// Copyright 2015 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 std::cmp::{Ordering, min}; use std::iter::ExactSizeIterator; use std::fmt::Write; use {Indent, Shape, Spanned}; use codemap::SpanUtils; use rewrite::{Rewrite, RewriteContext}; use lists::{write_list, itemize_list, ListFormatting, SeparatorTactic, ListTactic, DefinitiveListTactic, definitive_tactic, ListItem, format_item_list, struct_lit_shape, struct_lit_tactic, shape_for_tactic, struct_lit_formatting}; use string::{StringFormat, rewrite_string}; use utils::{extra_offset, last_line_width, wrap_str, binary_search, first_line_width, semicolon_for_stmt, trimmed_last_line_width, left_most_sub_expr, stmt_expr, colon_spaces, contains_skip, mk_sp}; use visitor::FmtVisitor; use config::{Config, IndentStyle, MultilineStyle, ControlBraceStyle, Style}; use comment::{FindUncommented, rewrite_comment, contains_comment, recover_comment_removed}; use types::{rewrite_path, PathContext, can_be_overflowed_type}; use items::{span_lo_for_arg, span_hi_for_arg}; use chains::rewrite_chain; use macros::{rewrite_macro, MacroPosition}; use patterns::{TuplePatField, can_be_overflowed_pat}; use syntax::{ast, ptr}; use syntax::codemap::{CodeMap, Span, BytePos}; use syntax::parse::classify; impl Rewrite for ast::Expr { fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option { format_expr(self, ExprType::SubExpression, context, shape) } } #[derive(PartialEq)] enum ExprType { Statement, SubExpression, } fn combine_attr_and_expr( context: &RewriteContext, shape: Shape, attr_str: &str, expr_str: &str, ) -> String { let separator = if attr_str.is_empty() { String::new() } else { if expr_str.contains('\n') || attr_str.contains('\n') || attr_str.len() + expr_str.len() > shape.width { format!("\n{}", shape.indent.to_string(context.config)) } else { String::from(" ") } }; format!("{}{}{}", attr_str, separator, expr_str) } fn format_expr( expr: &ast::Expr, expr_type: ExprType, context: &RewriteContext, shape: Shape, ) -> Option { let attr_rw = (&*expr.attrs).rewrite(context, shape); if contains_skip(&*expr.attrs) { if let Some(attr_str) = attr_rw { return Some(combine_attr_and_expr( context, shape, &attr_str, &context.snippet(expr.span), )); } else { return Some(context.snippet(expr.span)); } } let expr_rw = match expr.node { ast::ExprKind::Array(ref expr_vec) => { rewrite_array( expr_vec.iter().map(|e| &**e), mk_sp(context.codemap.span_after(expr.span, "["), expr.span.hi), context, shape, ) } ast::ExprKind::Lit(ref l) => { match l.node { ast::LitKind::Str(_, ast::StrStyle::Cooked) => { rewrite_string_lit(context, l.span, shape) } _ => { wrap_str( context.snippet(expr.span), context.config.max_width(), shape, ) } } } ast::ExprKind::Call(ref callee, ref args) => { let inner_span = mk_sp(callee.span.hi, expr.span.hi); rewrite_call_with_binary_search( context, &**callee, &args.iter().map(|x| &**x).collect::>()[..], inner_span, shape, ) } ast::ExprKind::Paren(ref subexpr) => rewrite_paren(context, subexpr, shape), ast::ExprKind::Binary(ref op, ref lhs, ref rhs) => { // FIXME: format comments between operands and operator rewrite_pair( &**lhs, &**rhs, "", &format!(" {} ", context.snippet(op.span)), "", context, shape, ) } ast::ExprKind::Unary(ref op, ref subexpr) => rewrite_unary_op(context, op, subexpr, shape), ast::ExprKind::Struct(ref path, ref fields, ref base) => { rewrite_struct_lit( context, path, fields, base.as_ref().map(|e| &**e), expr.span, shape, ) } ast::ExprKind::Tup(ref items) => { rewrite_tuple( context, &items.iter().map(|x| &**x).collect::>()[..], expr.span, shape, ) } ast::ExprKind::If(..) | ast::ExprKind::IfLet(..) | ast::ExprKind::ForLoop(..) | ast::ExprKind::Loop(..) | ast::ExprKind::While(..) | ast::ExprKind::WhileLet(..) => { to_control_flow(expr, expr_type).and_then(|control_flow| { control_flow.rewrite(context, shape) }) } ast::ExprKind::Block(ref block) => block.rewrite(context, shape), ast::ExprKind::Match(ref cond, ref arms) => { rewrite_match(context, cond, arms, shape, expr.span) } ast::ExprKind::Path(ref qself, ref path) => { rewrite_path(context, PathContext::Expr, qself.as_ref(), path, shape) } ast::ExprKind::Assign(ref lhs, ref rhs) => { rewrite_assignment(context, lhs, rhs, None, shape) } ast::ExprKind::AssignOp(ref op, ref lhs, ref rhs) => { rewrite_assignment(context, lhs, rhs, Some(op), shape) } ast::ExprKind::Continue(ref opt_ident) => { let id_str = match *opt_ident { Some(ident) => format!(" {}", ident.node), None => String::new(), }; wrap_str( format!("continue{}", id_str), context.config.max_width(), shape, ) } ast::ExprKind::Break(ref opt_ident, ref opt_expr) => { let id_str = match *opt_ident { Some(ident) => format!(" {}", ident.node), None => String::new(), }; if let Some(ref expr) = *opt_expr { rewrite_unary_prefix(context, &format!("break{} ", id_str), &**expr, shape) } else { wrap_str( format!("break{}", id_str), context.config.max_width(), shape, ) } } ast::ExprKind::Closure(capture, ref fn_decl, ref body, _) => { rewrite_closure(capture, fn_decl, body, expr.span, context, shape) } ast::ExprKind::Try(..) | ast::ExprKind::Field(..) | ast::ExprKind::TupField(..) | ast::ExprKind::MethodCall(..) => rewrite_chain(expr, context, shape), ast::ExprKind::Mac(ref mac) => { // Failure to rewrite a marco should not imply failure to // rewrite the expression. rewrite_macro(mac, None, context, shape, MacroPosition::Expression).or_else(|| { wrap_str( context.snippet(expr.span), context.config.max_width(), shape, ) }) } ast::ExprKind::Ret(None) => { wrap_str("return".to_owned(), context.config.max_width(), shape) } ast::ExprKind::Ret(Some(ref expr)) => { rewrite_unary_prefix(context, "return ", &**expr, shape) } ast::ExprKind::Box(ref expr) => rewrite_unary_prefix(context, "box ", &**expr, shape), ast::ExprKind::AddrOf(mutability, ref expr) => { rewrite_expr_addrof(context, mutability, expr, shape) } ast::ExprKind::Cast(ref expr, ref ty) => { rewrite_pair(&**expr, &**ty, "", " as ", "", context, shape) } ast::ExprKind::Type(ref expr, ref ty) => { rewrite_pair(&**expr, &**ty, "", ": ", "", context, shape) } ast::ExprKind::Index(ref expr, ref index) => { rewrite_index(&**expr, &**index, context, shape) } ast::ExprKind::Repeat(ref expr, ref repeats) => { let (lbr, rbr) = if context.config.spaces_within_square_brackets() { ("[ ", " ]") } else { ("[", "]") }; rewrite_pair(&**expr, &**repeats, lbr, "; ", rbr, context, shape) } ast::ExprKind::Range(ref lhs, ref rhs, limits) => { let delim = match limits { ast::RangeLimits::HalfOpen => "..", ast::RangeLimits::Closed => "...", }; match (lhs.as_ref().map(|x| &**x), rhs.as_ref().map(|x| &**x)) { (Some(ref lhs), Some(ref rhs)) => { let sp_delim = if context.config.spaces_around_ranges() { format!(" {} ", delim) } else { delim.into() }; rewrite_pair(&**lhs, &**rhs, "", &sp_delim, "", context, shape) } (None, Some(ref rhs)) => { let sp_delim = if context.config.spaces_around_ranges() { format!("{} ", delim) } else { delim.into() }; rewrite_unary_prefix(context, &sp_delim, &**rhs, shape) } (Some(ref lhs), None) => { let sp_delim = if context.config.spaces_around_ranges() { format!(" {}", delim) } else { delim.into() }; rewrite_unary_suffix(context, &sp_delim, &**lhs, shape) } (None, None) => wrap_str(delim.into(), context.config.max_width(), shape), } } // We do not format these expressions yet, but they should still // satisfy our width restrictions. ast::ExprKind::InPlace(..) | ast::ExprKind::InlineAsm(..) => { wrap_str( context.snippet(expr.span), context.config.max_width(), shape, ) } ast::ExprKind::Catch(ref block) => { if let rewrite @ Some(_) = try_one_line_block(context, shape, "do catch ", block) { return rewrite; } // 9 = `do catch ` let budget = shape.width.checked_sub(9).unwrap_or(0); Some(format!( "{}{}", "do catch ", try_opt!( block.rewrite(&context, Shape::legacy(budget, shape.indent)) ) )) } }; match (attr_rw, expr_rw) { (Some(attr_str), Some(expr_str)) => { recover_comment_removed( combine_attr_and_expr(context, shape, &attr_str, &expr_str), expr.span, context, shape, ) } _ => None, } } fn try_one_line_block( context: &RewriteContext, shape: Shape, prefix: &str, block: &ast::Block, ) -> Option { if is_simple_block(block, context.codemap) { let expr_shape = Shape::legacy(shape.width - prefix.len(), shape.indent); let expr_str = try_opt!(block.stmts[0].rewrite(context, expr_shape)); let result = format!("{}{{ {} }}", prefix, expr_str); if result.len() <= shape.width && !result.contains('\n') { return Some(result); } } None } pub fn rewrite_pair( lhs: &LHS, rhs: &RHS, prefix: &str, infix: &str, suffix: &str, context: &RewriteContext, shape: Shape, ) -> Option where LHS: Rewrite, RHS: Rewrite, { // Get "full width" rhs and see if it fits on the current line. This // usually works fairly well since it tends to place operands of // operations with high precendence close together. // Note that this is non-conservative, but its just to see if it's even // worth trying to put everything on one line. let rhs_shape = try_opt!(shape.sub_width(suffix.len())); let rhs_result = rhs.rewrite(context, rhs_shape); if let Some(rhs_result) = rhs_result { // This is needed in case of line break not caused by a // shortage of space, but by end-of-line comments, for example. if !rhs_result.contains('\n') { let lhs_shape = try_opt!(try_opt!(shape.offset_left(prefix.len())).sub_width( infix.len(), )); let lhs_result = lhs.rewrite(context, lhs_shape); if let Some(lhs_result) = lhs_result { let mut result = format!("{}{}{}", prefix, lhs_result, infix); let remaining_width = shape .width .checked_sub(last_line_width(&result) + suffix.len()) .unwrap_or(0); if rhs_result.len() <= remaining_width { result.push_str(&rhs_result); result.push_str(suffix); return Some(result); } // Try rewriting the rhs into the remaining space. let rhs_shape = shape.shrink_left(last_line_width(&result) + suffix.len()); if let Some(rhs_shape) = rhs_shape { if let Some(rhs_result) = rhs.rewrite(context, rhs_shape) { // FIXME this should always hold. if rhs_result.len() <= remaining_width { result.push_str(&rhs_result); result.push_str(suffix); return Some(result); } } } } } } // We have to use multiple lines. // Re-evaluate the rhs because we have more space now: let infix = infix.trim_right(); let rhs_shape = match context.config.control_style() { Style::Legacy => { try_opt!(shape.sub_width(suffix.len() + prefix.len())).visual_indent(prefix.len()) } Style::Rfc => { // Try to calculate the initial constraint on the right hand side. let rhs_overhead = context .config .max_width() .checked_sub(shape.used_width() + shape.width) .unwrap_or(0); try_opt!( Shape::indented(shape.indent.block_indent(context.config), context.config) .sub_width(rhs_overhead) ) } }; let rhs_result = try_opt!(rhs.rewrite(context, rhs_shape)); let lhs_overhead = shape.used_width() + prefix.len() + infix.len(); let lhs_shape = Shape { width: try_opt!(context.config.max_width().checked_sub(lhs_overhead)), ..shape }; let lhs_result = try_opt!(lhs.rewrite(context, lhs_shape)); Some(format!( "{}{}{}\n{}{}{}", prefix, lhs_result, infix, rhs_shape.indent.to_string(context.config), rhs_result, suffix )) } pub fn rewrite_array<'a, I>( expr_iter: I, span: Span, context: &RewriteContext, shape: Shape, ) -> Option where I: Iterator, { let bracket_size = if context.config.spaces_within_square_brackets() { 2 // "[ " } else { 1 // "[" }; let nested_shape = match context.config.array_layout() { IndentStyle::Block => shape.block().block_indent(context.config.tab_spaces()), IndentStyle::Visual => { try_opt!(shape.visual_indent(bracket_size).sub_width( bracket_size * 2, )) } }; let items = itemize_list( context.codemap, expr_iter, "]", |item| item.span.lo, |item| item.span.hi, |item| item.rewrite(context, nested_shape), span.lo, span.hi, ).collect::>(); if items.is_empty() { if context.config.spaces_within_square_brackets() { return Some("[ ]".to_string()); } else { return Some("[]".to_string()); } } let has_long_item = items.iter().any(|li| { li.item.as_ref().map(|s| s.len() > 10).unwrap_or(false) }); let tactic = match context.config.array_layout() { IndentStyle::Block => { // FIXME wrong shape in one-line case match shape.width.checked_sub(2 * bracket_size) { Some(width) => { let tactic = ListTactic::LimitedHorizontalVertical(context.config.array_width()); definitive_tactic(&items, tactic, width) } None => DefinitiveListTactic::Vertical, } } IndentStyle::Visual => { if has_long_item || items.iter().any(ListItem::is_multiline) { definitive_tactic( &items, ListTactic::LimitedHorizontalVertical(context.config.array_width()), nested_shape.width, ) } else { DefinitiveListTactic::Mixed } } }; let fmt = ListFormatting { tactic: tactic, separator: ",", trailing_separator: SeparatorTactic::Never, shape: nested_shape, ends_with_newline: false, config: context.config, }; let list_str = try_opt!(write_list(&items, &fmt)); let result = if context.config.array_layout() == IndentStyle::Visual || tactic != DefinitiveListTactic::Vertical { if context.config.spaces_within_square_brackets() && list_str.len() > 0 { format!("[ {} ]", list_str) } else { format!("[{}]", list_str) } } else { format!( "[\n{}{},\n{}]", nested_shape.indent.to_string(context.config), list_str, shape.block().indent.to_string(context.config) ) }; Some(result) } // Return type is (prefix, extra_offset) fn rewrite_closure_fn_decl( capture: ast::CaptureBy, fn_decl: &ast::FnDecl, body: &ast::Expr, span: Span, context: &RewriteContext, shape: Shape, ) -> Option<(String, usize)> { 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 = try_opt!(try_opt!(shape.shrink_left(mover.len())).sub_width(4)); // 1 = | let argument_offset = nested_shape.indent + 1; let arg_shape = try_opt!(nested_shape.shrink_left(1)).visual_indent(0); let ret_str = try_opt!(fn_decl.output.rewrite(context, arg_shape)); let arg_items = itemize_list( context.codemap, fn_decl.inputs.iter(), "|", |arg| span_lo_for_arg(arg), |arg| span_hi_for_arg(arg), |arg| arg.rewrite(context, arg_shape), context.codemap.span_after(span, "|"), body.span.lo, ); let item_vec = arg_items.collect::>(); // 1 = space between arguments and return type. let horizontal_budget = nested_shape .width .checked_sub(ret_str.len() + 1) .unwrap_or(0); let tactic = definitive_tactic(&item_vec, ListTactic::HorizontalVertical, horizontal_budget); let arg_shape = match tactic { DefinitiveListTactic::Horizontal => try_opt!(arg_shape.sub_width(ret_str.len() + 1)), _ => arg_shape, }; let fmt = ListFormatting { tactic: tactic, separator: ",", trailing_separator: SeparatorTactic::Never, shape: arg_shape, ends_with_newline: false, config: context.config, }; let list_str = try_opt!(write_list(&item_vec, &fmt)); let mut prefix = format!("{}|{}|", mover, list_str); // 1 = space between `|...|` and body. let extra_offset = extra_offset(&prefix, shape) + 1; if !ret_str.is_empty() { if prefix.contains('\n') { prefix.push('\n'); prefix.push_str(&argument_offset.to_string(context.config)); } else { prefix.push(' '); } prefix.push_str(&ret_str); } Some((prefix, extra_offset)) } // This functions is pretty messy because of the rules around closures and blocks: // FIXME - the below is probably no longer true in full. // * if there is a return type, then there must be braces, // * given a closure with braces, whether that is parsed to give an inner block // or not depends on if there is a return type and if there are statements // in that block, // * if the first expression in the body ends with a block (i.e., is a // statement without needing a semi-colon), then adding or removing braces // can change whether it is treated as an expression or statement. fn rewrite_closure( capture: ast::CaptureBy, fn_decl: &ast::FnDecl, body: &ast::Expr, span: Span, context: &RewriteContext, shape: Shape, ) -> Option { let (prefix, extra_offset) = try_opt!(rewrite_closure_fn_decl( capture, fn_decl, body, span, context, shape, )); // 1 = space between `|...|` and body. let body_shape = try_opt!(shape.offset_left(extra_offset)); if let ast::ExprKind::Block(ref block) = body.node { // The body of the closure is an empty block. if block.stmts.is_empty() && !block_contains_comment(block, context.codemap) { return Some(format!("{} {{}}", prefix)); } // Figure out if the block is necessary. let needs_block = block.rules != ast::BlockCheckMode::Default || block.stmts.len() > 1 || context.inside_macro || block_contains_comment(block, context.codemap) || prefix.contains('\n'); let no_return_type = if let ast::FunctionRetTy::Default(_) = fn_decl.output { true } else { false }; if no_return_type && !needs_block { // lock.stmts.len() == 1 if let Some(ref expr) = stmt_expr(&block.stmts[0]) { if let Some(rw) = rewrite_closure_expr(expr, &prefix, context, body_shape) { return Some(rw); } } } if !needs_block { // We need braces, but we might still prefer a one-liner. let stmt = &block.stmts[0]; // 4 = braces and spaces. if let Some(body_shape) = body_shape.sub_width(4) { // Checks if rewrite succeeded and fits on a single line. if let Some(rewrite) = and_one_line(stmt.rewrite(context, body_shape)) { return Some(format!("{} {{ {} }}", prefix, rewrite)); } } } // Either we require a block, or tried without and failed. rewrite_closure_block(&block, &prefix, context, body_shape) } else { rewrite_closure_expr(body, &prefix, context, body_shape).or_else(|| { // The closure originally had a non-block expression, but we can't fit on // one line, so we'll insert a block. rewrite_closure_with_block(context, body_shape, &prefix, body) }) } } // Rewrite closure with a single expression wrapping its body with block. fn rewrite_closure_with_block( context: &RewriteContext, shape: Shape, prefix: &str, body: &ast::Expr, ) -> Option { let block = ast::Block { stmts: vec![ ast::Stmt { id: ast::NodeId::new(0), node: ast::StmtKind::Expr(ptr::P(body.clone())), span: body.span, }, ], id: ast::NodeId::new(0), rules: ast::BlockCheckMode::Default, span: body.span, }; rewrite_closure_block(&block, prefix, context, shape) } // Rewrite closure with a single expression without wrapping its body with block. fn rewrite_closure_expr( expr: &ast::Expr, prefix: &str, context: &RewriteContext, shape: Shape, ) -> Option { let mut rewrite = expr.rewrite(context, shape); if classify::expr_requires_semi_to_be_stmt(left_most_sub_expr(expr)) { rewrite = and_one_line(rewrite); } rewrite.map(|rw| format!("{} {}", prefix, rw)) } // Rewrite closure whose body is block. fn rewrite_closure_block( block: &ast::Block, prefix: &str, context: &RewriteContext, shape: Shape, ) -> Option { // Start with visual indent, then fall back to block indent if the // closure is large. let block_threshold = context.config.closure_block_indent_threshold(); if block_threshold >= 0 { if let Some(block_str) = block.rewrite(&context, shape) { if block_str.matches('\n').count() <= block_threshold as usize && !need_block_indent(&block_str, shape) { if let Some(block_str) = block_str.rewrite(context, shape) { return Some(format!("{} {}", prefix, block_str)); } } } } // The body of the closure is big enough to be block indented, that // means we must re-format. let block_shape = shape.block().with_max_width(context.config); let block_str = try_opt!(block.rewrite(&context, block_shape)); Some(format!("{} {}", prefix, block_str)) } fn and_one_line(x: Option) -> Option { x.and_then(|x| if x.contains('\n') { None } else { Some(x) }) } fn nop_block_collapse(block_str: Option, budget: usize) -> Option { debug!("nop_block_collapse {:?} {}", block_str, budget); block_str.map(|block_str| { if block_str.starts_with('{') && budget >= 2 && (block_str[1..].find(|c: char| !c.is_whitespace()).unwrap() == block_str.len() - 2) { "{}".to_owned() } else { block_str.to_owned() } }) } impl Rewrite for ast::Block { fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option { // shape.width is used only for the single line case: either the empty block `{}`, // or an unsafe expression `unsafe { e }`. if self.stmts.is_empty() && !block_contains_comment(self, context.codemap) && shape.width >= 2 { return Some("{}".to_owned()); } // If a block contains only a single-line comment, then leave it on one line. let user_str = context.snippet(self.span); let user_str = user_str.trim(); if user_str.starts_with('{') && user_str.ends_with('}') { let comment_str = user_str[1..user_str.len() - 1].trim(); if self.stmts.is_empty() && !comment_str.contains('\n') && !comment_str.starts_with("//") && comment_str.len() + 4 <= shape.width { return Some(format!("{{ {} }}", comment_str)); } } let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config); visitor.block_indent = shape.indent; visitor.is_if_else_block = context.is_if_else_block; let prefix = match self.rules { ast::BlockCheckMode::Unsafe(..) => { let snippet = context.snippet(self.span); let open_pos = try_opt!(snippet.find_uncommented("{")); visitor.last_pos = self.span.lo + BytePos(open_pos as u32); // Extract comment between unsafe and block start. let trimmed = &snippet[6..open_pos].trim(); let prefix = if !trimmed.is_empty() { // 9 = "unsafe {".len(), 7 = "unsafe ".len() let budget = try_opt!(shape.width.checked_sub(9)); format!( "unsafe {} ", try_opt!(rewrite_comment( trimmed, true, Shape::legacy(budget, shape.indent + 7), context.config, )) ) } else { "unsafe ".to_owned() }; if let result @ Some(_) = try_one_line_block(context, shape, &prefix, self) { return result; } prefix } ast::BlockCheckMode::Default => { visitor.last_pos = self.span.lo; String::new() } }; visitor.visit_block(self); if visitor.failed && shape.indent.alignment != 0 { self.rewrite( context, Shape::indented(shape.indent.block_only(), context.config), ) } else { Some(format!("{}{}", prefix, visitor.buffer)) } } } impl Rewrite for ast::Stmt { fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option { let result = match self.node { ast::StmtKind::Local(ref local) => local.rewrite(context, shape), ast::StmtKind::Expr(ref ex) | ast::StmtKind::Semi(ref ex) => { let suffix = if semicolon_for_stmt(self) { ";" } else { "" }; format_expr( ex, match self.node { ast::StmtKind::Expr(_) => ExprType::SubExpression, ast::StmtKind::Semi(_) => ExprType::Statement, _ => unreachable!(), }, context, try_opt!(shape.sub_width(suffix.len())), ).map(|s| s + suffix) } ast::StmtKind::Mac(..) | ast::StmtKind::Item(..) => None, }; result.and_then(|res| { recover_comment_removed(res, self.span, context, shape) }) } } // Rewrite condition if the given expression has one. fn rewrite_cond(context: &RewriteContext, expr: &ast::Expr, shape: Shape) -> Option { match expr.node { ast::ExprKind::Match(ref cond, _) => { // `match `cond` {` let cond_shape = match context.config.control_style() { Style::Legacy => try_opt!(shape.shrink_left(6).and_then(|s| s.sub_width(2))), Style::Rfc => try_opt!(shape.offset_left(8)), }; cond.rewrite(context, cond_shape) } ast::ExprKind::Block(ref block) if block.stmts.len() == 1 => { stmt_expr(&block.stmts[0]).and_then(|e| rewrite_cond(context, e, shape)) } _ => { to_control_flow(expr, ExprType::SubExpression).and_then(|control_flow| { let alt_block_sep = String::from("\n") + &shape.indent.block_only().to_string(context.config); control_flow .rewrite_cond(context, shape, &alt_block_sep) .and_then(|rw| Some(rw.0)) }) } } } // Abstraction over control flow expressions #[derive(Debug)] struct ControlFlow<'a> { cond: Option<&'a ast::Expr>, block: &'a ast::Block, else_block: Option<&'a ast::Expr>, label: Option, pat: Option<&'a ast::Pat>, keyword: &'a str, matcher: &'a str, connector: &'a str, allow_single_line: bool, // True if this is an `if` expression in an `else if` :-( hacky nested_if: bool, span: Span, } fn to_control_flow<'a>(expr: &'a ast::Expr, expr_type: ExprType) -> Option> { match expr.node { ast::ExprKind::If(ref cond, ref if_block, ref else_block) => { Some(ControlFlow::new_if( cond, None, if_block, else_block.as_ref().map(|e| &**e), expr_type == ExprType::SubExpression, false, expr.span, )) } ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref else_block) => { Some(ControlFlow::new_if( cond, Some(pat), if_block, else_block.as_ref().map(|e| &**e), expr_type == ExprType::SubExpression, false, expr.span, )) } ast::ExprKind::ForLoop(ref pat, ref cond, ref block, label) => { Some(ControlFlow::new_for(pat, cond, block, label, expr.span)) } ast::ExprKind::Loop(ref block, label) => Some( ControlFlow::new_loop(block, label, expr.span), ), ast::ExprKind::While(ref cond, ref block, label) => Some(ControlFlow::new_while( None, cond, block, label, expr.span, )), ast::ExprKind::WhileLet(ref pat, ref cond, ref block, label) => { Some(ControlFlow::new_while( Some(pat), cond, block, label, expr.span, )) } _ => None, } } impl<'a> ControlFlow<'a> { fn new_if( cond: &'a ast::Expr, pat: Option<&'a ast::Pat>, block: &'a ast::Block, else_block: Option<&'a ast::Expr>, allow_single_line: bool, nested_if: bool, span: Span, ) -> ControlFlow<'a> { ControlFlow { cond: Some(cond), block: block, else_block: else_block, label: None, pat: pat, keyword: "if", matcher: match pat { Some(..) => "let", None => "", }, connector: " =", allow_single_line: allow_single_line, nested_if: nested_if, span: span, } } fn new_loop( block: &'a ast::Block, label: Option, span: Span, ) -> ControlFlow<'a> { ControlFlow { cond: None, block: block, else_block: None, label: label, pat: None, keyword: "loop", matcher: "", connector: "", allow_single_line: false, nested_if: false, span: span, } } fn new_while( pat: Option<&'a ast::Pat>, cond: &'a ast::Expr, block: &'a ast::Block, label: Option, span: Span, ) -> ControlFlow<'a> { ControlFlow { cond: Some(cond), block: block, else_block: None, label: label, pat: pat, keyword: "while", matcher: match pat { Some(..) => "let", None => "", }, connector: " =", allow_single_line: false, nested_if: false, span: span, } } fn new_for( pat: &'a ast::Pat, cond: &'a ast::Expr, block: &'a ast::Block, label: Option, span: Span, ) -> ControlFlow<'a> { ControlFlow { cond: Some(cond), block: block, else_block: None, label: label, pat: Some(pat), keyword: "for", matcher: "", connector: " in", allow_single_line: false, nested_if: false, span: span, } } fn rewrite_single_line( &self, pat_expr_str: &str, context: &RewriteContext, width: usize, ) -> Option { assert!(self.allow_single_line); let else_block = try_opt!(self.else_block); let fixed_cost = self.keyword.len() + " { } else { }".len(); if let ast::ExprKind::Block(ref else_node) = else_block.node { if !is_simple_block(self.block, context.codemap) || !is_simple_block(else_node, context.codemap) || pat_expr_str.contains('\n') { return None; } let new_width = try_opt!(width.checked_sub(pat_expr_str.len() + fixed_cost)); let expr = &self.block.stmts[0]; let if_str = try_opt!(expr.rewrite( context, Shape::legacy(new_width, Indent::empty()), )); let new_width = try_opt!(new_width.checked_sub(if_str.len())); let else_expr = &else_node.stmts[0]; let else_str = try_opt!(else_expr.rewrite( context, Shape::legacy(new_width, Indent::empty()), )); if if_str.contains('\n') || else_str.contains('\n') { return None; } let result = format!( "{} {} {{ {} }} else {{ {} }}", self.keyword, pat_expr_str, if_str, else_str ); if result.len() <= width { return Some(result); } } None } } impl<'a> ControlFlow<'a> { fn rewrite_cond( &self, context: &RewriteContext, shape: Shape, alt_block_sep: &str, ) -> Option<(String, usize)> { let constr_shape = if self.nested_if { // We are part of an if-elseif-else chain. Our constraints are tightened. // 7 = "} else " .len() try_opt!(shape.shrink_left(7)) } else { shape }; let label_string = rewrite_label(self.label); // 1 = space after keyword. let offset = self.keyword.len() + label_string.len() + 1; let pat_expr_string = match self.cond { Some(cond) => { let mut cond_shape = match context.config.control_style() { Style::Legacy => try_opt!(constr_shape.shrink_left(offset)), Style::Rfc => try_opt!(constr_shape.offset_left(offset)), }; if context.config.control_brace_style() != ControlBraceStyle::AlwaysNextLine { // 2 = " {".len() cond_shape = try_opt!(cond_shape.sub_width(2)); } try_opt!(rewrite_pat_expr( context, self.pat, cond, self.matcher, self.connector, self.keyword, cond_shape, )) } None => String::new(), }; let force_newline_brace = context.config.control_style() == Style::Rfc && pat_expr_string.contains('\n'); // Try to format if-else on single line. if self.allow_single_line && context.config.single_line_if_else_max_width() > 0 { let trial = self.rewrite_single_line(&pat_expr_string, context, shape.width); if let Some(cond_str) = trial { if cond_str.len() <= context.config.single_line_if_else_max_width() { return Some((cond_str, 0)); } } } let cond_span = if let Some(cond) = self.cond { cond.span } else { mk_sp(self.block.span.lo, self.block.span.lo) }; // for event in event let between_kwd_cond = mk_sp( context.codemap.span_after(self.span, self.keyword.trim()), self.pat.map_or( cond_span.lo, |p| if self.matcher.is_empty() { p.span.lo } else { context.codemap.span_before(self.span, self.matcher.trim()) }, ), ); let between_kwd_cond_comment = extract_comment(between_kwd_cond, context, shape); let after_cond_comment = extract_comment(mk_sp(cond_span.hi, self.block.span.lo), context, shape); let block_sep = if self.cond.is_none() && between_kwd_cond_comment.is_some() { "" } else if context.config.control_brace_style() == ControlBraceStyle::AlwaysNextLine || force_newline_brace { alt_block_sep } else { " " }; let used_width = if pat_expr_string.contains('\n') { last_line_width(&pat_expr_string) } else { // 2 = spaces after keyword and condition. label_string.len() + self.keyword.len() + pat_expr_string.len() + 2 }; Some(( format!( "{}{}{}{}{}", label_string, self.keyword, between_kwd_cond_comment.as_ref().map_or( if pat_expr_string.is_empty() || pat_expr_string.starts_with('\n') { "" } else { " " }, |s| &**s, ), pat_expr_string, after_cond_comment.as_ref().map_or(block_sep, |s| &**s) ), used_width, )) } } impl<'a> Rewrite for ControlFlow<'a> { fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option { debug!("ControlFlow::rewrite {:?} {:?}", self, shape); let alt_block_sep = String::from("\n") + &shape.indent.block_only().to_string(context.config); let (cond_str, used_width) = try_opt!(self.rewrite_cond(context, shape, &alt_block_sep)); // If `used_width` is 0, it indicates that whole control flow is written in a single line. if used_width == 0 { return Some(cond_str); } let block_width = shape.width.checked_sub(used_width).unwrap_or(0); // This is used only for the empty block case: `{}`. So, we use 1 if we know // we should avoid the single line case. let block_width = if self.else_block.is_some() || self.nested_if { min(1, block_width) } else { block_width }; let block_shape = Shape { width: block_width, ..shape }; let mut block_context = context.clone(); block_context.is_if_else_block = self.else_block.is_some(); let block_str = try_opt!(self.block.rewrite(&block_context, block_shape)); let mut result = format!("{}{}", cond_str, block_str); if let Some(else_block) = self.else_block { let shape = Shape::indented(shape.indent, context.config); let mut last_in_chain = false; let rewrite = match else_block.node { // If the else expression is another if-else expression, prevent it // from being formatted on a single line. // Note how we're passing the original shape, as the // cost of "else" should not cascade. ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref next_else_block) => { ControlFlow::new_if( cond, Some(pat), if_block, next_else_block.as_ref().map(|e| &**e), false, true, mk_sp(else_block.span.lo, self.span.hi), ).rewrite(context, shape) } ast::ExprKind::If(ref cond, ref if_block, ref next_else_block) => { ControlFlow::new_if( cond, None, if_block, next_else_block.as_ref().map(|e| &**e), false, true, mk_sp(else_block.span.lo, self.span.hi), ).rewrite(context, shape) } _ => { last_in_chain = true; // When rewriting a block, the width is only used for single line // blocks, passing 1 lets us avoid that. let else_shape = Shape { width: min(1, shape.width), ..shape }; else_block.rewrite(context, else_shape) } }; let between_kwd_else_block = mk_sp( self.block.span.hi, context.codemap.span_before( mk_sp(self.block.span.hi, else_block.span.lo), "else", ), ); let between_kwd_else_block_comment = extract_comment(between_kwd_else_block, context, shape); let after_else = mk_sp( context.codemap.span_after( mk_sp(self.block.span.hi, else_block.span.lo), "else", ), else_block.span.lo, ); let after_else_comment = extract_comment(after_else, context, shape); let between_sep = match context.config.control_brace_style() { ControlBraceStyle::AlwaysNextLine | ControlBraceStyle::ClosingNextLine => &*alt_block_sep, ControlBraceStyle::AlwaysSameLine => " ", }; let after_sep = match context.config.control_brace_style() { ControlBraceStyle::AlwaysNextLine if last_in_chain => &*alt_block_sep, _ => " ", }; try_opt!( write!( &mut result, "{}else{}", between_kwd_else_block_comment.as_ref().map_or( between_sep, |s| &**s, ), after_else_comment.as_ref().map_or(after_sep, |s| &**s) ).ok() ); result.push_str(&try_opt!(rewrite)); } Some(result) } } fn rewrite_label(label: Option) -> String { match label { Some(ident) => format!("{}: ", ident.node), None => "".to_owned(), } } fn extract_comment(span: Span, context: &RewriteContext, shape: Shape) -> Option { let comment_str = context.snippet(span); if contains_comment(&comment_str) { let comment = try_opt!(rewrite_comment( comment_str.trim(), false, shape, context.config, )); Some(format!( "\n{indent}{}\n{indent}", comment, indent = shape.indent.to_string(context.config) )) } else { None } } fn block_contains_comment(block: &ast::Block, codemap: &CodeMap) -> bool { let snippet = codemap.span_to_snippet(block.span).unwrap(); contains_comment(&snippet) } // Checks that a block contains no statements, an expression and no comments. // FIXME: incorrectly returns false when comment is contained completely within // the expression. pub fn is_simple_block(block: &ast::Block, codemap: &CodeMap) -> bool { (block.stmts.len() == 1 && stmt_is_expr(&block.stmts[0]) && !block_contains_comment(block, codemap)) } /// Checks whether a block contains at most one statement or expression, and no comments. pub fn is_simple_block_stmt(block: &ast::Block, codemap: &CodeMap) -> bool { block.stmts.len() <= 1 && !block_contains_comment(block, codemap) } /// Checks whether a block contains no statements, expressions, or comments. pub fn is_empty_block(block: &ast::Block, codemap: &CodeMap) -> bool { block.stmts.is_empty() && !block_contains_comment(block, codemap) } pub fn stmt_is_expr(stmt: &ast::Stmt) -> bool { match stmt.node { ast::StmtKind::Expr(..) => true, _ => false, } } fn is_unsafe_block(block: &ast::Block) -> bool { if let ast::BlockCheckMode::Unsafe(..) = block.rules { true } else { false } } // inter-match-arm-comment-rules: // - all comments following a match arm before the start of the next arm // are about the second arm fn rewrite_match_arm_comment( context: &RewriteContext, missed_str: &str, shape: Shape, arm_indent_str: &str, ) -> Option { // The leading "," is not part of the arm-comment let missed_str = match missed_str.find_uncommented(",") { Some(n) => &missed_str[n + 1..], None => &missed_str[..], }; let mut result = String::new(); // any text not preceeded by a newline is pushed unmodified to the block let first_brk = missed_str.find(|c: char| c == '\n').unwrap_or(0); result.push_str(&missed_str[..first_brk]); let missed_str = &missed_str[first_brk..]; // If missed_str had one newline, it starts with it let first = missed_str.find(|c: char| !c.is_whitespace()).unwrap_or( missed_str .len(), ); if missed_str[..first].chars().filter(|c| c == &'\n').count() >= 2 { // Excessive vertical whitespace before comment should be preserved // FIXME handle vertical whitespace better result.push('\n'); } let missed_str = missed_str[first..].trim(); if !missed_str.is_empty() { let comment = try_opt!(rewrite_comment(&missed_str, false, shape, context.config)); result.push('\n'); result.push_str(arm_indent_str); result.push_str(&comment); } Some(result) } fn rewrite_match( context: &RewriteContext, cond: &ast::Expr, arms: &[ast::Arm], shape: Shape, span: Span, ) -> Option { if arms.is_empty() { return None; } // `match `cond` {` let cond_shape = match context.config.control_style() { Style::Legacy => try_opt!(shape.shrink_left(6).and_then(|s| s.sub_width(2))), Style::Rfc => try_opt!(shape.offset_left(8)), }; let cond_str = try_opt!(cond.rewrite(context, cond_shape)); let alt_block_sep = String::from("\n") + &shape.indent.block_only().to_string(context.config); let block_sep = match context.config.control_brace_style() { ControlBraceStyle::AlwaysSameLine => " ", _ => alt_block_sep.as_str(), }; let mut result = format!("match {}{}{{", cond_str, block_sep); let arm_shape = if context.config.indent_match_arms() { shape.block_indent(context.config.tab_spaces()) } else { shape.block_indent(0) }; let arm_indent_str = arm_shape.indent.to_string(context.config); let open_brace_pos = context.codemap.span_after( mk_sp(cond.span.hi, arm_start_pos(&arms[0])), "{", ); for (i, arm) in arms.iter().enumerate() { // Make sure we get the stuff between arms. let missed_str = if i == 0 { context.snippet(mk_sp(open_brace_pos, arm_start_pos(arm))) } else { context.snippet(mk_sp(arm_end_pos(&arms[i - 1]), arm_start_pos(arm))) }; let comment = try_opt!(rewrite_match_arm_comment( context, &missed_str, arm_shape, &arm_indent_str, )); result.push_str(&comment); result.push('\n'); result.push_str(&arm_indent_str); let arm_str = arm.rewrite(&context, arm_shape.with_max_width(context.config)); if let Some(ref arm_str) = arm_str { result.push_str(arm_str); } else { // We couldn't format the arm, just reproduce the source. let snippet = context.snippet(mk_sp(arm_start_pos(arm), arm_end_pos(arm))); result.push_str(&snippet); result.push_str(arm_comma(context.config, &arm.body)); } } // BytePos(1) = closing match brace. let last_span = mk_sp(arm_end_pos(&arms[arms.len() - 1]), span.hi - BytePos(1)); let last_comment = context.snippet(last_span); let comment = try_opt!(rewrite_match_arm_comment( context, &last_comment, arm_shape, &arm_indent_str, )); result.push_str(&comment); result.push('\n'); result.push_str(&shape.indent.to_string(context.config)); result.push('}'); Some(result) } fn arm_start_pos(arm: &ast::Arm) -> BytePos { let &ast::Arm { ref attrs, ref pats, .. } = arm; if !attrs.is_empty() { return attrs[0].span.lo; } pats[0].span.lo } fn arm_end_pos(arm: &ast::Arm) -> BytePos { arm.body.span.hi } fn arm_comma(config: &Config, body: &ast::Expr) -> &'static str { if config.match_block_trailing_comma() { "," } else if let ast::ExprKind::Block(ref block) = body.node { if let ast::BlockCheckMode::Default = block.rules { "" } else { "," } } else { "," } } // Match arms. impl Rewrite for ast::Arm { fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option { debug!("Arm::rewrite {:?} {:?}", self, shape); let &ast::Arm { ref attrs, ref pats, ref guard, ref body, } = self; let attr_str = if !attrs.is_empty() { if contains_skip(attrs) { return None; } format!( "{}\n{}", try_opt!(attrs.rewrite(context, shape)), shape.indent.to_string(context.config) ) } else { String::new() }; // Patterns // 5 = ` => {` let pat_shape = try_opt!(shape.sub_width(5)); let pat_strs = try_opt!( pats.iter() .map(|p| p.rewrite(context, pat_shape)) .collect::>>() ); let all_simple = pat_strs.iter().all(|p| pat_is_simple(p)); let items: Vec<_> = pat_strs.into_iter().map(ListItem::from_str).collect(); let fmt = ListFormatting { tactic: if all_simple { DefinitiveListTactic::Mixed } else { DefinitiveListTactic::Vertical }, separator: " |", trailing_separator: SeparatorTactic::Never, shape: pat_shape, ends_with_newline: false, config: context.config, }; let pats_str = try_opt!(write_list(items, &fmt)); let guard_shape = if pats_str.contains('\n') { shape.with_max_width(context.config) } else { shape }; let guard_str = try_opt!(rewrite_guard( context, guard, guard_shape, trimmed_last_line_width(&pats_str), )); let pats_str = format!("{}{}", pats_str, guard_str); let (mut extend, body) = match body.node { ast::ExprKind::Block(ref block) if !is_unsafe_block(block) && is_simple_block(block, context.codemap) && context.config.wrap_match_arms() => { if let ast::StmtKind::Expr(ref expr) = block.stmts[0].node { (false, &**expr) } else { (false, &**body) } } ast::ExprKind::Call(_, ref args) => (args.len() == 1, &**body), ast::ExprKind::Closure(..) | ast::ExprKind::Struct(..) | ast::ExprKind::Tup(..) => (true, &**body), _ => (false, &**body), }; extend &= context.use_block_indent(); let comma = arm_comma(&context.config, body); let alt_block_sep = String::from("\n") + &shape.indent.block_only().to_string(context.config); let pat_width = extra_offset(&pats_str, shape); // Let's try and get the arm body on the same line as the condition. // 4 = ` => `.len() if shape.width > pat_width + comma.len() + 4 { let arm_shape = shape .offset_left(pat_width + 4) .unwrap() .sub_width(comma.len()) .unwrap(); let rewrite = nop_block_collapse(body.rewrite(context, arm_shape), arm_shape.width); let is_block = if let ast::ExprKind::Block(..) = body.node { true } else { false }; match rewrite { Some(ref body_str) if (!body_str.contains('\n') && body_str.len() <= arm_shape.width) || !context.config.wrap_match_arms() || (extend && first_line_width(body_str) <= arm_shape.width) || is_block => { let block_sep = match context.config.control_brace_style() { ControlBraceStyle::AlwaysNextLine if is_block => alt_block_sep.as_str(), _ => " ", }; return Some(format!( "{}{} =>{}{}{}", attr_str.trim_left(), pats_str, block_sep, body_str, comma )); } _ => {} } } // FIXME: we're doing a second rewrite of the expr; This may not be // necessary. let body_shape = try_opt!(shape.block_left(context.config.tab_spaces())); let next_line_body = try_opt!(nop_block_collapse( body.rewrite(context, body_shape), body_shape.width, )); let indent_str = shape.indent.block_indent(context.config).to_string( context.config, ); let (body_prefix, body_suffix) = if context.config.wrap_match_arms() { if context.config.match_block_trailing_comma() { ("{", "},") } else { ("{", "}") } } else { ("", ",") }; let block_sep = match context.config.control_brace_style() { ControlBraceStyle::AlwaysNextLine => alt_block_sep + body_prefix + "\n", _ if body_prefix.is_empty() => "\n".to_owned(), _ => " ".to_owned() + body_prefix + "\n", }; if context.config.wrap_match_arms() { Some(format!( "{}{} =>{}{}{}\n{}{}", attr_str.trim_left(), pats_str, block_sep, indent_str, next_line_body, shape.indent.to_string(context.config), body_suffix )) } else { Some(format!( "{}{} =>{}{}{}{}", attr_str.trim_left(), pats_str, block_sep, indent_str, next_line_body, body_suffix )) } } } // A pattern is simple if it is very short or it is short-ish and just a path. // E.g. `Foo::Bar` is simple, but `Foo(..)` is not. fn pat_is_simple(pat_str: &str) -> bool { pat_str.len() <= 16 || (pat_str.len() <= 24 && pat_str.chars().all(|c| c.is_alphabetic() || c == ':')) } // The `if ...` guard on a match arm. fn rewrite_guard( context: &RewriteContext, guard: &Option>, shape: Shape, // The amount of space used up on this line for the pattern in // the arm (excludes offset). pattern_width: usize, ) -> Option { if let Some(ref guard) = *guard { // First try to fit the guard string on the same line as the pattern. // 4 = ` if `, 5 = ` => {` if let Some(cond_shape) = shape.shrink_left(pattern_width + 4).and_then( |s| s.sub_width(5), ) { if let Some(cond_str) = guard.rewrite(context, cond_shape).and_then(|s| { s.rewrite(context, cond_shape) }) { if !cond_str.contains('\n') { return Some(format!(" if {}", cond_str)); } } } // Not enough space to put the guard after the pattern, try a newline. // 3 == `if ` if let Some(cond_shape) = Shape::indented( shape.indent.block_indent(context.config) + 3, context.config, ).sub_width(3) { if let Some(cond_str) = guard.rewrite(context, cond_shape) { return Some(format!( "\n{}if {}", shape.indent.block_indent(context.config).to_string( context.config, ), cond_str )); } } None } else { Some(String::new()) } } fn rewrite_pat_expr( context: &RewriteContext, pat: Option<&ast::Pat>, expr: &ast::Expr, matcher: &str, // Connecting piece between pattern and expression, // *without* trailing space. connector: &str, keyword: &str, shape: Shape, ) -> Option { debug!("rewrite_pat_expr {:?} {:?} {:?}", shape, pat, expr); let mut pat_string = String::new(); let mut result = match pat { Some(pat) => { let matcher = if matcher.is_empty() { matcher.to_owned() } else { format!("{} ", matcher) }; let pat_shape = try_opt!(try_opt!(shape.offset_left(matcher.len())).sub_width( connector.len(), )); pat_string = try_opt!(pat.rewrite(context, pat_shape)); format!("{}{}{}", matcher, pat_string, connector) } None => String::new(), }; // Consider only the last line of the pat string. let extra_offset = extra_offset(&result, shape); // The expression may (partially) fit on the current line. if shape.width > extra_offset + 1 { let spacer = if pat.is_some() { " " } else { "" }; let expr_shape = try_opt!(shape.offset_left(extra_offset + spacer.len())); let expr_rewrite = expr.rewrite(context, expr_shape); if let Some(expr_string) = expr_rewrite { if pat.is_none() || pat_is_simple(&pat_string) || !expr_string.contains('\n') { result.push_str(spacer); result.push_str(&expr_string); return Some(result); } } } if pat.is_none() && keyword == "if" { return None; } let nested_indent = shape.indent.block_only().block_indent(context.config); // The expression won't fit on the current line, jump to next. result.push('\n'); result.push_str(&nested_indent.to_string(context.config)); let expr_rewrite = expr.rewrite(&context, Shape::indented(nested_indent, context.config)); result.push_str(&try_opt!(expr_rewrite)); Some(result) } fn rewrite_string_lit(context: &RewriteContext, span: Span, shape: Shape) -> Option { let string_lit = context.snippet(span); if !context.config.format_strings() && !context.config.force_format_strings() { return Some(string_lit); } if !context.config.force_format_strings() && !string_requires_rewrite(context, span, &string_lit, shape) { return Some(string_lit); } let fmt = StringFormat { opener: "\"", closer: "\"", line_start: " ", line_end: "\\", shape: shape, trim_end: false, config: context.config, }; // Remove the quote characters. let str_lit = &string_lit[1..string_lit.len() - 1]; rewrite_string(str_lit, &fmt) } fn string_requires_rewrite( context: &RewriteContext, span: Span, string: &str, shape: Shape, ) -> bool { if context.codemap.lookup_char_pos(span.lo).col.0 != shape.indent.width() { return true; } for (i, line) in string.lines().enumerate() { if i == 0 { if line.len() > shape.width { return true; } } else { if line.len() > shape.width + shape.indent.width() { return true; } } } false } pub fn rewrite_call_with_binary_search( context: &RewriteContext, callee: &R, args: &[&ast::Expr], span: Span, shape: Shape, ) -> Option where R: Rewrite, { let closure = |callee_max_width| { // FIXME using byte lens instead of char lens (and probably all over the // place too) let callee_shape = Shape { width: callee_max_width, ..shape }; let callee_str = callee.rewrite(context, callee_shape).ok_or( Ordering::Greater, )?; rewrite_call_inner( context, &callee_str, args, span, shape, context.config.fn_call_width(), false, ) }; binary_search(1, shape.width, closure) } pub fn rewrite_call( context: &RewriteContext, callee: &str, args: &[ptr::P], span: Span, shape: Shape, ) -> Option { rewrite_call_inner( context, &callee, &args.iter().map(|x| &**x).collect::>(), span, shape, context.config.fn_call_width(), false, ).ok() } pub fn rewrite_call_inner<'a, T>( context: &RewriteContext, callee_str: &str, args: &[&T], span: Span, shape: Shape, args_max_width: usize, force_trailing_comma: bool, ) -> Result where T: Rewrite + Spanned + ToExpr + 'a, { // 2 = `( `, 1 = `(` let paren_overhead = if context.config.spaces_within_parens() { 2 } else { 1 }; let used_width = extra_offset(&callee_str, shape); let one_line_width = shape .width .checked_sub(used_width + 2 * paren_overhead) .ok_or(Ordering::Greater)?; let nested_shape = shape_from_fn_call_style( context, shape, used_width + 2 * paren_overhead, used_width + paren_overhead, ).ok_or(Ordering::Greater)?; let span_lo = context.codemap.span_after(span, "("); let args_span = mk_sp(span_lo, span.hi); let (extendable, list_str) = rewrite_call_args( context, args, args_span, nested_shape, one_line_width, args_max_width, force_trailing_comma, ).or_else(|| if context.use_block_indent() { rewrite_call_args( context, args, args_span, Shape::indented( shape.block().indent.block_indent(context.config), context.config, ), 0, 0, force_trailing_comma, ) } else { None }) .ok_or(Ordering::Less)?; if !context.use_block_indent() && need_block_indent(&list_str, nested_shape) && !extendable { let mut new_context = context.clone(); new_context.use_block = true; return rewrite_call_inner( &new_context, callee_str, args, span, shape, args_max_width, force_trailing_comma, ); } let args_shape = shape.sub_width(last_line_width(&callee_str)).ok_or( Ordering::Less, )?; Ok(format!( "{}{}", callee_str, wrap_args_with_parens( context, &list_str, extendable, args_shape, nested_shape, ) )) } fn need_block_indent(s: &str, shape: Shape) -> bool { s.lines().skip(1).any(|s| { s.find(|c| !char::is_whitespace(c)).map_or(false, |w| { w + 1 < shape.indent.width() }) }) } fn rewrite_call_args<'a, T>( context: &RewriteContext, args: &[&T], span: Span, shape: Shape, one_line_width: usize, args_max_width: usize, force_trailing_comma: bool, ) -> Option<(bool, String)> where T: Rewrite + Spanned + ToExpr + 'a, { let mut item_context = context.clone(); item_context.inside_macro = false; let items = itemize_list( context.codemap, args.iter(), ")", |item| item.span().lo, |item| item.span().hi, |item| item.rewrite(&item_context, shape), span.lo, span.hi, ); let mut item_vec: Vec<_> = items.collect(); // Try letting the last argument overflow to the next line with block // indentation. If its first line fits on one line with the other arguments, // we format the function arguments horizontally. let tactic = try_overflow_last_arg( &item_context, &mut item_vec, &args[..], shape, one_line_width, args_max_width, ); let fmt = ListFormatting { tactic: tactic, separator: ",", trailing_separator: if force_trailing_comma { SeparatorTactic::Always } else if context.inside_macro || !context.use_block_indent() { SeparatorTactic::Never } else { context.config.trailing_comma() }, shape: shape, ends_with_newline: false, config: context.config, }; write_list(&item_vec, &fmt).map(|args_str| { (tactic != DefinitiveListTactic::Vertical, args_str) }) } fn try_overflow_last_arg<'a, T>( context: &RewriteContext, item_vec: &mut Vec, args: &[&T], shape: Shape, one_line_width: usize, args_max_width: usize, ) -> DefinitiveListTactic where T: Rewrite + Spanned + ToExpr + 'a, { let overflow_last = can_be_overflowed(&context, args); // Replace the last item with its first line to see if it fits with // first arguments. let (orig_last, placeholder) = if overflow_last { let mut context = context.clone(); if let Some(expr) = args[args.len() - 1].to_expr() { match expr.node { ast::ExprKind::MethodCall(..) => context.force_one_line_chain = true, _ => (), } } last_arg_shape(&context, &item_vec, shape, args_max_width) .map_or((None, None), |arg_shape| { rewrite_last_arg_with_overflow( &context, args[args.len() - 1], &mut item_vec[args.len() - 1], arg_shape, ) }) } else { (None, None) }; let tactic = definitive_tactic( &*item_vec, ListTactic::LimitedHorizontalVertical(args_max_width), one_line_width, ); // Replace the stub with the full overflowing last argument if the rewrite // succeeded and its first line fits with the other arguments. match (overflow_last, tactic, placeholder) { (true, DefinitiveListTactic::Horizontal, placeholder @ Some(..)) => { item_vec[args.len() - 1].item = placeholder; } (true, _, _) => { item_vec[args.len() - 1].item = orig_last; } (false, _, _) => {} } tactic } fn last_arg_shape( context: &RewriteContext, items: &Vec, shape: Shape, args_max_width: usize, ) -> Option { let overhead = items.iter().rev().skip(1).fold(0, |acc, i| { acc + i.item.as_ref().map_or(0, |s| first_line_width(&s)) }); let max_width = min(args_max_width, shape.width); let arg_indent = if context.use_block_indent() { shape.block().indent.block_unindent(context.config) } else { shape.block().indent }; Some(Shape { width: try_opt!(max_width.checked_sub(overhead)), indent: arg_indent, offset: 0, }) } fn rewrite_last_arg_with_overflow<'a, T>( context: &RewriteContext, last_arg: &T, last_item: &mut ListItem, shape: Shape, ) -> (Option, Option) where T: Rewrite + Spanned + ToExpr + 'a, { let rewrite = if let Some(expr) = last_arg.to_expr() { match expr.node { // When overflowing the closure which consists of a single control flow expression, // force to use block if its condition uses multi line. ast::ExprKind::Closure(capture, ref fn_decl, ref body, _) => { let try_closure_with_block = || { let body = match body.node { ast::ExprKind::Block(ref block) if block.stmts.len() == 1 => { try_opt!(stmt_expr(&block.stmts[0])) } _ => body, }; let (prefix, extra_offset) = try_opt!(rewrite_closure_fn_decl( capture, fn_decl, body, expr.span, context, shape, )); let shape = try_opt!(shape.offset_left(extra_offset)); rewrite_cond(context, body, shape).map_or(None, |cond| if cond.contains('\n') { rewrite_closure_with_block(context, shape, &prefix, body) } else { None }) }; try_closure_with_block().or_else(|| expr.rewrite(context, shape)) } _ => expr.rewrite(context, shape), } } else { last_arg.rewrite(context, shape) }; let orig_last = last_item.item.clone(); if let Some(rewrite) = rewrite { let rewrite_first_line = Some(rewrite[..first_line_width(&rewrite)].to_owned()); last_item.item = rewrite_first_line; (orig_last, Some(rewrite)) } else { (orig_last, None) } } fn can_be_overflowed<'a, T>(context: &RewriteContext, args: &[&T]) -> bool where T: Rewrite + Spanned + ToExpr + 'a, { args.last().map_or( false, |x| x.can_be_overflowed(context, args.len()), ) } pub fn can_be_overflowed_expr(context: &RewriteContext, expr: &ast::Expr, args_len: usize) -> bool { match expr.node { ast::ExprKind::Match(..) => { (context.use_block_indent() && args_len == 1) || (context.config.fn_call_style() == IndentStyle::Visual && args_len > 1) } ast::ExprKind::If(..) | ast::ExprKind::IfLet(..) | ast::ExprKind::ForLoop(..) | ast::ExprKind::Loop(..) | ast::ExprKind::While(..) | ast::ExprKind::WhileLet(..) => { context.config.combine_control_expr() && context.use_block_indent() && args_len == 1 } ast::ExprKind::Block(..) | ast::ExprKind::Closure(..) => { context.use_block_indent() || context.config.fn_call_style() == IndentStyle::Visual && args_len > 1 } ast::ExprKind::Call(..) | ast::ExprKind::MethodCall(..) | ast::ExprKind::Mac(..) | ast::ExprKind::Struct(..) => context.use_block_indent() && args_len == 1, ast::ExprKind::Tup(..) => context.use_block_indent(), 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, _) => can_be_overflowed_expr(context, expr, args_len), _ => false, } } fn paren_overhead(context: &RewriteContext) -> usize { if context.config.spaces_within_parens() { 4 } else { 2 } } pub fn wrap_args_with_parens( context: &RewriteContext, args_str: &str, is_extendable: bool, shape: Shape, nested_shape: Shape, ) -> String { if !context.use_block_indent() || (context.inside_macro && !args_str.contains('\n') && args_str.len() + paren_overhead(context) <= shape.width) || is_extendable { if context.config.spaces_within_parens() && args_str.len() > 0 { format!("( {} )", args_str) } else { format!("({})", args_str) } } else { format!( "(\n{}{}\n{})", nested_shape.indent.to_string(context.config), args_str, shape.block().indent.to_string(context.config) ) } } fn rewrite_paren(context: &RewriteContext, subexpr: &ast::Expr, shape: Shape) -> Option { debug!("rewrite_paren, shape: {:?}", shape); let paren_overhead = paren_overhead(context); let sub_shape = try_opt!(shape.sub_width(paren_overhead / 2)).visual_indent(paren_overhead / 2); let paren_wrapper = |s: &str| if context.config.spaces_within_parens() && s.len() > 0 { format!("( {} )", s) } else { format!("({})", s) }; let subexpr_str = try_opt!(subexpr.rewrite(context, sub_shape)); debug!("rewrite_paren, subexpr_str: `{:?}`", subexpr_str); if subexpr_str.contains('\n') { Some(paren_wrapper(&subexpr_str)) } else { if subexpr_str.len() + paren_overhead <= shape.width { Some(paren_wrapper(&subexpr_str)) } else { let sub_shape = try_opt!(shape.offset_left(2)); let subexpr_str = try_opt!(subexpr.rewrite(context, sub_shape)); Some(paren_wrapper(&subexpr_str)) } } } fn rewrite_index( expr: &ast::Expr, index: &ast::Expr, context: &RewriteContext, shape: Shape, ) -> Option { let expr_str = try_opt!(expr.rewrite(context, shape)); let (lbr, rbr) = if context.config.spaces_within_square_brackets() { ("[ ", " ]") } else { ("[", "]") }; let offset = expr_str.len() + lbr.len(); if let Some(index_shape) = shape.visual_indent(offset).sub_width(offset + rbr.len()) { if let Some(index_str) = index.rewrite(context, index_shape) { return Some(format!("{}{}{}{}", expr_str, lbr, index_str, rbr)); } } let indent = shape.indent.block_indent(&context.config); let indent = indent.to_string(&context.config); // FIXME this is not right, since we don't take into account that shape.width // might be reduced from max_width by something on the right. let budget = try_opt!(context.config.max_width().checked_sub( indent.len() + lbr.len() + rbr.len(), )); let index_str = try_opt!(index.rewrite(context, Shape::legacy(budget, shape.indent))); Some(format!( "{}\n{}{}{}{}", expr_str, indent, lbr, index_str, rbr )) } fn rewrite_struct_lit<'a>( context: &RewriteContext, path: &ast::Path, fields: &'a [ast::Field], base: Option<&'a ast::Expr>, span: Span, shape: Shape, ) -> Option { debug!("rewrite_struct_lit: shape {:?}", shape); enum StructLitField<'a> { Regular(&'a ast::Field), Base(&'a ast::Expr), } // 2 = " {".len() let path_shape = try_opt!(shape.sub_width(2)); let path_str = try_opt!(rewrite_path( context, PathContext::Expr, None, path, path_shape, )); if fields.len() == 0 && base.is_none() { return Some(format!("{} {{}}", path_str)); } let field_iter = fields.into_iter().map(StructLitField::Regular).chain( base.into_iter().map(StructLitField::Base), ); // Foo { a: Foo } - indent is +3, width is -5. let (h_shape, v_shape) = try_opt!(struct_lit_shape(shape, context, path_str.len() + 3, 2)); let span_lo = |item: &StructLitField| match *item { StructLitField::Regular(field) => field.span.lo, StructLitField::Base(expr) => { let last_field_hi = fields.last().map_or(span.lo, |field| field.span.hi); let snippet = context.snippet(mk_sp(last_field_hi, expr.span.lo)); let pos = snippet.find_uncommented("..").unwrap(); last_field_hi + BytePos(pos as u32) } }; let span_hi = |item: &StructLitField| match *item { StructLitField::Regular(field) => field.span.hi, StructLitField::Base(expr) => expr.span.hi, }; let rewrite = |item: &StructLitField| match *item { StructLitField::Regular(field) => { // The 1 taken from the v_budget is for the comma. rewrite_field(context, field, try_opt!(v_shape.sub_width(1))) } StructLitField::Base(expr) => { // 2 = .. expr.rewrite(context, try_opt!(v_shape.shrink_left(2))) .map(|s| format!("..{}", s)) } }; let items = itemize_list( context.codemap, field_iter, "}", span_lo, span_hi, rewrite, context.codemap.span_after(span, "{"), span.hi, ); let item_vec = items.collect::>(); let tactic = struct_lit_tactic(h_shape, context, &item_vec); let nested_shape = shape_for_tactic(tactic, h_shape, v_shape); let fmt = struct_lit_formatting(nested_shape, tactic, context, base.is_some()); let fields_str = try_opt!(write_list(&item_vec, &fmt)); let fields_str = if context.config.struct_lit_style() == IndentStyle::Block && (fields_str.contains('\n') || context.config.struct_lit_multiline_style() == MultilineStyle::ForceMulti || fields_str.len() > h_shape.map(|s| s.width).unwrap_or(0)) { format!( "\n{}{}\n{}", v_shape.indent.to_string(context.config), fields_str, shape.indent.to_string(context.config) ) } else { // One liner or visual indent. format!(" {} ", fields_str) }; Some(format!("{} {{{}}}", path_str, fields_str)) // FIXME if context.config.struct_lit_style() == Visual, but we run out // of space, we should fall back to BlockIndent. } pub fn struct_lit_field_separator(config: &Config) -> &str { colon_spaces( config.space_before_struct_lit_field_colon(), config.space_after_struct_lit_field_colon(), ) } fn rewrite_field(context: &RewriteContext, field: &ast::Field, shape: Shape) -> Option { let name = &field.ident.node.to_string(); if field.is_shorthand { Some(name.to_string()) } else { let separator = struct_lit_field_separator(context.config); let overhead = name.len() + separator.len(); let mut expr_shape = try_opt!(shape.sub_width(overhead)); expr_shape.offset += overhead; let expr = field.expr.rewrite(context, expr_shape); let mut attrs_str = try_opt!((*field.attrs).rewrite(context, shape)); if !attrs_str.is_empty() { attrs_str.push_str(&format!("\n{}", shape.indent.to_string(context.config))); }; match expr { Some(e) => Some(format!("{}{}{}{}", attrs_str, name, separator, e)), None => { let expr_offset = shape.indent.block_indent(context.config); let expr = field.expr.rewrite( context, Shape::indented(expr_offset, context.config), ); expr.map(|s| { format!( "{}{}:\n{}{}", attrs_str, name, expr_offset.to_string(&context.config), s ) }) } } } } fn shape_from_fn_call_style( context: &RewriteContext, shape: Shape, overhead: usize, offset: usize, ) -> Option { if context.use_block_indent() { Some(shape.block().block_indent(context.config.tab_spaces())) } else { shape.visual_indent(offset).sub_width(overhead) } } fn rewrite_tuple_in_visual_indent_style<'a, T>( context: &RewriteContext, items: &[&T], span: Span, shape: Shape, ) -> Option where T: Rewrite + Spanned + ToExpr + 'a, { let mut items = items.iter(); // In case of length 1, need a trailing comma debug!("rewrite_tuple_in_visual_indent_style {:?}", shape); if items.len() == 1 { // 3 = "(" + ",)" let nested_shape = try_opt!(shape.sub_width(3)).visual_indent(1); return items.next().unwrap().rewrite(context, nested_shape).map( |s| { if context.config.spaces_within_parens() { format!("( {}, )", s) } else { format!("({},)", s) } }, ); } let list_lo = context.codemap.span_after(span, "("); let nested_shape = try_opt!(shape.sub_width(2)).visual_indent(1); let items = itemize_list( context.codemap, items, ")", |item| item.span().lo, |item| item.span().hi, |item| item.rewrite(context, nested_shape), list_lo, span.hi - BytePos(1), ); let list_str = try_opt!(format_item_list(items, nested_shape, context.config)); if context.config.spaces_within_parens() && list_str.len() > 0 { Some(format!("( {} )", list_str)) } else { Some(format!("({})", list_str)) } } pub fn rewrite_tuple<'a, T>( context: &RewriteContext, items: &[&T], span: Span, shape: Shape, ) -> Option where T: Rewrite + Spanned + ToExpr + 'a, { debug!("rewrite_tuple {:?}", shape); if context.use_block_indent() { // We use the same rule as funcation call for rewriting tuple. rewrite_call_inner( context, &String::new(), items, span, shape, context.config.fn_call_width(), items.len() == 1, ).ok() } else { rewrite_tuple_in_visual_indent_style(context, items, span, shape) } } pub fn rewrite_unary_prefix( context: &RewriteContext, prefix: &str, rewrite: &R, shape: Shape, ) -> Option { rewrite .rewrite(context, try_opt!(shape.offset_left(prefix.len()))) .map(|r| format!("{}{}", prefix, r)) } // FIXME: this is probably not correct for multi-line Rewrites. we should // subtract suffix.len() from the last line budget, not the first! pub fn rewrite_unary_suffix( context: &RewriteContext, suffix: &str, rewrite: &R, shape: Shape, ) -> Option { rewrite .rewrite(context, try_opt!(shape.sub_width(suffix.len()))) .map(|mut r| { r.push_str(suffix); r }) } fn rewrite_unary_op( context: &RewriteContext, op: &ast::UnOp, expr: &ast::Expr, shape: Shape, ) -> Option { // For some reason, an UnOp is not spanned like BinOp! let operator_str = match *op { ast::UnOp::Deref => "*", ast::UnOp::Not => "!", ast::UnOp::Neg => "-", }; rewrite_unary_prefix(context, operator_str, expr, shape) } fn rewrite_assignment( context: &RewriteContext, lhs: &ast::Expr, rhs: &ast::Expr, op: Option<&ast::BinOp>, shape: Shape, ) -> Option { let operator_str = match op { Some(op) => context.snippet(op.span), None => "=".to_owned(), }; // 1 = space between lhs and operator. let lhs_shape = try_opt!(shape.sub_width(operator_str.len() + 1)); let lhs_str = format!( "{} {}", try_opt!(lhs.rewrite(context, lhs_shape)), operator_str ); rewrite_assign_rhs(context, lhs_str, rhs, shape) } // The left hand side must contain everything up to, and including, the // assignment operator. pub fn rewrite_assign_rhs>( context: &RewriteContext, lhs: S, ex: &ast::Expr, shape: Shape, ) -> Option { let mut result = lhs.into(); let last_line_width = last_line_width(&result) - if result.contains('\n') { shape.indent.width() } else { 0 }; // 1 = space between operator and rhs. let orig_shape = try_opt!(shape.block_indent(0).offset_left(last_line_width + 1)); let rhs = match ex.node { ast::ExprKind::Mac(ref mac) => { match rewrite_macro(mac, None, context, orig_shape, MacroPosition::Expression) { None if !context.snippet(ex.span).contains("\n") => { context.snippet(ex.span).rewrite(context, orig_shape) } rhs @ _ => rhs, } } _ => ex.rewrite(context, orig_shape), }; fn count_line_breaks(src: &str) -> usize { src.chars().filter(|&x| x == '\n').count() } match rhs { Some(ref new_str) if count_line_breaks(new_str) < 2 => { result.push(' '); result.push_str(new_str); } _ => { // Expression did not fit on the same line as the identifier or is // at least three lines big. Try splitting the line and see // if that works better. let new_shape = try_opt!(shape.block_left(context.config.tab_spaces())); let new_rhs = ex.rewrite(context, new_shape); // FIXME: DRY! match (rhs, new_rhs) { (Some(ref orig_rhs), Some(ref replacement_rhs)) if count_line_breaks(orig_rhs) > count_line_breaks(replacement_rhs) + 1 || (orig_rhs.rewrite(context, shape).is_none() && replacement_rhs.rewrite(context, new_shape).is_some()) => { result.push_str(&format!("\n{}", new_shape.indent.to_string(context.config))); result.push_str(replacement_rhs); } (None, Some(ref final_rhs)) => { result.push_str(&format!("\n{}", new_shape.indent.to_string(context.config))); result.push_str(final_rhs); } (None, None) => return None, (Some(ref orig_rhs), _) => { result.push(' '); result.push_str(orig_rhs); } } } } Some(result) } fn rewrite_expr_addrof( context: &RewriteContext, mutability: ast::Mutability, expr: &ast::Expr, shape: Shape, ) -> Option { let operator_str = match mutability { ast::Mutability::Immutable => "&", ast::Mutability::Mutable => "&mut ", }; rewrite_unary_prefix(context, operator_str, expr, shape) } pub trait ToExpr { fn to_expr(&self) -> Option<&ast::Expr>; fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool; } impl ToExpr for ast::Expr { fn to_expr(&self) -> Option<&ast::Expr> { Some(self) } fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool { can_be_overflowed_expr(context, self, len) } } impl ToExpr for ast::Ty { fn to_expr(&self) -> Option<&ast::Expr> { None } fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool { can_be_overflowed_type(context, self, len) } } impl<'a> ToExpr for TuplePatField<'a> { fn to_expr(&self) -> Option<&ast::Expr> { None } fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool { can_be_overflowed_pat(context, self, len) } }