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/* 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 std::io::Write;
use std::fmt::Write as FmtWrite;
/// A struct that makes it easier to print out a pretty tree of data, which
/// can be visually scanned more easily.
pub struct PrintTree<W>
where
W: Write
{
/// The current level of recursion.
level: u32,
/// An item which is queued up, so that we can determine if we need
/// a mid-tree prefix or a branch ending prefix.
queued_item: Option<String>,
// We hold lines until they are done, and then output them all at
// once
line_buffer: String,
/// The sink to print to.
sink: W,
}
/// A trait that makes it easy to describe a pretty tree of data,
/// regardless of the printing destination, to either print it
/// directly to stdout, or serialize it as in the debugger
pub trait PrintTreePrinter {
fn new_level(&mut self, title: String);
fn end_level(&mut self);
fn add_item(&mut self, text: String);
}
// The default does nothing but log
impl PrintTree<std::io::Sink> {
pub fn new(title: &str) -> Self {
PrintTree::new_with_sink(title, std::io::sink())
}
}
impl<W> PrintTree<W>
where
W: Write
{
pub fn new_with_sink(title: &str, sink: W) -> Self {
let mut result = PrintTree {
level: 1,
queued_item: None,
line_buffer: String::new(),
sink,
};
writeln!(result.line_buffer, "\u{250c} {}", title).unwrap();
result.flush_line();
result
}
fn print_level_prefix(&mut self) {
for _ in 0 .. self.level {
write!(self.line_buffer, "\u{2502} ").unwrap();
}
}
fn flush_queued_item(&mut self, prefix: &str) {
if let Some(queued_item) = self.queued_item.take() {
self.print_level_prefix();
writeln!(self.line_buffer, "{} {}", prefix, queued_item).unwrap();
self.flush_line();
}
}
fn flush_line(&mut self) {
debug!("{}", self.line_buffer);
self.sink.write_all(self.line_buffer.as_bytes()).unwrap();
self.line_buffer.clear();
}
}
impl<W> PrintTreePrinter for PrintTree<W>
where
W: Write
{
/// Descend one level in the tree with the given title.
fn new_level(&mut self, title: String) {
self.flush_queued_item("\u{251C}\u{2500}");
self.print_level_prefix();
writeln!(self.line_buffer, "\u{251C}\u{2500} {}", title).unwrap();
self.flush_line();
self.level = self.level + 1;
}
/// Ascend one level in the tree.
fn end_level(&mut self) {
self.flush_queued_item("\u{2514}\u{2500}");
self.level = self.level - 1;
}
/// Add an item to the current level in the tree.
fn add_item(&mut self, text: String) {
self.flush_queued_item("\u{251C}\u{2500}");
self.queued_item = Some(text);
}
}
impl<W> Drop for PrintTree<W>
where
W: Write
{
fn drop(&mut self) {
self.flush_queued_item("\u{9492}\u{9472}");
}
}
pub trait PrintableTree {
fn print_with<T: PrintTreePrinter>(&self, pt: &mut T);
}
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