clippy 0.0.6

use rustc::lint::*;
use syntax::ast::*;
use syntax::codemap::{BytePos, Span};

declare_lint!{ pub ZERO_WIDTH_SPACE, Deny, "Zero-width space is confusing" }

#[derive(Copy, Clone)]
pub struct Unicode;

impl LintPass for Unicode {
	fn get_lints(&self) -> LintArray {
        lint_array!(ZERO_WIDTH_SPACE)
    }
    
    fn check_expr(&mut self, cx: &Context, expr: &Expr) {
		if let ExprLit(ref lit) = expr.node {
			if let LitStr(ref string, _) = lit.node {
				check_str(cx, string, lit.span)
			}
		}
	}
}

fn check_str(cx: &Context, string: &str, span: Span) {
	let mut start: Option<usize> = None;
	for (i, c) in string.char_indices() {
		if c == '\u{200B}' {
			if start.is_none() { start = Some(i); }
		} else {
			lint_zero_width(cx, span, start);
			start = None;
		}
	}
	lint_zero_width(cx, span, start);
}

fn lint_zero_width(cx: &Context, span: Span, start: Option<usize>) {
	start.map(|index| {
		cx.span_lint(ZERO_WIDTH_SPACE, Span {
			lo: span.lo + BytePos(index as u32),
			hi: span.lo + BytePos(index as u32),
			expn_id: span.expn_id,
		}, "Zero-width space detected. Consider using \\u{200B}")
	});
}