syntax_parser_generator/readers/
reader.rs

1/// A unique interface for accessing a sequence of input items.
2///
3/// This interface is used by the lexical analyzer when accessing input text, and needs to be
4/// implemented for reading bytes ([`Reader<u8>`]) before the underlying input text can be parsed.
5///
6/// # Implementation
7///
8/// A [Reader] should maintain 3 conceptual pointers into the input sequence of items, dubbed
9/// `head`, `cursor`, and `tail`. All should initially point to the beginning of the sequence. The
10/// interface provides an API for managing these pointers, and accessing the underlying data. This
11/// API is internally used by lexical analyzers.
12pub trait Reader<T> {
13    /// Reads the item pointed by `cursor`, and advance `cursor` to the next item.
14    ///
15    /// Returns [None] if `cursor` points to no valid item (for example - when the input is
16    /// exhausted).
17    fn read_next(&mut self) -> Option<T>;
18
19    /// Set `head` to point to the item pointed by `cursor`.
20    fn set_head(&mut self);
21
22    /// Set `tail` to point to the item pointed by `cursor`.
23    fn set_tail(&mut self);
24
25    /// Set `cursor` to point to the item pointed by `tail`.
26    fn move_cursor_to_tail(&mut self);
27
28    /// Get an iterator over all items between `head` (inclusive) and `tail` (exclusive).
29    fn get_sequence(&self) -> impl Iterator<Item=T>;
30
31    /// Set `cursor` and `head` to point to the item pointed by `tail`.
32    fn restart_from_tail(&mut self) {
33        self.move_cursor_to_tail();
34        self.set_head();
35        self.set_tail();
36    }
37}
syntax_parser_generator/readers/reader.rs

syntax_parser_generator/readers/
reader.rs
