syntacks 0.1.0-alpha0.2

An opinionated parser library for Rust
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134

use std::{
	cmp::{max, min},
	marker::PhantomData,
	ops::{Add, AddAssign},
	str::{from_utf8, Utf8Error},
};

use crate::{Source, StringSource};

#[derive(Clone, Copy, Debug)]
pub struct SourceSpan<'src, S>
where
	S: Source<'src>,
{
	source: S,
	byte_start: usize,
	byte_end: usize,
	_phantom: PhantomData<&'src S>,
}

impl<'src, S> SourceSpan<'src, S>
where
	S: Source<'src>,
{
	pub fn new(source: S, byte_start: usize, byte_end: usize) -> Self {
		Self {
			source,
			byte_start,
			byte_end,
			_phantom: PhantomData,
		}
	}

	pub fn len(&self) -> usize {
		self.byte_end - self.byte_start
	}

	pub fn is_empty(&self) -> bool {
		self.len() == 0
	}

	pub fn start(&self) -> Self {
		Self {
			source: self.source.clone(),
			byte_start: self.byte_start,
			byte_end: self.byte_start,
			_phantom: PhantomData,
		}
	}

	pub fn end(&self) -> Self {
		Self {
			source: self.source.clone(),
			byte_start: self.byte_end,
			byte_end: self.byte_end,
			_phantom: PhantomData,
		}
	}
}

impl<'src> SourceSpan<'src, StringSource<'src>> {
	pub fn as_str(&'src self) -> Result<&str, Utf8Error> {
		from_utf8(&self.source.bytes()[self.byte_start..self.byte_end])
	}
}

impl<'src, S> Add for SourceSpan<'src, S>
where
	S: Source<'src>,
{
	type Output = Self;

	fn add(self, rhs: Self) -> Self::Output {
		assert!(self.source == rhs.source);

		Self {
			source: self.source,
			byte_start: min(self.byte_start, rhs.byte_start),
			byte_end: max(self.byte_end, rhs.byte_end),
			_phantom: PhantomData,
		}
	}
}

impl<'src, S> AddAssign for SourceSpan<'src, S>
where
	S: Source<'src>,
{
	fn add_assign(&mut self, rhs: Self) {
		assert!(self.source == rhs.source);

		self.byte_start = min(self.byte_start, rhs.byte_start);
		self.byte_end = max(self.byte_end, rhs.byte_end);
	}
}

#[cfg(test)]
mod test {
	use std::marker::PhantomData;

	use crate::StringSource;

	use super::SourceSpan;

	static SOURCE: &str = "some test source";

	fn source() -> StringSource<'static> {
		StringSource::new(SOURCE)
	}

	#[test]
	fn add_source_span() {
		let source = source();

		let span1 = SourceSpan {
			source,
			byte_start: 0,
			byte_end: 4,
			_phantom: PhantomData,
		};
		let span2 = SourceSpan {
			source,
			byte_start: 6,
			byte_end: 10,
			_phantom: PhantomData,
		};

		let span3 = span1 + span2;

		assert_eq!(0, span3.byte_start);
		assert_eq!(10, span3.byte_end);
		assert_eq!("some test ", span3.as_str().unwrap());
	}
}