873 lines
30 KiB
Rust
873 lines
30 KiB
Rust
// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! Formatting of chained expressions, i.e. expressions which are chained by
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//! dots: struct and enum field access, method calls, and try shorthand (?).
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//!
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//! Instead of walking these subexpressions one-by-one, as is our usual strategy
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//! for expression formatting, we collect maximal sequences of these expressions
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//! and handle them simultaneously.
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//!
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//! Whenever possible, the entire chain is put on a single line. If that fails,
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//! we put each subexpression on a separate, much like the (default) function
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//! argument function argument strategy.
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//!
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//! Depends on config options: `chain_indent` is the indent to use for
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//! blocks in the parent/root/base of the chain (and the rest of the chain's
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//! alignment).
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//! E.g., `let foo = { aaaa; bbb; ccc }.bar.baz();`, we would layout for the
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//! following values of `chain_indent`:
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//! Block:
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//!
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//! ```ignore
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//! let foo = {
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//! aaaa;
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//! bbb;
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//! ccc
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//! }.bar
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//! .baz();
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//! ```
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//!
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//! Visual:
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//!
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//! ```ignore
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//! let foo = {
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//! aaaa;
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//! bbb;
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//! ccc
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//! }
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//! .bar
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//! .baz();
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//! ```
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//!
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//! If the first item in the chain is a block expression, we align the dots with
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//! the braces.
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//! Block:
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//!
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//! ```ignore
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//! let a = foo.bar
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//! .baz()
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//! .qux
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//! ```
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//!
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//! Visual:
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//!
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//! ```ignore
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//! let a = foo.bar
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//! .baz()
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//! .qux
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//! ```
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use comment::rewrite_comment;
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use config::IndentStyle;
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use expr::rewrite_call;
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use lists::{extract_post_comment, extract_pre_comment, get_comment_end};
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use macros::convert_try_mac;
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use rewrite::{Rewrite, RewriteContext};
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use shape::Shape;
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use source_map::SpanUtils;
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use utils::{
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first_line_width, last_line_extendable, last_line_width, mk_sp, trimmed_last_line_width,
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wrap_str,
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};
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use std::borrow::Cow;
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use std::cmp::min;
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use std::iter;
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use syntax::source_map::{BytePos, Span};
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use syntax::{ast, ptr};
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pub fn rewrite_chain(expr: &ast::Expr, context: &RewriteContext, shape: Shape) -> Option<String> {
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let chain = Chain::from_ast(expr, context);
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debug!("rewrite_chain {:?} {:?}", chain, shape);
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// If this is just an expression with some `?`s, then format it trivially and
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// return early.
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if chain.children.is_empty() {
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return chain.parent.rewrite(context, shape);
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}
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chain.rewrite(context, shape)
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}
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#[derive(Debug)]
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enum CommentPosition {
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Back,
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Top,
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}
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// An expression plus trailing `?`s to be formatted together.
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#[derive(Debug)]
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struct ChainItem {
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kind: ChainItemKind,
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tries: usize,
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span: Span,
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}
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// FIXME: we can't use a reference here because to convert `try!` to `?` we
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// synthesise the AST node. However, I think we could use `Cow` and that
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// would remove a lot of cloning.
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#[derive(Debug)]
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enum ChainItemKind {
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Parent(ast::Expr),
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MethodCall(
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ast::PathSegment,
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Vec<ast::GenericArg>,
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Vec<ptr::P<ast::Expr>>,
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),
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StructField(ast::Ident),
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TupleField(ast::Ident, bool),
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Comment(String, CommentPosition),
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}
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impl ChainItemKind {
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fn is_block_like(&self, context: &RewriteContext, reps: &str) -> bool {
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match self {
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ChainItemKind::Parent(ref expr) => is_block_expr(context, expr, reps),
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ChainItemKind::MethodCall(..) => reps.contains('\n'),
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ChainItemKind::StructField(..)
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| ChainItemKind::TupleField(..)
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| ChainItemKind::Comment(..) => false,
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}
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}
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fn is_tup_field_access(expr: &ast::Expr) -> bool {
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match expr.node {
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ast::ExprKind::Field(_, ref field) => {
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field.name.to_string().chars().all(|c| c.is_digit(10))
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}
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_ => false,
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}
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}
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fn from_ast(context: &RewriteContext, expr: &ast::Expr) -> (ChainItemKind, Span) {
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let (kind, span) = match expr.node {
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ast::ExprKind::MethodCall(ref segment, ref expressions) => {
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let types = if let Some(ref generic_args) = segment.args {
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if let ast::GenericArgs::AngleBracketed(ref data) = **generic_args {
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data.args.clone()
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} else {
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vec![]
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}
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} else {
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vec![]
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};
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let span = mk_sp(expressions[0].span.hi(), expr.span.hi());
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let kind = ChainItemKind::MethodCall(segment.clone(), types, expressions.clone());
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(kind, span)
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}
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ast::ExprKind::Field(ref nested, field) => {
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let kind = if Self::is_tup_field_access(expr) {
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ChainItemKind::TupleField(field, Self::is_tup_field_access(nested))
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} else {
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ChainItemKind::StructField(field)
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};
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let span = mk_sp(nested.span.hi(), field.span.hi());
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(kind, span)
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}
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_ => return (ChainItemKind::Parent(expr.clone()), expr.span),
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};
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// Remove comments from the span.
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let lo = context.snippet_provider.span_before(span, ".");
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(kind, mk_sp(lo, span.hi()))
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}
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}
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impl Rewrite for ChainItem {
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fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
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let shape = shape.sub_width(self.tries)?;
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let rewrite = match self.kind {
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ChainItemKind::Parent(ref expr) => expr.rewrite(context, shape)?,
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ChainItemKind::MethodCall(ref segment, ref types, ref exprs) => {
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Self::rewrite_method_call(segment.ident, types, exprs, self.span, context, shape)?
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}
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ChainItemKind::StructField(ident) => format!(".{}", ident.name),
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ChainItemKind::TupleField(ident, nested) => {
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format!("{}.{}", if nested { " " } else { "" }, ident.name)
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}
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ChainItemKind::Comment(ref comment, _) => {
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rewrite_comment(comment, false, shape, context.config)?
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}
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};
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Some(format!("{}{}", rewrite, "?".repeat(self.tries)))
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}
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}
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impl ChainItem {
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fn new(context: &RewriteContext, expr: &ast::Expr, tries: usize) -> ChainItem {
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let (kind, span) = ChainItemKind::from_ast(context, expr);
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ChainItem { kind, tries, span }
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}
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fn comment(span: Span, comment: String, pos: CommentPosition) -> ChainItem {
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ChainItem {
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kind: ChainItemKind::Comment(comment, pos),
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tries: 0,
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span,
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}
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}
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fn is_comment(&self) -> bool {
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match self.kind {
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ChainItemKind::Comment(..) => true,
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_ => false,
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}
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}
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fn rewrite_method_call(
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method_name: ast::Ident,
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types: &[ast::GenericArg],
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args: &[ptr::P<ast::Expr>],
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span: Span,
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context: &RewriteContext,
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shape: Shape,
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) -> Option<String> {
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let type_str = if types.is_empty() {
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String::new()
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} else {
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let type_list = types
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.iter()
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.map(|ty| ty.rewrite(context, shape))
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.collect::<Option<Vec<_>>>()?;
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format!("::<{}>", type_list.join(", "))
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};
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let callee_str = format!(".{}{}", method_name, type_str);
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rewrite_call(context, &callee_str, &args[1..], span, shape)
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}
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}
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#[derive(Debug)]
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struct Chain {
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parent: ChainItem,
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children: Vec<ChainItem>,
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}
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impl Chain {
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fn from_ast(expr: &ast::Expr, context: &RewriteContext) -> Chain {
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let subexpr_list = Self::make_subexpr_list(expr, context);
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// Un-parse the expression tree into ChainItems
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let mut rev_children = vec![];
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let mut sub_tries = 0;
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for subexpr in &subexpr_list {
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match subexpr.node {
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ast::ExprKind::Try(_) => sub_tries += 1,
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_ => {
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rev_children.push(ChainItem::new(context, subexpr, sub_tries));
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sub_tries = 0;
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}
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}
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}
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fn is_tries(s: &str) -> bool {
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s.chars().all(|c| c == '?')
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}
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fn handle_post_comment(
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post_comment_span: Span,
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post_comment_snippet: &str,
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prev_span_end: &mut BytePos,
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children: &mut Vec<ChainItem>,
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) {
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let white_spaces: &[_] = &[' ', '\t'];
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if post_comment_snippet
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.trim_matches(white_spaces)
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.starts_with('\n')
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{
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// No post comment.
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return;
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}
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// HACK: Treat `?`s as separators.
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let trimmed_snippet = post_comment_snippet.trim_matches('?');
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let comment_end = get_comment_end(trimmed_snippet, "?", "", false);
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let maybe_post_comment = extract_post_comment(trimmed_snippet, comment_end, "?")
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.and_then(|comment| {
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if comment.is_empty() {
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None
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} else {
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Some((comment, comment_end))
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}
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});
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if let Some((post_comment, comment_end)) = maybe_post_comment {
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children.push(ChainItem::comment(
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post_comment_span,
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post_comment,
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CommentPosition::Back,
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));
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*prev_span_end = *prev_span_end + BytePos(comment_end as u32);
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}
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}
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let parent = rev_children.pop().unwrap();
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let mut children = vec![];
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let mut prev_span_end = parent.span.hi();
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let mut iter = rev_children.into_iter().rev().peekable();
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if let Some(first_chain_item) = iter.peek() {
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let comment_span = mk_sp(prev_span_end, first_chain_item.span.lo());
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let comment_snippet = context.snippet(comment_span);
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if !is_tries(comment_snippet.trim()) {
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handle_post_comment(
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comment_span,
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comment_snippet,
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&mut prev_span_end,
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&mut children,
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);
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}
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}
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while let Some(chain_item) = iter.next() {
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let comment_snippet = context.snippet(chain_item.span);
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// FIXME: Figure out the way to get a correct span when converting `try!` to `?`.
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let handle_comment =
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!(context.config.use_try_shorthand() || is_tries(comment_snippet.trim()));
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// Pre-comment
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if handle_comment {
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let pre_comment_span = mk_sp(prev_span_end, chain_item.span.lo());
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let pre_comment_snippet = context.snippet(pre_comment_span);
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let pre_comment_snippet = pre_comment_snippet.trim().trim_matches('?');
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let (pre_comment, _) = extract_pre_comment(pre_comment_snippet);
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match pre_comment {
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Some(ref comment) if !comment.is_empty() => {
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children.push(ChainItem::comment(
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pre_comment_span,
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comment.to_owned(),
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CommentPosition::Top,
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));
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}
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_ => (),
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}
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}
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prev_span_end = chain_item.span.hi();
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children.push(chain_item);
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// Post-comment
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if !handle_comment || iter.peek().is_none() {
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continue;
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}
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let next_lo = iter.peek().unwrap().span.lo();
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let post_comment_span = mk_sp(prev_span_end, next_lo);
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let post_comment_snippet = context.snippet(post_comment_span);
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handle_post_comment(
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post_comment_span,
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post_comment_snippet,
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&mut prev_span_end,
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&mut children,
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);
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}
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Chain { parent, children }
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}
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// Returns a Vec of the prefixes of the chain.
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// E.g., for input `a.b.c` we return [`a.b.c`, `a.b`, 'a']
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fn make_subexpr_list(expr: &ast::Expr, context: &RewriteContext) -> Vec<ast::Expr> {
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let mut subexpr_list = vec![expr.clone()];
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while let Some(subexpr) = Self::pop_expr_chain(subexpr_list.last().unwrap(), context) {
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subexpr_list.push(subexpr.clone());
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}
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subexpr_list
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}
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// Returns the expression's subexpression, if it exists. When the subexpr
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// is a try! macro, we'll convert it to shorthand when the option is set.
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fn pop_expr_chain(expr: &ast::Expr, context: &RewriteContext) -> Option<ast::Expr> {
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match expr.node {
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ast::ExprKind::MethodCall(_, ref expressions) => {
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Some(Self::convert_try(&expressions[0], context))
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}
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ast::ExprKind::Field(ref subexpr, _) | ast::ExprKind::Try(ref subexpr) => {
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Some(Self::convert_try(subexpr, context))
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}
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_ => None,
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}
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}
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fn convert_try(expr: &ast::Expr, context: &RewriteContext) -> ast::Expr {
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match expr.node {
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ast::ExprKind::Mac(ref mac) if context.config.use_try_shorthand() => {
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if let Some(subexpr) = convert_try_mac(mac, context) {
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subexpr
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} else {
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expr.clone()
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}
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}
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_ => expr.clone(),
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}
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}
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}
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impl Rewrite for Chain {
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fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
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debug!("rewrite chain {:?} {:?}", self, shape);
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let mut formatter = match context.config.indent_style() {
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IndentStyle::Block => Box::new(ChainFormatterBlock::new(self)) as Box<ChainFormatter>,
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IndentStyle::Visual => Box::new(ChainFormatterVisual::new(self)) as Box<ChainFormatter>,
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};
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formatter.format_root(&self.parent, context, shape)?;
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if let Some(result) = formatter.pure_root() {
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return wrap_str(result, context.config.max_width(), shape);
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}
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// Decide how to layout the rest of the chain.
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let child_shape = formatter.child_shape(context, shape)?;
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formatter.format_children(context, child_shape)?;
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formatter.format_last_child(context, shape, child_shape)?;
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let result = formatter.join_rewrites(context, child_shape)?;
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wrap_str(result, context.config.max_width(), shape)
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}
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}
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// There are a few types for formatting chains. This is because there is a lot
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// in common between formatting with block vs visual indent, but they are
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// different enough that branching on the indent all over the place gets ugly.
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// Anything that can format a chain is a ChainFormatter.
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trait ChainFormatter {
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// Parent is the first item in the chain, e.g., `foo` in `foo.bar.baz()`.
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// Root is the parent plus any other chain items placed on the first line to
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// avoid an orphan. E.g.,
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// ```
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// foo.bar
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// .baz()
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// ```
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// If `bar` were not part of the root, then foo would be orphaned and 'float'.
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fn format_root(
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&mut self,
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parent: &ChainItem,
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context: &RewriteContext,
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shape: Shape,
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) -> Option<()>;
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fn child_shape(&self, context: &RewriteContext, shape: Shape) -> Option<Shape>;
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fn format_children(&mut self, context: &RewriteContext, child_shape: Shape) -> Option<()>;
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fn format_last_child(
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&mut self,
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context: &RewriteContext,
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shape: Shape,
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child_shape: Shape,
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) -> Option<()>;
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fn join_rewrites(&self, context: &RewriteContext, child_shape: Shape) -> Option<String>;
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// Returns `Some` if the chain is only a root, None otherwise.
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fn pure_root(&mut self) -> Option<String>;
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}
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// Data and behaviour that is shared by both chain formatters. The concrete
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// formatters can delegate much behaviour to `ChainFormatterShared`.
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struct ChainFormatterShared<'a> {
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// The current working set of child items.
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children: &'a [ChainItem],
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// The current rewrites of items (includes trailing `?`s, but not any way to
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// connect the rewrites together).
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rewrites: Vec<String>,
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// Whether the chain can fit on one line.
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fits_single_line: bool,
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// The number of children in the chain. This is not equal to `self.children.len()`
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// because `self.children` will change size as we process the chain.
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child_count: usize,
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}
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impl<'a> ChainFormatterShared<'a> {
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fn new(chain: &'a Chain) -> ChainFormatterShared<'a> {
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ChainFormatterShared {
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children: &chain.children,
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rewrites: Vec::with_capacity(chain.children.len() + 1),
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fits_single_line: false,
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child_count: chain.children.len(),
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}
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}
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fn pure_root(&mut self) -> Option<String> {
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if self.children.is_empty() {
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assert_eq!(self.rewrites.len(), 1);
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Some(self.rewrites.pop().unwrap())
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} else {
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None
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}
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}
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|
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// Rewrite the last child. The last child of a chain requires special treatment. We need to
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// know whether 'overflowing' the last child make a better formatting:
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//
|
|
// 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.child2.last_child(|a, b, c| {
|
|
// let x = foo(a, b, c);
|
|
// let y = bar(a, b, c);
|
|
//
|
|
// // ...
|
|
//
|
|
// result
|
|
// })
|
|
// ```
|
|
fn format_last_child(
|
|
&mut self,
|
|
may_extend: bool,
|
|
context: &RewriteContext,
|
|
shape: Shape,
|
|
child_shape: Shape,
|
|
) -> Option<()> {
|
|
let last = self.children.last()?;
|
|
let extendable = may_extend && last_line_extendable(&self.rewrites[0]);
|
|
let prev_last_line_width = last_line_width(&self.rewrites[0]);
|
|
|
|
// Total of all items excluding the last.
|
|
let almost_total = if extendable {
|
|
prev_last_line_width
|
|
} else {
|
|
self.rewrites.iter().fold(0, |a, b| a + b.len())
|
|
} + last.tries;
|
|
let one_line_budget = if self.child_count == 1 {
|
|
shape.width
|
|
} else {
|
|
min(shape.width, context.config.width_heuristics().chain_width)
|
|
}.saturating_sub(almost_total);
|
|
|
|
let all_in_one_line = !self.children.iter().any(ChainItem::is_comment)
|
|
&& self.rewrites.iter().all(|s| !s.contains('\n'))
|
|
&& one_line_budget > 0;
|
|
let last_shape = if all_in_one_line {
|
|
shape.sub_width(last.tries)?
|
|
} else if extendable {
|
|
child_shape.sub_width(last.tries)?
|
|
} else {
|
|
child_shape.sub_width(shape.rhs_overhead(context.config) + last.tries)?
|
|
};
|
|
|
|
let mut last_subexpr_str = None;
|
|
if all_in_one_line || extendable {
|
|
// First we try to 'overflow' the last child and see if it looks better than using
|
|
// vertical layout.
|
|
if let Some(one_line_shape) = last_shape.offset_left(almost_total) {
|
|
if let Some(rw) = last.rewrite(context, one_line_shape) {
|
|
// We allow overflowing here only if both of the following conditions match:
|
|
// 1. The entire chain fits in a single line except the last child.
|
|
// 2. `last_child_str.lines().count() >= 5`.
|
|
let line_count = rw.lines().count();
|
|
let could_fit_single_line = first_line_width(&rw) <= one_line_budget;
|
|
if could_fit_single_line && line_count >= 5 {
|
|
last_subexpr_str = Some(rw);
|
|
self.fits_single_line = all_in_one_line;
|
|
} 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.
|
|
let last_shape = child_shape
|
|
.sub_width(shape.rhs_overhead(context.config) + last.tries)?;
|
|
match last.rewrite(context, last_shape) {
|
|
Some(ref new_rw) if !could_fit_single_line => {
|
|
last_subexpr_str = Some(new_rw.clone());
|
|
}
|
|
Some(ref new_rw) if new_rw.lines().count() >= line_count => {
|
|
last_subexpr_str = Some(rw);
|
|
self.fits_single_line = could_fit_single_line && all_in_one_line;
|
|
}
|
|
new_rw @ Some(..) => {
|
|
last_subexpr_str = new_rw;
|
|
}
|
|
_ => {
|
|
last_subexpr_str = Some(rw);
|
|
self.fits_single_line = could_fit_single_line && all_in_one_line;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
last_subexpr_str = last_subexpr_str.or_else(|| last.rewrite(context, last_shape));
|
|
self.rewrites.push(last_subexpr_str?);
|
|
Some(())
|
|
}
|
|
|
|
fn join_rewrites(
|
|
&self,
|
|
context: &RewriteContext,
|
|
child_shape: Shape,
|
|
block_like_iter: impl Iterator<Item = bool>,
|
|
) -> Option<String> {
|
|
let connector = if self.fits_single_line {
|
|
// Yay, we can put everything on one line.
|
|
Cow::from("")
|
|
} else {
|
|
// Use new lines.
|
|
if *context.force_one_line_chain.borrow() {
|
|
return None;
|
|
}
|
|
child_shape.to_string_with_newline(context.config)
|
|
};
|
|
|
|
let mut rewrite_iter = self.rewrites.iter();
|
|
let mut result = rewrite_iter.next().unwrap().clone();
|
|
let children_iter = self.children.iter();
|
|
let iter = rewrite_iter.zip(block_like_iter).zip(children_iter);
|
|
|
|
for ((rewrite, prev_is_block_like), chain_item) in iter {
|
|
match chain_item.kind {
|
|
ChainItemKind::Comment(_, CommentPosition::Back) => result.push(' '),
|
|
ChainItemKind::Comment(_, CommentPosition::Top) => result.push_str(&connector),
|
|
_ => {
|
|
if !prev_is_block_like {
|
|
result.push_str(&connector);
|
|
}
|
|
}
|
|
}
|
|
result.push_str(&rewrite);
|
|
}
|
|
|
|
Some(result)
|
|
}
|
|
}
|
|
|
|
// Formats a chain using block indent.
|
|
struct ChainFormatterBlock<'a> {
|
|
shared: ChainFormatterShared<'a>,
|
|
// For each rewrite, whether the corresponding item is block-like.
|
|
is_block_like: Vec<bool>,
|
|
}
|
|
|
|
impl<'a> ChainFormatterBlock<'a> {
|
|
fn new(chain: &'a Chain) -> ChainFormatterBlock<'a> {
|
|
ChainFormatterBlock {
|
|
shared: ChainFormatterShared::new(chain),
|
|
is_block_like: Vec::with_capacity(chain.children.len() + 1),
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'a> ChainFormatter for ChainFormatterBlock<'a> {
|
|
fn format_root(
|
|
&mut self,
|
|
parent: &ChainItem,
|
|
context: &RewriteContext,
|
|
shape: Shape,
|
|
) -> Option<()> {
|
|
let mut root_rewrite: String = parent.rewrite(context, shape)?;
|
|
|
|
let mut root_ends_with_block = parent.kind.is_block_like(context, &root_rewrite);
|
|
let tab_width = context.config.tab_spaces().saturating_sub(shape.offset);
|
|
|
|
while root_rewrite.len() <= tab_width && !root_rewrite.contains('\n') {
|
|
let item = &self.shared.children[0];
|
|
if let ChainItemKind::Comment(..) = item.kind {
|
|
break;
|
|
}
|
|
let shape = shape.offset_left(root_rewrite.len())?;
|
|
match &item.rewrite(context, shape) {
|
|
Some(rewrite) => root_rewrite.push_str(rewrite),
|
|
None => break,
|
|
}
|
|
|
|
root_ends_with_block = item.kind.is_block_like(context, &root_rewrite);
|
|
|
|
self.shared.children = &self.shared.children[1..];
|
|
if self.shared.children.is_empty() {
|
|
break;
|
|
}
|
|
}
|
|
self.is_block_like.push(root_ends_with_block);
|
|
self.shared.rewrites.push(root_rewrite);
|
|
Some(())
|
|
}
|
|
|
|
fn child_shape(&self, context: &RewriteContext, shape: Shape) -> Option<Shape> {
|
|
Some(
|
|
if self.is_block_like[0] {
|
|
shape.block_indent(0)
|
|
} else {
|
|
shape.block_indent(context.config.tab_spaces())
|
|
}.with_max_width(context.config),
|
|
)
|
|
}
|
|
|
|
fn format_children(&mut self, context: &RewriteContext, child_shape: Shape) -> Option<()> {
|
|
for item in &self.shared.children[..self.shared.children.len() - 1] {
|
|
let rewrite = item.rewrite(context, child_shape)?;
|
|
self.is_block_like
|
|
.push(item.kind.is_block_like(context, &rewrite));
|
|
self.shared.rewrites.push(rewrite);
|
|
}
|
|
Some(())
|
|
}
|
|
|
|
fn format_last_child(
|
|
&mut self,
|
|
context: &RewriteContext,
|
|
shape: Shape,
|
|
child_shape: Shape,
|
|
) -> Option<()> {
|
|
self.shared
|
|
.format_last_child(true, context, shape, child_shape)
|
|
}
|
|
|
|
fn join_rewrites(&self, context: &RewriteContext, child_shape: Shape) -> Option<String> {
|
|
self.shared
|
|
.join_rewrites(context, child_shape, self.is_block_like.iter().cloned())
|
|
}
|
|
|
|
fn pure_root(&mut self) -> Option<String> {
|
|
self.shared.pure_root()
|
|
}
|
|
}
|
|
|
|
// Format a chain using visual indent.
|
|
struct ChainFormatterVisual<'a> {
|
|
shared: ChainFormatterShared<'a>,
|
|
// The extra offset from the chain's shape to the position of the `.`
|
|
offset: usize,
|
|
}
|
|
|
|
impl<'a> ChainFormatterVisual<'a> {
|
|
fn new(chain: &'a Chain) -> ChainFormatterVisual<'a> {
|
|
ChainFormatterVisual {
|
|
shared: ChainFormatterShared::new(chain),
|
|
offset: 0,
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'a> ChainFormatter for ChainFormatterVisual<'a> {
|
|
fn format_root(
|
|
&mut self,
|
|
parent: &ChainItem,
|
|
context: &RewriteContext,
|
|
shape: Shape,
|
|
) -> Option<()> {
|
|
let parent_shape = shape.visual_indent(0);
|
|
let mut root_rewrite = parent.rewrite(context, parent_shape)?;
|
|
let multiline = root_rewrite.contains('\n');
|
|
self.offset = if multiline {
|
|
last_line_width(&root_rewrite).saturating_sub(shape.used_width())
|
|
} else {
|
|
trimmed_last_line_width(&root_rewrite)
|
|
};
|
|
|
|
if !multiline || parent.kind.is_block_like(context, &root_rewrite) {
|
|
let item = &self.shared.children[0];
|
|
if let ChainItemKind::Comment(..) = item.kind {
|
|
self.shared.rewrites.push(root_rewrite);
|
|
return Some(());
|
|
}
|
|
let child_shape = parent_shape
|
|
.visual_indent(self.offset)
|
|
.sub_width(self.offset)?;
|
|
let rewrite = item.rewrite(context, child_shape)?;
|
|
match wrap_str(rewrite, context.config.max_width(), shape) {
|
|
Some(rewrite) => root_rewrite.push_str(&rewrite),
|
|
None => {
|
|
// We couldn't fit in at the visual indent, try the last
|
|
// indent.
|
|
let rewrite = item.rewrite(context, parent_shape)?;
|
|
root_rewrite.push_str(&rewrite);
|
|
self.offset = 0;
|
|
}
|
|
}
|
|
|
|
self.shared.children = &self.shared.children[1..];
|
|
}
|
|
|
|
self.shared.rewrites.push(root_rewrite);
|
|
Some(())
|
|
}
|
|
|
|
fn child_shape(&self, context: &RewriteContext, shape: Shape) -> Option<Shape> {
|
|
shape
|
|
.with_max_width(context.config)
|
|
.offset_left(self.offset)
|
|
.map(|s| s.visual_indent(0))
|
|
}
|
|
|
|
fn format_children(&mut self, context: &RewriteContext, child_shape: Shape) -> Option<()> {
|
|
for item in &self.shared.children[..self.shared.children.len() - 1] {
|
|
let rewrite = item.rewrite(context, child_shape)?;
|
|
self.shared.rewrites.push(rewrite);
|
|
}
|
|
Some(())
|
|
}
|
|
|
|
fn format_last_child(
|
|
&mut self,
|
|
context: &RewriteContext,
|
|
shape: Shape,
|
|
child_shape: Shape,
|
|
) -> Option<()> {
|
|
self.shared
|
|
.format_last_child(false, context, shape, child_shape)
|
|
}
|
|
|
|
fn join_rewrites(&self, context: &RewriteContext, child_shape: Shape) -> Option<String> {
|
|
self.shared
|
|
.join_rewrites(context, child_shape, iter::repeat(false))
|
|
}
|
|
|
|
fn pure_root(&mut self) -> Option<String> {
|
|
self.shared.pure_root()
|
|
}
|
|
}
|
|
|
|
// States whether an expression's last line exclusively consists of closing
|
|
// parens, braces, and brackets in its idiomatic formatting.
|
|
fn is_block_expr(context: &RewriteContext, expr: &ast::Expr, repr: &str) -> bool {
|
|
match expr.node {
|
|
ast::ExprKind::Mac(..)
|
|
| ast::ExprKind::Call(..)
|
|
| ast::ExprKind::MethodCall(..)
|
|
| ast::ExprKind::Struct(..)
|
|
| ast::ExprKind::While(..)
|
|
| ast::ExprKind::WhileLet(..)
|
|
| ast::ExprKind::If(..)
|
|
| ast::ExprKind::IfLet(..)
|
|
| ast::ExprKind::Block(..)
|
|
| ast::ExprKind::Loop(..)
|
|
| ast::ExprKind::ForLoop(..)
|
|
| ast::ExprKind::Match(..) => repr.contains('\n'),
|
|
ast::ExprKind::Paren(ref expr)
|
|
| ast::ExprKind::Binary(_, _, ref expr)
|
|
| ast::ExprKind::Index(_, ref expr)
|
|
| ast::ExprKind::Unary(_, ref expr)
|
|
| ast::ExprKind::Closure(_, _, _, _, ref expr, _)
|
|
| ast::ExprKind::Try(ref expr)
|
|
| ast::ExprKind::Yield(Some(ref expr)) => is_block_expr(context, expr, repr),
|
|
// This can only be a string lit
|
|
ast::ExprKind::Lit(_) => {
|
|
repr.contains('\n') && trimmed_last_line_width(repr) <= context.config.tab_spaces()
|
|
}
|
|
_ => false,
|
|
}
|
|
}
|