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use libc;
use std::cmp;
use std::mem;
use std::ptr;
use std::slice;
use super::buffer::*;
use super::datatypes::*;
use super::memory::*;
pub struct Builder<T>
where
T: ArrowPrimitiveType,
{
data: *mut T,
len: usize,
capacity: usize,
}
impl<T> Builder<T>
where
T: ArrowPrimitiveType,
{
pub fn new() -> Self {
Builder::with_capacity(64)
}
pub fn with_capacity(capacity: usize) -> Self {
let sz = mem::size_of::<T>();
let buffer = allocate_aligned((capacity * sz) as i64).unwrap();
Builder {
len: 0,
capacity,
data: buffer as *mut T,
}
}
pub fn len(&self) -> usize {
self.len
}
pub fn capacity(&self) -> usize {
self.capacity
}
pub fn slice_mut(&mut self, start: usize, end: usize) -> &mut [T] {
assert!(
end <= self.capacity as usize,
"the end of the slice must be within the capacity"
);
assert!(
start <= end,
"the start of the slice cannot exceed the end of the slice"
);
unsafe {
slice::from_raw_parts_mut(self.data.offset(start as isize), (end - start) as usize)
}
}
pub fn set_len(&mut self, len: usize) {
self.len = len;
}
pub fn push(&mut self, v: T) {
assert!(!self.data.is_null(), "cannot push onto uninitialized data");
if self.len == self.capacity {
let new_capacity = cmp::max(64, self.capacity * 2);
self.grow(new_capacity);
}
assert!(self.len < self.capacity, "new length exceeds capacity");
unsafe {
*self.data.offset(self.len as isize) = v;
}
self.len += 1;
}
pub fn set(&mut self, i: usize, v: T) {
assert!(
!self.data.is_null(),
"cannot set value if data is uninitialized"
);
assert!(i < self.capacity, "index exceeds capacity");
unsafe {
*self.data.offset(i as isize) = v;
}
}
pub fn push_slice(&mut self, slice: &[T]) {
self.reserve(slice.len());
let sz = mem::size_of::<T>();
unsafe {
libc::memcpy(
self.data.offset(self.len() as isize) as *mut libc::c_void,
slice.as_ptr() as *const libc::c_void,
slice.len() * sz,
);
}
self.len += slice.len();
}
pub fn reserve(&mut self, n: usize) {
if self.len + n > self.capacity {
let new_capacity = cmp::max(self.capacity * 2, n);
self.grow(new_capacity);
}
}
fn grow(&mut self, new_capacity: usize) {
let sz = mem::size_of::<T>();
let old_buffer = self.data;
let new_buffer = allocate_aligned((new_capacity * sz) as i64).unwrap();
unsafe {
libc::memcpy(
new_buffer as *mut libc::c_void,
old_buffer as *const libc::c_void,
self.len * sz,
);
}
self.capacity = new_capacity;
self.data = new_buffer as *mut T;
free_aligned(old_buffer as *const u8);
}
pub fn finish(&mut self) -> Buffer {
assert!(!self.data.is_null(), "data has not been initialized");
let p = self.data;
self.data = ptr::null_mut();
Buffer::from_raw_parts(p as *mut u8, self.len)
}
}
impl<T> Drop for Builder<T>
where
T: ArrowPrimitiveType,
{
fn drop(&mut self) {
if !self.data.is_null() {
free_aligned(self.data as *const u8);
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_builder_i32_empty() {
let mut b: Builder<i32> = Builder::with_capacity(5);
let a = b.finish();
assert_eq!(0, a.len());
}
#[test]
fn test_builder_i32_alloc_zero_bytes() {
let mut b: Builder<i32> = Builder::with_capacity(0);
b.push(123);
let a = b.finish();
assert_eq!(1, a.len());
}
#[test]
fn test_builder_i32() {
let mut b: Builder<i32> = Builder::with_capacity(5);
for i in 0..5 {
b.push(i);
}
let a = b.finish();
assert_eq!(5, a.len());
}
#[test]
fn test_builder_i32_grow_buffer() {
let mut b: Builder<i32> = Builder::with_capacity(2);
for i in 0..5 {
b.push(i);
}
let a = b.finish();
assert_eq!(5, a.len());
}
#[test]
fn test_reserve() {
let mut b: Builder<u8> = Builder::with_capacity(2);
assert_eq!(2, b.capacity());
b.reserve(2);
assert_eq!(2, b.capacity());
b.reserve(3);
assert_eq!(4, b.capacity());
}
#[test]
fn test_push_slice() {
let mut b: Builder<u8> = Builder::new();
b.push_slice("Hello, ".as_bytes());
b.push_slice("World!".as_bytes());
let buffer = b.finish();
assert_eq!(13, buffer.len());
}
#[test]
fn test_slice_empty_at_end() {
let mut b: Builder<u8> = Builder::with_capacity(2);
let s = b.slice_mut(2, 2);
assert_eq!(0, s.len());
}
#[test]
#[should_panic(expected = "the end of the slice must be within the capacity")]
fn test_slice_start_out_of_bounds() {
let mut b: Builder<u8> = Builder::with_capacity(2);
b.slice_mut(3, 3);
}
#[test]
#[should_panic(expected = "the end of the slice must be within the capacity")]
fn test_slice_end_out_of_bounds() {
let mut b: Builder<u8> = Builder::with_capacity(2);
b.slice_mut(0, 3);
}
#[test]
#[should_panic(expected = "the start of the slice cannot exceed the end of the slice")]
fn test_slice_end_before_start() {
let mut b: Builder<u8> = Builder::with_capacity(2);
b.slice_mut(1, 0);
}
}