X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=src%2Fclosures.rs;h=e688db1c39d7c79209178ef2c1ae108fa909647d;hb=f5ce84e4f25304dfbf9efeb26a85ef3c9ad594ad;hp=f6a3d8436f29629d6dd4ccaf9714973044a4c210;hpb=fc1909d311cebd2920b968b8fe161267c12c5fe1;p=rust.git diff --git a/src/closures.rs b/src/closures.rs index f6a3d8436f2..e688db1c39d 100644 --- a/src/closures.rs +++ b/src/closures.rs @@ -1,25 +1,17 @@ -// Copyright 2017 The Rust Project Developers. See the COPYRIGHT -// file at the top-level directory of this distribution and at -// http://rust-lang.org/COPYRIGHT. -// -// Licensed under the Apache License, Version 2.0 or the MIT license -// , at your -// option. This file may not be copied, modified, or distributed -// except according to those terms. - -use config::lists::*; -use syntax::parse::classify; -use syntax::source_map::Span; -use syntax::{ast, ptr}; - -use expr::{block_contains_comment, is_simple_block, is_unsafe_block, rewrite_cond, ToExpr}; -use items::{span_hi_for_arg, span_lo_for_arg}; -use lists::{definitive_tactic, itemize_list, write_list, ListFormatting, Separator}; -use rewrite::{Rewrite, RewriteContext}; -use shape::Shape; -use source_map::SpanUtils; -use utils::{last_line_width, left_most_sub_expr, stmt_expr}; +use rustc_ast::{ast, ptr}; +use rustc_span::Span; + +use crate::attr::get_attrs_from_stmt; +use crate::config::lists::*; +use crate::config::Version; +use crate::expr::{block_contains_comment, is_simple_block, is_unsafe_block, rewrite_cond}; +use crate::items::{span_hi_for_param, span_lo_for_param}; +use crate::lists::{definitive_tactic, itemize_list, write_list, ListFormatting, Separator}; +use crate::overflow::OverflowableItem; +use crate::rewrite::{Rewrite, RewriteContext}; +use crate::shape::Shape; +use crate::source_map::SpanUtils; +use crate::utils::{last_line_width, left_most_sub_expr, stmt_expr, NodeIdExt}; // This module is pretty messy because of the rules around closures and blocks: // FIXME - the below is probably no longer true in full. @@ -31,34 +23,34 @@ // statement without needing a semi-colon), then adding or removing braces // can change whether it is treated as an expression or statement. -pub fn rewrite_closure( +pub(crate) fn rewrite_closure( capture: ast::CaptureBy, - asyncness: ast::IsAsync, + is_async: &ast::Async, movability: ast::Movability, fn_decl: &ast::FnDecl, body: &ast::Expr, span: Span, - context: &RewriteContext, + context: &RewriteContext<'_>, shape: Shape, ) -> Option { debug!("rewrite_closure {:?}", body); let (prefix, extra_offset) = rewrite_closure_fn_decl( - capture, asyncness, movability, fn_decl, body, span, context, shape, + capture, is_async, movability, fn_decl, body, span, context, shape, )?; // 1 = space between `|...|` and body. let body_shape = shape.offset_left(extra_offset)?; - if let ast::ExprKind::Block(ref block, _) = body.node { + if let ast::ExprKind::Block(ref block, _) = body.kind { // The body of the closure is an empty block. - if block.stmts.is_empty() && !block_contains_comment(block, context.source_map) { + if block.stmts.is_empty() && !block_contains_comment(context, block) { return body .rewrite(context, shape) .map(|s| format!("{} {}", prefix, s)); } let result = match fn_decl.output { - ast::FunctionRetTy::Default(_) => { + ast::FnRetTy::Default(_) if !context.inside_macro() => { try_rewrite_without_block(body, &prefix, context, shape, body_shape) } _ => None, @@ -80,7 +72,7 @@ pub fn rewrite_closure( fn try_rewrite_without_block( expr: &ast::Expr, prefix: &str, - context: &RewriteContext, + context: &RewriteContext<'_>, shape: Shape, body_shape: Shape, ) -> Option { @@ -96,12 +88,13 @@ fn try_rewrite_without_block( fn get_inner_expr<'a>( expr: &'a ast::Expr, prefix: &str, - context: &RewriteContext, + context: &RewriteContext<'_>, ) -> &'a ast::Expr { - if let ast::ExprKind::Block(ref block, _) = expr.node { + if let ast::ExprKind::Block(ref block, _) = expr.kind { if !needs_block(block, prefix, context) { - // block.stmts.len() == 1 - if let Some(expr) = stmt_expr(&block.stmts[0]) { + // block.stmts.len() == 1 except with `|| {{}}`; + // https://github.com/rust-lang/rustfmt/issues/3844 + if let Some(expr) = block.stmts.first().and_then(stmt_expr) { return get_inner_expr(expr, prefix, context); } } @@ -111,15 +104,20 @@ fn get_inner_expr<'a>( } // Figure out if a block is necessary. -fn needs_block(block: &ast::Block, prefix: &str, context: &RewriteContext) -> bool { +fn needs_block(block: &ast::Block, prefix: &str, context: &RewriteContext<'_>) -> bool { + let has_attributes = block.stmts.first().map_or(false, |first_stmt| { + !get_attrs_from_stmt(first_stmt).is_empty() + }); + is_unsafe_block(block) || block.stmts.len() > 1 - || block_contains_comment(block, context.source_map) + || has_attributes + || block_contains_comment(context, block) || prefix.contains('\n') } fn veto_block(e: &ast::Expr) -> bool { - match e.node { + match e.kind { ast::ExprKind::Call(..) | ast::ExprKind::Binary(..) | ast::ExprKind::Cast(..) @@ -135,30 +133,44 @@ fn veto_block(e: &ast::Expr) -> bool { } // Rewrite closure with a single expression wrapping its body with block. +// || { #[attr] foo() } -> Block { #[attr] foo() } fn rewrite_closure_with_block( body: &ast::Expr, prefix: &str, - context: &RewriteContext, + context: &RewriteContext<'_>, shape: Shape, ) -> Option { let left_most = left_most_sub_expr(body); - let veto_block = veto_block(body) && !classify::expr_requires_semi_to_be_stmt(left_most); + let veto_block = veto_block(body) && !expr_requires_semi_to_be_stmt(left_most); if veto_block { return None; } let block = ast::Block { stmts: vec![ast::Stmt { - id: ast::NodeId::new(0), - node: ast::StmtKind::Expr(ptr::P(body.clone())), + id: ast::NodeId::root(), + kind: ast::StmtKind::Expr(ptr::P(body.clone())), span: body.span, }], - id: ast::NodeId::new(0), + id: ast::NodeId::root(), rules: ast::BlockCheckMode::Default, - span: body.span, - recovered: false, + tokens: None, + span: body + .attrs + .first() + .map(|attr| attr.span.to(body.span)) + .unwrap_or(body.span), + could_be_bare_literal: false, }; - let block = ::expr::rewrite_block_with_visitor(context, "", &block, None, None, shape, false)?; + let block = crate::expr::rewrite_block_with_visitor( + context, + "", + &block, + Some(&body.attrs), + None, + shape, + false, + )?; Some(format!("{} {}", prefix, block)) } @@ -166,18 +178,19 @@ fn rewrite_closure_with_block( fn rewrite_closure_expr( expr: &ast::Expr, prefix: &str, - context: &RewriteContext, + context: &RewriteContext<'_>, shape: Shape, ) -> Option { fn allow_multi_line(expr: &ast::Expr) -> bool { - match expr.node { + match expr.kind { ast::ExprKind::Match(..) + | ast::ExprKind::Async(..) | ast::ExprKind::Block(..) - | ast::ExprKind::Catch(..) + | ast::ExprKind::TryBlock(..) | ast::ExprKind::Loop(..) | ast::ExprKind::Struct(..) => true, - ast::ExprKind::AddrOf(_, ref expr) + ast::ExprKind::AddrOf(_, _, ref expr) | ast::ExprKind::Box(ref expr) | ast::ExprKind::Try(ref expr) | ast::ExprKind::Unary(_, ref expr) @@ -198,14 +211,15 @@ fn allow_multi_line(expr: &ast::Expr) -> bool { } else { Some(rw) } - }).map(|rw| format!("{} {}", prefix, rw)) + }) + .map(|rw| format!("{} {}", prefix, rw)) } // Rewrite closure whose body is block. fn rewrite_closure_block( block: &ast::Block, prefix: &str, - context: &RewriteContext, + context: &RewriteContext<'_>, shape: Shape, ) -> Option { Some(format!("{} {}", prefix, block.rewrite(context, shape)?)) @@ -214,50 +228,50 @@ fn rewrite_closure_block( // Return type is (prefix, extra_offset) fn rewrite_closure_fn_decl( capture: ast::CaptureBy, - asyncness: ast::IsAsync, + asyncness: &ast::Async, movability: ast::Movability, fn_decl: &ast::FnDecl, body: &ast::Expr, span: Span, - context: &RewriteContext, + context: &RewriteContext<'_>, shape: Shape, ) -> Option<(String, usize)> { - let is_async = if asyncness.is_async() { "async " } else { "" }; - let mover = if capture == ast::CaptureBy::Value { - "move " + let immovable = if movability == ast::Movability::Static { + "static " } else { "" }; - let immovable = if movability == ast::Movability::Static { - "static " + let is_async = if asyncness.is_async() { "async " } else { "" }; + let mover = if capture == ast::CaptureBy::Value { + "move " } else { "" }; // 4 = "|| {".len(), which is overconservative when the closure consists of // a single expression. let nested_shape = shape - .shrink_left(is_async.len() + mover.len() + immovable.len())? + .shrink_left(immovable.len() + is_async.len() + mover.len())? .sub_width(4)?; // 1 = | - let argument_offset = nested_shape.indent + 1; - let arg_shape = nested_shape.offset_left(1)?.visual_indent(0); - let ret_str = fn_decl.output.rewrite(context, arg_shape)?; + let param_offset = nested_shape.indent + 1; + let param_shape = nested_shape.offset_left(1)?.visual_indent(0); + let ret_str = fn_decl.output.rewrite(context, param_shape)?; - let arg_items = itemize_list( + let param_items = itemize_list( context.snippet_provider, fn_decl.inputs.iter(), "|", ",", - |arg| span_lo_for_arg(arg), - |arg| span_hi_for_arg(context, arg), - |arg| arg.rewrite(context, arg_shape), + |param| span_lo_for_param(param), + |param| span_hi_for_param(context, param), + |param| param.rewrite(context, param_shape), context.snippet_provider.span_after(span, "|"), body.span.lo(), false, ); - let item_vec = arg_items.collect::>(); - // 1 = space between arguments and return type. + let item_vec = param_items.collect::>(); + // 1 = space between parameters and return type. let horizontal_budget = nested_shape.width.saturating_sub(ret_str.len() + 1); let tactic = definitive_tactic( &item_vec, @@ -265,21 +279,21 @@ fn rewrite_closure_fn_decl( Separator::Comma, horizontal_budget, ); - let arg_shape = match tactic { - DefinitiveListTactic::Horizontal => arg_shape.sub_width(ret_str.len() + 1)?, - _ => arg_shape, + let param_shape = match tactic { + DefinitiveListTactic::Horizontal => param_shape.sub_width(ret_str.len() + 1)?, + _ => param_shape, }; - let fmt = ListFormatting::new(arg_shape, context.config) + let fmt = ListFormatting::new(param_shape, context.config) .tactic(tactic) .preserve_newline(true); let list_str = write_list(&item_vec, &fmt)?; - let mut prefix = format!("{}{}{}|{}|", is_async, immovable, mover, list_str); + let mut prefix = format!("{}{}{}|{}|", immovable, is_async, mover, list_str); if !ret_str.is_empty() { if prefix.contains('\n') { prefix.push('\n'); - prefix.push_str(&argument_offset.to_string(context.config)); + prefix.push_str(¶m_offset.to_string(context.config)); } else { prefix.push(' '); } @@ -293,25 +307,26 @@ fn rewrite_closure_fn_decl( // Rewriting closure which is placed at the end of the function call's arg. // Returns `None` if the reformatted closure 'looks bad'. -pub fn rewrite_last_closure( - context: &RewriteContext, +pub(crate) fn rewrite_last_closure( + context: &RewriteContext<'_>, expr: &ast::Expr, shape: Shape, ) -> Option { - if let ast::ExprKind::Closure(capture, asyncness, movability, ref fn_decl, ref body, _) = - expr.node + if let ast::ExprKind::Closure(capture, ref is_async, movability, ref fn_decl, ref body, _) = + expr.kind { - let body = match body.node { + let body = match body.kind { ast::ExprKind::Block(ref block, _) if !is_unsafe_block(block) - && is_simple_block(block, Some(&body.attrs), context.source_map) => + && !context.inside_macro() + && is_simple_block(context, block, Some(&body.attrs)) => { stmt_expr(&block.stmts[0]).unwrap_or(body) } _ => body, }; let (prefix, extra_offset) = rewrite_closure_fn_decl( - capture, asyncness, movability, fn_decl, body, expr.span, context, shape, + capture, is_async, movability, fn_decl, body, expr.span, context, shape, )?; // If the closure goes multi line before its body, do not overflow the closure. if prefix.contains('\n') { @@ -322,20 +337,23 @@ pub fn rewrite_last_closure( // We force to use block for the body of the closure for certain kinds of expressions. if is_block_closure_forced(context, body) { - return rewrite_closure_with_block(body, &prefix, context, body_shape).and_then( + return rewrite_closure_with_block(body, &prefix, context, body_shape).map( |body_str| { - // If the expression can fit in a single line, we need not force block closure. - if body_str.lines().count() <= 7 { - match rewrite_closure_expr(body, &prefix, context, shape) { - Some(ref single_line_body_str) - if !single_line_body_str.contains('\n') => - { - Some(single_line_body_str.clone()) + match fn_decl.output { + ast::FnRetTy::Default(..) if body_str.lines().count() <= 7 => { + // If the expression can fit in a single line, we need not force block + // closure. However, if the closure has a return type, then we must + // keep the blocks. + match rewrite_closure_expr(body, &prefix, context, shape) { + Some(single_line_body_str) + if !single_line_body_str.contains('\n') => + { + single_line_body_str + } + _ => body_str, } - _ => Some(body_str), } - } else { - Some(body_str) + _ => body_str, } }, ); @@ -343,9 +361,9 @@ pub fn rewrite_last_closure( // When overflowing the closure which consists of a single control flow expression, // force to use block if its condition uses multi line. - let is_multi_lined_cond = rewrite_cond(context, body, body_shape) - .map(|cond| cond.contains('\n') || cond.len() > body_shape.width) - .unwrap_or(false); + let is_multi_lined_cond = rewrite_cond(context, body, body_shape).map_or(false, |cond| { + cond.contains('\n') || cond.len() > body_shape.width + }); if is_multi_lined_cond { return rewrite_closure_with_block(body, &prefix, context, body_shape); } @@ -356,43 +374,54 @@ pub fn rewrite_last_closure( None } -/// Returns true if the given vector of arguments has more than one `ast::ExprKind::Closure`. -pub fn args_have_many_closure(args: &[&T]) -> bool -where - T: ToExpr, -{ +/// Returns `true` if the given vector of arguments has more than one `ast::ExprKind::Closure`. +pub(crate) fn args_have_many_closure(args: &[OverflowableItem<'_>]) -> bool { args.iter() - .filter(|arg| { - arg.to_expr() - .map(|e| match e.node { - ast::ExprKind::Closure(..) => true, - _ => false, - }).unwrap_or(false) - }).count() + .filter_map(OverflowableItem::to_expr) + .filter(|expr| matches!(expr.kind, ast::ExprKind::Closure(..))) + .count() > 1 } -fn is_block_closure_forced(context: &RewriteContext, expr: &ast::Expr) -> bool { +fn is_block_closure_forced(context: &RewriteContext<'_>, expr: &ast::Expr) -> bool { // If we are inside macro, we do not want to add or remove block from closure body. if context.inside_macro() { false } else { - is_block_closure_forced_inner(expr) + is_block_closure_forced_inner(expr, context.config.version()) } } -fn is_block_closure_forced_inner(expr: &ast::Expr) -> bool { - match expr.node { - ast::ExprKind::If(..) - | ast::ExprKind::IfLet(..) - | ast::ExprKind::While(..) - | ast::ExprKind::WhileLet(..) - | ast::ExprKind::ForLoop(..) => true, - ast::ExprKind::AddrOf(_, ref expr) +fn is_block_closure_forced_inner(expr: &ast::Expr, version: Version) -> bool { + match expr.kind { + ast::ExprKind::If(..) | ast::ExprKind::While(..) | ast::ExprKind::ForLoop(..) => true, + ast::ExprKind::Loop(..) if version == Version::Two => true, + ast::ExprKind::AddrOf(_, _, ref expr) | ast::ExprKind::Box(ref expr) | ast::ExprKind::Try(ref expr) | ast::ExprKind::Unary(_, ref expr) - | ast::ExprKind::Cast(ref expr, _) => is_block_closure_forced_inner(expr), + | ast::ExprKind::Cast(ref expr, _) => is_block_closure_forced_inner(expr, version), _ => false, } } + +/// Does this expression require a semicolon to be treated +/// as a statement? The negation of this: 'can this expression +/// be used as a statement without a semicolon' -- is used +/// as an early-bail-out in the parser so that, for instance, +/// if true {...} else {...} +/// |x| 5 +/// isn't parsed as (if true {...} else {...} | x) | 5 +// From https://github.com/rust-lang/rust/blob/master/src/libsyntax/parse/classify.rs. +fn expr_requires_semi_to_be_stmt(e: &ast::Expr) -> bool { + match e.kind { + ast::ExprKind::If(..) + | ast::ExprKind::Match(..) + | ast::ExprKind::Block(..) + | ast::ExprKind::While(..) + | ast::ExprKind::Loop(..) + | ast::ExprKind::ForLoop(..) + | ast::ExprKind::TryBlock(..) => false, + _ => true, + } +}