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//! Generic CBOR tokenization.
use core::ops::{Deref, DerefMut};
use crate::data::Token;
use crate::decode::Error;
/// An [`Iterator`] over CBOR tokens.
///
/// The `Iterator` implementation calls [`Tokenizer::token`] until end of input has been reached.
///
/// *Requires feature* `"half"`.
#[derive(Debug, Clone)]
pub struct Tokenizer<'a, 'b> {
decoder: Decoder<'a, 'b>
}
impl<'a, 'b> Iterator for Tokenizer<'a, 'b> {
type Item = Result<Token<'b>, Error>;
fn next(&mut self) -> Option<Self::Item> {
match self.token() {
Ok(t) => Some(Ok(t)),
Err(e) if e.is_end_of_input() => None,
Err(e) => Some(Err(e))
}
}
}
impl<'b> From<crate::Decoder<'b>> for Tokenizer<'_, 'b> {
fn from(d: crate::Decoder<'b>) -> Self {
Tokenizer { decoder: Decoder::Owned(d) }
}
}
impl<'a, 'b> From<&'a mut crate::Decoder<'b>> for Tokenizer<'a, 'b> {
fn from(d: &'a mut crate::Decoder<'b>) -> Self {
Tokenizer { decoder: Decoder::Borrowed(d) }
}
}
impl<'a, 'b> Tokenizer<'a, 'b> {
/// Create a new Tokenizer for the given input bytes.
pub fn new(bytes: &'b[u8]) -> Self {
Tokenizer { decoder: Decoder::Owned(crate::Decoder::new(bytes)) }
}
/// Decode the next token.
///
/// Note that a sequence of tokens may not necessarily represent
/// well-formed CBOR items.
pub fn token(&mut self) -> Result<Token<'b>, Error> {
match self.decoder.decode() {
Ok(tk) => Ok(tk),
Err(e) => {
let end = self.decoder.input().len();
self.decoder.set_position(end); // drain decoder
Err(e)
}
}
}
}
#[cfg(feature = "alloc")]
impl core::fmt::Display for Tokenizer<'_, '_> {
fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
/// Control stack element.
enum E {
N(bool), // get next token (true => token is required)
T, // tag
A(Option<u64>), // array
M(Option<u64>), // map
B, // indefinite bytes
D, // indefinite text
S(&'static str), // display string
X(&'static str) // display string (unless next token is BREAK)
}
let mut iter = self.clone().peekable();
let mut stack = alloc::vec::Vec::new();
while iter.peek().is_some() {
stack.push(E::N(false));
while let Some(elt) = stack.pop() {
match elt {
E::N(required) => match iter.next() {
Some(Ok(Token::Array(n))) => {
stack.push(E::A(Some(n)));
f.write_str("[")?
}
Some(Ok(Token::Map(n))) => {
stack.push(E::M(Some(n)));
f.write_str("{")?
}
Some(Ok(Token::BeginArray)) => {
stack.push(E::A(None));
f.write_str("[_ ")?
}
Some(Ok(Token::BeginMap)) => {
stack.push(E::M(None));
f.write_str("{_ ")?
}
Some(Ok(Token::BeginBytes)) => if let Some(Ok(Token::Break)) = iter.peek() {
iter.next();
f.write_str("''_")?
} else {
stack.push(E::B);
f.write_str("(_ ")?
}
Some(Ok(Token::BeginString)) => if let Some(Ok(Token::Break)) = iter.peek() {
iter.next();
f.write_str("\"\"_")?
} else {
stack.push(E::D);
f.write_str("(_ ")?
}
Some(Ok(Token::Tag(t))) => {
stack.push(E::T);
write!(f, "{}(", u64::from(t))?
}
Some(Ok(t)) => t.fmt(f)?,
Some(Err(e)) => {
write!(f, " !!! decoding error: {e}")?;
return Ok(())
}
None => if required {
f.write_str(" !!! decoding error: unexpected end of input")?;
return Ok(())
} else {
continue
}
}
E::S(s) => f.write_str(s)?,
E::X(s) => match iter.peek() {
Some(Ok(Token::Break)) | None => continue,
Some(Ok(_)) => f.write_str(s)?,
Some(Err(e)) => {
write!(f, " !!! decoding error: {e}")?;
return Ok(())
}
}
E::T => {
stack.push(E::S(")"));
stack.push(E::N(true))
}
E::A(Some(0)) => f.write_str("]")?,
E::A(Some(1)) => {
stack.push(E::A(Some(0)));
stack.push(E::N(true))
}
E::A(Some(n)) => {
stack.push(E::A(Some(n - 1)));
stack.push(E::S(", "));
stack.push(E::N(true))
}
E::A(None) => match iter.peek() {
None => {
f.write_str(" !!! indefinite array not closed")?;
return Ok(())
}
Some(Ok(Token::Break)) => {
iter.next();
f.write_str("]")?
}
_ => {
stack.push(E::A(None));
stack.push(E::X(", "));
stack.push(E::N(true))
}
}
E::M(Some(0)) => f.write_str("}")?,
E::M(Some(1)) => {
stack.push(E::M(Some(0)));
stack.push(E::N(true));
stack.push(E::S(": "));
stack.push(E::N(true))
}
E::M(Some(n)) => {
stack.push(E::M(Some(n - 1)));
stack.push(E::S(", "));
stack.push(E::N(true));
stack.push(E::S(": "));
stack.push(E::N(true))
}
E::M(None) => match iter.peek() {
None => {
f.write_str(" !!! indefinite map not closed")?;
return Ok(())
}
Some(Ok(Token::Break)) => {
iter.next();
f.write_str("}")?
}
_ => {
stack.push(E::M(None));
stack.push(E::X(", "));
stack.push(E::N(true));
stack.push(E::S(": "));
stack.push(E::N(true))
}
}
E::B => match iter.peek() {
None => {
f.write_str(" !!! indefinite byte string not closed")?;
return Ok(())
}
Some(Ok(Token::Break)) => {
iter.next();
f.write_str(")")?
}
_ => {
stack.push(E::B);
stack.push(E::X(", "));
stack.push(E::N(true))
}
}
E::D => match iter.peek() {
None => {
f.write_str(" !!! indefinite string not closed")?;
return Ok(())
}
Some(Ok(Token::Break)) => {
iter.next();
f.write_str(")")?
}
_ => {
stack.push(E::D);
stack.push(E::X(", "));
stack.push(E::N(true))
}
}
}
}
}
Ok(())
}
}
/// Either own or borrow a decoder (similar to `alloc::borrow::Cow`).
#[derive(Debug)]
enum Decoder<'a, 'b> {
Owned(crate::Decoder<'b>),
Borrowed(&'a mut crate::Decoder<'b>)
}
impl<'b> Deref for Decoder<'_, 'b> {
type Target = crate::Decoder<'b>;
fn deref(&self) -> &Self::Target {
match self {
Self::Owned(d) => d,
Self::Borrowed(d) => d
}
}
}
impl<'b> DerefMut for Decoder<'_, 'b> {
fn deref_mut(&mut self) -> &mut Self::Target {
match self {
Self::Owned(d) => d,
Self::Borrowed(d) => d
}
}
}
impl Clone for Decoder<'_, '_> {
fn clone(&self) -> Self {
match self {
Self::Owned(d) => Self::Owned(d.clone()),
Self::Borrowed(d) => Self::Owned((*d).clone())
}
}
}