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Extract building the suggestion of manual_memcpy

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rail 2020-04-27 19:44:44 +12:00
parent 9fc6f37778
commit 582614fbbe
1 changed files with 80 additions and 74 deletions
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154
clippy_lints/src/loops.rs
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@ -905,6 +905,85 @@ fn get_assignment<'a, 'tcx>(e: &'tcx Expr<'tcx>) -> Option<(&'tcx Expr<'tcx>, &'
iter_a.into_iter().flatten().chain(iter_b.into_iter())
}
fn build_manual_memcpy_suggestion<'a, 'tcx>(
cx: &LateContext<'a, 'tcx>,
start: &Expr<'_>,
end: &Expr<'_>,
limits: ast::RangeLimits,
dst_var: FixedOffsetVar<'_>,
src_var: FixedOffsetVar<'_>,
) -> String {
fn print_sum(arg1: &str, arg2: &Offset) -> String {
match (arg1, &arg2.value[..], arg2.sign) {
("0", "0", _) => "0".into(),
("0", x, OffsetSign::Positive) | (x, "0", _) => x.into(),
("0", x, OffsetSign::Negative) => format!("-{}", x),
(x, y, OffsetSign::Positive) => format!("({} + {})", x, y),
(x, y, OffsetSign::Negative) => {
if x == y {
"0".into()
} else {
format!("({} - {})", x, y)
}
},
}
}
fn print_offset(start_str: &str, inline_offset: &Offset) -> String {
let offset = print_sum(start_str, inline_offset);
if offset.as_str() == "0" {
"".into()
} else {
offset
}
}
let print_limit = |end: &Expr<'_>, offset: Offset, var: &Expr<'_>| {
if_chain! {
if let ExprKind::MethodCall(method, _, len_args) = end.kind;
if method.ident.name == sym!(len);
if len_args.len() == 1;
if let Some(arg) = len_args.get(0);
if var_def_id(cx, arg) == var_def_id(cx, var);
then {
match offset.sign {
OffsetSign::Negative => format!("({} - {})", snippet(cx, end.span, "<src>.len()"), offset.value),
OffsetSign::Positive => "".into(),
}
} else {
let end_str = match limits {
ast::RangeLimits::Closed => {
let end = sugg::Sugg::hir(cx, end, "<count>");
format!("{}", end + sugg::ONE)
},
ast::RangeLimits::HalfOpen => format!("{}", snippet(cx, end.span, "..")),
};
print_sum(&end_str, &offset)
}
}
};
let start_str = snippet(cx, start.span, "").to_string();
let dst_offset = print_offset(&start_str, &dst_var.offset);
let dst_limit = print_limit(end, dst_var.offset, dst_var.var);
let src_offset = print_offset(&start_str, &src_var.offset);
let src_limit = print_limit(end, src_var.offset, src_var.var);
let dst_var_name = snippet_opt(cx, dst_var.var.span).unwrap_or_else(|| "???".into());
let src_var_name = snippet_opt(cx, src_var.var.span).unwrap_or_else(|| "???".into());
let dst = if dst_offset == "" && dst_limit == "" {
dst_var_name
} else {
format!("{}[{}..{}]", dst_var_name, dst_offset, dst_limit)
};
format!(
"{}.clone_from_slice(&{}[{}..{}])",
dst, src_var_name, src_offset, src_limit
)
}
/// Checks for for loops that sequentially copy items from one slice-like
/// object to another.
fn detect_manual_memcpy<'a, 'tcx>(
@ -922,57 +1001,6 @@ fn detect_manual_memcpy<'a, 'tcx>(
{
// the var must be a single name
if let PatKind::Binding(_, canonical_id, _, _) = pat.kind {
fn print_sum(arg1: &str, arg2: &Offset) -> String {
match (arg1, &arg2.value[..], arg2.sign) {
("0", "0", _) => "0".into(),
("0", x, OffsetSign::Positive) | (x, "0", _) => x.into(),
("0", x, OffsetSign::Negative) => format!("-{}", x),
(x, y, OffsetSign::Positive) => format!("({} + {})", x, y),
(x, y, OffsetSign::Negative) => {
if x == y {
"0".into()
} else {
format!("({} - {})", x, y)
}
},
}
}
fn print_offset(start_str: &str, inline_offset: &Offset) -> String {
let offset = print_sum(start_str, inline_offset);
if offset.as_str() == "0" {
"".into()
} else {
offset
}
}
let print_limit = |end: &Expr<'_>, offset: Offset, var: &Expr<'_>| {
if_chain! {
if let ExprKind::MethodCall(method, _, len_args) = end.kind;
if method.ident.name == sym!(len);
if len_args.len() == 1;
if let Some(arg) = len_args.get(0);
if var_def_id(cx, arg) == var_def_id(cx, var);
then {
match offset.sign {
OffsetSign::Negative => format!("({} - {})", snippet(cx, end.span, "<src>.len()"), offset.value),
OffsetSign::Positive => "".into(),
}
} else {
let end_str = match limits {
ast::RangeLimits::Closed => {
let end = sugg::Sugg::hir(cx, end, "<count>");
format!("{}", end + sugg::ONE)
},
ast::RangeLimits::HalfOpen => format!("{}", snippet(cx, end.span, "..")),
};
print_sum(&end_str, &offset)
}
}
};
// The only statements in the for loops can be indexed assignments from
// indexed retrievals.
let big_sugg = get_assignments(body)
@ -998,29 +1026,7 @@ fn print_offset(start_str: &str, inline_offset: &Offset) -> String {
}
})
})
.map(|o| {
o.map(|(dst_var, src_var)| {
let start_str = snippet(cx, start.span, "").to_string();
let dst_offset = print_offset(&start_str, &dst_var.offset);
let dst_limit = print_limit(end, dst_var.offset, dst_var.var);
let src_offset = print_offset(&start_str, &src_var.offset);
let src_limit = print_limit(end, src_var.offset, src_var.var);
let dst_var_name = snippet_opt(cx, dst_var.var.span).unwrap_or_else(|| "???".into());
let src_var_name = snippet_opt(cx, src_var.var.span).unwrap_or_else(|| "???".into());
let dst = if dst_offset == "" && dst_limit == "" {
dst_var_name
} else {
format!("{}[{}..{}]", dst_var_name, dst_offset, dst_limit)
};
format!(
"{}.clone_from_slice(&{}[{}..{}])",
dst, src_var_name, src_offset, src_limit
)
})
})
.map(|o| o.map(|(dst, src)| build_manual_memcpy_suggestion(cx, start, end, limits, dst, src)))
.collect::<Option<Vec<_>>>()
.filter(|v| !v.is_empty())
.map(|v| v.join("\n "));