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