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#[macro_use]
extern crate uucore;
use std::collections::{HashMap, HashSet};
use std::fs::File;
use std::io::{stdin, BufRead, BufReader, Read};
use std::path::Path;
static NAME: &str = "tsort";
static VERSION: &str = env!("CARGO_PKG_VERSION");
pub fn uumain(args: impl uucore::Args) -> i32 {
let args = args.collect_str();
let mut opts = getopts::Options::new();
opts.optflag("h", "help", "display this help and exit");
opts.optflag("V", "version", "output version information and exit");
let matches = match opts.parse(&args[1..]) {
Ok(m) => m,
Err(f) => crash!(1, "{}", f),
};
if matches.opt_present("h") {
println!("{} {}", NAME, VERSION);
println!();
println!("Usage:");
println!(" {} [OPTIONS] FILE", NAME);
println!();
println!("{}", opts.usage("Topological sort the strings in FILE. Strings are defined as any sequence of tokens separated by whitespace (tab, space, or newline). If FILE is not passed in, stdin is used instead."));
return 0;
}
if matches.opt_present("V") {
println!("{} {}", NAME, VERSION);
return 0;
}
let files = matches.free.clone();
let input = if files.len() > 1 {
crash!(1, "{}, extra operand '{}'", NAME, matches.free[1]);
} else if files.is_empty() {
"-".to_owned()
} else {
files[0].clone()
};
let mut stdin_buf;
let mut file_buf;
let mut reader = BufReader::new(if input == "-" {
stdin_buf = stdin();
&mut stdin_buf as &mut dyn Read
} else {
file_buf = match File::open(Path::new(&input)) {
Ok(a) => a,
_ => {
show_error!("{}: No such file or directory", input);
return 1;
}
};
&mut file_buf as &mut dyn Read
});
let mut g = Graph::new();
loop {
let mut line = String::new();
match reader.read_line(&mut line) {
Ok(_) => {
let tokens: Vec<String> = line
.trim_end()
.split_whitespace()
.map(|s| s.to_owned())
.collect();
if tokens.is_empty() {
break;
}
for ab in tokens.chunks(2) {
match ab.len() {
2 => g.add_edge(&ab[0], &ab[1]),
_ => crash!(1, "{}: input contains an odd number of tokens", input),
}
}
}
_ => break,
}
}
g.run_tsort();
if !g.is_acyclic() {
crash!(1, "{}, input contains a loop:", input);
}
for x in &g.result {
println!("{}", x);
}
0
}
struct Graph {
in_edges: HashMap<String, HashSet<String>>,
out_edges: HashMap<String, Vec<String>>,
result: Vec<String>,
}
impl Graph {
fn new() -> Graph {
Graph {
in_edges: HashMap::new(),
out_edges: HashMap::new(),
result: vec![],
}
}
fn has_node(&self, n: &str) -> bool {
self.in_edges.contains_key(n)
}
fn has_edge(&self, from: &str, to: &str) -> bool {
self.in_edges[to].contains(from)
}
fn init_node(&mut self, n: &str) {
self.in_edges.insert(n.to_string(), HashSet::new());
self.out_edges.insert(n.to_string(), vec![]);
}
fn add_edge(&mut self, from: &str, to: &str) {
if !self.has_node(to) {
self.init_node(to);
}
if !self.has_node(from) {
self.init_node(from);
}
if from != to && !self.has_edge(from, to) {
self.in_edges.get_mut(to).unwrap().insert(from.to_string());
self.out_edges.get_mut(from).unwrap().push(to.to_string());
}
}
fn run_tsort(&mut self) {
let mut start_nodes = vec![];
for (n, edges) in &self.in_edges {
if edges.is_empty() {
start_nodes.push(n.clone());
}
}
while !start_nodes.is_empty() {
let n = start_nodes.remove(0);
self.result.push(n.clone());
let n_out_edges = self.out_edges.get_mut(&n).unwrap();
for m in n_out_edges.iter() {
let m_in_edges = self.in_edges.get_mut(m).unwrap();
m_in_edges.remove(&n);
if m_in_edges.is_empty() {
start_nodes.push(m.clone());
}
}
n_out_edges.clear();
}
}
fn is_acyclic(&self) -> bool {
for edges in self.out_edges.values() {
if !edges.is_empty() {
return false;
}
}
true
}
}