markab_parser/order_parser/
parser.rs

1use crate::{
2	equal::Equal,
3	map_parser::MapParser,
4	order_parser::{
5		OrderParserError,
6		OrderParserRequirement,
7	},
8	Parser,
9};
10use either::{
11	Either,
12	Left,
13	Right,
14};
15use std::marker::PhantomData;
16
17#[derive(Debug)]
18pub struct OrderParser<'a, P1, P2>
19where
20	P1: Parser<'a>,
21	P2: Parser<'a>,
22{
23	first: P1,
24	second: P2,
25	_a: PhantomData<&'a ()>,
26}
27
28impl<'a, P1, P2> OrderParser<'a, P1, P2>
29where
30	P1: Parser<'a>,
31	P2: Parser<'a>,
32{
33	pub fn new(first: P1, second: P2) -> Self
34	{
35		Self {
36			first,
37			second,
38			_a: PhantomData,
39		}
40	}
41}
42
43impl<'a, P1, P2> OrderParser<'a, P1, P2>
44where
45	P1: Parser<'a>,
46	P2: Parser<'a>,
47	P2::Output: Equal<P1::Output>,
48{
49	pub fn merge(self) -> MapParser<'a, Self, P1::Output>
50	{
51		self.map(&|res| {
52			match res
53			{
54				Left(first) => first,
55				Right(second) => second.ident(),
56			}
57		})
58	}
59}
60
61impl<'a, P1, P2> Parser<'a> for OrderParser<'a, P1, P2>
62where
63	P1: Parser<'a>,
64	P2: Parser<'a>,
65{
66	type Error = OrderParserError<'a, P1, P2>;
67	type Output = Either<P1::Output, P2::Output>;
68	type Requirement = OrderParserRequirement<'a, P1, P2>;
69	type RequirementContext = ();
70
71	fn parse(&self, src: &'a str, pos: &mut usize) -> Result<Self::Output, Self::Error>
72	{
73		let from = *pos;
74		let first = match self.first.parse(src, pos)
75		{
76			Ok(res) => return Ok(Left(res)),
77			Err(err) => err,
78		};
79		let second = match self.second.parse(src, pos)
80		{
81			Ok(res) => return Ok(Right(res)),
82			Err(err) => err,
83		};
84		Err(OrderParserError::new(
85			from,
86			self.requirement(None),
87			(first, second),
88		))
89	}
90
91	fn skip(&self, src: &'a str, pos: &mut usize) -> Result<(), Self::Error>
92	{
93		let from = *pos;
94		match self.first.skip(src, pos)
95		{
96			Ok(()) => Ok(()),
97			Err(first) =>
98			{
99				self.second.skip(src, pos).map_err(|second| {
100					OrderParserError::new(from, self.requirement(None), (first, second))
101				})
102			}
103		}
104	}
105
106	fn requirement(&self, _: Option<&Self::RequirementContext>) -> Self::Requirement
107	{
108		OrderParserRequirement::new(self.first.requirement(None), self.second.requirement(None))
109	}
110}
markab_parser/order_parser/parser.rs

markab_parser/order_parser/
parser.rs
