Struct wast::parser::Cursor

pub struct Cursor<'a> { /* fields omitted */ }

An immutable cursor into a list of tokens.

This cursor cannot be mutated but can be used to parse more tokens in a list of tokens. Cursors are created from the [Parser::step] method. This is a very low-level parsing structure and you likely won't use it much.

Methods

impl<'a> Cursor<'a>

pub fn cur_span(&self) -> Span

Returns the span of the next Token token.

Does not take into account whitespace or comments.

pub fn error(&self, msg: impl Display) -> Error

Same as [Parser::error], but works with the current token in this [Cursor] instead.

pub fn lparen(self) -> Option<Self>

Attempts to advance this cursor if the current token is a (.

If the current token is (, returns a new [Cursor] pointing at the rest of the tokens in the stream. Otherwise returns None.

This function will automatically skip over any comments, whitespace, or unknown annotations.

pub fn rparen(self) -> Option<Self>

Attempts to advance this cursor if the current token is a ).

If the current token is ), returns a new [Cursor] pointing at the rest of the tokens in the stream. Otherwise returns None.

This function will automatically skip over any comments, whitespace, or unknown annotations.

pub fn id(self) -> Option<(&'a str, Self)>

Attempts to advance this cursor if the current token is a Token::Id

If the current token is Id, returns the identifier minus the leading $ character as well as a new [Cursor] pointing at the rest of the tokens in the stream. Otherwise returns None.

This function will automatically skip over any comments, whitespace, or unknown annotations.

pub fn keyword(self) -> Option<(&'a str, Self)>

Attempts to advance this cursor if the current token is a Token::Keyword

If the current token is Keyword, returns the keyword as well as a new [Cursor] pointing at the rest of the tokens in the stream. Otherwise returns None.

This function will automatically skip over any comments, whitespace, or unknown annotations.

pub fn reserved(self) -> Option<(&'a str, Self)>

Attempts to advance this cursor if the current token is a Token::Reserved

If the current token is Reserved, returns the reserved token as well as a new [Cursor] pointing at the rest of the tokens in the stream. Otherwise returns None.

This function will automatically skip over any comments, whitespace, or unknown annotations.

pub fn integer(self) -> Option<(&'a Integer<'a>, Self)>

Attempts to advance this cursor if the current token is a Token::Integer

If the current token is Integer, returns the integer as well as a new [Cursor] pointing at the rest of the tokens in the stream. Otherwise returns None.

This function will automatically skip over any comments, whitespace, or unknown annotations.

pub fn float(self) -> Option<(&'a Float<'a>, Self)>

Attempts to advance this cursor if the current token is a Token::Float

If the current token is Float, returns the float as well as a new [Cursor] pointing at the rest of the tokens in the stream. Otherwise returns None.

This function will automatically skip over any comments, whitespace, or unknown annotations.

pub fn string(self) -> Option<(&'a [u8], Self)>

Attempts to advance this cursor if the current token is a Token::String

If the current token is String, returns the byte value of the string as well as a new [Cursor] pointing at the rest of the tokens in the stream. Otherwise returns None.

This function will automatically skip over any comments, whitespace, or unknown annotations.

pub fn annotation(self) -> Option<(&'a str, Self)>

Attempts to advance this cursor if the current token is a Token::Reserved and looks like the start of an annotation.

Annotations are a WebAssembly proposal for the text format which allows placing structured text inside of a text file, for example to specify the name section or other custom sections.

This function will attempt to see if the current token is the @foo part of the annotation. This requires the previous token to be ( and the current token is Reserved which starts with @ and has a nonzero length for the following name.

Note that this will skip unknown annoations. Only pre-registered annotations will be returned here.

This function will automatically skip over any comments, whitespace, or unknown annotations.

pub fn comment(self) -> Option<(&'a Comment<'a>, Self)>

Attempts to advance this cursor if the current token is a Source::Comment

This function will only skip whitespace, no other tokens.

Trait Implementations

impl<'a> Clone for Cursor<'a>

fn clone(&self) -> Cursor<'a>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'a> Copy for Cursor<'a>