Add a benchmark to avoid file I/O.

benches/read.rs

@@ -2,9 +2,25 @@ use criterion::{criterion_group, criterion_main, Criterion};
 use iof::{unwrap, InputStream, ReadInto, ReadOneInto};
 use std::{
     fs::{read_to_string, File},
-    io::{BufRead, BufReader, Cursor},
+    io::{self, BufRead, BufReader, Cursor, Read, Write},
 };
 
+#[derive(Clone)]
+struct LazyWriter(std::ops::Range<i32>);
+
+impl Read for LazyWriter {
+    fn read(&mut self, mut buf: &mut [u8]) -> io::Result<usize> {
+        if let Some(num) = self.0.next() {
+            let s = format!("{} ", num);
+            let len = s.len();
+            buf.write_all(s.as_bytes())?;
+            Ok(len)
+        } else {
+            Ok(0)
+        }
+    }
+}
+
 fn template<R: BufRead>(
     case: &'static str,
     count: usize,
@@ -112,5 +128,15 @@ fn file(c: &mut Criterion) {
     }))(c);
 }
 
-criterion_group!(benches, cursor, file);
+fn lazy(c: &mut Criterion) {
+    let writer = LazyWriter(0..COUNT as i32);
+    {
+        (template("lazy - long", COUNT, || BufReader::new(writer.clone())))(c);
+    }
+    {
+        (template("lazy - short", COUNT, || BufReader::new(writer.clone())))(c);
+    }
+}
+
+criterion_group!(benches, cursor, file, lazy);
 criterion_main!(benches);

examples/benchmark_integers.rs

@@ -4,8 +4,8 @@ use iof::{sep_by, show, unwrap};
 use std::{fs::File, ops::Range, path::PathBuf};
 
 fn main() {
-    const INTEGERS: [Range<i64>; 3] = [
-        -0x10000i64..0x10000i64,
+    const INTEGERS: [Range<i32>; 3] = [
+        -0x10000..0x10000,
         -0x80000000..-0x7fff0000,
         0x70000000..0x70010000,
     ];