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use std::collections::HashSet;
use rustyline::hint::{Hint, Hinter};
use rustyline::history::DefaultHistory;
use rustyline::Context;
use rustyline::{Completer, Helper, Highlighter, Validator};
use rustyline::{Editor, Result};
#[derive(Completer, Helper, Validator, Highlighter)]
struct DIYHinter {
// It's simple example of rustyline, for more efficient, please use ** radix trie **
hints: HashSet<CommandHint>,
}
#[derive(Hash, Debug, PartialEq, Eq)]
struct CommandHint {
display: String,
complete_up_to: usize,
}
impl Hint for CommandHint {
fn display(&self) -> &str {
&self.display
}
fn completion(&self) -> Option<&str> {
if self.complete_up_to > 0 {
Some(&self.display[..self.complete_up_to])
} else {
None
}
}
}
impl CommandHint {
fn new(text: &str, complete_up_to: &str) -> Self {
assert!(text.starts_with(complete_up_to));
Self {
display: text.into(),
complete_up_to: complete_up_to.len(),
}
}
fn suffix(&self, strip_chars: usize) -> Self {
Self {
display: self.display[strip_chars..].to_owned(),
complete_up_to: self.complete_up_to.saturating_sub(strip_chars),
}
}
}
impl Hinter for DIYHinter {
type Hint = CommandHint;
fn hint(&self, line: &str, pos: usize, _ctx: &Context<'_>) -> Option<CommandHint> {
if line.is_empty() || pos < line.len() {
return None;
}
self.hints
.iter()
.filter_map(|hint| {
// expect hint after word complete, like redis cli, add condition:
// line.ends_with(" ")
if hint.display.starts_with(line) {
Some(hint.suffix(pos))
} else {
None
}
})
.next()
}
}
fn diy_hints() -> HashSet<CommandHint> {
let mut set = HashSet::new();
set.insert(CommandHint::new("help", "help"));
set.insert(CommandHint::new("get key", "get "));
set.insert(CommandHint::new("set key value", "set "));
set.insert(CommandHint::new("hget key field", "hget "));
set.insert(CommandHint::new("hset key field value", "hset "));
set
}
fn main() -> Result<()> {
println!("This is a DIY hint hack of rustyline");
let h = DIYHinter { hints: diy_hints() };
let mut rl: Editor<DIYHinter, DefaultHistory> = Editor::new()?;
rl.set_helper(Some(h));
loop {
let input = rl.readline("> ")?;
println!("input: {input}");
}
}
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