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use util::pad_u32;
use {Word, Token, Bytes};
fn pad_bytes(bytes: &[u8]) -> Vec<Word> {
let mut result = vec![pad_u32(bytes.len() as u32)];
result.extend(pad_fixed_bytes(bytes));
result
}
fn pad_fixed_bytes(bytes: &[u8]) -> Vec<Word> {
let len = (bytes.len() + 31) / 32;
let mut result = Vec::with_capacity(len);
for i in 0..len {
let mut padded = [0u8; 32];
let to_copy = match i == len - 1 {
false => 32,
true => match bytes.len() % 32 {
0 => 32,
x => x,
},
};
let offset = 32 * i;
padded[..to_copy].copy_from_slice(&bytes[offset..offset + to_copy]);
result.push(padded);
}
result
}
#[derive(Debug)]
enum Mediate {
Raw(Vec<Word>),
Prefixed(Vec<Word>),
PrefixedArray(Vec<Mediate>),
PrefixedArrayWithLength(Vec<Mediate>),
}
impl Mediate {
fn head_len(&self) -> u32 {
match *self {
Mediate::Raw(ref raw) => 32 * raw.len() as u32,
Mediate::Prefixed(_) | Mediate::PrefixedArray(_) | Mediate::PrefixedArrayWithLength(_) => 32,
}
}
fn tail_len(&self) -> u32 {
match *self {
Mediate::Raw(_) => 0,
Mediate::Prefixed(ref pre) => pre.len() as u32 * 32,
Mediate::PrefixedArray(ref mediates) => mediates.iter().fold(0, |acc, m| acc + m.head_len() + m.tail_len()),
Mediate::PrefixedArrayWithLength(ref mediates) => mediates.iter().fold(32, |acc, m| acc + m.head_len() + m.tail_len()),
}
}
fn head(&self, suffix_offset: u32) -> Vec<Word> {
match *self {
Mediate::Raw(ref raw) => raw.clone(),
Mediate::Prefixed(_) | Mediate::PrefixedArray(_) | Mediate::PrefixedArrayWithLength(_) => {
vec![pad_u32(suffix_offset)]
}
}
}
fn tail(&self) -> Vec<Word> {
match *self {
Mediate::Raw(_) => vec![],
Mediate::Prefixed(ref raw) => raw.clone(),
Mediate::PrefixedArray(ref mediates) => encode_head_tail(mediates),
Mediate::PrefixedArrayWithLength(ref mediates) => {
let mut result = vec![pad_u32(mediates.len() as u32)];
let head_tail = encode_head_tail(mediates);
result.extend(head_tail);
result
},
}
}
}
fn encode_head_tail(mediates: &Vec<Mediate>) -> Vec<Word> {
let heads_len = mediates.iter()
.fold(0, |acc, m| acc + m.head_len());
let (mut result, len) = mediates.iter()
.fold(
(Vec::with_capacity(heads_len as usize), heads_len),
|(mut acc, offset), m| {
acc.extend(m.head(offset));
(acc, offset + m.tail_len())
}
);
let tails = mediates.iter()
.fold(
Vec::with_capacity((len - heads_len) as usize),
|mut acc, m| {
acc.extend(m.tail());
acc
}
);
result.extend(tails);
result
}
pub fn encode(tokens: &[Token]) -> Bytes {
let mediates = &tokens.iter()
.map(encode_token)
.collect();
encode_head_tail(mediates).iter()
.flat_map(|word| word.to_vec())
.collect()
}
fn encode_token(token: &Token) -> Mediate {
match *token {
Token::Address(ref address) => {
let mut padded = [0u8; 32];
padded[12..].copy_from_slice(address.as_ref());
Mediate::Raw(vec![padded])
},
Token::Bytes(ref bytes) => Mediate::Prefixed(pad_bytes(bytes)),
Token::String(ref s) => Mediate::Prefixed(pad_bytes(s.as_bytes())),
Token::FixedBytes(ref bytes) => Mediate::Raw(pad_fixed_bytes(bytes)),
Token::Int(int) => Mediate::Raw(vec![int.into()]),
Token::Uint(uint) => Mediate::Raw(vec![uint.into()]),
Token::Bool(b) => {
let mut value = [0u8; 32];
if b {
value[31] = 1;
}
Mediate::Raw(vec![value])
},
Token::Array(ref tokens) => {
let mediates = tokens.iter()
.map(encode_token)
.collect();
Mediate::PrefixedArrayWithLength(mediates)
},
Token::FixedArray(ref tokens) => {
let mediates = tokens.iter()
.map(encode_token)
.collect();
if token.is_dynamic() {
Mediate::PrefixedArray(mediates)
} else {
Mediate::Raw(encode_head_tail(&mediates))
}
},
}
}