mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-12-20 18:13:36 +00:00
470 lines
17 KiB
Rust
470 lines
17 KiB
Rust
//! Contains utility functions to generate suggestions.
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#![deny(missing_docs_in_private_items)]
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// currently ignores lifetimes and generics
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#![allow(use_self)]
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use rustc::hir;
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use rustc::lint::{EarlyContext, LateContext, LintContext};
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use rustc_errors;
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use std::borrow::Cow;
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use std::fmt::Display;
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use std;
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use syntax::codemap::{CharPos, Span};
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use syntax::parse::token;
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use syntax::print::pprust::token_to_string;
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use syntax::util::parser::AssocOp;
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use syntax::ast;
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use utils::{higher, snippet, snippet_opt};
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/// A helper type to build suggestion correctly handling parenthesis.
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pub enum Sugg<'a> {
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/// An expression that never needs parenthesis such as `1337` or `[0; 42]`.
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NonParen(Cow<'a, str>),
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/// An expression that does not fit in other variants.
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MaybeParen(Cow<'a, str>),
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/// A binary operator expression, including `as`-casts and explicit type
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/// coercion.
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BinOp(AssocOp, Cow<'a, str>),
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}
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/// Literal constant `1`, for convenience.
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pub const ONE: Sugg<'static> = Sugg::NonParen(Cow::Borrowed("1"));
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impl<'a> Display for Sugg<'a> {
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fn fmt(&self, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
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match *self {
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Sugg::NonParen(ref s) |
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Sugg::MaybeParen(ref s) |
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Sugg::BinOp(_, ref s) => s.fmt(f),
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}
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}
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}
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#[allow(wrong_self_convention)] // ok, because of the function `as_ty` method
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impl<'a> Sugg<'a> {
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/// Prepare a suggestion from an expression.
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pub fn hir_opt(cx: &LateContext, expr: &hir::Expr) -> Option<Self> {
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snippet_opt(cx, expr.span).map(|snippet| {
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let snippet = Cow::Owned(snippet);
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match expr.node {
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hir::ExprAddrOf(..) |
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hir::ExprBox(..) |
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hir::ExprClosure(.., _) |
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hir::ExprIf(..) |
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hir::ExprUnary(..) |
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hir::ExprMatch(..) => Sugg::MaybeParen(snippet),
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hir::ExprAgain(..) |
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hir::ExprYield(..) |
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hir::ExprArray(..) |
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hir::ExprBlock(..) |
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hir::ExprBreak(..) |
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hir::ExprCall(..) |
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hir::ExprField(..) |
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hir::ExprIndex(..) |
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hir::ExprInlineAsm(..) |
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hir::ExprLit(..) |
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hir::ExprLoop(..) |
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hir::ExprMethodCall(..) |
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hir::ExprPath(..) |
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hir::ExprRepeat(..) |
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hir::ExprRet(..) |
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hir::ExprStruct(..) |
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hir::ExprTup(..) |
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hir::ExprTupField(..) |
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hir::ExprWhile(..) => Sugg::NonParen(snippet),
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hir::ExprAssign(..) => Sugg::BinOp(AssocOp::Assign, snippet),
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hir::ExprAssignOp(op, ..) => Sugg::BinOp(hirbinop2assignop(op), snippet),
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hir::ExprBinary(op, ..) => Sugg::BinOp(AssocOp::from_ast_binop(higher::binop(op.node)), snippet),
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hir::ExprCast(..) => Sugg::BinOp(AssocOp::As, snippet),
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hir::ExprType(..) => Sugg::BinOp(AssocOp::Colon, snippet),
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}
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})
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}
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/// Convenience function around `hir_opt` for suggestions with a default
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/// text.
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pub fn hir(cx: &LateContext, expr: &hir::Expr, default: &'a str) -> Self {
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Self::hir_opt(cx, expr).unwrap_or_else(|| Sugg::NonParen(Cow::Borrowed(default)))
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}
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/// Prepare a suggestion from an expression.
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pub fn ast(cx: &EarlyContext, expr: &ast::Expr, default: &'a str) -> Self {
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use syntax::ast::RangeLimits;
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let snippet = snippet(cx, expr.span, default);
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match expr.node {
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ast::ExprKind::AddrOf(..) |
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ast::ExprKind::Box(..) |
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ast::ExprKind::Closure(..) |
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ast::ExprKind::If(..) |
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ast::ExprKind::IfLet(..) |
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ast::ExprKind::InPlace(..) |
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ast::ExprKind::Unary(..) |
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ast::ExprKind::Match(..) => Sugg::MaybeParen(snippet),
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ast::ExprKind::Block(..) |
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ast::ExprKind::Break(..) |
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ast::ExprKind::Call(..) |
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ast::ExprKind::Catch(..) |
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ast::ExprKind::Continue(..) |
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ast::ExprKind::Yield(..) |
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ast::ExprKind::Field(..) |
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ast::ExprKind::ForLoop(..) |
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ast::ExprKind::Index(..) |
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ast::ExprKind::InlineAsm(..) |
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ast::ExprKind::Lit(..) |
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ast::ExprKind::Loop(..) |
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ast::ExprKind::Mac(..) |
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ast::ExprKind::MethodCall(..) |
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ast::ExprKind::Paren(..) |
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ast::ExprKind::Path(..) |
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ast::ExprKind::Repeat(..) |
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ast::ExprKind::Ret(..) |
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ast::ExprKind::Struct(..) |
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ast::ExprKind::Try(..) |
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ast::ExprKind::Tup(..) |
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ast::ExprKind::TupField(..) |
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ast::ExprKind::Array(..) |
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ast::ExprKind::While(..) |
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ast::ExprKind::WhileLet(..) => Sugg::NonParen(snippet),
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ast::ExprKind::Range(.., RangeLimits::HalfOpen) => Sugg::BinOp(AssocOp::DotDot, snippet),
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ast::ExprKind::Range(.., RangeLimits::Closed) => Sugg::BinOp(AssocOp::DotDotDot, snippet),
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ast::ExprKind::Assign(..) => Sugg::BinOp(AssocOp::Assign, snippet),
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ast::ExprKind::AssignOp(op, ..) => Sugg::BinOp(astbinop2assignop(op), snippet),
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ast::ExprKind::Binary(op, ..) => Sugg::BinOp(AssocOp::from_ast_binop(op.node), snippet),
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ast::ExprKind::Cast(..) => Sugg::BinOp(AssocOp::As, snippet),
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ast::ExprKind::Type(..) => Sugg::BinOp(AssocOp::Colon, snippet),
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}
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}
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/// Convenience method to create the `<lhs> && <rhs>` suggestion.
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pub fn and(self, rhs: Self) -> Sugg<'static> {
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make_binop(ast::BinOpKind::And, &self, &rhs)
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}
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/// Convenience method to create the `<lhs> as <rhs>` suggestion.
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pub fn as_ty<R: Display>(self, rhs: R) -> Sugg<'static> {
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make_assoc(AssocOp::As, &self, &Sugg::NonParen(rhs.to_string().into()))
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}
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/// Convenience method to create the `&<expr>` suggestion.
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pub fn addr(self) -> Sugg<'static> {
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make_unop("&", self)
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}
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/// Convenience method to create the `&mut <expr>` suggestion.
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pub fn mut_addr(self) -> Sugg<'static> {
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make_unop("&mut ", self)
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}
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/// Convenience method to create the `*<expr>` suggestion.
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pub fn deref(self) -> Sugg<'static> {
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make_unop("*", self)
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}
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/// Convenience method to create the `<lhs>..<rhs>` or `<lhs>...<rhs>`
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/// suggestion.
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pub fn range(self, end: Self, limit: ast::RangeLimits) -> Sugg<'static> {
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match limit {
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ast::RangeLimits::HalfOpen => make_assoc(AssocOp::DotDot, &self, &end),
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ast::RangeLimits::Closed => make_assoc(AssocOp::DotDotDot, &self, &end),
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}
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}
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/// Add parenthesis to any expression that might need them. Suitable to the
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/// `self` argument of
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/// a method call (eg. to build `bar.foo()` or `(1 + 2).foo()`).
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pub fn maybe_par(self) -> Self {
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match self {
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Sugg::NonParen(..) => self,
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// (x) and (x).y() both don't need additional parens
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Sugg::MaybeParen(sugg) => {
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if sugg.starts_with('(') && sugg.ends_with(')') {
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Sugg::MaybeParen(sugg)
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} else {
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Sugg::NonParen(format!("({})", sugg).into())
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}
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},
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Sugg::BinOp(_, sugg) => Sugg::NonParen(format!("({})", sugg).into()),
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}
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}
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}
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impl<'a, 'b> std::ops::Add<Sugg<'b>> for Sugg<'a> {
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type Output = Sugg<'static>;
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fn add(self, rhs: Sugg<'b>) -> Sugg<'static> {
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make_binop(ast::BinOpKind::Add, &self, &rhs)
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}
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}
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impl<'a, 'b> std::ops::Sub<Sugg<'b>> for Sugg<'a> {
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type Output = Sugg<'static>;
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fn sub(self, rhs: Sugg<'b>) -> Sugg<'static> {
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make_binop(ast::BinOpKind::Sub, &self, &rhs)
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}
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}
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impl<'a> std::ops::Not for Sugg<'a> {
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type Output = Sugg<'static>;
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fn not(self) -> Sugg<'static> {
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make_unop("!", self)
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}
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}
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/// Helper type to display either `foo` or `(foo)`.
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struct ParenHelper<T> {
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/// Whether parenthesis are needed.
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paren: bool,
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/// The main thing to display.
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wrapped: T,
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}
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impl<T> ParenHelper<T> {
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/// Build a `ParenHelper`.
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fn new(paren: bool, wrapped: T) -> Self {
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Self {
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paren: paren,
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wrapped: wrapped,
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}
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}
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}
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impl<T: Display> Display for ParenHelper<T> {
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fn fmt(&self, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
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if self.paren {
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write!(f, "({})", self.wrapped)
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} else {
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self.wrapped.fmt(f)
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}
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}
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}
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/// Build the string for `<op><expr>` adding parenthesis when necessary.
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///
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/// For convenience, the operator is taken as a string because all unary
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/// operators have the same
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/// precedence.
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pub fn make_unop(op: &str, expr: Sugg) -> Sugg<'static> {
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Sugg::MaybeParen(format!("{}{}", op, expr.maybe_par()).into())
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}
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/// Build the string for `<lhs> <op> <rhs>` adding parenthesis when necessary.
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///
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/// Precedence of shift operator relative to other arithmetic operation is
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/// often confusing so
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/// parenthesis will always be added for a mix of these.
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pub fn make_assoc(op: AssocOp, lhs: &Sugg, rhs: &Sugg) -> Sugg<'static> {
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/// Whether the operator is a shift operator `<<` or `>>`.
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fn is_shift(op: &AssocOp) -> bool {
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matches!(*op, AssocOp::ShiftLeft | AssocOp::ShiftRight)
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}
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/// Whether the operator is a arithmetic operator (`+`, `-`, `*`, `/`, `%`).
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fn is_arith(op: &AssocOp) -> bool {
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matches!(
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*op,
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AssocOp::Add | AssocOp::Subtract | AssocOp::Multiply | AssocOp::Divide | AssocOp::Modulus
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)
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}
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/// Whether the operator `op` needs parenthesis with the operator `other`
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/// in the direction
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/// `dir`.
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fn needs_paren(op: &AssocOp, other: &AssocOp, dir: Associativity) -> bool {
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other.precedence() < op.precedence() ||
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(other.precedence() == op.precedence() &&
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((op != other && associativity(op) != dir) ||
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(op == other && associativity(op) != Associativity::Both))) ||
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is_shift(op) && is_arith(other) || is_shift(other) && is_arith(op)
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}
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let lhs_paren = if let Sugg::BinOp(ref lop, _) = *lhs {
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needs_paren(&op, lop, Associativity::Left)
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} else {
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false
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};
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let rhs_paren = if let Sugg::BinOp(ref rop, _) = *rhs {
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needs_paren(&op, rop, Associativity::Right)
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} else {
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false
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};
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let lhs = ParenHelper::new(lhs_paren, lhs);
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let rhs = ParenHelper::new(rhs_paren, rhs);
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let sugg = match op {
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AssocOp::Add | AssocOp::BitAnd | AssocOp::BitOr | AssocOp::BitXor | AssocOp::Divide | AssocOp::Equal |
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AssocOp::Greater | AssocOp::GreaterEqual | AssocOp::LAnd | AssocOp::LOr | AssocOp::Less |
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AssocOp::LessEqual | AssocOp::Modulus | AssocOp::Multiply | AssocOp::NotEqual | AssocOp::ShiftLeft |
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AssocOp::ShiftRight | AssocOp::Subtract => {
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format!("{} {} {}", lhs, op.to_ast_binop().expect("Those are AST ops").to_string(), rhs)
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},
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AssocOp::Inplace => format!("in ({}) {}", lhs, rhs),
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AssocOp::Assign => format!("{} = {}", lhs, rhs),
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AssocOp::AssignOp(op) => format!("{} {}= {}", lhs, token_to_string(&token::BinOp(op)), rhs),
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AssocOp::As => format!("{} as {}", lhs, rhs),
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AssocOp::DotDot => format!("{}..{}", lhs, rhs),
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AssocOp::DotDotDot => format!("{}...{}", lhs, rhs),
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AssocOp::Colon => format!("{}: {}", lhs, rhs),
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};
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Sugg::BinOp(op, sugg.into())
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}
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/// Convinience wrapper arround `make_assoc` and `AssocOp::from_ast_binop`.
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pub fn make_binop(op: ast::BinOpKind, lhs: &Sugg, rhs: &Sugg) -> Sugg<'static> {
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make_assoc(AssocOp::from_ast_binop(op), lhs, rhs)
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}
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#[derive(PartialEq, Eq, Clone, Copy)]
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/// Operator associativity.
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enum Associativity {
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/// The operator is both left-associative and right-associative.
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Both,
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/// The operator is left-associative.
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Left,
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/// The operator is not associative.
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None,
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/// The operator is right-associative.
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Right,
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}
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/// Return the associativity/fixity of an operator. The difference with
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/// `AssocOp::fixity` is that
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/// an operator can be both left and right associative (such as `+`:
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/// `a + b + c == (a + b) + c == a + (b + c)`.
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///
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/// Chained `as` and explicit `:` type coercion never need inner parenthesis so
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/// they are considered
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/// associative.
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fn associativity(op: &AssocOp) -> Associativity {
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use syntax::util::parser::AssocOp::*;
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match *op {
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Inplace | Assign | AssignOp(_) => Associativity::Right,
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Add | BitAnd | BitOr | BitXor | LAnd | LOr | Multiply | As | Colon => Associativity::Both,
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Divide | Equal | Greater | GreaterEqual | Less | LessEqual | Modulus | NotEqual | ShiftLeft | ShiftRight |
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Subtract => Associativity::Left,
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DotDot | DotDotDot => Associativity::None,
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}
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}
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/// Convert a `hir::BinOp` to the corresponding assigning binary operator.
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fn hirbinop2assignop(op: hir::BinOp) -> AssocOp {
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use rustc::hir::BinOp_::*;
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use syntax::parse::token::BinOpToken::*;
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AssocOp::AssignOp(match op.node {
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BiAdd => Plus,
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BiBitAnd => And,
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BiBitOr => Or,
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BiBitXor => Caret,
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BiDiv => Slash,
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BiMul => Star,
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BiRem => Percent,
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BiShl => Shl,
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BiShr => Shr,
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BiSub => Minus,
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BiAnd | BiEq | BiGe | BiGt | BiLe | BiLt | BiNe | BiOr => panic!("This operator does not exist"),
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})
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}
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/// Convert an `ast::BinOp` to the corresponding assigning binary operator.
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fn astbinop2assignop(op: ast::BinOp) -> AssocOp {
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use syntax::ast::BinOpKind::*;
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use syntax::parse::token::BinOpToken;
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AssocOp::AssignOp(match op.node {
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Add => BinOpToken::Plus,
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BitAnd => BinOpToken::And,
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BitOr => BinOpToken::Or,
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BitXor => BinOpToken::Caret,
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Div => BinOpToken::Slash,
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Mul => BinOpToken::Star,
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Rem => BinOpToken::Percent,
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Shl => BinOpToken::Shl,
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Shr => BinOpToken::Shr,
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Sub => BinOpToken::Minus,
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And | Eq | Ge | Gt | Le | Lt | Ne | Or => panic!("This operator does not exist"),
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})
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}
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/// Return the indentation before `span` if there are nothing but `[ \t]`
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/// before it on its line.
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fn indentation<'a, T: LintContext<'a>>(cx: &T, span: Span) -> Option<String> {
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let lo = cx.sess().codemap().lookup_char_pos(span.lo());
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if let Some(line) = lo.file.get_line(
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lo.line - 1, /* line numbers in `Loc` are 1-based */
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)
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{
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if let Some((pos, _)) = line.char_indices().find(|&(_, c)| c != ' ' && c != '\t') {
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// we can mix char and byte positions here because we only consider `[ \t]`
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if lo.col == CharPos(pos) {
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Some(line[..pos].into())
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} else {
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None
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}
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} else {
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None
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}
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} else {
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None
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}
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}
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/// Convenience extension trait for `DiagnosticBuilder`.
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pub trait DiagnosticBuilderExt<'a, T: LintContext<'a>> {
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/// Suggests to add an attribute to an item.
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///
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/// Correctly handles indentation of the attribute and item.
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///
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/// # Example
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///
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/// ```rust,ignore
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/// db.suggest_item_with_attr(cx, item, "#[derive(Default)]");
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/// ```
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fn suggest_item_with_attr<D: Display + ?Sized>(&mut self, cx: &T, item: Span, msg: &str, attr: &D);
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/// Suggest to add an item before another.
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///
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/// The item should not be indented (expect for inner indentation).
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///
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/// # Example
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///
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/// ```rust,ignore
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/// db.suggest_prepend_item(cx, item,
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/// "fn foo() {
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/// bar();
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/// }");
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/// ```
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fn suggest_prepend_item(&mut self, cx: &T, item: Span, msg: &str, new_item: &str);
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}
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impl<'a, 'b, 'c, T: LintContext<'c>> DiagnosticBuilderExt<'c, T> for rustc_errors::DiagnosticBuilder<'b> {
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fn suggest_item_with_attr<D: Display + ?Sized>(&mut self, cx: &T, item: Span, msg: &str, attr: &D) {
|
|
if let Some(indent) = indentation(cx, item) {
|
|
let span = item.with_hi(item.lo());
|
|
|
|
self.span_suggestion(span, msg, format!("{}\n{}", attr, indent));
|
|
}
|
|
}
|
|
|
|
fn suggest_prepend_item(&mut self, cx: &T, item: Span, msg: &str, new_item: &str) {
|
|
if let Some(indent) = indentation(cx, item) {
|
|
let span = item.with_hi(item.lo());
|
|
|
|
let mut first = true;
|
|
let new_item = new_item
|
|
.lines()
|
|
.map(|l| if first {
|
|
first = false;
|
|
format!("{}\n", l)
|
|
} else {
|
|
format!("{}{}\n", indent, l)
|
|
})
|
|
.collect::<String>();
|
|
|
|
self.span_suggestion(span, msg, format!("{}\n{}", new_item, indent));
|
|
}
|
|
}
|
|
}
|