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rust/src/expr.rs
Nick Cameron 7fb288f0b3 Merge pull request #1487 from topecongiro/issue1470 
Use block indent when visual indent exceeds max_width
2017-05-02 10:45:23 +12:00

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// 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 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use std::cmp::{Ordering, min};
use std::borrow::Borrow;
use std::mem::swap;
use std::ops::Deref;
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};
use visitor::FmtVisitor;
use config::{Config, IndentStyle, MultilineStyle, ControlBraceStyle};
use comment::{FindUncommented, rewrite_comment, contains_comment, recover_comment_removed};
use types::{rewrite_path, PathContext};
use items::{span_lo_for_arg, span_hi_for_arg};
use chains::rewrite_chain;
use macros::{rewrite_macro, MacroPosition};
use syntax::{ast, ptr};
use syntax::codemap::{CodeMap, Span, BytePos, mk_sp};
use syntax::parse::classify;
impl Rewrite for ast::Expr {
fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
format_expr(self, ExprType::SubExpression, context, shape)
}
}
#[derive(PartialEq)]
enum ExprType {
Statement,
SubExpression,
}
fn format_expr(expr: &ast::Expr,
expr_type: ExprType,
context: &RewriteContext,
shape: Shape)
-> Option<String> {
let result = 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(context, &**callee, args, inner_span, shape, false)
}
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), expr.span, shape)
}
ast::ExprKind::While(ref cond, ref block, label) => {
ControlFlow::new_while(None, cond, block, label, expr.span).rewrite(context, shape)
}
ast::ExprKind::WhileLet(ref pat, ref cond, ref block, label) => {
ControlFlow::new_while(Some(pat), cond, block, label, expr.span).rewrite(context, shape)
}
ast::ExprKind::ForLoop(ref pat, ref cond, ref block, label) => {
ControlFlow::new_for(pat, cond, block, label, expr.span).rewrite(context, shape)
}
ast::ExprKind::Loop(ref block, label) => {
ControlFlow::new_loop(block, label, expr.span).rewrite(context, shape)
}
ast::ExprKind::Block(ref block) => block.rewrite(context, shape),
ast::ExprKind::If(ref cond, ref if_block, ref else_block) => {
ControlFlow::new_if(cond,
None,
if_block,
else_block.as_ref().map(|e| &**e),
expr_type == ExprType::SubExpression,
false,
expr.span)
.rewrite(context, shape)
}
ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref else_block) => {
ControlFlow::new_if(cond,
Some(pat),
if_block,
else_block.as_ref().map(|e| &**e),
expr_type == ExprType::SubExpression,
false,
expr.span)
.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,
expr.span)
} 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, expr.span)
}
ast::ExprKind::Box(ref expr) => {
rewrite_unary_prefix(context, "box ", &**expr, shape, expr.span)
}
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, expr.span)
}
(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)
}
};
result.and_then(|res| recover_comment_removed(res, expr.span, context, shape))
}
pub fn rewrite_pair<LHS, RHS>(lhs: &LHS,
rhs: &RHS,
prefix: &str,
infix: &str,
suffix: &str,
context: &RewriteContext,
shape: Shape)
-> Option<String>
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!(shape.sub_width(prefix.len() + 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))
.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 lhs_budget = try_opt!(context
.config
.max_width
.checked_sub(shape.used_width() + prefix.len() +
infix.len()));
let rhs_shape = try_opt!(shape.sub_width(suffix.len() + prefix.len()))
.visual_indent(prefix.len());
let rhs_result = try_opt!(rhs.rewrite(context, rhs_shape));
let lhs_result = try_opt!(lhs.rewrite(context,
Shape {
width: lhs_budget,
..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<String>
where I: Iterator<Item = &'a ast::Expr>
{
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::<Vec<_>>();
if items.is_empty() {
if context.config.spaces_within_square_brackets {
return Some("[ ]".to_string());
} else {
return Some("[]".to_string());
}
}
let has_long_item = try_opt!(items
.iter()
.map(|li| li.item.as_ref().map(|s| s.len() > 10))
.fold(Some(false),
|acc, x| acc.and_then(|y| x.map(|x| x || y))));
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)
}
// 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<String> {
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::<Vec<_>>();
// 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);
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);
}
// 1 = space between `|...|` and body.
let extra_offset = extra_offset(&prefix, shape) + 1;
let body_shape = try_opt!(shape.sub_width(extra_offset)).add_offset(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 ||
block_contains_comment(block, context.codemap) ||
prefix.contains('\n');
if ret_str.is_empty() && !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.
let mut rewrite = stmt.rewrite(context, try_opt!(body_shape.sub_width(4)));
// Checks if rewrite succeeded and fits on a single line.
rewrite = and_one_line(rewrite);
if let Some(rewrite) = rewrite {
return Some(format!("{} {{ {} }}", prefix, rewrite));
}
}
// Either we require a block, or tried without and failed.
return rewrite_closure_block(&block, prefix, context, body_shape);
}
if let Some(rw) = rewrite_closure_expr(body, &prefix, context, body_shape) {
return Some(rw);
}
// The closure originally had a non-block expression, but we can't fit on
// one line, so we'll insert a block.
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,
};
return rewrite_closure_block(&block, prefix, context, body_shape);
fn rewrite_closure_expr(expr: &ast::Expr,
prefix: &str,
context: &RewriteContext,
shape: Shape)
-> Option<String> {
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))
}
fn rewrite_closure_block(block: &ast::Block,
prefix: String,
context: &RewriteContext,
shape: Shape)
-> Option<String> {
// Start with visual indent, then fall back to block indent if the
// closure is large.
let rewrite = try_opt!(block.rewrite(&context, shape));
let block_threshold = context.config.closure_block_indent_threshold;
if block_threshold < 0 || rewrite.matches('\n').count() <= block_threshold as usize {
if let Some(rewrite) = wrap_str(rewrite, context.config.max_width, shape) {
return Some(format!("{} {}", prefix, rewrite));
}
}
// The body of the closure is big enough to be block indented, that
// means we must re-format.
let block_shape = shape.block();
let rewrite = try_opt!(block.rewrite(&context, block_shape));
Some(format!("{} {}",
prefix,
try_opt!(wrap_str(rewrite, block_shape.width, block_shape))))
}
}
fn and_one_line(x: Option<String>) -> Option<String> {
x.and_then(|x| if x.contains('\n') { None } else { Some(x) })
}
fn nop_block_collapse(block_str: Option<String>, budget: usize) -> Option<String> {
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<String> {
// 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;
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 is_simple_block(self, context.codemap) && prefix.len() < shape.width {
let expr_str =
self.stmts[0].rewrite(context,
Shape::legacy(shape.width - prefix.len(),
shape.indent));
let expr_str = try_opt!(expr_str);
let result = format!("{}{{ {} }}", prefix, expr_str);
if result.len() <= shape.width && !result.contains('\n') {
return Some(result);
}
}
prefix
}
ast::BlockCheckMode::Default => {
visitor.last_pos = self.span.lo;
String::new()
}
};
visitor.visit_block(self);
Some(format!("{}{}", prefix, visitor.buffer))
}
}
impl Rewrite for ast::Stmt {
fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
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))
}
}
// 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<ast::SpannedIdent>,
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,
}
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<ast::SpannedIdent>,
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<ast::SpannedIdent>,
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<ast::SpannedIdent>,
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<String> {
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> Rewrite for ControlFlow<'a> {
fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
debug!("ControlFlow::rewrite {:?} {:?}", self, shape);
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 add_offset = self.keyword.len() + label_string.len() + 1;
let pat_expr_string = match self.cond {
Some(cond) => {
let mut cond_shape = try_opt!(constr_shape.shrink_left(add_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,
cond_shape))
}
None => String::new(),
};
// 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 trial.is_some() &&
trial.as_ref().unwrap().len() <= context.config.single_line_if_else_max_width {
return trial;
}
}
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
};
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 block_str = try_opt!(self.block.rewrite(context, block_shape));
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 alt_block_sep = String::from("\n") +
&shape.indent.block_only().to_string(context.config);
let block_sep = if self.cond.is_none() && between_kwd_cond_comment.is_some() {
""
} else if context.config.control_brace_style ==
ControlBraceStyle::AlwaysNextLine {
alt_block_sep.as_str()
} else {
" "
};
let mut result = 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),
block_str);
if let Some(else_block) = self.else_block {
// Since this is an else block, we should not indent for the assignment preceding
// the original if, so set shape.offset to 0.
let shape = Shape { offset: 0, ..shape };
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.visual_indent(0))
}
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.visual_indent(0))
}
_ => {
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<ast::SpannedIdent>) -> String {
match label {
Some(ident) => format!("{}: ", ident.node),
None => "".to_owned(),
}
}
fn extract_comment(span: Span, context: &RewriteContext, shape: Shape) -> Option<String> {
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<String> {
// 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<String> {
if arms.is_empty() {
return None;
}
// `match `cond` {`
let cond_shape = try_opt!(shape.shrink_left(6));
let cond_shape = try_opt!(cond_shape.sub_width(2));
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,
Shape {
width: context.config.max_width - arm_shape.indent.width(),
..arm_shape
});
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<String> {
debug!("Arm::rewrite {:?} {:?}", self, shape);
let &ast::Arm {
ref attrs,
ref pats,
ref guard,
ref body,
} = self;
// FIXME this is all a bit grotty, would be nice to abstract out the
// treatment of attributes.
let attr_str = if !attrs.is_empty() {
// We only use this visitor for the attributes, should we use it for
// more?
let mut attr_visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
attr_visitor.block_indent = shape.indent.block_only();
attr_visitor.last_pos = attrs[0].span.lo;
if attr_visitor.visit_attrs(attrs) {
// Attributes included a skip instruction.
return None;
}
attr_visitor.format_missing(pats[0].span.lo);
attr_visitor.buffer.to_string()
} 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::<Option<Vec<_>>>());
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 {
width: context.config.max_width - shape.indent.width(),
..shape
}
} 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 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 {
expr
} else {
&**body
}
}
_ => &**body,
};
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') || !context.config.wrap_match_arms ||
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.sub_width(context.config.tab_spaces))
.block_indent(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<ptr::P<ast::Expr>>,
shape: Shape,
// The amount of space used up on this line for the pattern in
// the arm (excludes offset).
pattern_width: usize)
-> Option<String> {
if let Some(ref guard) = *guard {
// First try to fit the guard string on the same line as the pattern.
// 4 = ` if `, 5 = ` => {`
let overhead = pattern_width + 4 + 5;
if overhead < shape.width {
let cond_shape = shape
.shrink_left(pattern_width + 4)
.unwrap()
.sub_width(5)
.unwrap();
let cond_str = guard.rewrite(context, cond_shape);
if let Some(cond_str) = cond_str {
return Some(format!(" if {}", cond_str));
}
}
// Not enough space to put the guard after the pattern, try a newline.
let overhead = shape.indent.block_indent(context.config).width() + 4 + 5;
if overhead < shape.width {
let cond_str = guard.rewrite(context,
Shape::legacy(shape.width - overhead,
// 3 == `if `
shape.indent.block_indent(context.config) +
3));
if let Some(cond_str) = cond_str {
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,
shape: Shape)
-> Option<String> {
debug!("rewrite_pat_expr {:?} {:?}", shape, pat);
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.shrink_left(matcher.len()))
.sub_width(connector.len()));
let 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.sub_width(extra_offset + spacer.len()))
.add_offset(extra_offset + spacer.len());
let expr_rewrite = expr.rewrite(context, expr_shape);
if let Some(expr_string) = expr_rewrite {
let pat_simple = pat.and_then(|p| {
p.rewrite(context,
Shape::legacy(context.config.max_width,
Indent::empty()))
})
.map(|s| pat_is_simple(&s));
if pat.is_none() || pat_simple.unwrap_or(false) || !expr_string.contains('\n') {
result.push_str(spacer);
result.push_str(&expr_string);
return Some(result);
}
}
}
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::legacy(try_opt!(context.config
.max_width
.checked_sub(nested_indent.width())),
nested_indent));
result.push_str(&try_opt!(expr_rewrite));
Some(result)
}
fn rewrite_string_lit(context: &RewriteContext, span: Span, shape: Shape) -> Option<String> {
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<R>(context: &RewriteContext,
callee: &R,
args: &[ptr::P<ast::Expr>],
span: Span,
shape: Shape,
force_no_trailing_comma: bool)
-> Option<String>
where R: Rewrite
{
let closure = |callee_max_width| {
rewrite_call_inner(context,
callee,
callee_max_width,
args,
span,
shape,
force_no_trailing_comma)
};
// 2 is for parens
let max_width = try_opt!(shape.width.checked_sub(2));
binary_search(1, max_width, closure)
}
fn rewrite_call_inner<R>(context: &RewriteContext,
callee: &R,
max_callee_width: usize,
args: &[ptr::P<ast::Expr>],
span: Span,
shape: Shape,
force_no_trailing_comma: bool)
-> Result<String, Ordering>
where R: Rewrite
{
let callee = callee.borrow();
// FIXME using byte lens instead of char lens (and probably all over the
// place too)
let callee_str = match callee.rewrite(context,
Shape {
width: max_callee_width,
..shape
}) {
Some(string) => {
if !string.contains('\n') && string.len() > max_callee_width {
panic!("{:?} {}", string, max_callee_width);
} else {
string
}
}
None => return Err(Ordering::Greater),
};
let span_lo = context.codemap.span_after(span, "(");
let span = mk_sp(span_lo, span.hi);
let used_width = extra_offset(&callee_str, shape);
let nested_shape = match context.config.fn_call_style {
IndentStyle::Block => {
shape
.block()
.block_indent(context.config.tab_spaces)
.sub_width(context.config.tab_spaces)
}
// 1 = (, 2 = ().
IndentStyle::Visual => {
shape
.visual_indent(used_width + 1)
.sub_width(used_width + 2)
}
};
let nested_shape = match nested_shape {
Some(s) => s,
None => return Err(Ordering::Greater),
};
let arg_count = args.len();
let items = itemize_list(context.codemap,
args.iter(),
")",
|item| item.span.lo,
|item| item.span.hi,
|item| item.rewrite(context, nested_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 overflow_last = match args.last().map(|x| &x.node) {
Some(&ast::ExprKind::Closure(..)) |
Some(&ast::ExprKind::Block(..)) if arg_count > 1 => true,
_ => false,
};
let mut orig_last = None;
let mut placeholder = None;
// Replace the last item with its first line to see if it fits with
// first arguments.
if overflow_last {
let nested_shape = Shape {
indent: nested_shape.indent.block_only(),
..nested_shape
};
let rewrite = args.last().unwrap().rewrite(context, nested_shape);
if let Some(rewrite) = rewrite {
let rewrite_first_line = Some(rewrite[..first_line_width(&rewrite)].to_owned());
placeholder = Some(rewrite);
swap(&mut item_vec[arg_count - 1].item, &mut orig_last);
item_vec[arg_count - 1].item = rewrite_first_line;
}
}
let one_line_width = shape.width.checked_sub(used_width + 2);
let one_line_width = match one_line_width {
Some(olw) => olw,
None => return Err(Ordering::Greater),
};
let one_line_shape = Shape {
width: one_line_width,
..nested_shape
};
let tactic =
definitive_tactic(&item_vec,
ListTactic::LimitedHorizontalVertical(context.config.fn_call_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[arg_count - 1].item = placeholder;
}
(true, _, _) => {
item_vec[arg_count - 1].item = orig_last;
}
(false, _, _) => {}
}
let fmt = ListFormatting {
tactic: tactic,
separator: ",",
trailing_separator: if force_no_trailing_comma ||
context.config.fn_call_style == IndentStyle::Visual {
SeparatorTactic::Never
} else {
context.config.trailing_comma
},
shape: one_line_shape,
ends_with_newline: false,
config: context.config,
};
let list_str = match write_list(&item_vec, &fmt) {
Some(str) => str,
None => return Err(Ordering::Less),
};
let result = if context.config.fn_call_style == IndentStyle::Visual ||
!list_str.contains('\n') {
if context.config.spaces_within_parens && list_str.len() > 0 {
format!("{}( {} )", callee_str, list_str)
} else {
format!("{}({})", callee_str, list_str)
}
} else {
format!("{}(\n{}{}\n{})",
callee_str,
nested_shape.indent.to_string(context.config),
list_str,
shape.block().indent.to_string(context.config))
};
Ok(result)
}
fn rewrite_paren(context: &RewriteContext, subexpr: &ast::Expr, shape: Shape) -> Option<String> {
debug!("rewrite_paren, shape: {:?}", shape);
// 1 is for opening paren, 2 is for opening+closing, we want to keep the closing
// paren on the same line as the subexpr.
let sub_shape = try_opt!(shape.sub_width(2)).visual_indent(1);
let subexpr_str = subexpr.rewrite(context, sub_shape);
debug!("rewrite_paren, subexpr_str: `{:?}`", subexpr_str);
subexpr_str.map(|s| if context.config.spaces_within_parens && s.len() > 0 {
format!("( {} )", s)
} else {
format!("({})", s)
})
}
fn rewrite_index(expr: &ast::Expr,
index: &ast::Expr,
context: &RewriteContext,
shape: Shape)
-> Option<String> {
let expr_str = try_opt!(expr.rewrite(context, shape));
let (lbr, rbr) = if context.config.spaces_within_square_brackets {
("[ ", " ]")
} else {
("[", "]")
};
let budget = shape
.width
.checked_sub(expr_str.len() + lbr.len() + rbr.len())
.unwrap_or(0);
let index_str = index.rewrite(context, Shape::legacy(budget, shape.indent));
if let Some(index_str) = index_str {
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<String> {
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::<Vec<_>>();
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 type_annotation_separator(config: &Config) -> &str {
colon_spaces(config.space_before_type_annotation,
config.space_after_type_annotation_colon)
}
fn rewrite_field(context: &RewriteContext, field: &ast::Field, shape: Shape) -> Option<String> {
let name = &field.ident.node.to_string();
if field.is_shorthand {
Some(name.to_string())
} else {
let separator = type_annotation_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);
match expr {
Some(e) => Some(format!("{}{}{}", name, separator, e)),
None => {
let expr_offset = shape.indent.block_indent(context.config);
let expr = field
.expr
.rewrite(context,
Shape::legacy(try_opt!(context
.config
.max_width
.checked_sub(expr_offset.width())),
expr_offset));
expr.map(|s| format!("{}:\n{}{}", name, expr_offset.to_string(&context.config), s))
}
}
}
}
pub fn rewrite_tuple<'a, I>(context: &RewriteContext,
mut items: I,
span: Span,
shape: Shape)
-> Option<String>
where I: ExactSizeIterator,
<I as Iterator>::Item: Deref,
<I::Item as Deref>::Target: Rewrite + Spanned + 'a
{
debug!("rewrite_tuple {:?}", shape);
// In case of length 1, need a trailing comma
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_unary_prefix<R: Rewrite>(context: &RewriteContext,
prefix: &str,
rewrite: &R,
mut shape: Shape,
span: Span)
-> Option<String> {
// Heuristic: if unary is `&` and `rewrite` contains `{`,
// it is likely that block indent is preferred to visual indent.
if prefix == "&" {
let snippet = String::from(context.snippet(span).trim_left_matches('&'));
let first_line = try_opt!(snippet.lines().nth(0));
if first_line.contains("{") {
shape = try_opt!(shape.sub_width(prefix.len())).block_indent(0);
} else {
shape = try_opt!(shape.shrink_left(prefix.len())).visual_indent(0);
}
} else {
shape = try_opt!(shape.shrink_left(prefix.len())).visual_indent(0);
}
rewrite
.rewrite(context, shape)
.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<R: Rewrite>(context: &RewriteContext,
suffix: &str,
rewrite: &R,
shape: Shape)
-> Option<String> {
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<String> {
// 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, expr.span)
}
fn rewrite_assignment(context: &RewriteContext,
lhs: &ast::Expr,
rhs: &ast::Expr,
op: Option<&ast::BinOp>,
shape: Shape)
-> Option<String> {
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<S: Into<String>>(context: &RewriteContext,
lhs: S,
ex: &ast::Expr,
shape: Shape)
-> Option<String> {
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 max_width = try_opt!(shape.width.checked_sub(last_line_width + 1));
let rhs = ex.rewrite(context,
Shape::offset(max_width,
shape.indent,
shape.indent.alignment + last_line_width + 1));
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_offset = shape.indent.block_indent(context.config);
let max_width = try_opt!((shape.width + shape.indent.width())
.checked_sub(new_offset.width()));
let new_shape = Shape::legacy(max_width, new_offset);
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_offset.to_string(context.config)));
result.push_str(replacement_rhs);
}
(None, Some(ref final_rhs)) => {
result.push_str(&format!("\n{}", new_offset.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<String> {
let operator_str = match mutability {
ast::Mutability::Immutable => "&",
ast::Mutability::Mutable => "&mut ",
};
rewrite_unary_prefix(context, operator_str, expr, shape, expr.span)
}
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