gaze 0.5.0

Gaze is a small utility library with the goal of making it easier to scan/lex text and collections.
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

// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.

use unicode_segmentation::UnicodeSegmentation;

pub mod nibblers;

pub struct Gaze<I> {
    offset: usize,
    input: Vec<I>,
}

impl<I> Gaze<I> {
    /// A helper constructor that takes a str and converts it to a Vec of graphemes.
    pub fn from_str(text: &str) -> Gaze<&str> {
        let input = text.graphemes(true).collect::<Vec<&str>>();
        Gaze { input, offset: 0 }
    }

    /// Construct a Gaze instances from a Vec.
    pub fn from_vec(input: Vec<I>) -> Gaze<I> {
        Gaze { input, offset: 0 }
    }

    /// Returns true if all data has been consumed.
    pub fn is_complete(&self) -> bool {
        self.offset >= self.input.len()
    }

    /// Look at the next
    pub fn peek(&self) -> Option<I>
    where
        I: Clone,
    {
        if self.is_complete() {
            None
        } else {
            Some(self.input[self.offset].clone())
        }
    }

    pub fn next(&mut self) -> Option<I>
    where
        I: Clone,
    {
        if self.is_complete() {
            None
        } else {
            let next = Some(self.input[self.offset].clone());
            self.offset += 1;
            next
        }
    }

    pub fn attemptf<O>(&mut self, nibbler: &mut impl Fn(&mut Gaze<I>) -> Option<O>) -> Option<O>
    // (impl Nibbler<I, O> + ?Sized)) -> Option<O>
    where
        I: Clone,
        O: Clone,
    {
        let start_of_this_loop = self.offset;
        let res = nibbler(self);
        match res {
            Some(_) => res,
            None => {
                self.offset = start_of_this_loop;
                None
            }
        }
    }

    pub fn attempt<O>(&mut self, nibbler: &mut (impl Nibbler<I, O> + ?Sized)) -> Option<O>
    where
        I: Clone,
        O: Clone,
    {
        let start_of_this_loop = self.offset;
        let res = nibbler.run(self);
        match res {
            Some(_) => res,
            None => {
                self.offset = start_of_this_loop;
                None
            }
        }
    }
}

pub trait Nibbler<I, O> {
    fn run(&mut self, gaze: &mut Gaze<I>) -> Option<O>;
}