Add parsing capabilities; change to read CSV files instead of standard input

Cargo.toml

@@ -8,3 +8,4 @@ edition = "2018"
 
 [dependencies]
 csv = "1.1.3"
+argparse = "0.2.2"

src/grid.rs

@@ -2,7 +2,7 @@ use std::rc::{Rc, Weak};
 use std::cell::{RefCell};
 use std::fmt::Formatter;
 
-static mut DEBUG: bool = false;
+pub static mut DEBUG: bool = false;
 
 #[derive(Clone, Debug, Eq, PartialEq)]
 pub enum CellValue {

src/main.rs

@@ -5,24 +5,65 @@ use sudoku_solver::solver::solve_grid;
 
 
 fn main() {
-    let mut grid = read_grid().unwrap();
+    let mut debug = false;
+    let mut filename = String::new();
+    { // this block limits scope of borrows by ap.refer() method
+        let mut ap = argparse::ArgumentParser::new();
+        ap.set_description("Solve Sudoku puzzles");
+        ap.refer(&mut debug)
+            .add_option(&["--debug"], argparse::StoreTrue, "Run in debug mode");
 
-    println!("{}", grid);
+        ap.refer(&mut filename)
+            .required()
+            .add_argument("filename", argparse::Store, "Path to puzzle CSV file");
+
+        ap.parse_args_or_exit();
+    }
+
+    if debug {
+        unsafe {
+            sudoku_solver::grid::DEBUG = true;
+            sudoku_solver::solver::DEBUG = true;
+        }
+    }
+
+
+    let mut grid = match read_grid(&filename) {
+        Ok(grid) => grid,
+        Err(e) => {
+            eprintln!("Error while reading grid: \"{}\"", e);
+            std::process::exit(1);
+        }
+    };
+
+    println!("Grid to be solved:\n{}", grid);
 
     println!("Solving grid");
     solve_grid(&mut grid);
-    println!("{}", grid);
+
+    println!("Solved grid:\n{}", grid);
+
+
 }
 
-fn read_grid() -> Result<Grid, &'static str> {
+fn read_grid(filename: &str) -> Result<Grid, String> {
-    let mut reader = csv::ReaderBuilder::new()
+    let reader_result = csv::ReaderBuilder::new()
         .has_headers(false)
-        .from_reader(std::io::stdin());
+        .from_path(filename);
+
+    let mut reader = match reader_result {
+        Ok(reader) => reader,
+        Err(e) => {
+            let e = e.to_string();
+            return Err(e);
+        }
+    };
+
     let grid = Grid::new();
     let mut row = 0;
     for result in reader.records() {
         if row > 8 {
-            return Err("Hit row limit");
+            return Err("Hit row limit".to_string());
         }
 
         let record = result.unwrap();
@@ -39,7 +80,7 @@ fn read_grid() -> Result<Grid, &'static str> {
                             }
 
                         },
-                        Err(_error) => {return Err("Invalid cell value")}
+                        Err(_error) => {return Err("Invalid cell value".to_string())}
                     };
 
                 },

src/solver.rs

@@ -5,7 +5,7 @@ use std::collections::HashSet;
 
 use crate::grid::{Cell, Line, Grid, CellValue, LineType};
 
-static mut DEBUG: bool = false;
+pub static mut DEBUG: bool = false;
 
 struct FauxCell{
     index: usize,