From f15987b34a554ee7db1df643cebe8be9e0317e38 Mon Sep 17 00:00:00 2001
From: Geoffroy Couprie <geo.couprie@gmail.com>
Date: Thu, 4 May 2017 21:31:37 +0200
Subject: [PATCH] initial commit

---
 .gitignore  |   3 +
 .travis.yml |  25 +++++
 Cargo.toml  |   6 ++
 README.md   |   5 +
 src/lib.rs  | 270 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 309 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 .travis.yml
 create mode 100644 Cargo.toml
 create mode 100644 README.md
 create mode 100644 src/lib.rs

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..4308d82
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+target/
+**/*.rs.bk
+Cargo.lock
diff --git a/.travis.yml b/.travis.yml
new file mode 100644
index 0000000..2f1177d
--- /dev/null
+++ b/.travis.yml
@@ -0,0 +1,25 @@
+language: rust
+
+cache: cargo
+
+rust:
+  - nightly
+  - beta
+  - stable
+
+
+before_script:
+  - cargo install cargo-travis --force
+  - export PATH=$HOME/.cargo/bin:$PATH;
+
+script:
+  - cargo build
+  - cargo test
+
+after_success:
+  - cargo coveralls
+
+
+dist: trusty
+#sudo: false
+
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..1cfafd1
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "circular"
+version = "0.1.0"
+authors = ["Geoffroy Couprie <geo.couprie@gmail.com>"]
+
+[dependencies]
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..3b6ab91
--- /dev/null
+++ b/README.md
@@ -0,0 +1,5 @@
+# Circular
+
+Circular is a stream abstraction designed for use with nom. It can expose the
+available data, a mutable slice of the available space, and it separates
+reading data from actually consuming it from the buffer.
diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..ecfb057
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,270 @@
+use std::{cmp, ptr};
+use std::io::{self,Write,Read};
+use std::iter::repeat;
+
+#[derive(Debug,PartialEq,Clone)]
+pub struct Buffer {
+  memory:   Vec<u8>,
+  capacity: usize,
+  position: usize,
+  end:      usize
+}
+
+impl Buffer {
+  pub fn with_capacity(capacity: usize) -> Buffer {
+    let mut v = Vec::with_capacity(capacity);
+    v.extend(repeat(0).take(capacity));
+    Buffer {
+      memory:   v,
+      capacity: capacity,
+      position: 0,
+      end:      0
+    }
+  }
+
+  pub fn from_slice(sl: &[u8]) -> Buffer {
+    Buffer {
+      memory:   Vec::from(sl),
+      capacity: sl.len(),
+      position: 0,
+      end:      sl.len()
+    }
+  }
+
+  pub fn grow(&mut self, new_size: usize) -> bool {
+    if self.capacity >= new_size {
+      return false;
+    }
+
+    self.memory.resize(new_size, 0);
+    self.capacity = new_size;
+    true
+  }
+
+  pub fn available_data(&self) -> usize {
+    self.end - self.position
+  }
+
+  pub fn available_space(&self) -> usize {
+    self.capacity - self.end
+  }
+
+  pub fn capacity(&self) -> usize {
+    self.capacity
+  }
+
+  pub fn empty(&self) -> bool {
+    self.position == self.end
+  }
+
+  pub fn consume(&mut self, count: usize) -> usize {
+    let cnt        = cmp::min(count, self.available_data());
+    self.position += cnt;
+    if self.position > self.capacity / 2 {
+      //trace!("consume shift: pos {}, end {}", self.position, self.end);
+      self.shift();
+    }
+    cnt
+  }
+
+  pub fn fill(&mut self, count: usize) -> usize {
+    let cnt   = cmp::min(count, self.available_space());
+    self.end += cnt;
+    if self.available_space() < self.available_data() + cnt {
+      //trace!("fill shift: pos {}, end {}", self.position, self.end);
+      self.shift();
+    }
+
+    cnt
+  }
+
+  pub fn reset(&mut self) {
+    self.position = 0;
+    self.end      = 0;
+  }
+
+  pub fn data(&self) -> &[u8] {
+    &self.memory[self.position..self.end]
+  }
+
+  pub fn space(&mut self) -> &mut[u8] {
+    &mut self.memory[self.end..self.capacity]
+  }
+
+  pub fn shift(&mut self) {
+    if self.position > 0 {
+      unsafe {
+        let length = self.end - self.position;
+        ptr::copy( (&self.memory[self.position..self.end]).as_ptr(), (&mut self.memory[..length]).as_mut_ptr(), length);
+        self.position = 0;
+        self.end      = length;
+      }
+    }
+  }
+
+  pub fn delete_slice(&mut self, start: usize, length: usize) -> Option<usize> {
+    if start + length >= self.available_data() {
+      return None
+    }
+
+    unsafe {
+      let begin    = self.position + start;
+      let next_end = self.end - length;
+      ptr::copy(
+        (&self.memory[begin+length..self.end]).as_ptr(),
+        (&mut self.memory[begin..next_end]).as_mut_ptr(),
+        self.end - (begin+length)
+      );
+      self.end = next_end;
+    }
+    Some(self.available_data())
+  }
+
+  pub fn replace_slice(&mut self, data: &[u8], start: usize, length: usize) -> Option<usize> {
+    let data_len = data.len();
+    if start + length > self.available_data() ||
+      self.position + start + data_len > self.capacity {
+      return None
+    }
+
+    unsafe {
+      let begin     = self.position + start;
+      let slice_end = begin + data_len;
+      // we reduced the data size
+      if data_len < length {
+        ptr::copy(data.as_ptr(), (&mut self.memory[begin..slice_end]).as_mut_ptr(), data_len);
+
+        ptr::copy((&self.memory[start+length..self.end]).as_ptr(), (&mut self.memory[slice_end..]).as_mut_ptr(), self.end - (start + length));
+        self.end = self.end - (length - data_len);
+
+      // we put more data in the buffer
+      } else {
+        ptr::copy((&self.memory[start+length..self.end]).as_ptr(), (&mut self.memory[start+data_len..]).as_mut_ptr(), self.end - (start + length));
+        ptr::copy(data.as_ptr(), (&mut self.memory[begin..slice_end]).as_mut_ptr(), data_len);
+        self.end = self.end + data_len - length;
+      }
+    }
+    Some(self.available_data())
+  }
+
+  pub fn insert_slice(&mut self, data: &[u8], start: usize) -> Option<usize> {
+    let data_len = data.len();
+    if start > self.available_data() ||
+      self.position + self.end + data_len > self.capacity {
+      return None
+    }
+
+    unsafe {
+      let begin     = self.position + start;
+      let slice_end = begin + data_len;
+      ptr::copy((&self.memory[start..self.end]).as_ptr(), (&mut self.memory[start+data_len..]).as_mut_ptr(), self.end - start);
+      ptr::copy(data.as_ptr(), (&mut self.memory[begin..slice_end]).as_mut_ptr(), data_len);
+      self.end = self.end + data_len;
+    }
+    Some(self.available_data())
+  }
+}
+
+impl Write for Buffer {
+  fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+    match self.space().write(buf) {
+      Ok(size) => { self.fill(size); Ok(size) },
+      err      => err
+    }
+  }
+
+  fn flush(&mut self) -> io::Result<()> {
+    Ok(())
+  }
+}
+
+impl Read for Buffer {
+  fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+    let len = cmp::min(self.available_data(), buf.len());
+    unsafe {
+      ptr::copy((&self.memory[self.position..self.position+len]).as_ptr(), buf.as_mut_ptr(), len);
+      self.position += len;
+    }
+    Ok(len)
+  }
+}
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+  use std::io::Write;
+
+  #[test]
+  fn fill_and_consume() {
+    let mut b = Buffer::with_capacity(10);
+    assert_eq!(b.available_data(), 0);
+    assert_eq!(b.available_space(), 10);
+    let res = b.write(&b"abcd"[..]);
+    assert_eq!(res.ok(), Some(4));
+    assert_eq!(b.available_data(), 4);
+    assert_eq!(b.available_space(), 6);
+
+    assert_eq!(b.data(), &b"abcd"[..]);
+
+    b.consume(2);
+    assert_eq!(b.available_data(), 2);
+    assert_eq!(b.available_space(), 6);
+    assert_eq!(b.data(), &b"cd"[..]);
+
+    b.shift();
+    assert_eq!(b.available_data(), 2);
+    assert_eq!(b.available_space(), 8);
+    assert_eq!(b.data(), &b"cd"[..]);
+
+    assert_eq!(b.write(&b"efghijklmnop"[..]).ok(), Some(8));
+    assert_eq!(b.available_data(), 10);
+    assert_eq!(b.available_space(), 0);
+    assert_eq!(b.data(), &b"cdefghijkl"[..]);
+    b.shift();
+    assert_eq!(b.available_data(), 10);
+    assert_eq!(b.available_space(), 0);
+    assert_eq!(b.data(), &b"cdefghijkl"[..]);
+  }
+
+  #[test]
+  fn delete() {
+    let mut b = Buffer::with_capacity(10);
+    let res = b.write(&b"abcdefgh"[..]);
+    assert_eq!(b.available_data(), 8);
+    assert_eq!(b.available_space(), 2);
+
+    assert_eq!(b.delete_slice(2, 3), Some(5));
+    assert_eq!(b.available_data(), 5);
+    assert_eq!(b.available_space(), 5);
+    assert_eq!(b.data(), &b"abfgh"[..]);
+
+    assert_eq!(b.delete_slice(5, 2), None);
+    assert_eq!(b.delete_slice(4, 2), None);
+  }
+
+  #[test]
+  fn replace() {
+    let mut b = Buffer::with_capacity(10);
+    let res = b.write(&b"abcdefgh"[..]);
+    assert_eq!(b.available_data(), 8);
+    assert_eq!(b.available_space(), 2);
+
+    assert_eq!(b.replace_slice(&b"ABC"[..], 2, 3), Some(8));
+    assert_eq!(b.available_data(), 8);
+    assert_eq!(b.available_space(), 2);
+    assert_eq!(b.data(), &b"abABCfgh"[..]);
+
+    assert_eq!(b.replace_slice(&b"XYZ"[..], 8, 3), None);
+    assert_eq!(b.replace_slice(&b"XYZ"[..], 6, 3), None);
+
+    assert_eq!(b.replace_slice(&b"XYZ"[..], 2, 4), Some(7));
+    assert_eq!(b.available_data(), 7);
+    assert_eq!(b.available_space(), 3);
+    assert_eq!(b.data(), &b"abXYZgh"[..]);
+
+    assert_eq!(b.replace_slice(&b"123"[..], 2, 2), Some(8));
+    assert_eq!(b.available_data(), 8);
+    assert_eq!(b.available_space(), 2);
+    assert_eq!(b.data(), &b"ab123Zgh"[..]);
+  }
+}