Struct galvanize::reader::Reader

pub struct Reader<'a, F: Read + Seek + 'a> { /* fields omitted */ }

Allows you to read from CDB.

Example

Given a file stored at filename with the following contents:

{
    "key": "value",
}

this is how you can read the stored value:

use galvanize::Reader;
use std::fs::File;

let key = "key".as_bytes();

let mut f = try!(File::open(filename));
let mut cdb_reader = try!(Reader::new(&mut f));
let stored_vals = cdb_reader.get(key);
assert_eq!(stored_vals.len(), 1);
assert_eq!(&stored_vals[0][..], &"value".as_bytes()[..]);

// The CDB contains only one entry:
assert_eq!(cdb_reader.len(), 1);

// Accessing a key that isn't in the CDB:
let non_existing_key = "non_existing_key".as_bytes();
let empty = cdb_reader.get(non_existing_key);
assert_eq!(empty.len(), 0);

assert!(cdb_reader.get_first(non_existing_key).is_err());

Methods

impl<'a, F: Read + Seek + 'a> Reader<'a, F>

fn new(file: &'a mut F) -> Result<Reader<'a, F>>

Creates a new Reader consuming the provided file.

fn len(&self) -> usize

How many (key, value) pairs are there in this Read Only CDB.

fn get(&mut self, key: &[u8]) -> Vec<Vec<u8>>

Return a Vec of all the values under the given key.

fn keys(&mut self) -> Vec<Vec<u8>>

Return a Vec of all the keys in this Read Only CDB.

Keep in mind that if there're duplicated keys, they will appear multiple times in the resulting Vec.

fn get_first(&mut self, key: &[u8]) -> Result<Vec<u8>>

Pull the value bytes for the first occurence of the given key in this CDB.

fn get_from_pos(&mut self, key: &[u8], index: u32) -> Result<Vec<u8>>

Pull the value bytes for the indexst occurence of the given key in this CDB.

impl<'a> Reader<'a, File>

fn as_writer(self) -> Result<Writer<'a, File>>

Transform this Reader into a Writer using the same underlying file.

The underlying file will have its hash table truncated. This will be regenerated on Writer drop.

Trait Implementations

impl<'a, F: Debug + Read + Seek + 'a> Debug for Reader<'a, F>

fn fmt(&self, __arg_0: &mut Formatter) -> Result

Formats the value using the given formatter.

impl<'a, 'file: 'a, F: Read + Seek + 'file> IntoIterator for &'a mut Reader<'file, F>

Convert a Reader CDB into an Iterator.

One use of this, is using Rust's for loop syntax.

Example

let mut f = File::open(filename).unwrap();

let mut cdb_reader = Reader::new(&mut f).ok().unwrap();
let len = cdb_reader.len();

for (k, v) in cdb_reader.into_iter() {
    // Consume the (k, v) pair.
}

type Item = (Vec<u8>, Vec<u8>)

A single key, value pair.

type IntoIter = ItemIterator<'a, 'file, F>

The ItemIterator type this will convert into.

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.