(|(line_number, item)| -> Line {
+            let missing_line_indicator: MissingLineIndicator = Default::default();
+            let left = item.clone().left().unwrap_or(missing_line_indicator.value.clone());
+            let right = item.right().unwrap_or(missing_line_indicator.value);
 
             if left != right {
-                Box::new(DifferingLine::new(line as i32 + 1, left, right))
+                Line::DifferingLine(line_number as i32 + 1, left, right)
             } else {
-                Box::new(MatchedLine::new(line as i32 + 1, left))
+                Line::MatchedLine(line_number as i32 + 1, left)
             }
         })
         .collect()
@@ -31,14 +31,16 @@ fn main() {
     let left_file = read_to_string("a.txt").expect("Left file not found");
     let right_file = read_to_string("b.txt").expect("Right file not found");
 
-    let lines: Vec<Box<dyn Line>> = get_lines(&left_file, &right_file);
+    let lines: Vec<Line> = get_lines(&left_file, &right_file);
 
     let mut differences_counter: i32 = 0;
     for line in lines.iter() {
-        let line = line.deref();
         print!("{}", line);
-        if line.is_differing() {
-            differences_counter += 1;
+        match line {
+            Line::MatchedLine(_, _) => {}
+            Line::DifferingLine(_, _, _) => {
+                differences_counter += 1
+            }
         }
     }
     println!();