added some types, optimize error handling

src/csv/compare.rs

@@ -88,7 +88,7 @@ pub fn write_to_file(filename: String, diff: Vec<CsvLine>) {
     }
 }
 
-pub fn compare(reader: BufReader<File>, reader2: BufReader<File>, params: &Params) -> Vec<CsvLine> {
+pub fn compare(reader: BufReader<File>, reader2: BufReader<File>, params: &Params) -> Result<Vec<CsvLine>, String> {
     let vec1: Vec<CsvLine> = reader
         .lines()
         .map(|line| {
@@ -105,8 +105,8 @@ pub fn compare(reader: BufReader<File>, reader2: BufReader<File>, params: &Param
         })
         .collect();
 
-    let mut diff1: Vec<CsvLine> = find_diff(&vec1, &vec2, params);
+    let mut diff1: Vec<CsvLine> = find_diff(&vec1, &vec2, params)?;
-    let mut diff2: Vec<CsvLine> = find_diff(&vec2, &vec1, params);
+    let mut diff2: Vec<CsvLine> = find_diff(&vec2, &vec1, params)?;
 
     if params.output.is_none() {
         print_lines(&diff1, &diff2, params);
@@ -114,14 +114,17 @@ pub fn compare(reader: BufReader<File>, reader2: BufReader<File>, params: &Param
 
     diff1.append(&mut diff2);
 
-    diff1
+    Ok(diff1)
 }
 
-fn find_diff(vec1: &[CsvLine], vec2: &[CsvLine], params: &Params) -> Vec<CsvLine> {
+fn find_diff(vec1: &[CsvLine], vec2: &[CsvLine], params: &Params) -> Result<Vec<CsvLine>, String> {
     let mut diff: Vec<CsvLine> = Vec::new();
     for i in vec1.iter() {
         let splitter: Vec<&str> = i.line.split(params.delimiter()).collect();
-        let value = splitter[params.column];
+        if splitter.len() <= params.column {
+            return Err("Column out of bound".to_string());
+        }
+        let value: &str = splitter[params.column];
 
         let found = !matches!(
             vec2.iter().position(|r| {
@@ -137,7 +140,7 @@ fn find_diff(vec1: &[CsvLine], vec2: &[CsvLine], params: &Params) -> Vec<CsvLine
         }
     }
 
-    diff
+    Ok(diff)
 }
 
 #[cfg(test)]
@@ -167,7 +170,7 @@ mod test {
             column: 1,
             output: Some("./assets/result.csv".to_owned()),
         };
-        let result: Vec<CsvLine> = compare(file1, file2, &params);
+        let result: Vec<CsvLine> = compare(file1, file2, &params).unwrap();
         assert_eq!(3, result.len());
     }
 }

src/main.rs

@@ -15,17 +15,41 @@ use crate::csv::compare::{write_to_file, Params};
 fn main() {
     let args = MyArgs::parse();
 
-    let mut params = Params::new_from_matches(args);
+    let mut params: Params = Params::new_from_matches(args);
 
-    let file = File::open(params.source()).expect("Can't find source file");
+    let file: File = {
-    let file2 = File::open(params.compared()).expect("Cant't find compared file");
+        let this = File::open(params.source());
+        match this {
+            Ok(file) => file,
+            Err(e) => {
+                eprintln!("Can't find source file: {}", e);
+                return;
+            }
+        }
+    };
+    let file2 = {
+        let this = File::open(params.compared());
+        match this {
+            Ok(file) => file,
+            Err(e) => {
+                eprintln!("Cant't find compared file: {}", e);
+                return;
+            }
+        }
+    };
 
-    let reader = BufReader::new(file);
+    let reader: BufReader<File> = BufReader::new(file);
-    let reader2 = BufReader::new(file2);
+    let reader2: BufReader<File> = BufReader::new(file2);
 
-    let diff = compare::compare(reader, reader2, &params);
+    let diff: Vec<compare::CsvLine> = match compare::compare(reader, reader2, &params) {
+        Ok(d) => d,
+        Err(e) => {
+            eprintln!("{e}");
+            return;
+        }
+    };
 
-    let option_string_ref = params.output_mut();
+    let option_string_ref: &Option<String> = params.output_mut();
     if let Some(string_ref) = option_string_ref {
         write_to_file(string_ref.clone(), diff);
     }