kailua_langsvr 1.0.4

// hover help: wait for checker outputs and get the informations from given position

use kailua_env::{Pos, Source};
use kailua_diag::{Localize, Localized};
use kailua_types::ty::{TypeContext, Display};
use kailua_check::env::Output;

use diags;
use protocol::*;

pub fn help<F>(output: &Output, pos: Pos, source: &Source, mut localize: F) -> Option<Hover>
    where F: for<'a> FnMut(&'a Localize) -> Localized<'a, Localize>
{
    // find all slot-associated spans that contains the pos...
    let spans = output.spanned_slots().contains(pos);
    // ...and pick the smallest one among them (there should be at most one such span).
    let closest_slot = spans.min_by_key(|slot| slot.span.len());

    // format the slot if available
    if let Some(slot) = closest_slot {
        // the resulting output should be colorized as if it's in `--:`.
        // in order to use a single syntax, we use a sequence of random invisible
        // characters to "trick" the colorizer.
        const TYPE_PREFIX: &'static str =
            "\u{200c}\u{200d}\u{200d}\u{200c}\u{2060}\u{200c}\u{200b}\u{200d}\
             \u{200c}\u{200c}\u{200d}\u{200b}\u{2060}\u{200d}\u{2060}\u{2060}";

        let range = diags::translate_span(slot.span, source).map(|(_, range)| range);
        let types = output.types() as &TypeContext;
        Some(Hover {
            contents: vec![
                MarkedString {
                    language: format!("lua"),
                    value: format!("{}{:0.1}", TYPE_PREFIX, localize(&slot.display(types))),
                }
            ],
            range: range,
        })
    } else {
        None
    }
}