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use leveldb_sys::{leveldb_iterator_t, leveldb_iter_seek_to_first, leveldb_iter_destroy,
leveldb_iter_seek_to_last, leveldb_create_iterator, leveldb_iter_valid,
leveldb_iter_next, leveldb_iter_key, leveldb_iter_value,
leveldb_readoptions_destroy, leveldb_iter_seek};
use libc::{size_t, c_char};
use super::Database;
use super::options::{ReadOptions, c_readoptions};
use std::slice::from_raw_parts;
#[allow(missing_docs)]
struct RawIterator {
ptr: *mut leveldb_iterator_t,
}
#[allow(missing_docs)]
impl Drop for RawIterator {
fn drop(&mut self) {
unsafe { leveldb_iter_destroy(self.ptr) }
}
}
pub struct Iterator<'a> {
move_next: bool,
#[allow(dead_code)]
database: &'a Database,
iter: RawIterator,
}
pub trait Iterable<'a> {
fn iter(&'a self, options: ReadOptions<'a>) -> Iterator;
}
impl<'a> Iterable<'a> for Database {
fn iter(&'a self, options: ReadOptions<'a>) -> Iterator {
Iterator::new(self, options)
}
}
impl<'a> Iterator<'a> {
fn new(database: &'a Database, options: ReadOptions<'a>) -> Iterator<'a> {
unsafe {
let c_readoptions = c_readoptions(&options);
let ptr = leveldb_create_iterator(database.database.ptr, c_readoptions);
leveldb_readoptions_destroy(c_readoptions);
leveldb_iter_seek_to_first(ptr);
Iterator {
move_next: false,
iter: RawIterator { ptr: ptr },
database: database,
}
}
}
fn valid(&self) -> bool {
unsafe {
leveldb_iter_valid(self.iter.ptr) != 0
}
}
fn advance(&mut self) {
unsafe {
leveldb_iter_next(self.iter.ptr);
}
}
unsafe fn key(&self) -> &[u8] {
let length: size_t = 0;
let value = leveldb_iter_key(self.iter.ptr, &length) as *const u8;
from_raw_parts(value, length as usize)
}
unsafe fn value(&self) -> &[u8] {
let length: size_t = 0;
let value = leveldb_iter_value(self.iter.ptr, &length) as *const u8;
from_raw_parts(value, length as usize)
}
pub fn seek_to_first(&mut self) {
unsafe { leveldb_iter_seek_to_first(self.iter.ptr) }
}
pub fn seek_to_last(&mut self) {
unsafe { leveldb_iter_seek_to_last(self.iter.ptr); }
}
pub fn seek(&mut self, key: &[u8]) {
unsafe {
leveldb_iter_seek(self.iter.ptr,
key.as_ptr() as *mut c_char,
key.len() as size_t);
}
}
pub fn next(&mut self) -> Option<(&[u8], &[u8])> {
if self.move_next {
self.advance();
}
self.move_next = true;
if self.valid() {
unsafe {
Some((self.key(), self.value()))
}
} else {
None
}
}
pub fn peek(&mut self) -> Option<(&[u8], &[u8])> {
if self.move_next {
self.advance();
}
self.move_next = false;
if self.valid() {
unsafe {
Some((self.key(), self.value()))
}
} else {
None
}
}
}