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|
use super::{
error::{ParseError, TakeError},
position::LineCol,
};
pub trait Parser {
fn next(&mut self) -> Option<char>;
fn peek(&mut self) -> Option<char>;
fn pos(&self) -> LineCol;
fn take<P: Parse>(&mut self) -> Result<P, TakeError> {
P::take(self)
}
fn parse<P: Parse>(self) -> Result<P, ParseError>
where
Self: Sized,
{
P::parse(self)
}
fn consume_str(&mut self, s: &'static str) -> Result<(), TakeError> {
let mut count = 0;
for exp in s.chars() {
if let Some(got) = self.peek() {
if got == exp {
self.next();
count += 1
} else {
let mut out = String::from(&s[..count]);
out.push(got);
return Err(TakeError::BadString(self.pos(), out, s));
}
} else {
return Err(TakeError::EndOfStream(self.pos()));
}
}
Ok(())
}
}
pub struct IterWrapper<T: ?Sized> {
pos: LineCol,
next: Option<char>,
iter: T,
}
impl<T: Iterator<Item = char>> IterWrapper<T> {
pub fn new(iter: T) -> Self {
Self {
pos: LineCol::default(),
next: None,
iter,
}
}
}
impl<I: ?Sized + Iterator<Item = char>> Parser for IterWrapper<I> {
fn next(&mut self) -> Option<char> {
match self.next.take().or_else(|| self.iter.next()) {
x @ Some('\n')
| x @ Some('\x0B')
| x @ Some('\x0C')
| x @ Some('\u{85}')
| x @ Some('\u{2028}')
| x @ Some('\u{2029}') => {
self.pos.line += 1;
self.pos.col = 0;
x
}
Some('\x0D') => {
if self.peek() == Some('\n') {
self.pos.col += 1;
} else {
self.pos.line += 1;
self.pos.col = 0;
}
Some('\x0D')
}
x => {
self.pos.col += 1;
x
}
}
}
fn peek(&mut self) -> Option<char> {
if self.next.is_none() {
self.next = self.iter.next();
}
self.next.as_ref().copied()
}
fn pos(&self) -> LineCol {
self.pos
}
}
pub trait Parse: Sized {
fn take<P: Parser + ?Sized>(input: &mut P) -> Result<Self, TakeError>;
fn parse<P: Parser>(mut input: P) -> Result<Self, ParseError> {
let res = Self::take(&mut input)?;
if input.peek().is_some() {
Err(ParseError::InputContinues(input.pos()))
} else {
Ok(res)
}
}
fn take_str(input: &str) -> Result<Self, TakeError> {
Self::take(&mut IterWrapper::new(input.chars()))
}
fn parse_str(input: &str) -> Result<Self, ParseError> {
Self::parse(IterWrapper::new(input.chars()))
}
}
impl Parse for () {
fn take<P: Parser + ?Sized>(_: &mut P) -> Result<Self, TakeError> {
Ok(())
}
}
impl<A: Parse, B: Parse> Parse for (A, B) {
fn take<P: Parser + ?Sized>(input: &mut P) -> Result<Self, TakeError> {
let a = input.take()?;
let b = input.take()?;
Ok((a, b))
}
fn parse<P: Parser>(mut input: P) -> Result<Self, ParseError> {
let a = A::take(&mut input)?;
let b = B::parse(input)?;
Ok((a, b))
}
}
impl<T: Parse + Sized> Parse for Box<T> {
fn take<P: Parser + ?Sized>(input: &mut P) -> Result<Self, TakeError> {
Ok(Box::new(input.take()?))
}
fn parse<P: Parser>(input: P) -> Result<Self, ParseError> {
Ok(Box::new(input.parse()?))
}
}
|
