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Use a more flexible if_chain! macro

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This commit is contained in:
Chris Wong 2016-12-27 11:43:19 +13:00
parent f991ebaa78
commit b2ff33fea6
2 changed files with 25 additions and 61 deletions
maud_macros/src/lints
doctype_html.rsutil.rs

26
maud_macros/src/lints/doctype_html.rs
View file

@ -20,23 +20,21 @@ impl LintPass for DoctypeHtml {
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for DoctypeHtml { impl<'a, 'tcx> LateLintPass<'a, 'tcx> for DoctypeHtml {
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) { fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
if_let_chain! {[ if_chain! {
// It's a function call... // It's a function call...
let ExprCall(ref path_expr, ref args) = expr.node, if let ExprCall(ref path_expr, ref args) = expr.node;
// ... where the argument is a literal "<!doctype html>" // ... where the argument is a literal "<!doctype html>"
let Some(first_arg) = args.first(), if let Some(first_arg) = args.first();
let ExprLit(ref lit) = first_arg.node, if let ExprLit(ref lit) = first_arg.node;
let LitKind::Str(s, _) = lit.node, if let LitKind::Str(s, _) = lit.node;
s.as_str().eq_ignore_ascii_case("<!doctype html>"), if s.as_str().eq_ignore_ascii_case("<!doctype html>");
], {
// ... and the callee is `maud::PreEscaped` // ... and the callee is `maud::PreEscaped`
if let ExprPath(ref qpath) = path_expr.node { if let ExprPath(ref qpath) = path_expr.node;
let def_id = cx.tcx.tables().qpath_def(qpath, path_expr.id).def_id(); let def_id = cx.tcx.tables().qpath_def(qpath, path_expr.id).def_id();
if match_def_path(cx, def_id, &["maud", "PreEscaped", "{{constructor}}"]) { if match_def_path(cx, def_id, &["maud", "PreEscaped", "{{constructor}}"]) {
cx.struct_span_lint(MAUD_DOCTYPE_HTML, expr.span, cx.struct_span_lint(MAUD_DOCTYPE_HTML, expr.span,
"use `maud::DOCTYPE_HTML` instead").emit(); "use `maud::DOCTYPE_HTML` instead").emit();
}
} }
}} }
} }
} }

60
maud_macros/src/lints/util.rs
View file

@ -7,60 +7,26 @@ use rustc::lint::LateContext;
use rustc::ty; use rustc::ty;
use syntax::symbol::{InternedString, Symbol}; use syntax::symbol::{InternedString, Symbol};
/// Produce a nested chain of if-lets and ifs from the patterns:
///
/// ```rust,ignore
/// if_let_chain! {[
/// let Some(y) = x,
/// y.len() == 2,
/// let Some(z) = y,
/// ], {
/// block
/// }}
/// ```
///
/// becomes
///
/// ```rust,ignore
/// if let Some(y) = x {
/// if y.len() == 2 {
/// if let Some(z) = y {
/// block
/// }
/// }
/// }
/// ```
#[macro_export] #[macro_export]
macro_rules! if_let_chain { macro_rules! if_chain {
([let $pat:pat = $expr:expr, $($tt:tt)+], $block:block) => { (let $pat:pat = $expr:expr; $($tt:tt)+) => {
{
let $pat = $expr;
if_chain! { $($tt)+ }
}
};
(if let $pat:pat = $expr:expr; $($tt:tt)+) => {
if let $pat = $expr { if let $pat = $expr {
if_let_chain!{ [$($tt)+], $block } if_chain! { $($tt)+ }
} }
}; };
([let $pat:pat = $expr:expr], $block:block) => { (if $expr:expr; $($tt:tt)+) => {
if let $pat = $expr {
$block
}
};
([let $pat:pat = $expr:expr,], $block:block) => {
if let $pat = $expr {
$block
}
};
([$expr:expr, $($tt:tt)+], $block:block) => {
if $expr { if $expr {
if_let_chain!{ [$($tt)+], $block } if_chain! { $($tt)+ }
} }
}; };
([$expr:expr], $block:block) => { ($expr:expr) => {
if $expr { $expr
$block
}
};
([$expr:expr,], $block:block) => {
if $expr {
$block
}
}; };
} }