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use byteorder::{ByteOrder, LittleEndian};
use types::*;
use iter::Iterator;
/// Table provides functions to read Flatbuffer data.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct Table<'a> {
buffer: &'a [u8],
pos: usize
}
impl<'a> Table<'a> {
/// Create a table using from a slice using data starting at `pos`.
/// First `UOffsetT` should indicate the offset from the root
/// of the table to the begining of the object.
///
/// In the following example pos should be 0:
/// ```
/// 16, 0, 0, 0, // root of table: points to object <---------
/// 0, 0, // padding
/// 10, 0, // vtable bytes
/// 8, 0, // size of object
/// 7, 0, // start of value 0
/// 6, 0, // start of value 1
/// 5, 0, // start of value 2
/// 10, 0, 0, 0, // start of object..ie. vtable offset
/// 0, // padding
/// 77, // value 2
/// 66, // value 1
/// 55, // value 0
/// ```
pub fn from_offset(buffer: &[u8], pos: usize) -> Table {
let n = read_uoffset(&buffer, pos);
Table {
buffer: buffer,
pos: n as usize + pos
}
}
/// Create a table for an object.
/// `pos` should be the offset to the first byte of
/// useable data.
///
/// In the following example pos should be 16:
/// ```
/// 16, 0, 0, 0, // root of table: points to object
/// 0, 0, // padding
/// 10, 0, // vtable bytes
/// 8, 0, // size of object
/// 7, 0, // start of value 0
/// 6, 0, // start of value 1
/// 5, 0, // start of value 2
/// 10, 0, 0, 0, // start of object..ie. vtable offset <---------
/// 0, // padding
/// 77, // value 2
/// 66, // value 1
/// 55, // value 0
/// ```
pub fn with_pos(buffer: &[u8], pos: usize) -> Table {
Table {
buffer: buffer,
pos: pos
}
}
/// Return an object table at offset.
/// See `from_offset`.
pub fn get_root(&self, offset: UOffsetT) -> Table {
Table::from_offset(self.buffer, self.pos + offset as usize)
}
/// Return an object table at offset specified by offset.
pub fn get_indirect_root(&self, offset: UOffsetT) -> Table {
let actual_offset = self.pos as u32 + offset + self.get_u32(offset);
Table::with_pos(&self.buffer, actual_offset as usize)
}
// Returns a slice of table including the vtable.
//
// First element of root table is Offset to vtable used
// and is by default a negative direction.
#[inline(always)]
fn vtable(&self) -> &[u8] {
let vt_offset = read_soffset(&self.buffer, self.pos);
let vtable = (self.pos as i32 - vt_offset) as usize;
&self.buffer[vtable..]
}
/// Returns the field offset or 0 if the field was not present.
pub fn field_offset(&self, field: VOffsetT) -> UOffsetT {
let vtable = self.vtable();
let vt_size = LittleEndian::read_u16(vtable);
if field < vt_size {
return LittleEndian::read_u16(&vtable[field as usize..]) as u32
}
0
}
/// Returns the `bool` value of the field at the offset written in the
/// vtable `slot`.
pub fn get_slot_bool(&self, slot: VOffsetT, default: bool) -> bool {
let offset = self.field_offset(slot);
if offset != 0 {
return self.get_bool(offset)
}
default
}
/// Returns the `u8` value of the field at the offset written in the
/// vtable `slot`.
pub fn get_slot_u8(&self, slot: VOffsetT, default: u8) -> u8 {
let offset = self.field_offset(slot);
if offset != 0 {
return self.get_u8(offset)
}
default
}
/// Returns the `i8` value of the field at the offset written in the
/// vtable `slot`.
pub fn get_slot_i8(&self, slot: VOffsetT, default: i8) -> i8 {
let offset = self.field_offset(slot);
if offset != 0 {
return self.get_i8(offset)
}
default
}
/// Returns the `u16` value of the field at the offset written in the
/// vtable `slot`.
pub fn get_slot_u16(&self, slot: VOffsetT, default: u16) -> u16 {
let offset = self.field_offset(slot);
if offset != 0 {
return self.get_u16(offset)
}
default
}
/// Returns the `i16` value of the field at the offset written in the
/// vtable `slot`.
pub fn get_slot_i16(&self, slot: VOffsetT, default: i16) -> i16 {
let offset = self.field_offset(slot);
if offset != 0 {
return self.get_i16(offset)
}
default
}
/// Returns the `u32` value of the field at the offset written in the
/// vtable `slot`.
pub fn get_slot_u32(&self, slot: VOffsetT, default: u32) -> u32 {
let offset = self.field_offset(slot);
if offset != 0 {
return self.get_u32(offset)
}
default
}
/// Returns the `i32` value of the field at the offset written in the
/// vtable `slot`.
pub fn get_slot_i32(&self, slot: VOffsetT, default: i32) -> i32 {
let offset = self.field_offset(slot);
if offset != 0 {
return self.get_i32(offset)
}
default
}
/// Returns the `u64` value of the field at the offset written in the
/// vtable `slot`.
pub fn get_slot_u64(&self, slot: VOffsetT, default: u64) -> u64 {
let offset = self.field_offset(slot);
if offset != 0 {
return self.get_u64(offset)
}
default
}
/// Returns the `i64` value of the field at the offset written in the
/// vtable `slot`.
pub fn get_slot_i64(&self, slot: VOffsetT, default: i64) -> i64 {
let offset = self.field_offset(slot);
if offset != 0 {
return self.get_i64(offset)
}
default
}
/// Returns the `f32` value of the field at the offset written in the
/// vtable `slot`.
pub fn get_slot_f32(&self, slot: VOffsetT, default: f32) -> f32 {
let offset = self.field_offset(slot);
if offset != 0 {
return self.get_f32(offset)
}
default
}
/// Returns the `f64` value of the field at the offset written in the
/// vtable `slot`.
pub fn get_slot_f64(&self, slot: VOffsetT, default: f64) -> f64 {
let offset = self.field_offset(slot);
if offset != 0 {
return self.get_f64(offset)
}
default
}
/// Returns the `&str` value of the field at the offset written in the
/// vtable `slot`.
pub fn get_slot_str(&self, slot: VOffsetT) -> &str {
let offset = self.field_offset(slot);
if offset != 0 {
return self.get_str(offset)
}
""
}
/// Returns the struct `T` value of the field at the offset written in the
/// vtable `slot`.
pub fn get_slot_struct<T: From<Table<'a>>>(&self, slot: VOffsetT) -> Option<T> {
let offset = self.field_offset(slot);
if offset != 0 {
return Some(self.get_struct(offset))
}
None
}
/// Returns the unsigned byte vector value of the field at the offset written in the
/// vtable `slot`.
pub fn get_slot_vector<T>(&self, slot: VOffsetT) -> Iterator<'a, T> {
let offset = self.field_offset(slot);
if offset != 0 {
return self.get_vector::<T>(offset)
}
Default::default()
}
/// ByteVector gets an unsigned byte slice from data stored inside
/// the flatbuffer.
pub fn get_vector<T>(&self, offset: UOffsetT) -> Iterator<'a, T> {
let mut offset = offset as usize + self.pos;
offset += read_uoffset(self.buffer, offset) as usize;
let start = offset + UOFFSETT_SIZE;
let length = read_uoffset(self.buffer, offset) as usize;
Iterator::new(&self.buffer, start, length)
}
/// Returns a value of `bool` at `offset`.
pub fn get_bool(&self, offset: UOffsetT) -> bool {
let pos = self.pos as usize;
self.buffer[pos + offset as usize] == 1
}
/// Returns a value of `u8` at `offset`.
pub fn get_u8(&self, offset: UOffsetT) -> u8 {
let pos = self.pos as usize;
self.buffer[pos + offset as usize]
}
/// Returns a value of `i8` at `offset`.
pub fn get_i8(&self, offset: UOffsetT) -> i8 {
let pos = self.pos as usize;
self.buffer[pos + offset as usize] as i8
}
/// Returns a value of `u16` at `offset`.
pub fn get_u16(&self, offset: UOffsetT) -> u16 {
let pos = self.pos as usize;
LittleEndian::read_u16(&self.buffer[pos + offset as usize..])
}
/// Returns a value of `i16` at `offset`.
pub fn get_i16(&self, offset: UOffsetT) -> i16 {
let pos = self.pos as usize;
LittleEndian::read_i16(&self.buffer[pos + offset as usize..])
}
/// Returns a value of `u32` at `offset`.
pub fn get_u32(&self, offset: UOffsetT) -> u32 {
let pos = self.pos as usize;
LittleEndian::read_u32(&self.buffer[pos + offset as usize..])
}
/// Returns a value of `i32` at `offset`.
pub fn get_i32(&self, offset: UOffsetT) -> i32 {
let pos = self.pos as usize;
LittleEndian::read_i32(&self.buffer[pos + offset as usize..])
}
/// Returns a value of `u64` at `offset`.
pub fn get_u64(&self, offset: UOffsetT) -> u64 {
let pos = self.pos as usize;
LittleEndian::read_u64(&self.buffer[pos + offset as usize..])
}
/// Returns a value of `i64` at `offset`.
pub fn get_i64(&self, offset: UOffsetT) -> i64 {
let pos = self.pos as usize;
LittleEndian::read_i64(&self.buffer[pos + offset as usize..])
}
/// Returns a value of `f32` at `offset`.
pub fn get_f32(&self, offset: UOffsetT) -> f32 {
let pos = self.pos as usize;
LittleEndian::read_f32(&self.buffer[pos + offset as usize..])
}
/// Returns a value of `f64` at `offset`.
pub fn get_f64(&self, offset: UOffsetT) -> f64 {
let pos = self.pos as usize;
LittleEndian::read_f64(&self.buffer[pos + offset as usize..])
}
/// Returns a value of `&str` at `offset`.
pub fn get_str(&self, offset: UOffsetT) -> &str {
use std::str;
let mut offset = offset + self.pos as UOffsetT;
offset += read_uoffset(self.buffer, offset as usize);
let start = offset as usize + 4 as usize;
let length = read_uoffset(self.buffer, offset as usize) as usize;
let s = &self.buffer[start..start+length];
unsafe { str::from_utf8_unchecked(s) }
}
/// Retrieve a struct table from offset. Offset should point to then
/// first usable byte of data i.e. the Vtable offset.
pub fn get_struct<T: From<Table<'a>>>(&self, offset: UOffsetT) -> T {
let pos = self.pos as UOffsetT + offset;
let table = Table::with_pos(self.buffer, pos as usize);
table.into()
}
/// Accesor function for the tables position in the buffer.
#[inline]
pub fn get_pos(&self) -> UOffsetT {
self.pos as UOffsetT
}
/// Reads an `UOffsetT` at exact position.
pub fn read_uoffset(&self, offset: UOffsetT) -> UOffsetT {
read_uoffset(self.buffer, offset as usize)
}
/// Reads an `VOffsetT` at exact position.
pub fn read_voffset(&self, offset: UOffsetT) -> VOffsetT {
read_voffset(self.buffer, offset as usize)
}
/// Retrieves the `VOffsetT` in the vtable `slot`.
/// If the vtable value is zero, the default value `d` will be returned.
pub fn read_voffset_slot(&self, slot: VOffsetT, d: VOffsetT) -> VOffsetT {
let offset = self.field_offset(slot);
if offset != 0 {
return offset as VOffsetT
}
d
}
/// Get a reference to the raw buffer
#[inline]
pub fn get_bytes(&self) -> &[u8] {
self.buffer
}
}
/// Read a Unsigned offset value at given offset
pub fn read_uoffset(buf: &[u8], offset: usize) -> UOffsetT {
LittleEndian::read_u32(&buf[offset as usize..])
}
/// Read a Signed offset value at given offset
pub fn read_soffset(buf: &[u8], offset: usize) -> SOffsetT {
LittleEndian::read_i32(&buf[offset as usize..])
}
/// Read a Signed offset value at given offset
pub fn read_voffset(buf: &[u8], offset: usize) -> VOffsetT {
LittleEndian::read_u16(&buf[offset as usize..])
}
impl<'a> From<&'a [u8]> for Table<'a> {
fn from(buf: &[u8]) -> Table {
Table::from_offset(buf, 0)
}
}