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rust/src/expr.rs

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use std::borrow::Cow;
use std::cmp::min;
use itertools::Itertools;
use syntax::parse::token::DelimToken;
use syntax::source_map::{BytePos, SourceMap, Span};
use syntax::{ast, ptr};
use crate::chains::rewrite_chain;
use crate::closures;
use crate::comment::{
combine_strs_with_missing_comments, contains_comment, recover_comment_removed, rewrite_comment,
rewrite_missing_comment, CharClasses, FindUncommented,
};
use crate::config::lists::*;
use crate::config::{Config, ControlBraceStyle, IndentStyle, Version};
use crate::lists::{
definitive_tactic, itemize_list, shape_for_tactic, struct_lit_formatting, struct_lit_shape,
struct_lit_tactic, write_list, ListFormatting, ListItem, Separator,
};
use crate::macros::{rewrite_macro, MacroPosition};
use crate::matches::rewrite_match;
use crate::overflow::{self, IntoOverflowableItem, OverflowableItem};
use crate::pairs::{rewrite_all_pairs, rewrite_pair, PairParts};
use crate::patterns::is_short_pattern;
use crate::rewrite::{Rewrite, RewriteContext};
use crate::shape::{Indent, Shape};
use crate::source_map::{LineRangeUtils, SpanUtils};
use crate::spanned::Spanned;
use crate::string::{rewrite_string, StringFormat};
use crate::types::{rewrite_path, PathContext};
use crate::utils::{
colon_spaces, contains_skip, count_newlines, first_line_ends_with, inner_attributes,
last_line_extendable, last_line_width, mk_sp, outer_attributes, ptr_vec_to_ref_vec,
semicolon_for_expr, semicolon_for_stmt, wrap_str,
};
use crate::vertical::rewrite_with_alignment;
use crate::visitor::FmtVisitor;
impl Rewrite for ast::Expr {
fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
format_expr(self, ExprType::SubExpression, context, shape)
}
}
#[derive(Copy, Clone, PartialEq)]
pub enum ExprType {
Statement,
SubExpression,
}
pub fn format_expr(
expr: &ast::Expr,
expr_type: ExprType,
context: &RewriteContext<'_>,
shape: Shape,
) -> Option<String> {
skip_out_of_file_lines_range!(context, expr.span);
if contains_skip(&*expr.attrs) {
return Some(context.snippet(expr.span()).to_owned());
}
let shape = if expr_type == ExprType::Statement && semicolon_for_expr(context, expr) {
shape.sub_width(1)?
} else {
shape
};
let expr_rw = match expr.node {
ast::ExprKind::Array(ref expr_vec) => rewrite_array(
"",
expr_vec.iter(),
expr.span,
context,
shape,
choose_separator_tactic(context, expr.span),
None,
),
ast::ExprKind::Lit(ref l) => rewrite_literal(context, l, shape),
ast::ExprKind::Call(ref callee, ref args) => {
let inner_span = mk_sp(callee.span.hi(), expr.span.hi());
let callee_str = callee.rewrite(context, shape)?;
rewrite_call(context, &callee_str, args, inner_span, shape)
}
ast::ExprKind::Paren(ref subexpr) => rewrite_paren(context, subexpr, shape, expr.span),
ast::ExprKind::Binary(op, ref lhs, ref rhs) => {
// FIXME: format comments between operands and operator
rewrite_all_pairs(expr, shape, context).or_else(|| {
rewrite_pair(
&**lhs,
&**rhs,
PairParts::infix(&format!(" {} ", context.snippet(op.span))),
context,
shape,
context.config.binop_separator(),
)
})
}
ast::ExprKind::Unary(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(), expr.span, shape, items.len() == 1)
}
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, opt_label) => {
match expr_type {
ExprType::Statement => {
if is_unsafe_block(block) {
rewrite_block(block, Some(&expr.attrs), opt_label, context, shape)
} else if let rw @ Some(_) =
rewrite_empty_block(context, block, Some(&expr.attrs), opt_label, "", shape)
{
// Rewrite block without trying to put it in a single line.
rw
} else {
let prefix = block_prefix(context, block, shape)?;
rewrite_block_with_visitor(
context,
&prefix,
block,
Some(&expr.attrs),
opt_label,
shape,
true,
)
}
}
ExprType::SubExpression => {
rewrite_block(block, Some(&expr.attrs), opt_label, context, shape)
}
}
}
ast::ExprKind::Match(ref cond, ref arms) => {
rewrite_match(context, cond, arms, shape, expr.span, &expr.attrs)
}
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_label) => {
let id_str = match *opt_label {
Some(label) => format!(" {}", label.ident),
None => String::new(),
};
Some(format!("continue{}", id_str))
}
ast::ExprKind::Break(ref opt_label, ref opt_expr) => {
let id_str = match *opt_label {
Some(label) => format!(" {}", label.ident),
None => String::new(),
};
if let Some(ref expr) = *opt_expr {
rewrite_unary_prefix(context, &format!("break{} ", id_str), &**expr, shape)
} else {
Some(format!("break{}", id_str))
}
}
ast::ExprKind::Yield(ref opt_expr) => {
if let Some(ref expr) = *opt_expr {
rewrite_unary_prefix(context, "yield ", &**expr, shape)
} else {
Some("yield".to_string())
}
}
ast::ExprKind::Closure(capture, asyncness, movability, ref fn_decl, ref body, _) => {
closures::rewrite_closure(
capture, asyncness, movability, fn_decl, body, expr.span, context, shape,
)
}
ast::ExprKind::Try(..) | ast::ExprKind::Field(..) | ast::ExprKind::MethodCall(..) => {
rewrite_chain(expr, context, shape)
}
ast::ExprKind::Mac(ref mac) => {
rewrite_macro(mac, None, context, shape, MacroPosition::Expression).or_else(|| {
wrap_str(
context.snippet(expr.span).to_owned(),
context.config.max_width(),
shape,
)
})
}
ast::ExprKind::Ret(None) => Some("return".to_owned()),
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,
PairParts::infix(" as "),
context,
shape,
SeparatorPlace::Front,
),
ast::ExprKind::Type(ref expr, ref ty) => rewrite_pair(
&**expr,
&**ty,
PairParts::infix(": "),
context,
shape,
SeparatorPlace::Back,
),
ast::ExprKind::Index(ref expr, ref index) => {
rewrite_index(&**expr, &**index, context, shape)
}
ast::ExprKind::Repeat(ref expr, ref repeats) => rewrite_pair(
&**expr,
&*repeats.value,
PairParts::new("[", "; ", "]"),
context,
shape,
SeparatorPlace::Back,
),
ast::ExprKind::Range(ref lhs, ref rhs, limits) => {
let delim = match limits {
ast::RangeLimits::HalfOpen => "..",
ast::RangeLimits::Closed => "..=",
};
fn needs_space_before_range(context: &RewriteContext<'_>, lhs: &ast::Expr) -> bool {
match lhs.node {
ast::ExprKind::Lit(ref lit) => match lit.node {
ast::LitKind::FloatUnsuffixed(..) => {
context.snippet(lit.span).ends_with('.')
}
_ => false,
},
_ => false,
}
}
fn needs_space_after_range(rhs: &ast::Expr) -> bool {
match rhs.node {
// Don't format `.. ..` into `....`, which is invalid.
//
// This check is unnecessary for `lhs`, because a range
// starting from another range needs parentheses as `(x ..) ..`
// (`x .. ..` is a range from `x` to `..`).
ast::ExprKind::Range(None, _, _) => true,
_ => false,
}
}
let default_sp_delim = |lhs: Option<&ast::Expr>, rhs: Option<&ast::Expr>| {
let space_if = |b: bool| if b { " " } else { "" };
format!(
"{}{}{}",
lhs.map_or("", |lhs| space_if(needs_space_before_range(context, lhs))),
delim,
rhs.map_or("", |rhs| space_if(needs_space_after_range(rhs))),
)
};
match (lhs.as_ref().map(|x| &**x), rhs.as_ref().map(|x| &**x)) {
(Some(lhs), Some(rhs)) => {
let sp_delim = if context.config.spaces_around_ranges() {
format!(" {} ", delim)
} else {
default_sp_delim(Some(lhs), Some(rhs))
};
rewrite_pair(
&*lhs,
&*rhs,
PairParts::infix(&sp_delim),
context,
shape,
context.config.binop_separator(),
)
}
(None, Some(rhs)) => {
let sp_delim = if context.config.spaces_around_ranges() {
format!("{} ", delim)
} else {
default_sp_delim(None, Some(rhs))
};
rewrite_unary_prefix(context, &sp_delim, &*rhs, shape)
}
(Some(lhs), None) => {
let sp_delim = if context.config.spaces_around_ranges() {
format!(" {}", delim)
} else {
default_sp_delim(Some(lhs), None)
};
rewrite_unary_suffix(context, &sp_delim, &*lhs, shape)
}
(None, None) => Some(delim.to_owned()),
}
}
// We do not format these expressions yet, but they should still
// satisfy our width restrictions.
ast::ExprKind::InlineAsm(..) => Some(context.snippet(expr.span).to_owned()),
ast::ExprKind::TryBlock(ref block) => {
if let rw @ Some(_) =
rewrite_single_line_block(context, "try ", block, Some(&expr.attrs), None, shape)
{
rw
} else {
// 9 = `try `
let budget = shape.width.saturating_sub(9);
Some(format!(
"{}{}",
"try ",
rewrite_block(
block,
Some(&expr.attrs),
None,
context,
Shape::legacy(budget, shape.indent)
)?
))
}
}
ast::ExprKind::ObsoleteInPlace(ref lhs, ref rhs) => lhs
.rewrite(context, shape)
.map(|s| s + " <-")
.and_then(|lhs| rewrite_assign_rhs(context, lhs, &**rhs, shape)),
ast::ExprKind::Async(capture_by, _node_id, ref block) => {
let mover = if capture_by == ast::CaptureBy::Value {
"move "
} else {
""
};
if let rw @ Some(_) = rewrite_single_line_block(
context,
format!("{}{}", "async ", mover).as_str(),
block,
Some(&expr.attrs),
None,
shape,
) {
rw
} else {
// 6 = `async `
let budget = shape.width.saturating_sub(6);
Some(format!(
"{}{}{}",
"async ",
mover,
rewrite_block(
block,
Some(&expr.attrs),
None,
context,
Shape::legacy(budget, shape.indent)
)?
))
}
}
ast::ExprKind::Err => None,
};
expr_rw
.and_then(|expr_str| recover_comment_removed(expr_str, expr.span, context))
.and_then(|expr_str| {
let attrs = outer_attributes(&expr.attrs);
let attrs_str = attrs.rewrite(context, shape)?;
let span = mk_sp(
attrs.last().map_or(expr.span.lo(), |attr| attr.span.hi()),
expr.span.lo(),
);
combine_strs_with_missing_comments(context, &attrs_str, &expr_str, span, shape, false)
})
}
pub fn rewrite_array<'a, T: 'a + IntoOverflowableItem<'a>>(
name: &'a str,
exprs: impl Iterator<Item = &'a T>,
span: Span,
context: &'a RewriteContext<'_>,
shape: Shape,
force_separator_tactic: Option<SeparatorTactic>,
delim_token: Option<DelimToken>,
) -> Option<String> {
overflow::rewrite_with_square_brackets(
context,
name,
exprs,
shape,
span,
force_separator_tactic,
delim_token,
)
}
fn rewrite_empty_block(
context: &RewriteContext<'_>,
block: &ast::Block,
attrs: Option<&[ast::Attribute]>,
label: Option<ast::Label>,
prefix: &str,
shape: Shape,
) -> Option<String> {
if !block.stmts.is_empty() {
return None;
}
let label_str = rewrite_label(label);
if attrs.map_or(false, |a| !inner_attributes(a).is_empty()) {
return None;
}
if !block_contains_comment(block, context.source_map) && shape.width >= 2 {
return Some(format!("{}{}{{}}", prefix, label_str));
}
// If a block contains only a single-line comment, then leave it on one line.
let user_str = context.snippet(block.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 block.stmts.is_empty()
&& !comment_str.contains('\n')
&& !comment_str.starts_with("//")
&& comment_str.len() + 4 <= shape.width
{
return Some(format!("{}{}{{ {} }}", prefix, label_str, comment_str));
}
}
None
}
fn block_prefix(context: &RewriteContext<'_>, block: &ast::Block, shape: Shape) -> Option<String> {
Some(match block.rules {
ast::BlockCheckMode::Unsafe(..) => {
let snippet = context.snippet(block.span);
let open_pos = snippet.find_uncommented("{")?;
// Extract comment between unsafe and block start.
let trimmed = &snippet[6..open_pos].trim();
if !trimmed.is_empty() {
// 9 = "unsafe {".len(), 7 = "unsafe ".len()
let budget = shape.width.checked_sub(9)?;
format!(
"unsafe {} ",
rewrite_comment(
trimmed,
true,
Shape::legacy(budget, shape.indent + 7),
context.config,
)?
)
} else {
"unsafe ".to_owned()
}
}
ast::BlockCheckMode::Default => String::new(),
})
}
fn rewrite_single_line_block(
context: &RewriteContext<'_>,
prefix: &str,
block: &ast::Block,
attrs: Option<&[ast::Attribute]>,
label: Option<ast::Label>,
shape: Shape,
) -> Option<String> {
if is_simple_block(block, attrs, context.source_map) {
let expr_shape = shape.offset_left(last_line_width(prefix))?;
let expr_str = block.stmts[0].rewrite(context, expr_shape)?;
let label_str = rewrite_label(label);
let result = format!("{}{}{{ {} }}", prefix, label_str, expr_str);
if result.len() <= shape.width && !result.contains('\n') {
return Some(result);
}
}
None
}
pub fn rewrite_block_with_visitor(
context: &RewriteContext<'_>,
prefix: &str,
block: &ast::Block,
attrs: Option<&[ast::Attribute]>,
label: Option<ast::Label>,
shape: Shape,
has_braces: bool,
) -> Option<String> {
if let rw @ Some(_) = rewrite_empty_block(context, block, attrs, label, prefix, shape) {
return rw;
}
let mut visitor = FmtVisitor::from_context(context);
visitor.block_indent = shape.indent;
visitor.is_if_else_block = context.is_if_else_block();
match (block.rules, label) {
(ast::BlockCheckMode::Unsafe(..), _) | (ast::BlockCheckMode::Default, Some(_)) => {
let snippet = context.snippet(block.span);
let open_pos = snippet.find_uncommented("{")?;
visitor.last_pos = block.span.lo() + BytePos(open_pos as u32)
}
(ast::BlockCheckMode::Default, None) => visitor.last_pos = block.span.lo(),
}
let inner_attrs = attrs.map(inner_attributes);
let label_str = rewrite_label(label);
visitor.visit_block(block, inner_attrs.as_ref().map(|a| &**a), has_braces);
Some(format!("{}{}{}", prefix, label_str, visitor.buffer))
}
impl Rewrite for ast::Block {
fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
rewrite_block(self, None, None, context, shape)
}
}
fn rewrite_block(
block: &ast::Block,
attrs: Option<&[ast::Attribute]>,
label: Option<ast::Label>,
context: &RewriteContext<'_>,
shape: Shape,
) -> Option<String> {
let prefix = block_prefix(context, block, shape)?;
// shape.width is used only for the single line case: either the empty block `{}`,
// or an unsafe expression `unsafe { e }`.
if let rw @ Some(_) = rewrite_empty_block(context, block, attrs, label, &prefix, shape) {
return rw;
}
let result = rewrite_block_with_visitor(context, &prefix, block, attrs, label, shape, true);
if let Some(ref result_str) = result {
if result_str.lines().count() <= 3 {
if let rw @ Some(_) =
rewrite_single_line_block(context, &prefix, block, attrs, label, shape)
{
return rw;
}
}
}
result
}
impl Rewrite for ast::Stmt {
fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
skip_out_of_file_lines_range!(context, self.span());
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(context, self) {
";"
} else {
""
};
let shape = shape.sub_width(suffix.len())?;
format_expr(ex, ExprType::Statement, context, shape).map(|s| s + suffix)
}
ast::StmtKind::Mac(..) | ast::StmtKind::Item(..) => None,
};
result.and_then(|res| recover_comment_removed(res, self.span(), context))
}
}
// Rewrite condition if the given expression has one.
pub fn rewrite_cond(
context: &RewriteContext<'_>,
expr: &ast::Expr,
shape: Shape,
) -> Option<String> {
match expr.node {
ast::ExprKind::Match(ref cond, _) => {
// `match `cond` {`
let cond_shape = match context.config.indent_style() {
IndentStyle::Visual => shape.shrink_left(6).and_then(|s| s.sub_width(2))?,
IndentStyle::Block => shape.offset_left(8)?,
};
cond.rewrite(context, cond_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<ast::Label>,
pats: Vec<&'a ast::Pat>,
keyword: &'a str,
matcher: &'a str,
connector: &'a str,
allow_single_line: bool,
// HACK: `true` if this is an `if` expression in an `else if`.
nested_if: bool,
span: Span,
}
fn to_control_flow(expr: &ast::Expr, expr_type: ExprType) -> Option<ControlFlow<'_>> {
match expr.node {
ast::ExprKind::If(ref cond, ref if_block, ref else_block) => Some(ControlFlow::new_if(
cond,
vec![],
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,
ptr_vec_to_ref_vec(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(
vec![],
cond,
block,
label,
expr.span,
)),
ast::ExprKind::WhileLet(ref pat, ref cond, ref block, label) => Some(
ControlFlow::new_while(ptr_vec_to_ref_vec(pat), cond, block, label, expr.span),
),
_ => None,
}
}
fn choose_matcher(pats: &[&ast::Pat]) -> &'static str {
if pats.is_empty() { "" } else { "let" }
}
impl<'a> ControlFlow<'a> {
fn new_if(
cond: &'a ast::Expr,
pats: Vec<&'a ast::Pat>,
block: &'a ast::Block,
else_block: Option<&'a ast::Expr>,
allow_single_line: bool,
nested_if: bool,
span: Span,
) -> ControlFlow<'a> {
let matcher = choose_matcher(&pats);
ControlFlow {
cond: Some(cond),
block,
else_block,
label: None,
pats,
keyword: "if",
matcher,
connector: " =",
allow_single_line,
nested_if,
span,
}
}
fn new_loop(block: &'a ast::Block, label: Option<ast::Label>, span: Span) -> ControlFlow<'a> {
ControlFlow {
cond: None,
block,
else_block: None,
label,
pats: vec![],
keyword: "loop",
matcher: "",
connector: "",
allow_single_line: false,
nested_if: false,
span,
}
}
fn new_while(
pats: Vec<&'a ast::Pat>,
cond: &'a ast::Expr,
block: &'a ast::Block,
label: Option<ast::Label>,
span: Span,
) -> ControlFlow<'a> {
let matcher = choose_matcher(&pats);
ControlFlow {
cond: Some(cond),
block,
else_block: None,
label,
pats,
keyword: "while",
matcher,
connector: " =",
allow_single_line: false,
nested_if: false,
span,
}
}
fn new_for(
pat: &'a ast::Pat,
cond: &'a ast::Expr,
block: &'a ast::Block,
label: Option<ast::Label>,
span: Span,
) -> ControlFlow<'a> {
ControlFlow {
cond: Some(cond),
block,
else_block: None,
label,
pats: vec![pat],
keyword: "for",
matcher: "",
connector: " in",
allow_single_line: false,
nested_if: false,
span,
}
}
fn rewrite_single_line(
&self,
pat_expr_str: &str,
context: &RewriteContext<'_>,
width: usize,
) -> Option<String> {
assert!(self.allow_single_line);
let else_block = 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, None, context.source_map)
|| !is_simple_block(else_node, None, context.source_map)
|| pat_expr_str.contains('\n')
{
return None;
}
let new_width = width.checked_sub(pat_expr_str.len() + fixed_cost)?;
let expr = &self.block.stmts[0];
let if_str = expr.rewrite(context, Shape::legacy(new_width, Indent::empty()))?;
let new_width = new_width.checked_sub(if_str.len())?;
let else_expr = &else_node.stmts[0];
let else_str = 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
}
}
/// Returns `true` if the last line of pat_str has leading whitespace and it is wider than the
/// shape's indent.
fn last_line_offsetted(start_column: usize, pat_str: &str) -> bool {
let mut leading_whitespaces = 0;
for c in pat_str.chars().rev() {
match c {
'\n' => break,
_ if c.is_whitespace() => leading_whitespaces += 1,
_ => leading_whitespaces = 0,
}
}
leading_whitespaces > start_column
}
impl<'a> ControlFlow<'a> {
fn rewrite_pat_expr(
&self,
context: &RewriteContext<'_>,
expr: &ast::Expr,
shape: Shape,
offset: usize,
) -> Option<String> {
debug!("rewrite_pat_expr {:?} {:?} {:?}", shape, self.pats, expr);
let cond_shape = shape.offset_left(offset)?;
if !self.pats.is_empty() {
let matcher = if self.matcher.is_empty() {
self.matcher.to_owned()
} else {
format!("{} ", self.matcher)
};
let pat_shape = cond_shape
.offset_left(matcher.len())?
.sub_width(self.connector.len())?;
let pat_string = rewrite_multiple_patterns(context, &self.pats, pat_shape)?;
let result = format!("{}{}{}", matcher, pat_string, self.connector);
return rewrite_assign_rhs(context, result, expr, cond_shape);
}
let expr_rw = expr.rewrite(context, cond_shape);
// The expression may (partially) fit on the current line.
// We do not allow splitting between `if` and condition.
if self.keyword == "if" || expr_rw.is_some() {
return expr_rw;
}
// The expression won't fit on the current line, jump to next.
let nested_shape = shape
.block_indent(context.config.tab_spaces())
.with_max_width(context.config);
let nested_indent_str = nested_shape.indent.to_string_with_newline(context.config);
expr.rewrite(context, nested_shape)
.map(|expr_rw| format!("{}{}", nested_indent_str, expr_rw))
}
fn rewrite_cond(
&self,
context: &RewriteContext<'_>,
shape: Shape,
alt_block_sep: &str,
) -> Option<(String, usize)> {
// Do not take the rhs overhead from the upper expressions into account
// when rewriting pattern.
let new_width = context.budget(shape.used_width());
let fresh_shape = Shape {
width: new_width,
..shape
};
let constr_shape = if self.nested_if {
// We are part of an if-elseif-else chain. Our constraints are tightened.
// 7 = "} else " .len()
fresh_shape.offset_left(7)?
} else {
fresh_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) => self.rewrite_pat_expr(context, cond, constr_shape, offset)?,
None => String::new(),
};
let brace_overhead =
if context.config.control_brace_style() != ControlBraceStyle::AlwaysNextLine {
// 2 = ` {`
2
} else {
0
};
let one_line_budget = context
.config
.max_width()
.saturating_sub(constr_shape.used_width() + offset + brace_overhead);
let force_newline_brace = (pat_expr_string.contains('\n')
|| pat_expr_string.len() > one_line_budget)
&& (!last_line_extendable(&pat_expr_string)
|| last_line_offsetted(shape.used_width(), &pat_expr_string));
// Try to format if-else on single line.
if self.allow_single_line
&& context
.config
.width_heuristics()
.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
.width_heuristics()
.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`
// Do not include label in the span.
let lo = self
.label
.map_or(self.span.lo(), |label| label.ident.span.hi());
let between_kwd_cond = mk_sp(
context
.snippet_provider
.span_after(mk_sp(lo, self.span.hi()), self.keyword.trim()),
if self.pats.is_empty() {
cond_span.lo()
} else if self.matcher.is_empty() {
self.pats[0].span.lo()
} else {
context
.snippet_provider
.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<String> {
debug!("ControlFlow::rewrite {:?} {:?}", self, shape);
let alt_block_sep = &shape.indent.to_string_with_newline(context.config);
let (cond_str, used_width) = 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.saturating_sub(used_width);
// 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 = {
let old_val = context.is_if_else_block.replace(self.else_block.is_some());
let result =
rewrite_block_with_visitor(context, "", self.block, None, None, block_shape, true);
context.is_if_else_block.replace(old_val);
result?
};
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,
ptr_vec_to_ref_vec(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,
vec![],
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
};
format_expr(else_block, ExprType::Statement, context, else_shape)
}
};
let between_kwd_else_block = mk_sp(
self.block.span.hi(),
context
.snippet_provider
.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
.snippet_provider
.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,
_ => " ",
};
result.push_str(&format!(
"{}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),
));
result.push_str(&rewrite?);
}
Some(result)
}
}
fn rewrite_label(opt_label: Option<ast::Label>) -> Cow<'static, str> {
match opt_label {
Some(label) => Cow::from(format!("{}: ", label.ident)),
None => Cow::from(""),
}
}
fn extract_comment(span: Span, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
match rewrite_missing_comment(span, shape, context) {
Some(ref comment) if !comment.is_empty() => Some(format!(
"{indent}{}{indent}",
comment,
indent = shape.indent.to_string_with_newline(context.config)
)),
_ => None,
}
}
pub fn block_contains_comment(block: &ast::Block, source_map: &SourceMap) -> bool {
let snippet = source_map.span_to_snippet(block.span).unwrap();
contains_comment(&snippet)
}
// Checks that a block contains no statements, an expression and no comments or
// attributes.
// FIXME: incorrectly returns false when comment is contained completely within
// the expression.
pub fn is_simple_block(
block: &ast::Block,
attrs: Option<&[ast::Attribute]>,
source_map: &SourceMap,
) -> bool {
(block.stmts.len() == 1
&& stmt_is_expr(&block.stmts[0])
&& !block_contains_comment(block, source_map)
&& attrs.map_or(true, |a| a.is_empty()))
}
/// Checks whether a block contains at most one statement or expression, and no
/// comments or attributes.
pub fn is_simple_block_stmt(
block: &ast::Block,
attrs: Option<&[ast::Attribute]>,
source_map: &SourceMap,
) -> bool {
block.stmts.len() <= 1
&& !block_contains_comment(block, source_map)
&& attrs.map_or(true, |a| a.is_empty())
}
/// Checks whether a block contains no statements, expressions, comments, or
/// inner attributes.
pub fn is_empty_block(
block: &ast::Block,
attrs: Option<&[ast::Attribute]>,
source_map: &SourceMap,
) -> bool {
block.stmts.is_empty()
&& !block_contains_comment(block, source_map)
&& attrs.map_or(true, |a| inner_attributes(a).is_empty())
}
pub fn stmt_is_expr(stmt: &ast::Stmt) -> bool {
match stmt.node {
ast::StmtKind::Expr(..) => true,
_ => false,
}
}
pub(crate) fn stmt_is_if(stmt: &ast::Stmt) -> bool {
match stmt.node {
ast::StmtKind::Expr(ref e) => match e.node {
ast::ExprKind::If(..) => true,
_ => false,
},
_ => false,
}
}
pub fn is_unsafe_block(block: &ast::Block) -> bool {
if let ast::BlockCheckMode::Unsafe(..) = block.rules {
true
} else {
false
}
}
pub fn rewrite_multiple_patterns(
context: &RewriteContext<'_>,
pats: &[&ast::Pat],
shape: Shape,
) -> Option<String> {
let pat_strs = pats
.iter()
.map(|p| p.rewrite(context, shape))
.collect::<Option<Vec<_>>>()?;
let use_mixed_layout = pats
.iter()
.zip(pat_strs.iter())
.all(|(pat, pat_str)| is_short_pattern(pat, pat_str));
let items: Vec<_> = pat_strs.into_iter().map(ListItem::from_str).collect();
let tactic = if use_mixed_layout {
DefinitiveListTactic::Mixed
} else {
definitive_tactic(
&items,
ListTactic::HorizontalVertical,
Separator::VerticalBar,
shape.width,
)
};
let fmt = ListFormatting::new(shape, context.config)
.tactic(tactic)
.separator(" |")
.separator_place(context.config.binop_separator())
.ends_with_newline(false);
write_list(&items, &fmt)
}
pub fn rewrite_literal(context: &RewriteContext<'_>, l: &ast::Lit, shape: Shape) -> Option<String> {
match l.node {
ast::LitKind::Str(_, ast::StrStyle::Cooked) => rewrite_string_lit(context, l.span, shape),
_ => wrap_str(
context.snippet(l.span).to_owned(),
context.config.max_width(),
shape,
),
}
}
fn rewrite_string_lit(context: &RewriteContext<'_>, span: Span, shape: Shape) -> Option<String> {
let string_lit = context.snippet(span);
if !context.config.format_strings() {
if string_lit
.lines()
.dropping_back(1)
.all(|line| line.ends_with('\\'))
{
let new_indent = shape.visual_indent(1).indent;
let indented_string_lit = String::from(
string_lit
.lines()
.map(|line| {
format!(
"{}{}",
new_indent.to_string(context.config),
line.trim_start()
)
})
.collect::<Vec<_>>()
.join("\n")
.trim_start(),
);
return if context.config.version() == Version::Two {
Some(indented_string_lit)
} else {
wrap_str(indented_string_lit, context.config.max_width(), shape)
};
} else {
return wrap_str(string_lit.to_owned(), context.config.max_width(), shape);
}
}
// Remove the quote characters.
let str_lit = &string_lit[1..string_lit.len() - 1];
rewrite_string(
str_lit,
&StringFormat::new(shape.visual_indent(0), context.config),
shape.width.saturating_sub(2),
)
}
fn choose_separator_tactic(context: &RewriteContext<'_>, span: Span) -> Option<SeparatorTactic> {
if context.inside_macro() {
if span_ends_with_comma(context, span) {
Some(SeparatorTactic::Always)
} else {
Some(SeparatorTactic::Never)
}
} else {
None
}
}
pub fn rewrite_call(
context: &RewriteContext<'_>,
callee: &str,
args: &[ptr::P<ast::Expr>],
span: Span,
shape: Shape,
) -> Option<String> {
overflow::rewrite_with_parens(
context,
callee,
args.iter(),
shape,
span,
context.config.width_heuristics().fn_call_width,
choose_separator_tactic(context, span),
)
}
pub fn is_simple_expr(expr: &ast::Expr) -> bool {
match expr.node {
ast::ExprKind::Lit(..) => true,
ast::ExprKind::Path(ref qself, ref path) => qself.is_none() && path.segments.len() <= 1,
ast::ExprKind::AddrOf(_, ref expr)
| ast::ExprKind::Box(ref expr)
| ast::ExprKind::Cast(ref expr, _)
| ast::ExprKind::Field(ref expr, _)
| ast::ExprKind::Try(ref expr)
| ast::ExprKind::Unary(_, ref expr) => is_simple_expr(expr),
ast::ExprKind::Index(ref lhs, ref rhs) => is_simple_expr(lhs) && is_simple_expr(rhs),
ast::ExprKind::Repeat(ref lhs, ref rhs) => {
is_simple_expr(lhs) && is_simple_expr(&*rhs.value)
}
_ => false,
}
}
pub fn is_every_expr_simple(lists: &[OverflowableItem<'_>]) -> bool {
lists.iter().all(OverflowableItem::is_simple)
}
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.indent_style() == IndentStyle::Visual && args_len > 1)
|| context.config.overflow_delimited_expr()
}
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
}
// Handle always block-like expressions
ast::ExprKind::Async(..) | ast::ExprKind::Block(..) | ast::ExprKind::Closure(..) => true,
// Handle `[]` and `{}`-like expressions
ast::ExprKind::Array(..) | ast::ExprKind::Struct(..) => {
context.config.overflow_delimited_expr()
|| (context.use_block_indent() && args_len == 1)
}
ast::ExprKind::Mac(ref macro_) => {
match (macro_.node.delim, context.config.overflow_delimited_expr()) {
(ast::MacDelimiter::Bracket, true) | (ast::MacDelimiter::Brace, true) => true,
_ => context.use_block_indent() && args_len == 1,
}
}
// Handle parenthetical expressions
ast::ExprKind::Call(..) | ast::ExprKind::MethodCall(..) | ast::ExprKind::Tup(..) => {
context.use_block_indent() && args_len == 1
}
// Handle unary-like expressions
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,
}
}
pub fn is_nested_call(expr: &ast::Expr) -> bool {
match expr.node {
ast::ExprKind::Call(..) | ast::ExprKind::Mac(..) => true,
ast::ExprKind::AddrOf(_, ref expr)
| ast::ExprKind::Box(ref expr)
| ast::ExprKind::Try(ref expr)
| ast::ExprKind::Unary(_, ref expr)
| ast::ExprKind::Cast(ref expr, _) => is_nested_call(expr),
_ => false,
}
}
/// Returns `true` if a function call or a method call represented by the given span ends with a
/// trailing comma. This function is used when rewriting macro, as adding or removing a trailing
/// comma from macro can potentially break the code.
pub fn span_ends_with_comma(context: &RewriteContext<'_>, span: Span) -> bool {
let mut result: bool = Default::default();
let mut prev_char: char = Default::default();
let closing_delimiters = &[')', '}', ']'];
for (kind, c) in CharClasses::new(context.snippet(span).chars()) {
match c {
_ if kind.is_comment() || c.is_whitespace() => continue,
c if closing_delimiters.contains(&c) => {
result &= !closing_delimiters.contains(&prev_char);
}
',' => result = true,
_ => result = false,
}
prev_char = c;
}
result
}
fn rewrite_paren(
context: &RewriteContext<'_>,
mut subexpr: &ast::Expr,
shape: Shape,
mut span: Span,
) -> Option<String> {
debug!("rewrite_paren, shape: {:?}", shape);
// Extract comments within parens.
let mut pre_span;
let mut post_span;
let mut pre_comment;
let mut post_comment;
let remove_nested_parens = context.config.remove_nested_parens();
loop {
// 1 = "(" or ")"
pre_span = mk_sp(span.lo() + BytePos(1), subexpr.span.lo());
post_span = mk_sp(subexpr.span.hi(), span.hi() - BytePos(1));
pre_comment = rewrite_missing_comment(pre_span, shape, context)?;
post_comment = rewrite_missing_comment(post_span, shape, context)?;
// Remove nested parens if there are no comments.
if let ast::ExprKind::Paren(ref subsubexpr) = subexpr.node {
if remove_nested_parens && pre_comment.is_empty() && post_comment.is_empty() {
span = subexpr.span;
subexpr = subsubexpr;
continue;
}
}
break;
}
// 1 = `(` and `)`
let sub_shape = shape.offset_left(1)?.sub_width(1)?;
let subexpr_str = subexpr.rewrite(context, sub_shape)?;
let fits_single_line = !pre_comment.contains("//") && !post_comment.contains("//");
if fits_single_line {
Some(format!("({}{}{})", pre_comment, subexpr_str, post_comment))
} else {
rewrite_paren_in_multi_line(context, subexpr, shape, pre_span, post_span)
}
}
fn rewrite_paren_in_multi_line(
context: &RewriteContext<'_>,
subexpr: &ast::Expr,
shape: Shape,
pre_span: Span,
post_span: Span,
) -> Option<String> {
let nested_indent = shape.indent.block_indent(context.config);
let nested_shape = Shape::indented(nested_indent, context.config);
let pre_comment = rewrite_missing_comment(pre_span, nested_shape, context)?;
let post_comment = rewrite_missing_comment(post_span, nested_shape, context)?;
let subexpr_str = subexpr.rewrite(context, nested_shape)?;
let mut result = String::with_capacity(subexpr_str.len() * 2);
result.push('(');
if !pre_comment.is_empty() {
result.push_str(&nested_indent.to_string_with_newline(context.config));
result.push_str(&pre_comment);
}
result.push_str(&nested_indent.to_string_with_newline(context.config));
result.push_str(&subexpr_str);
if !post_comment.is_empty() {
result.push_str(&nested_indent.to_string_with_newline(context.config));
result.push_str(&post_comment);
}
result.push_str(&shape.indent.to_string_with_newline(context.config));
result.push(')');
Some(result)
}
fn rewrite_index(
expr: &ast::Expr,
index: &ast::Expr,
context: &RewriteContext<'_>,
shape: Shape,
) -> Option<String> {
let expr_str = expr.rewrite(context, shape)?;
let offset = last_line_width(&expr_str) + 1;
let rhs_overhead = shape.rhs_overhead(context.config);
let index_shape = if expr_str.contains('\n') {
Shape::legacy(context.config.max_width(), shape.indent)
.offset_left(offset)
.and_then(|shape| shape.sub_width(1 + rhs_overhead))
} else {
match context.config.indent_style() {
IndentStyle::Block => shape
.offset_left(offset)
.and_then(|shape| shape.sub_width(1)),
IndentStyle::Visual => shape.visual_indent(offset).sub_width(offset + 1),
}
};
let orig_index_rw = index_shape.and_then(|s| index.rewrite(context, s));
// Return if index fits in a single line.
match orig_index_rw {
Some(ref index_str) if !index_str.contains('\n') => {
return Some(format!("{}[{}]", expr_str, index_str));
}
_ => (),
}
// Try putting index on the next line and see if it fits in a single line.
let indent = shape.indent.block_indent(context.config);
let index_shape = Shape::indented(indent, context.config).offset_left(1)?;
let index_shape = index_shape.sub_width(1 + rhs_overhead)?;
let new_index_rw = index.rewrite(context, index_shape);
match (orig_index_rw, new_index_rw) {
(_, Some(ref new_index_str)) if !new_index_str.contains('\n') => Some(format!(
"{}{}[{}]",
expr_str,
indent.to_string_with_newline(context.config),
new_index_str,
)),
(None, Some(ref new_index_str)) => Some(format!(
"{}{}[{}]",
expr_str,
indent.to_string_with_newline(context.config),
new_index_str,
)),
(Some(ref index_str), _) => Some(format!("{}[{}]", expr_str, index_str)),
_ => None,
}
}
fn struct_lit_can_be_aligned(fields: &[ast::Field], base: Option<&ast::Expr>) -> bool {
if base.is_some() {
return false;
}
fields.iter().all(|field| !field.is_shorthand)
}
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 = shape.sub_width(2)?;
let path_str = rewrite_path(context, PathContext::Expr, None, path, path_shape)?;
if fields.is_empty() && base.is_none() {
return Some(format!("{} {{}}", path_str));
}
// Foo { a: Foo } - indent is +3, width is -5.
let (h_shape, v_shape) = struct_lit_shape(shape, context, path_str.len() + 3, 2)?;
let one_line_width = h_shape.map_or(0, |shape| shape.width);
let body_lo = context.snippet_provider.span_after(span, "{");
let fields_str = if struct_lit_can_be_aligned(fields, base)
&& context.config.struct_field_align_threshold() > 0
{
rewrite_with_alignment(
fields,
context,
v_shape,
mk_sp(body_lo, span.hi()),
one_line_width,
)?
} else {
let field_iter = fields
.iter()
.map(StructLitField::Regular)
.chain(base.into_iter().map(StructLitField::Base));
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, v_shape.sub_width(1)?, 0)
}
StructLitField::Base(expr) => {
// 2 = ..
expr.rewrite(context, v_shape.offset_left(2)?)
.map(|s| format!("..{}", s))
}
};
let items = itemize_list(
context.snippet_provider,
field_iter,
"}",
",",
span_lo,
span_hi,
rewrite,
body_lo,
span.hi(),
false,
);
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 ends_with_comma = span_ends_with_comma(context, span);
let force_no_trailing_comma = context.inside_macro() && !ends_with_comma;
let fmt = struct_lit_formatting(
nested_shape,
tactic,
context,
force_no_trailing_comma || base.is_some() || !context.use_block_indent(),
);
write_list(&item_vec, &fmt)?
};
let fields_str = wrap_struct_field(context, &fields_str, shape, v_shape, one_line_width);
Some(format!("{} {{{}}}", path_str, fields_str))
// FIXME if context.config.indent_style() == Visual, but we run out
// of space, we should fall back to BlockIndent.
}
pub fn wrap_struct_field(
context: &RewriteContext<'_>,
fields_str: &str,
shape: Shape,
nested_shape: Shape,
one_line_width: usize,
) -> String {
if context.config.indent_style() == IndentStyle::Block
&& (fields_str.contains('\n')
|| !context.config.struct_lit_single_line()
|| fields_str.len() > one_line_width)
{
format!(
"{}{}{}",
nested_shape.indent.to_string_with_newline(context.config),
fields_str,
shape.indent.to_string_with_newline(context.config)
)
} else {
// One liner or visual indent.
format!(" {} ", fields_str)
}
}
pub fn struct_lit_field_separator(config: &Config) -> &str {
colon_spaces(config)
}
pub fn rewrite_field(
context: &RewriteContext<'_>,
field: &ast::Field,
shape: Shape,
prefix_max_width: usize,
) -> Option<String> {
if contains_skip(&field.attrs) {
return Some(context.snippet(field.span()).to_owned());
}
let mut attrs_str = field.attrs.rewrite(context, shape)?;
if !attrs_str.is_empty() {
attrs_str.push_str(&shape.indent.to_string_with_newline(context.config));
};
let name = context.snippet(field.ident.span);
if field.is_shorthand {
Some(attrs_str + name)
} else {
let mut separator = String::from(struct_lit_field_separator(context.config));
for _ in 0..prefix_max_width.saturating_sub(name.len()) {
separator.push(' ');
}
let overhead = name.len() + separator.len();
let expr_shape = shape.offset_left(overhead)?;
let expr = field.expr.rewrite(context, expr_shape);
match expr {
Some(ref e) if e.as_str() == name && context.config.use_field_init_shorthand() => {
Some(attrs_str + name)
}
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 rewrite_tuple_in_visual_indent_style<'a, T: 'a + IntoOverflowableItem<'a>>(
context: &RewriteContext<'_>,
mut items: impl Iterator<Item = &'a T>,
span: Span,
shape: Shape,
is_singleton_tuple: bool,
) -> Option<String> {
// In case of length 1, need a trailing comma
debug!("rewrite_tuple_in_visual_indent_style {:?}", shape);
if is_singleton_tuple {
// 3 = "(" + ",)"
let nested_shape = shape.sub_width(3)?.visual_indent(1);
return items
.next()
.unwrap()
.rewrite(context, nested_shape)
.map(|s| format!("({},)", s));
}
let list_lo = context.snippet_provider.span_after(span, "(");
let nested_shape = shape.sub_width(2)?.visual_indent(1);
let items = itemize_list(
context.snippet_provider,
items,
")",
",",
|item| item.span().lo(),
|item| item.span().hi(),
|item| item.rewrite(context, nested_shape),
list_lo,
span.hi() - BytePos(1),
false,
);
let item_vec: Vec<_> = items.collect();
let tactic = definitive_tactic(
&item_vec,
ListTactic::HorizontalVertical,
Separator::Comma,
nested_shape.width,
);
let fmt = ListFormatting::new(nested_shape, context.config)
.tactic(tactic)
.ends_with_newline(false);
let list_str = write_list(&item_vec, &fmt)?;
Some(format!("({})", list_str))
}
pub fn rewrite_tuple<'a, T: 'a + IntoOverflowableItem<'a>>(
context: &'a RewriteContext<'_>,
items: impl Iterator<Item = &'a T>,
span: Span,
shape: Shape,
is_singleton_tuple: bool,
) -> Option<String> {
debug!("rewrite_tuple {:?}", shape);
if context.use_block_indent() {
// We use the same rule as function calls for rewriting tuples.
let force_tactic = if context.inside_macro() {
if span_ends_with_comma(context, span) {
Some(SeparatorTactic::Always)
} else {
Some(SeparatorTactic::Never)
}
} else if is_singleton_tuple {
Some(SeparatorTactic::Always)
} else {
None
};
overflow::rewrite_with_parens(
context,
"",
items,
shape,
span,
context.config.width_heuristics().fn_call_width,
force_tactic,
)
} else {
rewrite_tuple_in_visual_indent_style(context, items, span, shape, is_singleton_tuple)
}
}
pub fn rewrite_unary_prefix<R: Rewrite>(
context: &RewriteContext<'_>,
prefix: &str,
rewrite: &R,
shape: Shape,
) -> Option<String> {
rewrite
.rewrite(context, 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<R: Rewrite>(
context: &RewriteContext<'_>,
suffix: &str,
rewrite: &R,
shape: Shape,
) -> Option<String> {
rewrite
.rewrite(context, 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!
rewrite_unary_prefix(context, ast::UnOp::to_string(op), expr, shape)
}
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 => "=",
};
// 1 = space between lhs and operator.
let lhs_shape = shape.sub_width(operator_str.len() + 1)?;
let lhs_str = format!("{} {}", lhs.rewrite(context, lhs_shape)?, operator_str);
rewrite_assign_rhs(context, lhs_str, rhs, shape)
}
/// Controls where to put the rhs.
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub enum RhsTactics {
/// Use heuristics.
Default,
/// Put the rhs on the next line if it uses multiple line, without extra indentation.
ForceNextLineWithoutIndent,
}
// The left hand side must contain everything up to, and including, the
// assignment operator.
pub fn rewrite_assign_rhs<S: Into<String>, R: Rewrite>(
context: &RewriteContext<'_>,
lhs: S,
ex: &R,
shape: Shape,
) -> Option<String> {
rewrite_assign_rhs_with(context, lhs, ex, shape, RhsTactics::Default)
}
pub fn rewrite_assign_rhs_with<S: Into<String>, R: Rewrite>(
context: &RewriteContext<'_>,
lhs: S,
ex: &R,
shape: Shape,
rhs_tactics: RhsTactics,
) -> Option<String> {
let lhs = lhs.into();
let last_line_width = last_line_width(&lhs).saturating_sub(if lhs.contains('\n') {
shape.indent.width()
} else {
0
});
// 1 = space between operator and rhs.
let orig_shape = shape.offset_left(last_line_width + 1).unwrap_or(Shape {
width: 0,
offset: shape.offset + last_line_width + 1,
..shape
});
let rhs = choose_rhs(
context,
ex,
orig_shape,
ex.rewrite(context, orig_shape),
rhs_tactics,
)?;
Some(lhs + &rhs)
}
fn choose_rhs<R: Rewrite>(
context: &RewriteContext<'_>,
expr: &R,
shape: Shape,
orig_rhs: Option<String>,
rhs_tactics: RhsTactics,
) -> Option<String> {
match orig_rhs {
Some(ref new_str) if !new_str.contains('\n') && new_str.len() <= shape.width => {
Some(format!(" {}", new_str))
}
_ => {
// Expression did not fit on the same line as the identifier.
// Try splitting the line and see if that works better.
let new_shape = shape_from_rhs_tactic(context, shape, rhs_tactics)?;
let new_rhs = expr.rewrite(context, new_shape);
let new_indent_str = &shape
.indent
.block_indent(context.config)
.to_string_with_newline(context.config);
match (orig_rhs, new_rhs) {
(Some(ref orig_rhs), Some(ref new_rhs))
if wrap_str(new_rhs.clone(), context.config.max_width(), new_shape)
.is_none() =>
{
Some(format!(" {}", orig_rhs))
}
(Some(ref orig_rhs), Some(ref new_rhs))
if prefer_next_line(orig_rhs, new_rhs, rhs_tactics) =>
{
Some(format!("{}{}", new_indent_str, new_rhs))
}
(None, Some(ref new_rhs)) => Some(format!("{}{}", new_indent_str, new_rhs)),
(None, None) => None,
(Some(orig_rhs), _) => Some(format!(" {}", orig_rhs)),
}
}
}
}
fn shape_from_rhs_tactic(
context: &RewriteContext<'_>,
shape: Shape,
rhs_tactic: RhsTactics,
) -> Option<Shape> {
match rhs_tactic {
RhsTactics::ForceNextLineWithoutIndent => shape
.with_max_width(context.config)
.sub_width(shape.indent.width()),
RhsTactics::Default => {
Shape::indented(shape.indent.block_indent(context.config), context.config)
.sub_width(shape.rhs_overhead(context.config))
}
}
}
pub fn prefer_next_line(orig_rhs: &str, next_line_rhs: &str, rhs_tactics: RhsTactics) -> bool {
rhs_tactics == RhsTactics::ForceNextLineWithoutIndent
|| !next_line_rhs.contains('\n')
|| count_newlines(orig_rhs) > count_newlines(next_line_rhs) + 1
|| first_line_ends_with(orig_rhs, '(') && !first_line_ends_with(next_line_rhs, '(')
|| first_line_ends_with(orig_rhs, '{') && !first_line_ends_with(next_line_rhs, '{')
|| first_line_ends_with(orig_rhs, '[') && !first_line_ends_with(next_line_rhs, '[')
}
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)
}
pub fn is_method_call(expr: &ast::Expr) -> bool {
match expr.node {
ast::ExprKind::MethodCall(..) => true,
ast::ExprKind::AddrOf(_, ref expr)
| ast::ExprKind::Box(ref expr)
| ast::ExprKind::Cast(ref expr, _)
| ast::ExprKind::Try(ref expr)
| ast::ExprKind::Unary(_, ref expr) => is_method_call(expr),
_ => false,
}
}
#[cfg(test)]
mod test {
use super::last_line_offsetted;
#[test]
fn test_last_line_offsetted() {
let lines = "one\n two";
assert_eq!(last_line_offsetted(2, lines), true);
assert_eq!(last_line_offsetted(4, lines), false);
assert_eq!(last_line_offsetted(6, lines), false);
let lines = "one two";
assert_eq!(last_line_offsetted(2, lines), false);
assert_eq!(last_line_offsetted(0, lines), false);
let lines = "\ntwo";
assert_eq!(last_line_offsetted(2, lines), false);
assert_eq!(last_line_offsetted(0, lines), false);
let lines = "one\n two three";
assert_eq!(last_line_offsetted(2, lines), true);
let lines = "one\n two three";
assert_eq!(last_line_offsetted(2, lines), false);
}
}
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