245 lines
8.0 KiB
Rust
245 lines
8.0 KiB
Rust
use std::ffi::OsString;
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use std::fs::read_dir;
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use std::path::{Path, PathBuf};
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use std::io::ErrorKind;
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use anyhow::{Context, Result};
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use crate::args::Args;
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use crate::unit::Unit;
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use rayon::prelude::*;
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#[derive(Debug, Clone)]
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pub struct Directory {
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name: PathBuf,
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size: u64,
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children: Vec<Directory>,
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}
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impl Directory {
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#[inline]
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pub const fn size(&self) -> u64 {
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self.size
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}
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#[inline]
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pub fn path(&self) -> &Path {
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self.name.as_ref()
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}
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pub fn new< P: AsRef<Path> >(path: P, args: &Args) -> Result<Option<Self>> {
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let path = path.as_ref();
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// NOTE: I go back and forth on canonicalize()ing all the time.
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// I feel like it changes every commit. The performance loss seems
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// to be negligible, even when I do crazy things like `hb -p /`
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let name = match path.canonicalize() {
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Ok(path) => path,
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Err(_) if args.persistant() => return Ok(None),
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Err(e) => return Err(e.into()),
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}
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.file_name()
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.map_or_else(|| OsString::from("/"), ToOwned::to_owned)
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.into();
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// symlink_metadata() is the same as metadata() but it doesn't
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// traverse symlinks, so that we can exclude them if necessary
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let meta = match path.symlink_metadata() {
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Ok(md) => md,
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Err(_) if args.persistant() => return Ok(None),
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Err(e) => return Err(e.into()),
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};
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if args.should_exclude(path, &meta) {
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// finding a file to exclude is behaviourally
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// equivalent to hitting an error in persistant
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// mode: just continue
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return Ok(None)
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}
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let dir = match read_dir(path) {
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Ok(dir) => dir,
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Err(io_error) => match io_error.kind() {
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ErrorKind::NotADirectory => {
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return Ok(Some(
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Self {
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name,
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size: meta.len(),
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children: Vec::new()
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}
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))
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},
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other => return Result::context(
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Err(io_error),
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format!("{}: {}", path.display(), other)
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),
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}
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};
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// this is a compicated iterator pattern. I'll do my best to explain.
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// 1. the end result is that we `reduce()` the iterator to a single
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// (u64, Vec<Directory>) tuple to return. this is done by...
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let (size, children) = match
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// 2. taking the iterator over the directory and parallelising it...
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dir.par_bridge()
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// 3, this is the recursive step: try to create new Directory
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// objects from each item in the iterator
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.map(|entry| Self::new(entry?.path(), args))
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// 4. the fold (this is try_fold because we're iterating over Result.).
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// each fold adds a directory as a child and increases the total size
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.try_fold(
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|| (0, Vec::new()),
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|(mut size, mut children), dir| -> Result<(u64, Vec<Self>)> {
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let dir = match (dir, args.persistant()) {
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(Ok(Some(d)), _) => d,
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(Ok(None), _) | (Err(_), true) => return Result::Ok((size, children)),
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(Err(e), false) => return Err(e),
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};
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size += dir.size;
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if args.should_print(dir.path()) {
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// since size was increased, this just prevents
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// the directory from appearing in printing
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children.push(dir);
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}
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// have to specify anyhow::Result::Ok otherwise it complains
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// that it can't infer the E in Result<T, E>
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Result::Ok((size, children))
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}
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)
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// 5. the final step is to reduce, which is as simple as concatenating
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// every vector and summing up their sizes.
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.try_reduce(
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|| (0, Vec::new()),
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|(asize, mut avec), (bsize, bvec)| {
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avec.extend(bvec);
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Result::Ok((asize + bsize, avec))
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}
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) {
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// remember that this is a match statement?
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Ok(tuple) => tuple,
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Err(_) if args.persistant() => return Ok(None),
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Err(e) => return Err(e),
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};
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// final notes:
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// 1. I am unsure if it is better to do a bunch of partial sums
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// during the fold() and reduce() steps, or if it is best to
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// have them only do data collection and sum the lengths
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// later. intuitively we would want to do everything in
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// parallel but I have no data to support this.
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// 2. this is a super complicated iterator pattern, If anyone
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// knows how to simplify it I'm all ears, but being
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// parallel is the main advantage it has over du so I don't
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// want to abandon that, even though a serial for loop is
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// *incredibly* clearer.
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Ok(Some(
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Self {
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name,
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size,
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children,
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}
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))
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}
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pub fn tree(self, unit: Unit) -> String {
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// since self.size is definitionally the greatest value, the tab length
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// is just the length of self.len, plus two for a tab width
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let tab_size = unit.convert(self.size).len() + 2;
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self.vectorise(unit)
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.iter()
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.map(|e| e.stringify_tabbed(tab_size))
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.reduce(|s1, s2| s1 + "\n" + &s2)
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.unwrap_or_default()
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}
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/// TODO: make not recursive, take &self if possible,
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/// and maybe write directly to stdout to not use so much mem
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fn vectorise(self, unit: Unit) -> Vec<TreeEntry> {
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let mut result = Vec::new();
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result.push(TreeEntry::new(
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self.name.display().to_string(), self.size, unit
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));
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let mut new_entry_part = TreePart::First;
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let mut continue_part = TreePart::Wait;
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let len = self.children.len();
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// this is the display algorithm. it's built on the variables
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// `new_entry_part` and `continue_part`. for most times, when
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// we introduce a new item (which happens every iteration of
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// the loop), it is `first` tree part and we can pad with the
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// `wait` part. the last element of each one should however
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// be introduced with a `last` part, and padding should with
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// `blank`
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for (idx, child) in self.children.into_iter().enumerate() {
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if idx+1 == len {
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new_entry_part = TreePart::Last;
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continue_part = TreePart::Blank;
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}
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let subtree = child.vectorise(unit);
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for mut item in subtree {
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if item.parts.is_empty() {
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item.parts.push(new_entry_part);
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} else {
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item.parts.push(continue_part);
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}
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result.push(item);
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}
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}
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result
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}
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}
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#[derive(Debug)]
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struct TreeEntry {
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parts: Vec<TreePart>,
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path: String,
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size: u64,
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unit: Unit
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}
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impl TreeEntry {
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fn new(path: String, size: u64, unit: Unit) -> Self {
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Self {
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parts: Vec::new(), path, size, unit
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}
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}
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fn stringify_tabbed(&self, tab_size: usize) -> String {
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let mut result = format!("{:<tab_size$}", self.unit.convert(self.size));
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for part in self.parts.iter().rev() {
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result += part.display();
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}
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result += " ";
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result += &self.path;
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result
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}
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}
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#[derive(PartialEq, Eq, Debug, Clone, Copy)]
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enum TreePart {
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/// `├──`
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First,
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/// `│ `
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Wait,
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/// `└──`
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Last,
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/// (blank)
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Blank
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}
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impl TreePart {
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/// convert to ascii art
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pub const fn display(&self) -> &str {
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match self {
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Self::First => "├──",
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Self::Wait => "│ ",
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Self::Last => "└──",
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Self::Blank => " ",
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}
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}
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} |