+//! Contains utility functions to generate suggestions.
+#![deny(missing_docs_in_private_items)]
+
use rustc::hir;
-use rustc::lint::{EarlyContext, LateContext};
+use rustc::lint::{EarlyContext, LateContext, LintContext};
+use rustc_errors;
use std::borrow::Cow;
+use std::fmt::Display;
use std;
-use syntax::ast;
+use syntax::codemap::{CharPos, Span};
+use syntax::print::pprust::binop_to_string;
use syntax::util::parser::AssocOp;
+use syntax::ast;
use utils::{higher, snippet, snippet_opt};
-use syntax::print::pprust::binop_to_string;
/// A helper type to build suggestion correctly handling parenthesis.
pub enum Sugg<'a> {
/// Literal constant `1`, for convenience.
pub const ONE: Sugg<'static> = Sugg::NonParen(Cow::Borrowed("1"));
-impl<'a> std::fmt::Display for Sugg<'a> {
+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)
- }
+ 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);
hir::ExprUnary(..) |
hir::ExprMatch(..) => Sugg::MaybeParen(snippet),
hir::ExprAgain(..) |
+ hir::ExprArray(..) |
hir::ExprBlock(..) |
hir::ExprBreak(..) |
hir::ExprCall(..) |
hir::ExprStruct(..) |
hir::ExprTup(..) |
hir::ExprTupField(..) |
- hir::ExprVec(..) |
hir::ExprWhile(..) => Sugg::NonParen(snippet),
hir::ExprAssign(..) => Sugg::BinOp(AssocOp::Assign, snippet),
hir::ExprAssignOp(op, ..) => Sugg::BinOp(hirbinop2assignop(op), 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;
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)
pub fn maybe_par(self) -> Self {
match self {
Sugg::NonParen(..) => self,
- Sugg::MaybeParen(sugg) | Sugg::BinOp(_, sugg) => Sugg::NonParen(format!("({})", sugg).into()),
+ // (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()),
}
}
}
}
}
+/// 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,
}
}
-impl<T: std::fmt::Display> std::fmt::Display for ParenHelper<T> {
+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)
/// 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)
+ 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)
+ (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 {
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::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, binop_to_string(op), rhs),
}
#[derive(PartialEq, Eq)]
+/// 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,
}
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
+ 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,
}
}
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));
+ }
+ }
+}
projects / rust.git / blobdiff