Struct Buffer

pub struct Buffer { /* private fields */ }

A growable source file that can be parsed incrementally.

let mut buffer = welly_parser::Buffer::default();
buffer.push_str("hw = \"Hello, world!\\n\";\n");
buffer.push_str("for _ in 10 { print(hw); }");
while let Some(token) = buffer.try_parse() {
    println!("{:#?}", token);
}

Implementations

impl Buffer

pub fn remainder(&self) -> &str

Returns the suffix of the source code that has not yet been parsed.

pub fn clear(&mut self)

Discard remainder().

pub fn push_str(&mut self, source: &str)

Append source to the source code. Requires !self.is_complete().

pub fn complete(&mut self)

Inform self that it has all the source code.

This can be important, as in the following example:

let mut buffer = welly_parser::Buffer::default();
buffer.push_str("if c {}"); // Could be followed by `else`.
assert!(buffer.try_parse().is_none());
buffer.complete(); // Exclude `else`.
assert!(buffer.try_parse().is_some());

pub fn is_complete(&self) -> bool

Returns true if more source code can be added with self.push_str().

pub fn try_parse(&mut self) -> Option<(Rc<str>, Token)>

Attempt to parse [self.remainder()]. Hopefully the returned Token is a Stmt. Other possibilities can be found in [welly].

Some((source, token)) indicates that there was enough source code to parse a Token (which might be an error message). Locations are relative to the returned source, which is removed from self.

None indicates that there was not enough source code, either because we need to wait for more, or because there is no more. In this case self is not modified.

Trait Implementations

impl Debug for Buffer

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Buffer

fn default() -> Self

Returns the “default value” for a type.