tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
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print_tree.rs (3278B)

      1 /* This Source Code Form is subject to the terms of the Mozilla Public
      2 * License, v. 2.0. If a copy of the MPL was not distributed with this
      3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      4 
      5 use std::io::Write;
      6 use std::fmt::Write as FmtWrite;
      7 
      8 /// A struct that makes it easier to print out a pretty tree of data, which
      9 /// can be visually scanned more easily.
     10 pub struct PrintTree<W>
     11 where
     12    W: Write
     13 {
     14    /// The current level of recursion.
     15    level: u32,
     16 
     17    /// An item which is queued up, so that we can determine if we need
     18    /// a mid-tree prefix or a branch ending prefix.
     19    queued_item: Option<String>,
     20 
     21    // We hold lines until they are done, and then output them all at
     22    // once
     23    line_buffer: String,
     24 
     25    /// The sink to print to.
     26    sink: W,
     27 }
     28 
     29 /// A trait that makes it easy to describe a pretty tree of data,
     30 /// regardless of the printing destination, to either print it
     31 /// directly to stdout, or serialize it as in the debugger
     32 pub trait PrintTreePrinter {
     33    fn new_level(&mut self, title: String);
     34    fn end_level(&mut self);
     35    fn add_item(&mut self, text: String);
     36 }
     37 
     38 // The default does nothing but log
     39 impl PrintTree<std::io::Sink> {
     40    pub fn new(title: &str) -> Self {
     41        PrintTree::new_with_sink(title, std::io::sink())
     42    }
     43 }
     44 
     45 impl<W> PrintTree<W>
     46 where
     47    W: Write
     48 {
     49    pub fn new_with_sink(title: &str, sink: W) -> Self {
     50        let mut result = PrintTree {
     51            level: 1,
     52            queued_item: None,
     53            line_buffer: String::new(),
     54            sink,
     55        };
     56 
     57        writeln!(result.line_buffer, "\u{250c} {}", title).unwrap();
     58        result.flush_line();
     59        result
     60    }
     61 
     62    fn print_level_prefix(&mut self) {
     63        for _ in 0 .. self.level {
     64            write!(self.line_buffer, "\u{2502}  ").unwrap();
     65        }
     66    }
     67 
     68    fn flush_queued_item(&mut self, prefix: &str) {
     69        if let Some(queued_item) = self.queued_item.take() {
     70            self.print_level_prefix();
     71            writeln!(self.line_buffer, "{} {}", prefix, queued_item).unwrap();
     72            self.flush_line();
     73        }
     74    }
     75 
     76    fn flush_line(&mut self) {
     77        debug!("{}", self.line_buffer);
     78        self.sink.write_all(self.line_buffer.as_bytes()).unwrap();
     79        self.line_buffer.clear();
     80    }
     81 }
     82 
     83 impl<W> PrintTreePrinter for PrintTree<W>
     84 where
     85    W: Write
     86 {
     87    /// Descend one level in the tree with the given title.
     88    fn new_level(&mut self, title: String) {
     89        self.flush_queued_item("\u{251C}\u{2500}");
     90 
     91        self.print_level_prefix();
     92        writeln!(self.line_buffer, "\u{251C}\u{2500} {}", title).unwrap();
     93        self.flush_line();
     94 
     95        self.level = self.level + 1;
     96    }
     97 
     98    /// Ascend one level in the tree.
     99    fn end_level(&mut self) {
    100        self.flush_queued_item("\u{2514}\u{2500}");
    101        self.level = self.level - 1;
    102    }
    103 
    104    /// Add an item to the current level in the tree.
    105    fn add_item(&mut self, text: String) {
    106        self.flush_queued_item("\u{251C}\u{2500}");
    107        self.queued_item = Some(text);
    108    }
    109 }
    110 
    111 impl<W> Drop for PrintTree<W>
    112 where
    113    W: Write
    114 {
    115    fn drop(&mut self) {
    116        self.flush_queued_item("\u{9492}\u{9472}");
    117    }
    118 }
    119 
    120 pub trait PrintableTree {
    121    fn print_with<T: PrintTreePrinter>(&self, pt: &mut T);
    122 }