read iter ext

generator-native/Cargo.lock

@@ -3,3 +3,20 @@
 [[package]]
 name = "generator-native"
 version = "0.1.0"
+dependencies = [
+ "heaparray",
+]
+
+[[package]]
+name = "heaparray"
+version = "0.1.0"
+source = "git+https://github.com/notflan/heaparray#6b57c19cf82a71f6bd6e566be7cf36ef1926def7"
+dependencies = [
+ "libc",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.70"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3baa92041a6fec78c687fa0cc2b3fae8884f743d672cf551bed1d6dac6988d0f"

generator-native/Cargo.toml

@@ -7,3 +7,4 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+heaparray = { git = "https://github.com/notflan/heaparray" }

generator-native/src/iter/file.rs

@@ -0,0 +1,71 @@
+use std::{
+    io::{
+	Read,
+    },
+};
+use heaparray::{
+    heap,
+};
+
+pub struct BufferedReadIter<F>
+where F: Read
+{
+    iter: F,
+    buffer: Box<[u8]>,
+    buffer_len: usize,
+}
+
+impl<F: Read> Iterator for BufferedReadIter<F>
+{
+    type Item = Box<[u8]>;
+
+    fn next(&mut self) -> Option<Self::Item>
+    {
+	if self.buffer_len >= self.buffer.len() {
+	    // Buffer is full.
+	    return Some(self.swap_out());
+	}
+	
+	if let Ok(read) = self.iter.read(&mut self.buffer[self.buffer_len..])
+	{
+	    self.buffer_len += read;
+	    if self.buffer_len ==0 {
+		None
+	    } else {
+		Some(self.swap_out())
+	    }
+	} else {
+	    None
+	}
+    }
+}
+
+impl<F: Read> BufferedReadIter<F>
+{
+    fn swap_out(&mut self) -> Box<[u8]>
+    {
+	let len = self.buffer_len;
+	self.buffer_len=0;
+
+	heaparray::box_slice(&mut self.buffer[..len])
+    }
+
+    pub fn new(iter: F, buffer_len: usize) -> Self {
+	let buffer = heap![u8; buffer_len].into_box();
+	Self {
+	    iter,
+	    buffer_len: 0,
+	    buffer,
+	}
+    }
+}
+
+pub trait ReadIterExt: Read + Sized
+{
+    fn into_iter(self, buffer_len: usize) -> BufferedReadIter<Self>
+    {
+	BufferedReadIter::new(self, buffer_len)
+    }
+}
+impl<T: Read> ReadIterExt for T{}
+

generator-native/src/iter/group.rs

@@ -43,7 +43,6 @@ where I: Iterator<Item=T>
     }
 }
 
-use super::*;
 pub trait GroupExt: Iterator + Sized {
     fn group_at(self, at: usize) -> GroupIter<<Self as Iterator>::Item, Self>
     {

generator-native/src/iter/mod.rs

@@ -1,3 +1,12 @@
-
 mod group;
 pub use group::*;
+
+mod file;
+pub use file::*;
+
+pub mod prelude
+{
+    pub use super::{
+	ReadIterExt, GroupExt,
+    };
+}

generator-native/src/main.rs

@@ -1,5 +1,28 @@
+extern crate heaparray;
+
+use std::{
+    fs::{
+	self, File, OpenOptions,
+    },
+    io,
+    error::Error,
+};
+
 mod iter;
+use iter::prelude::*;
+
+fn main() -> Result<(), Box<dyn Error>>{
+
+    /*let file = OpenOptions::new()
+	.read(true)
+	.open("test.txt")?;
+
+    for buf in file.into_iter(2).group_at(2)
+    {
+	println!("{:?}", buf);
+}*/
+
+    
 
-fn main() {
+    Ok(())
-    println!("Hello, world!");
 }