gix_fs/
stack.rs

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
use std::path::{Component, Path, PathBuf};

use crate::Stack;

/// Access
impl Stack {
    /// Returns the top-level path of the stack.
    pub fn root(&self) -> &Path {
        &self.root
    }

    /// Returns the absolute path the currently set path.
    pub fn current(&self) -> &Path {
        &self.current
    }

    /// Returns the currently set path relative to the [`root()`][Stack::root()].
    pub fn current_relative(&self) -> &Path {
        &self.current_relative
    }
}

/// A delegate for use in a [`Stack`].
pub trait Delegate {
    /// Called whenever we push a directory on top of the stack, and after the respective call to [`push()`](Self::push).
    ///
    /// It is only called if the currently acted on path is a directory in itself, which is determined by knowing
    /// that it's not the last component of the path.
    /// Use [`Stack::current()`] to see the directory.
    fn push_directory(&mut self, stack: &Stack) -> std::io::Result<()>;

    /// Called after any component was pushed, with the path available at [`Stack::current()`].
    ///
    /// `is_last_component` is `true` if the path is completely built, which typically means it's not a directory.
    fn push(&mut self, is_last_component: bool, stack: &Stack) -> std::io::Result<()>;

    /// Called right after a directory-component was popped off the stack.
    ///
    /// Use it to pop information off internal data structures. Note that no equivalent call exists for popping
    /// the file-component.
    fn pop_directory(&mut self);
}

impl Stack {
    /// Create a new instance with `root` being the base for all future paths we handle, assuming it to be valid which includes
    /// symbolic links to be included in it as well.
    pub fn new(root: PathBuf) -> Self {
        Stack {
            current: root.clone(),
            current_relative: PathBuf::with_capacity(128),
            valid_components: 0,
            root,
            current_is_directory: true,
        }
    }

    /// Set the current stack to point to the `relative` path and call `push_comp()` each time a new path component is popped
    /// along with the stacks state for inspection to perform an operation that produces some data.
    ///
    /// The full path to `relative` will be returned along with the data returned by `push_comp`.
    /// Note that this only works correctly for the delegate's `push_directory()` and `pop_directory()` methods if
    /// `relative` paths are terminal, so point to their designated file or directory.
    /// The path is also expected to be normalized, and should not contain extra separators, and must not contain `..`
    /// or have leading or trailing slashes (or additionally backslashes on Windows).
    pub fn make_relative_path_current(&mut self, relative: &Path, delegate: &mut dyn Delegate) -> std::io::Result<()> {
        if self.valid_components != 0 && relative.as_os_str().is_empty() {
            return Err(std::io::Error::new(
                std::io::ErrorKind::Other,
                "empty inputs are not allowed",
            ));
        }
        if self.valid_components == 0 {
            delegate.push_directory(self)?;
        }

        let mut components = relative.components().peekable();
        let mut existing_components = self.current_relative.components();
        let mut matching_components = 0;
        while let (Some(existing_comp), Some(new_comp)) = (existing_components.next(), components.peek()) {
            if existing_comp == *new_comp {
                components.next();
                matching_components += 1;
            } else {
                break;
            }
        }

        for _ in 0..self.valid_components - matching_components {
            self.current.pop();
            self.current_relative.pop();
            if self.current_is_directory {
                delegate.pop_directory();
            }
            self.current_is_directory = true;
        }
        self.valid_components = matching_components;

        if !self.current_is_directory && components.peek().is_some() {
            delegate.push_directory(self)?;
        }

        while let Some(comp) = components.next() {
            if !matches!(comp, Component::Normal(_)) {
                return Err(std::io::Error::new(
                    std::io::ErrorKind::Other,
                    format!(
                        "Input path \"{}\" contains relative or absolute components",
                        relative.display()
                    ),
                ));
            }
            let is_last_component = components.peek().is_none();
            self.current_is_directory = !is_last_component;
            self.current.push(comp);
            self.current_relative.push(comp);
            self.valid_components += 1;
            let res = delegate.push(is_last_component, self);
            if self.current_is_directory {
                delegate.push_directory(self)?;
            }

            if let Err(err) = res {
                self.current.pop();
                self.current_relative.pop();
                self.valid_components -= 1;
                return Err(err);
            }
        }
        Ok(())
    }
}