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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::{stdout, Stdout, Write};
/// 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>,
/// 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);
}
impl PrintTree<Stdout> {
pub fn new(title: &str) -> Self {
PrintTree::new_with_sink(title, stdout())
}
}
impl<W> PrintTree<W>
where
W: Write
{
pub fn new_with_sink(title: &str, mut sink: W) -> Self {
writeln!(sink, "\u{250c} {}", title).unwrap();
PrintTree {
level: 1,
queued_item: None,
sink,
}
}
fn print_level_prefix(&mut self) {
for _ in 0 .. self.level {
write!(self.sink, "\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.sink, "{} {}", prefix, queued_item).unwrap();
}
}
}
// The default `println!` based printer
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.sink, "\u{251C}\u{2500} {}", title).unwrap();
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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