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Move vec! unexpanding function to utils::higher

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This commit is contained in:
mcarton 2016-06-30 19:49:34 +02:00
parent 4dff4df577
commit 98f18f0474
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GPG Key ID: 5E427C794CBA45E8
2 changed files with 45 additions and 43 deletions
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42
clippy_lints/src/utils/higher.rs
View File

@ -1,8 +1,10 @@
//! This module contains functions for retrieve the original AST from lowered `hir`.
use rustc::hir;
use rustc::lint::LateContext;
use syntax::ast;
use utils::{match_path, paths};
use syntax::ptr::P;
use utils::{is_expn_of, match_path, paths};
/// Convert a hir binary operator to the corresponding `ast` type.
pub fn binop(op: hir::BinOp_) -> ast::BinOpKind {
@ -148,3 +150,41 @@ pub fn for_loop(expr: &hir::Expr) -> Option<(&hir::Pat, &hir::Expr, &hir::Expr)>
}}
None
}
/// Represent the pre-expansion arguments of a `vec!` invocation.
pub enum VecArgs<'a> {
/// `vec![elem; len]`
Repeat(&'a P<hir::Expr>, &'a P<hir::Expr>),
/// `vec![a, b, c]`
Vec(&'a [P<hir::Expr>]),
}
/// Returns the arguments of the `vec!` macro if this expression was expanded from `vec!`.
pub fn vec_macro<'e>(cx: &LateContext, expr: &'e hir::Expr) -> Option<VecArgs<'e>> {
if_let_chain!{[
let hir::ExprCall(ref fun, ref args) = expr.node,
let hir::ExprPath(_, ref path) = fun.node,
is_expn_of(cx, fun.span, "vec").is_some()
], {
return if match_path(path, &paths::VEC_FROM_ELEM) && args.len() == 2 {
// `vec![elem; size]` case
Some(VecArgs::Repeat(&args[0], &args[1]))
}
else if match_path(path, &["into_vec"]) && args.len() == 1 {
// `vec![a, b, c]` case
if_let_chain!{[
let hir::ExprBox(ref boxed) = args[0].node,
let hir::ExprVec(ref args) = boxed.node
], {
return Some(VecArgs::Vec(&*args));
}}
None
}
else {
None
};
}}
None
}

46
clippy_lints/src/vec.rs
View File

@ -2,8 +2,7 @@
use rustc::ty::TypeVariants;
use rustc::hir::*;
use syntax::codemap::Span;
use syntax::ptr::P;
use utils::{higher, is_expn_of, match_path, paths, snippet, span_lint_and_then};
use utils::{higher, snippet, span_lint_and_then};
/// **What it does:** This lint warns about using `&vec![..]` when using `&[..]` would be possible.
///
@ -51,12 +50,12 @@ fn check_expr(&mut self, cx: &LateContext, expr: &Expr) {
}
fn check_vec_macro(cx: &LateContext, vec: &Expr, span: Span) {
if let Some(vec_args) = unexpand(cx, vec) {
if let Some(vec_args) = higher::vec_macro(cx, vec) {
let snippet = match vec_args {
Args::Repeat(elem, len) => {
higher::VecArgs::Repeat(elem, len) => {
format!("&[{}; {}]", snippet(cx, elem.span, "elem"), snippet(cx, len.span, "len")).into()
}
Args::Vec(args) => {
higher::VecArgs::Vec(args) => {
if let Some(last) = args.iter().last() {
let span = Span {
lo: args[0].span.lo,
@ -77,40 +76,3 @@ fn check_vec_macro(cx: &LateContext, vec: &Expr, span: Span) {
}
}
/// Represent the pre-expansion arguments of a `vec!` invocation.
pub enum Args<'a> {
/// `vec![elem; len]`
Repeat(&'a P<Expr>, &'a P<Expr>),
/// `vec![a, b, c]`
Vec(&'a [P<Expr>]),
}
/// Returns the arguments of the `vec!` macro if this expression was expanded from `vec!`.
pub fn unexpand<'e>(cx: &LateContext, expr: &'e Expr) -> Option<Args<'e>> {
if_let_chain!{[
let ExprCall(ref fun, ref args) = expr.node,
let ExprPath(_, ref path) = fun.node,
is_expn_of(cx, fun.span, "vec").is_some()
], {
return if match_path(path, &paths::VEC_FROM_ELEM) && args.len() == 2 {
// `vec![elem; size]` case
Some(Args::Repeat(&args[0], &args[1]))
}
else if match_path(path, &["into_vec"]) && args.len() == 1 {
// `vec![a, b, c]` case
if_let_chain!{[
let ExprBox(ref boxed) = args[0].node,
let ExprVec(ref args) = boxed.node
], {
return Some(Args::Vec(&*args));
}}
None
}
else {
None
};
}}
None
}