/// alignment).
/// E.g., `let foo = { aaaa; bbb; ccc }.bar.baz();`, we would layout for the
/// following values of `chain_indent`:
+/// Block:
+/// ```
+/// let foo = {
+/// aaaa;
+/// bbb;
+/// ccc
+/// }.bar
+/// .baz();
+/// ```
/// Visual:
/// ```
/// let foo = {
/// .bar
/// .baz();
/// ```
-/// Inherit:
-/// ```
-/// let foo = {
-/// aaaa;
-/// bbb;
-/// ccc
-/// }
-/// .bar
-/// .baz();
-/// ```
-/// Tabbed:
-/// ```
-/// let foo = {
-/// aaaa;
-/// bbb;
-/// ccc
-/// }
-/// .bar
-/// .baz();
-/// ```
///
/// If the first item in the chain is a block expression, we align the dots with
/// the braces.
-/// Visual:
-/// ```
-/// let a = foo.bar
-/// .baz()
-/// .qux
-/// ```
-/// Inherit:
+/// Block:
/// ```
/// let a = foo.bar
-/// .baz()
-/// .qux
+/// .baz()
+/// .qux
/// ```
-/// Tabbed:
+/// Visual:
/// ```
/// let a = foo.bar
-/// .baz()
-/// .qux
+/// .baz()
+/// .qux
/// ```
use shape::Shape;
use expr::rewrite_call;
use macros::convert_try_mac;
use rewrite::{Rewrite, RewriteContext};
-use utils::{first_line_width, last_line_extendable, last_line_width, mk_sp, wrap_str};
+use utils::{first_line_width, last_line_extendable, last_line_width, mk_sp,
+ trimmed_last_line_width, wrap_str};
use std::cmp::min;
use std::iter;
let first_child_shape = if extend {
let overhead = last_line_width(&parent_rewrite);
- let offset = parent_rewrite.lines().rev().next().unwrap().trim().len();
+ let offset = trimmed_last_line_width(&parent_rewrite);
match context.config.chain_indent() {
IndentStyle::Visual => parent_shape.offset_left(overhead)?,
IndentStyle::Block => parent_shape.block().offset_left(offset)?,
last_line_width(&parent_rewrite)
} else {
rewrites.iter().fold(0, |a, b| a + b.len()) + parent_rewrite.len()
- };
+ } + suffix_try_num;
let one_line_budget = if rewrites.is_empty() && !context.config.chain_split_single_child() {
shape.width
} else {
let all_in_one_line = !parent_rewrite_contains_newline
&& rewrites.iter().all(|s| !s.contains('\n'))
&& almost_total < one_line_budget;
- let rewrite_last = || rewrite_chain_subexpr(last_subexpr, total_span, context, nested_shape);
+ let last_shape = match context.config.chain_indent() {
+ IndentStyle::Visual => other_child_shape.sub_width(shape.rhs_overhead(context.config))?,
+ IndentStyle::Block => other_child_shape,
+ };
+ let last_shape = last_shape.sub_width(suffix_try_num)?;
+
+ // Rewrite the last child. The last child of a chain requires special treatment. We need to
+ // know whether 'overflowing' the last child make a better formatting:
+ //
+ // A chain with overflowing the last child:
+ // ```
+ // parent.child1.child2.last_child(
+ // a,
+ // b,
+ // c,
+ // )
+ // ```
+ //
+ // A chain without overflowing the last child (in vertical layout):
+ // ```
+ // parent
+ // .child1
+ // .child2
+ // .last_child(a, b, c)
+ // ```
+ //
+ // In particular, overflowing is effective when the last child is a method with a multi-lined
+ // block-like argument (e.g. closure):
+ // ```
+ // parent.child1.chlid2.last_child(|a, b, c| {
+ // let x = foo(a, b, c);
+ // let y = bar(a, b, c);
+ //
+ // // ...
+ //
+ // result
+ // })
+ // ```
+
+ // `rewrite_last` rewrites the last child on its own line. We use a closure here instead of
+ // directly calling `rewrite_chain_subexpr()` to avoid exponential blowup.
+ let rewrite_last = || rewrite_chain_subexpr(last_subexpr, total_span, context, last_shape);
let (last_subexpr_str, fits_single_line) = if all_in_one_line || extend_last_subexr {
+ // First we try to 'overflow' the last child and see if it looks better than using
+ // vertical layout.
parent_shape.offset_left(almost_total).map(|shape| {
if let Some(rw) = rewrite_chain_subexpr(last_subexpr, total_span, context, shape) {
+ // We allow overflowing here only if both of the following conditions match:
+ // 1. The entire chain fits in a single line expect the last child.
+ // 2. `last_chlid_str.lines().count() >= 5`.
let line_count = rw.lines().count();
let fits_single_line = almost_total + first_line_width(&rw) <= one_line_budget;
- if (line_count >= 5 && fits_single_line) || extend_last_subexr {
+ if fits_single_line && line_count >= 5 {
(Some(rw), true)
} else {
+ // We could not know whether overflowing is better than using vertical layout,
+ // just by looking at the overflowed rewrite. Now we rewrite the last child
+ // on its own line, and compare two rewrites to choose which is better.
match rewrite_last() {
Some(ref new_rw) if !fits_single_line => (Some(new_rw.clone()), false),
Some(ref new_rw) if new_rw.lines().count() >= line_count => {
connector.as_str()
};
- let subexpr_num = subexpr_list.len();
let result = if is_small_parent && rewrites.len() > 1 {
- let second_connector = choose_first_connector(
- context,
- &rewrites[0],
- &rewrites[1],
- &connector,
- &subexpr_list[..subexpr_num - 1],
- false,
- );
+ let second_connector = if fits_single_line || rewrites[1] == "?"
+ || last_line_extendable(&rewrites[0])
+ || context.config.chain_indent() == IndentStyle::Visual
+ {
+ ""
+ } else {
+ &connector
+ };
format!(
"{}{}{}{}{}",
parent_rewrite,
first_connector,
rewrites[0],
second_connector,
- join_rewrites(&rewrites[1..], &subexpr_list[..subexpr_num - 1], &connector)
+ join_rewrites(&rewrites[1..], &connector)
)
} else {
format!(
"{}{}{}",
parent_rewrite,
first_connector,
- join_rewrites(&rewrites, subexpr_list, &connector)
+ join_rewrites(&rewrites, &connector)
)
};
let result = format!("{}{}", result, repeat_try(suffix_try_num));
- wrap_str(result, context.config.max_width(), shape)
-}
-
-fn is_extendable_parent(context: &RewriteContext, parent_str: &str) -> bool {
- context.config.chain_indent() == IndentStyle::Block && last_line_extendable(parent_str)
+ if context.config.chain_indent() == IndentStyle::Visual {
+ wrap_str(result, context.config.max_width(), shape)
+ } else {
+ Some(result)
+ }
}
// True if the chain is only `?`s.
Some(format!("{}{}", sub_expr, repeat_try(try_count)))
}
-fn join_rewrites(rewrites: &[String], subexps: &[ast::Expr], connector: &str) -> String {
+fn join_rewrites(rewrites: &[String], connector: &str) -> String {
let mut rewrite_iter = rewrites.iter();
let mut result = rewrite_iter.next().unwrap().clone();
- let mut subexpr_iter = subexps.iter().rev();
- subexpr_iter.next();
- for (rewrite, expr) in rewrite_iter.zip(subexpr_iter) {
- match expr.node {
- ast::ExprKind::Try(_) => (),
- _ => result.push_str(connector),
- };
+ for rewrite in rewrite_iter {
+ if rewrite != "?" {
+ result.push_str(connector);
+ }
result.push_str(&rewrite[..]);
}
}
}
-fn choose_first_connector<'a>(
- context: &RewriteContext,
- parent_str: &str,
- first_child_str: &str,
- connector: &'a str,
- subexpr_list: &[ast::Expr],
- extend: bool,
-) -> &'a str {
- if subexpr_list.is_empty() {
- ""
- } else if extend || subexpr_list.last().map_or(false, is_try)
- || is_extendable_parent(context, parent_str)
- {
- // 1 = ";", being conservative here.
- if last_line_width(parent_str) + first_line_width(first_child_str) + 1
- <= context.config.max_width()
- {
- ""
- } else {
- connector
- }
- } else {
- connector
- }
-}
-
fn rewrite_method_call(
method_name: ast::Ident,
types: &[ptr::P<ast::Ty>],
projects / rust.git / blobdiff