// Column type

use std::slice;

use std::io::{Write};

use byteorder::{WriteBytesExt, ReadBytesExt};

use catalog::mini_attribute::{TypeLabel, ty_byte_len};

pub trait TypeValue {

fn write_bytes(&self, wrt: &mut Write) -> std::io::Result<()>;

fn len(&self) -> u32;

fn as_string(&self) -> String;

fn as_pointer(&self) -> *const libc::c_void;

}

// This function transforms data in database to TypeValue, so use methods of

// byteorder crate.

pub fn load_type_value(tl: &TypeLabel, src: *const libc::c_void) -> Box<TypeValue> {

let len = ty_byte_len(tl);

match tl {

TypeLabel::Integer => {

let ptr: *const u8 = src as *const u8;

let mut s = unsafe { slice::from_raw_parts(ptr, len as usize) };

let i = s.read_i32::<byteorder::LittleEndian>().unwrap();

Box::new(Integer { elem: i })

}

}

}

// This function transforms input from user, mainly SQL, to

// TypeValue, so use `parse` method. We can call `unwrap` because

// `row` will be passed parser syntax check.

pub fn build_type_value(tl: &TypeLabel, row: &str) -> Box<TypeValue> {

match tl {

TypeLabel::Integer => {

let elem = row.parse::<i32>().unwrap();

Box::new(Integer { elem: elem })

}

}

}

// Signed 4 bytes integer

pub struct Integer {

pub elem: i32,

}

impl TypeValue for Integer {

fn write_bytes(&self, wrt: &mut Write) -> std::io::Result<()> {

wrt.write_i32::<byteorder::LittleEndian>(self.elem)

}

fn len(&self) -> u32 {

4

}

fn as_string(&self) -> String {

self.elem.to_string()

}

fn as_pointer(&self) -> *const libc::c_void {

let p: *const i32 = &self.elem;

p as *const libc::c_void

}

}