From c0a9f0a0f8085f8feb2e97b59f4538e1fc48d1fcfa08e970d11dab84a9d9fc04 Mon Sep 17 00:00:00 2001
From: Nicholas Johnson <nick@nicholasjohnson.ch>
Date: Mon, 13 May 2024 00:00:00 +0000
Subject: Use a buffered writer

Fewer system calls speeds up runtime.
---
 src/lib.rs | 48 ++++++++++++++++++++++++++----------------------
 1 file changed, 26 insertions(+), 22 deletions(-)

(limited to 'src')

diff --git a/src/lib.rs b/src/lib.rs
index b45cd54..3d7cf2d 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -21,22 +21,23 @@
 //! Classic two-colored Hitomezashi stitch pattern generator.
 
 use rand::distributions::{Bernoulli, Distribution};
-use std::io::{stdout, StdoutLock, Write};
-
-const TRANSPARENT_SQUARE: char = ' ';
-const OPAQUE_SQUARE: char = '█';
-
-fn print_square(lock: &mut StdoutLock, is_opaque: bool) {
-    write!(
-        lock,
-        "{}",
-        if is_opaque {
-            OPAQUE_SQUARE
-        } else {
-            TRANSPARENT_SQUARE
-        }
-    )
-    .unwrap();
+use std::io::{stdout, BufWriter, StdoutLock, Write};
+
+const TRANSPARENT_SQUARE: &str = " ";
+const OPAQUE_SQUARE: &str = "█";
+
+fn print_square(stream: &mut BufWriter<StdoutLock>, is_opaque: bool) {
+    stream
+        .write_all(
+            if is_opaque {
+                OPAQUE_SQUARE
+            } else {
+                TRANSPARENT_SQUARE
+            }
+            .to_string()
+            .as_bytes(),
+        )
+        .unwrap();
 }
 
 /// Prints a two-colored Hitomezashi stitch pattern of the specified dimensions.
@@ -105,19 +106,20 @@ pub fn generate(width: usize, height: usize, skew: Option<f64>) {
 
     let mut cur_row: Vec<bool> = Vec::with_capacity(width);
 
-    let mut lock = stdout().lock();
+    let lock = stdout().lock();
+    let mut stream = BufWriter::new(lock);
 
     /* Base case
      *
      * The first row has no preceding row, so it's computing using the column stitches */
     cur_row.push(first_square);
     for col in 0..(cur_row.capacity() - 1) {
-        print_square(&mut lock, cur_row[col]);
+        print_square(&mut stream, cur_row[col]);
         cur_row.push(cur_row[col] ^ col_bits[col]);
     }
 
-    print_square(&mut lock, cur_row[cur_row.capacity() - 1]);
-    writeln!(&mut lock).unwrap(); // End of base case
+    print_square(&mut stream, cur_row[cur_row.capacity() - 1]);
+    stream.write_all(b"\n").unwrap(); // End of base case
 
     for row_bit in row_bits.iter() {
         /* Recursive case
@@ -128,9 +130,11 @@ pub fn generate(width: usize, height: usize, skew: Option<f64>) {
             .zip(alt_bits.iter())
             .for_each(|(x1, &x2)| {
                 *x1 ^= x2 ^ row_bit;
-                print_square(&mut lock, *x1);
+                print_square(&mut stream, *x1);
             });
 
-        writeln!(&mut lock).unwrap(); // End of recursive case
+        stream.write_all(b"\n").unwrap(); // End of recursive case
     }
+
+    stream.flush().unwrap();
 }
-- 
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