-// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-//! Formatting of chained expressions, i.e. expressions which are chained by
-//! dots: struct and enum field access, method calls, and try shorthand (?).
+//! Formatting of chained expressions, i.e., expressions that are chained by
+//! dots: struct and enum field access, method calls, and try shorthand (`?`).
//!
//! Instead of walking these subexpressions one-by-one, as is our usual strategy
//! for expression formatting, we collect maximal sequences of these expressions
//! following values of `chain_indent`:
//! Block:
//!
-//! ```ignore
+//! ```text
//! let foo = {
//! aaaa;
//! bbb;
//!
//! Visual:
//!
-//! ```ignore
+//! ```text
//! let foo = {
//! aaaa;
//! bbb;
//! the braces.
//! Block:
//!
-//! ```ignore
+//! ```text
//! let a = foo.bar
//! .baz()
//! .qux
//!
//! Visual:
//!
-//! ```ignore
+//! ```text
//! let a = foo.bar
//! .baz()
//! .qux
//! ```
-use config::IndentStyle;
-use expr::rewrite_call;
-use macros::convert_try_mac;
-use rewrite::{Rewrite, RewriteContext};
-use shape::Shape;
-use spanned::Spanned;
-use utils::{first_line_width, last_line_extendable, last_line_width, mk_sp, wrap_str};
-
use std::borrow::Cow;
use std::cmp::min;
-use syntax::codemap::Span;
+use syntax::source_map::{BytePos, Span};
use syntax::{ast, ptr};
-pub fn rewrite_chain(expr: &ast::Expr, context: &RewriteContext, shape: Shape) -> Option<String> {
- debug!("rewrite_chain {:?}", shape);
+use crate::comment::{rewrite_comment, CharClasses, FullCodeCharKind, RichChar};
+use crate::config::IndentStyle;
+use crate::expr::rewrite_call;
+use crate::lists::extract_pre_comment;
+use crate::macros::convert_try_mac;
+use crate::rewrite::{Rewrite, RewriteContext};
+use crate::shape::Shape;
+use crate::source_map::SpanUtils;
+use crate::utils::{
+ self, first_line_width, last_line_extendable, last_line_width, mk_sp, rewrite_ident,
+ trimmed_last_line_width, wrap_str,
+};
+
+pub(crate) fn rewrite_chain(
+ expr: &ast::Expr,
+ context: &RewriteContext<'_>,
+ shape: Shape,
+) -> Option<String> {
let chain = Chain::from_ast(expr, context);
+ debug!("rewrite_chain {:?} {:?}", chain, shape);
+
// If this is just an expression with some `?`s, then format it trivially and
// return early.
if chain.children.is_empty() {
- let rewrite = chain.parent.expr.rewrite(context, shape.sub_width(chain.parent.tries)?)?;
- return Some(format!("{}{}", rewrite, "?".repeat(chain.parent.tries)));
+ return chain.parent.rewrite(context, shape);
}
- match context.config.indent_style() {
- IndentStyle::Block => rewrite_chain_block(chain, context, shape),
- IndentStyle::Visual => rewrite_chain_visual(chain, context, shape),
- }
+ chain.rewrite(context, shape)
+}
+
+#[derive(Debug)]
+enum CommentPosition {
+ Back,
+ Top,
}
// An expression plus trailing `?`s to be formatted together.
#[derive(Debug)]
struct ChainItem {
- expr: ast::Expr,
+ kind: ChainItemKind,
tries: usize,
+ span: Span,
+}
+
+// FIXME: we can't use a reference here because to convert `try!` to `?` we
+// synthesise the AST node. However, I think we could use `Cow` and that
+// would remove a lot of cloning.
+#[derive(Debug)]
+enum ChainItemKind {
+ Parent(ast::Expr),
+ MethodCall(
+ ast::PathSegment,
+ Vec<ast::GenericArg>,
+ Vec<ptr::P<ast::Expr>>,
+ ),
+ StructField(ast::Ident),
+ TupleField(ast::Ident, bool),
+ Await,
+ Comment(String, CommentPosition),
+}
+
+impl ChainItemKind {
+ fn is_block_like(&self, context: &RewriteContext<'_>, reps: &str) -> bool {
+ match self {
+ ChainItemKind::Parent(ref expr) => utils::is_block_expr(context, expr, reps),
+ ChainItemKind::MethodCall(..)
+ | ChainItemKind::StructField(..)
+ | ChainItemKind::TupleField(..)
+ | ChainItemKind::Await
+ | ChainItemKind::Comment(..) => false,
+ }
+ }
+
+ fn is_tup_field_access(expr: &ast::Expr) -> bool {
+ match expr.kind {
+ ast::ExprKind::Field(_, ref field) => {
+ field.name.to_string().chars().all(|c| c.is_digit(10))
+ }
+ _ => false,
+ }
+ }
+
+ fn from_ast(context: &RewriteContext<'_>, expr: &ast::Expr) -> (ChainItemKind, Span) {
+ let (kind, span) = match expr.kind {
+ ast::ExprKind::MethodCall(ref segment, ref expressions) => {
+ let types = if let Some(ref generic_args) = segment.args {
+ if let ast::GenericArgs::AngleBracketed(ref data) = **generic_args {
+ data.args.clone()
+ } else {
+ vec![]
+ }
+ } else {
+ vec![]
+ };
+ let span = mk_sp(expressions[0].span.hi(), expr.span.hi());
+ let kind = ChainItemKind::MethodCall(segment.clone(), types, expressions.clone());
+ (kind, span)
+ }
+ ast::ExprKind::Field(ref nested, field) => {
+ let kind = if Self::is_tup_field_access(expr) {
+ ChainItemKind::TupleField(field, Self::is_tup_field_access(nested))
+ } else {
+ ChainItemKind::StructField(field)
+ };
+ let span = mk_sp(nested.span.hi(), field.span.hi());
+ (kind, span)
+ }
+ ast::ExprKind::Await(ref nested) => {
+ let span = mk_sp(nested.span.hi(), expr.span.hi());
+ (ChainItemKind::Await, span)
+ }
+ _ => return (ChainItemKind::Parent(expr.clone()), expr.span),
+ };
+
+ // Remove comments from the span.
+ let lo = context.snippet_provider.span_before(span, ".");
+ (kind, mk_sp(lo, span.hi()))
+ }
+}
+
+impl Rewrite for ChainItem {
+ fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
+ let shape = shape.sub_width(self.tries)?;
+ let rewrite = match self.kind {
+ ChainItemKind::Parent(ref expr) => expr.rewrite(context, shape)?,
+ ChainItemKind::MethodCall(ref segment, ref types, ref exprs) => {
+ Self::rewrite_method_call(segment.ident, types, exprs, self.span, context, shape)?
+ }
+ ChainItemKind::StructField(ident) => format!(".{}", rewrite_ident(context, ident)),
+ ChainItemKind::TupleField(ident, nested) => format!(
+ "{}.{}",
+ if nested { " " } else { "" },
+ rewrite_ident(context, ident)
+ ),
+ ChainItemKind::Await => ".await".to_owned(),
+ ChainItemKind::Comment(ref comment, _) => {
+ rewrite_comment(comment, false, shape, context.config)?
+ }
+ };
+ Some(format!("{}{}", rewrite, "?".repeat(self.tries)))
+ }
+}
+
+impl ChainItem {
+ fn new(context: &RewriteContext<'_>, expr: &ast::Expr, tries: usize) -> ChainItem {
+ let (kind, span) = ChainItemKind::from_ast(context, expr);
+ ChainItem { kind, tries, span }
+ }
+
+ fn comment(span: Span, comment: String, pos: CommentPosition) -> ChainItem {
+ ChainItem {
+ kind: ChainItemKind::Comment(comment, pos),
+ tries: 0,
+ span,
+ }
+ }
+
+ fn is_comment(&self) -> bool {
+ match self.kind {
+ ChainItemKind::Comment(..) => true,
+ _ => false,
+ }
+ }
+
+ fn rewrite_method_call(
+ method_name: ast::Ident,
+ types: &[ast::GenericArg],
+ args: &[ptr::P<ast::Expr>],
+ span: Span,
+ context: &RewriteContext<'_>,
+ shape: Shape,
+ ) -> Option<String> {
+ let type_str = if types.is_empty() {
+ String::new()
+ } else {
+ let type_list = types
+ .iter()
+ .map(|ty| ty.rewrite(context, shape))
+ .collect::<Option<Vec<_>>>()?;
+
+ format!("::<{}>", type_list.join(", "))
+ };
+ let callee_str = format!(".{}{}", rewrite_ident(context, method_name), type_str);
+ rewrite_call(context, &callee_str, &args[1..], span, shape)
+ }
}
#[derive(Debug)]
struct Chain {
parent: ChainItem,
- // TODO do we need to clone the exprs?
children: Vec<ChainItem>,
}
impl Chain {
- fn from_ast(expr: &ast::Expr, context: &RewriteContext) -> Chain {
- let mut subexpr_list = make_subexpr_list(expr, context);
+ fn from_ast(expr: &ast::Expr, context: &RewriteContext<'_>) -> Chain {
+ let subexpr_list = Self::make_subexpr_list(expr, context);
// Un-parse the expression tree into ChainItems
- let mut children = vec![];
+ let mut rev_children = vec![];
let mut sub_tries = 0;
- loop {
- if subexpr_list.is_empty() {
- break;
- }
-
- let subexpr = subexpr_list.pop().unwrap();
- match subexpr.node {
+ for subexpr in &subexpr_list {
+ match subexpr.kind {
ast::ExprKind::Try(_) => sub_tries += 1,
_ => {
- children.push(ChainItem {
- expr: subexpr.clone(),
- tries: sub_tries,
- });
+ rev_children.push(ChainItem::new(context, subexpr, sub_tries));
sub_tries = 0;
}
}
}
- Chain {
- parent: children.remove(0),
- children,
+ fn is_tries(s: &str) -> bool {
+ s.chars().all(|c| c == '?')
}
- }
-}
-fn rewrite_chain_block(chain: Chain, context: &RewriteContext, shape: Shape) -> Option<String> {
- debug!("rewrite_chain_block {:?} {:?}", chain, shape);
- // Parent is the first item in the chain, e.g., `foo` in `foo.bar.baz()`.
- // Root is the parent plus any other chain items placed on the first line to
- // avoid an orphan. E.g.,
- // ```
- // foo.bar
- // .baz()
- // ```
- // If `bar` were not part of the root, then baz would be orphaned and 'float'.
- let mut root_rewrite = chain.parent.expr
- .rewrite(context, shape)
- .map(|parent_rw| parent_rw + &"?".repeat(chain.parent.tries))?;
-
- let mut children: &[_] = &chain.children;
- let mut root_ends_with_block = is_block_expr(context, &chain.parent.expr, &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 = &children[0];
- let shape = shape.offset_left(root_rewrite.len())?;
- match rewrite_chain_subexpr(&item.expr, context, shape) {
- Some(rewrite) => {
- root_rewrite.push_str(&rewrite);
- root_rewrite.push_str(&"?".repeat(item.tries));
+ fn is_post_comment(s: &str) -> bool {
+ let comment_start_index = s.chars().position(|c| c == '/');
+ if comment_start_index.is_none() {
+ return false;
+ }
+
+ let newline_index = s.chars().position(|c| c == '\n');
+ if newline_index.is_none() {
+ return true;
+ }
+
+ comment_start_index.unwrap() < newline_index.unwrap()
+ }
+
+ fn handle_post_comment(
+ post_comment_span: Span,
+ post_comment_snippet: &str,
+ prev_span_end: &mut BytePos,
+ children: &mut Vec<ChainItem>,
+ ) {
+ let white_spaces: &[_] = &[' ', '\t'];
+ if post_comment_snippet
+ .trim_matches(white_spaces)
+ .starts_with('\n')
+ {
+ // No post comment.
+ return;
+ }
+ let trimmed_snippet = trim_tries(post_comment_snippet);
+ if is_post_comment(&trimmed_snippet) {
+ children.push(ChainItem::comment(
+ post_comment_span,
+ trimmed_snippet.trim().to_owned(),
+ CommentPosition::Back,
+ ));
+ *prev_span_end = post_comment_span.hi();
+ }
+ }
+
+ let parent = rev_children.pop().unwrap();
+ let mut children = vec![];
+ let mut prev_span_end = parent.span.hi();
+ let mut iter = rev_children.into_iter().rev().peekable();
+ if let Some(first_chain_item) = iter.peek() {
+ let comment_span = mk_sp(prev_span_end, first_chain_item.span.lo());
+ let comment_snippet = context.snippet(comment_span);
+ if !is_tries(comment_snippet.trim()) {
+ handle_post_comment(
+ comment_span,
+ comment_snippet,
+ &mut prev_span_end,
+ &mut children,
+ );
}
- None => break,
}
+ while let Some(chain_item) = iter.next() {
+ let comment_snippet = context.snippet(chain_item.span);
+ // FIXME: Figure out the way to get a correct span when converting `try!` to `?`.
+ let handle_comment =
+ !(context.config.use_try_shorthand() || is_tries(comment_snippet.trim()));
+
+ // Pre-comment
+ if handle_comment {
+ let pre_comment_span = mk_sp(prev_span_end, chain_item.span.lo());
+ let pre_comment_snippet = trim_tries(context.snippet(pre_comment_span));
+ let (pre_comment, _) = extract_pre_comment(&pre_comment_snippet);
+ match pre_comment {
+ Some(ref comment) if !comment.is_empty() => {
+ children.push(ChainItem::comment(
+ pre_comment_span,
+ comment.to_owned(),
+ CommentPosition::Top,
+ ));
+ }
+ _ => (),
+ }
+ }
- root_ends_with_block = is_block_expr(context, &item.expr, &root_rewrite);
+ prev_span_end = chain_item.span.hi();
+ children.push(chain_item);
- children = &children[1..];
- if children.is_empty() {
- return Some(root_rewrite);
+ // Post-comment
+ if !handle_comment || iter.peek().is_none() {
+ continue;
+ }
+
+ let next_lo = iter.peek().unwrap().span.lo();
+ let post_comment_span = mk_sp(prev_span_end, next_lo);
+ let post_comment_snippet = context.snippet(post_comment_span);
+ handle_post_comment(
+ post_comment_span,
+ post_comment_snippet,
+ &mut prev_span_end,
+ &mut children,
+ );
}
+
+ Chain { parent, children }
}
- // Separate out the last item in the chain for special treatment below.
- let last = &children[children.len() - 1];
- children = &children[..children.len() - 1];
+ // Returns a Vec of the prefixes of the chain.
+ // E.g., for input `a.b.c` we return [`a.b.c`, `a.b`, 'a']
+ fn make_subexpr_list(expr: &ast::Expr, context: &RewriteContext<'_>) -> Vec<ast::Expr> {
+ let mut subexpr_list = vec![expr.clone()];
- // Decide how to layout the rest of the chain.
- let child_shape = if root_ends_with_block {
- shape
- } else {
- shape.block_indent(context.config.tab_spaces())
- }.with_max_width(context.config);
-
- let mut rewrites: Vec<String> = Vec::with_capacity(children.len() + 2);
- rewrites.push(root_rewrite);
- let mut is_block_like = Vec::with_capacity(children.len() + 2);
- is_block_like.push(root_ends_with_block);
- for item in children {
- let rewrite = rewrite_chain_subexpr(&item.expr, context, child_shape)?;
- is_block_like.push(is_block_expr(context, &item.expr, &rewrite));
- rewrites.push(format!("{}{}", rewrite, "?".repeat(item.tries)));
- }
-
- // Total of all items excluding the last.
- let extend_last_subexpr = last_line_extendable(&rewrites[rewrites.len() - 1]);
- let almost_total = if extend_last_subexpr {
- last_line_width(&rewrites[rewrites.len() - 1])
- } else {
- rewrites.iter().fold(0, |a, b| a + b.len())
- } + last.tries;
- let one_line_budget = if rewrites.len() == 1 {
- shape.width
- } else {
- min(shape.width, context.config.width_heuristics().chain_width)
- };
- let all_in_one_line = rewrites.iter().all(|s| !s.contains('\n'))
- && almost_total < one_line_budget;
- let last_shape = if all_in_one_line {
- shape.sub_width(last.tries)?
- } else {
- child_shape.sub_width(shape.rhs_overhead(context.config) + last.tries)?
- };
+ while let Some(subexpr) = Self::pop_expr_chain(subexpr_list.last().unwrap(), context) {
+ subexpr_list.push(subexpr.clone());
+ }
- // 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.child2.last_child(|a, b, c| {
- // let x = foo(a, b, c);
- // let y = bar(a, b, c);
- //
- // // ...
- //
- // result
- // })
- // ```
+ subexpr_list
+ }
- let mut last_subexpr_str = None;
- let mut fits_single_line = false;
- if all_in_one_line || extend_last_subexpr {
- // First we try to 'overflow' the last child and see if it looks better than using
- // vertical layout.
- if let Some(shape) = last_shape.offset_left(almost_total) {
- if let Some(rw) = rewrite_chain_subexpr(&last.expr, context, 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 = almost_total + first_line_width(&rw) <= one_line_budget;
- if fits_single_line && line_count >= 5 {
- last_subexpr_str = Some(rw);
- fits_single_line = true;
+ // Returns the expression's subexpression, if it exists. When the subexpr
+ // is a try! macro, we'll convert it to shorthand when the option is set.
+ fn pop_expr_chain(expr: &ast::Expr, context: &RewriteContext<'_>) -> Option<ast::Expr> {
+ match expr.kind {
+ ast::ExprKind::MethodCall(_, ref expressions) => {
+ Some(Self::convert_try(&expressions[0], context))
+ }
+ ast::ExprKind::Field(ref subexpr, _)
+ | ast::ExprKind::Try(ref subexpr)
+ | ast::ExprKind::Await(ref subexpr) => Some(Self::convert_try(subexpr, context)),
+ _ => None,
+ }
+ }
+
+ fn convert_try(expr: &ast::Expr, context: &RewriteContext<'_>) -> ast::Expr {
+ match expr.kind {
+ ast::ExprKind::Mac(ref mac) if context.config.use_try_shorthand() => {
+ if let Some(subexpr) = convert_try_mac(mac, context) {
+ subexpr
} 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_chain_subexpr(&last.expr, 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);
- fits_single_line = could_fit_single_line;
- }
- new_rw @ Some(..) => {
- last_subexpr_str = new_rw;
- }
- _ => {
- last_subexpr_str = Some(rw);
- fits_single_line = could_fit_single_line;
- }
- }
+ expr.clone()
}
}
+ _ => expr.clone(),
}
}
+}
- last_subexpr_str = last_subexpr_str.or_else(|| rewrite_chain_subexpr(&last.expr, context, last_shape));
- rewrites.push(format!("{}{}", last_subexpr_str?, "?".repeat(last.tries)));
+impl Rewrite for Chain {
+ fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
+ debug!("rewrite chain {:?} {:?}", self, shape);
- // We should never look at this, since we only look at the block-ness of the
- // previous item in the chain.
- is_block_like.push(false);
+ let mut formatter = match context.config.indent_style() {
+ IndentStyle::Block => {
+ Box::new(ChainFormatterBlock::new(self)) as Box<dyn ChainFormatter>
+ }
+ IndentStyle::Visual => {
+ Box::new(ChainFormatterVisual::new(self)) as Box<dyn ChainFormatter>
+ }
+ };
- let connector = if fits_single_line && all_in_one_line {
- // Yay, we can put everything on one line.
- Cow::from("")
- } else {
- // Use new lines.
- if *context.force_one_line_chain.borrow() {
- return None;
+ formatter.format_root(&self.parent, context, shape)?;
+ if let Some(result) = formatter.pure_root() {
+ return wrap_str(result, context.config.max_width(), shape);
}
- child_shape.indent.to_string_with_newline(context.config)
- };
- let result = join_rewrites(&rewrites, &is_block_like, &connector);
- Some(result)
-}
+ // Decide how to layout the rest of the chain.
+ let child_shape = formatter.child_shape(context, shape)?;
-fn rewrite_chain_visual(chain: Chain, context: &RewriteContext, shape: Shape) -> Option<String> {
- // Parent is the first item in the chain, e.g., `foo` in `foo.bar.baz()`.
- let parent_shape = if is_block_expr(context, &chain.parent.expr, "\n") {
- shape.visual_indent(0)
- } else {
- shape
- };
- let mut children: &[_] = &chain.children;
- let mut root_rewrite = chain.parent.expr
- .rewrite(context, parent_shape)
- .map(|parent_rw| parent_rw + &"?".repeat(chain.parent.tries))?;
-
- if !root_rewrite.contains('\n') && is_continuable(&chain.parent.expr) {
- let item = &children[0];
- let overhead = last_line_width(&root_rewrite);
- let shape = parent_shape.offset_left(overhead)?;
- let rewrite = rewrite_chain_subexpr(&item.expr, context, shape)?;
- root_rewrite.push_str(&rewrite);
- root_rewrite.push_str(&"?".repeat(item.tries));
- children = &children[1..];
- if children.is_empty() {
- return Some(root_rewrite);
- }
+ formatter.format_children(context, child_shape)?;
+ formatter.format_last_child(context, shape, child_shape)?;
+
+ let result = formatter.join_rewrites(context, child_shape)?;
+ wrap_str(result, context.config.max_width(), shape)
}
+}
- let last = &children[children.len() - 1];
- children = &children[..children.len() - 1];
+// There are a few types for formatting chains. This is because there is a lot
+// in common between formatting with block vs visual indent, but they are
+// different enough that branching on the indent all over the place gets ugly.
+// Anything that can format a chain is a ChainFormatter.
+trait ChainFormatter {
+ // Parent is the first item in the chain, e.g., `foo` in `foo.bar.baz()`.
+ // Root is the parent plus any other chain items placed on the first line to
+ // avoid an orphan. E.g.,
+ // ```text
+ // foo.bar
+ // .baz()
+ // ```
+ // If `bar` were not part of the root, then foo would be orphaned and 'float'.
+ fn format_root(
+ &mut self,
+ parent: &ChainItem,
+ context: &RewriteContext<'_>,
+ shape: Shape,
+ ) -> Option<()>;
+ fn child_shape(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<Shape>;
+ fn format_children(&mut self, context: &RewriteContext<'_>, child_shape: Shape) -> Option<()>;
+ fn format_last_child(
+ &mut self,
+ context: &RewriteContext<'_>,
+ shape: Shape,
+ child_shape: Shape,
+ ) -> Option<()>;
+ fn join_rewrites(&self, context: &RewriteContext<'_>, child_shape: Shape) -> Option<String>;
+ // Returns `Some` if the chain is only a root, None otherwise.
+ fn pure_root(&mut self) -> Option<String>;
+}
- let child_shape = shape.visual_indent(0).with_max_width(context.config);
+// Data and behaviour that is shared by both chain formatters. The concrete
+// formatters can delegate much behaviour to `ChainFormatterShared`.
+struct ChainFormatterShared<'a> {
+ // The current working set of child items.
+ children: &'a [ChainItem],
+ // The current rewrites of items (includes trailing `?`s, but not any way to
+ // connect the rewrites together).
+ rewrites: Vec<String>,
+ // Whether the chain can fit on one line.
+ fits_single_line: bool,
+ // The number of children in the chain. This is not equal to `self.children.len()`
+ // because `self.children` will change size as we process the chain.
+ child_count: usize,
+}
- let mut rewrites: Vec<String> = Vec::with_capacity(children.len() + 2);
- rewrites.push(root_rewrite);
- for item in chain.children.iter() {
- let rewrite = rewrite_chain_subexpr(&item.expr, context, child_shape)?;
- rewrites.push(format!("{}{}", rewrite, "?".repeat(item.tries)));
+impl<'a> ChainFormatterShared<'a> {
+ fn new(chain: &'a Chain) -> ChainFormatterShared<'a> {
+ ChainFormatterShared {
+ children: &chain.children,
+ rewrites: Vec::with_capacity(chain.children.len() + 1),
+ fits_single_line: false,
+ child_count: chain.children.len(),
+ }
}
- // Total of all items excluding the last.
- let almost_total = rewrites.iter().fold(0, |a, b| a + b.len()) + last.tries;
- let one_line_budget = if rewrites.len() == 1 {
- shape.width
- } else {
- min(shape.width, context.config.width_heuristics().chain_width)
- };
- let all_in_one_line = rewrites.iter().all(|s| !s.contains('\n'))
- && almost_total < one_line_budget;
- let last_shape = child_shape.sub_width(shape.rhs_overhead(context.config) + last.tries)?;
+ fn pure_root(&mut self) -> Option<String> {
+ if self.children.is_empty() {
+ assert_eq!(self.rewrites.len(), 1);
+ Some(self.rewrites.pop().unwrap())
+ } else {
+ None
+ }
+ }
// 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:
- // ```
+ // ```text
// parent.child1.child2.last_child(
// a,
// b,
// ```
//
// A chain without overflowing the last child (in vertical layout):
- // ```
+ // ```text
// parent
// .child1
// .child2
// ```
//
// In particular, overflowing is effective when the last child is a method with a multi-lined
- // block-like argument (e.g. closure):
- // ```
+ // block-like argument (e.g., closure):
+ // ```text
// 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()
+ .map(|rw| utils::unicode_str_width(&rw))
+ .sum()
+ } + 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.
+ let one_line_shape = if context.use_block_indent() {
+ last_shape.offset_left(almost_total)
+ } else {
+ last_shape
+ .visual_indent(almost_total)
+ .sub_width(almost_total)
+ };
- let mut last_subexpr_str = None;
- let mut fits_single_line = false;
- if all_in_one_line {
- // First we try to 'overflow' the last child and see if it looks better than using
- // vertical layout.
- if let Some(shape) = parent_shape.offset_left(almost_total) {
- if let Some(rw) = rewrite_chain_subexpr(&last.expr, context, 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 = almost_total + first_line_width(&rw) <= one_line_budget;
- if could_fit_single_line && line_count >= 5 {
- last_subexpr_str = Some(rw);
- fits_single_line = 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_chain_subexpr(&last.expr, 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);
- fits_single_line = could_fit_single_line;
- }
- new_rw @ Some(..) => {
- last_subexpr_str = new_rw;
- }
- _ => {
- last_subexpr_str = Some(rw);
- fits_single_line = could_fit_single_line;
+ if let Some(one_line_shape) = one_line_shape {
+ 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(|| rewrite_chain_subexpr(&last.expr, context, last_shape));
- rewrites.push(last_subexpr_str?);
-
- let connector = if fits_single_line && all_in_one_line {
- // Yay, we can put everything on one line.
- Cow::from("")
- } else {
- // Use new lines.
- if *context.force_one_line_chain.borrow() {
- return None;
+
+ let last_shape = if context.use_block_indent() {
+ last_shape
+ } else {
+ child_shape.sub_width(shape.rhs_overhead(context.config) + last.tries)?
+ };
+
+ 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) -> 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.get() {
+ 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(children_iter);
+
+ for (rewrite, chain_item) in iter {
+ match chain_item.kind {
+ ChainItemKind::Comment(_, CommentPosition::Back) => result.push(' '),
+ ChainItemKind::Comment(_, CommentPosition::Top) => result.push_str(&connector),
+ _ => result.push_str(&connector),
+ }
+ result.push_str(&rewrite);
}
- child_shape.indent.to_string_with_newline(context.config)
- };
-
- let result = format!("{}{}",
- join_rewrites_vis(&rewrites, &connector),
- "?".repeat(last.tries),
- );
- wrap_str(result, context.config.max_width(), shape)
+
+ Some(result)
+ }
}
-fn join_rewrites(rewrites: &[String], is_block_like: &[bool], connector: &str) -> String {
- let mut rewrite_iter = rewrites.iter();
- let mut result = rewrite_iter.next().unwrap().clone();
+// Formats a chain using block indent.
+struct ChainFormatterBlock<'a> {
+ shared: ChainFormatterShared<'a>,
+ root_ends_with_block: bool,
+}
- for (rewrite, prev_is_block_like) in rewrite_iter.zip(is_block_like.iter()) {
- if rewrite != "?" && !prev_is_block_like {
- result.push_str(connector);
+impl<'a> ChainFormatterBlock<'a> {
+ fn new(chain: &'a Chain) -> ChainFormatterBlock<'a> {
+ ChainFormatterBlock {
+ shared: ChainFormatterShared::new(chain),
+ root_ends_with_block: false,
}
- result.push_str(&rewrite);
}
-
- result
}
-fn join_rewrites_vis(rewrites: &[String], connector: &str) -> String {
- let mut rewrite_iter = rewrites.iter();
- let mut result = rewrite_iter.next().unwrap().clone();
+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 = last_line_extendable(&root_rewrite);
- for rewrite in rewrite_iter {
- if rewrite != "?" {
- result.push_str(connector);
+ self.shared.children = &self.shared.children[1..];
+ if self.shared.children.is_empty() {
+ break;
+ }
}
- result.push_str(&rewrite);
+ self.shared.rewrites.push(root_rewrite);
+ self.root_ends_with_block = root_ends_with_block;
+ Some(())
}
- result
-}
+ fn child_shape(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<Shape> {
+ Some(
+ if self.root_ends_with_block {
+ shape.block_indent(0)
+ } else {
+ shape.block_indent(context.config.tab_spaces())
+ }
+ .with_max_width(context.config),
+ )
+ }
-// 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(..) => {
- context.use_block_indent() && repr.contains('\n')
+ 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);
}
- 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),
- _ => false,
+ Some(())
}
-}
-// Returns a Vec of the prefixes of the chain.
-// E.g., for input `a.b.c` we return [`a.b.c`, `a.b`, 'a']
-fn make_subexpr_list(expr: &ast::Expr, context: &RewriteContext) -> Vec<ast::Expr> {
- let mut subexpr_list = vec![expr.clone()];
+ fn format_last_child(
+ &mut self,
+ context: &RewriteContext<'_>,
+ shape: Shape,
+ child_shape: Shape,
+ ) -> Option<()> {
+ self.shared
+ .format_last_child(true, context, shape, child_shape)
+ }
- while let Some(subexpr) = pop_expr_chain(subexpr_list.last().unwrap(), context) {
- subexpr_list.push(subexpr.clone());
+ fn join_rewrites(&self, context: &RewriteContext<'_>, child_shape: Shape) -> Option<String> {
+ self.shared.join_rewrites(context, child_shape)
}
- subexpr_list
+ fn pure_root(&mut self) -> Option<String> {
+ self.shared.pure_root()
+ }
}
-// Returns the expression's subexpression, if it exists. When the subexpr
-// is a try! macro, we'll convert it to shorthand when the option is set.
-fn pop_expr_chain(expr: &ast::Expr, context: &RewriteContext) -> Option<ast::Expr> {
- match expr.node {
- ast::ExprKind::MethodCall(_, ref expressions) => {
- Some(convert_try(&expressions[0], context))
- }
- ast::ExprKind::Field(ref subexpr, _) | ast::ExprKind::Try(ref subexpr) => {
- Some(convert_try(subexpr, context))
- }
- _ => None,
- }
+// 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,
}
-fn convert_try(expr: &ast::Expr, context: &RewriteContext) -> ast::Expr {
- match expr.node {
- ast::ExprKind::Mac(ref mac) if context.config.use_try_shorthand() => {
- if let Some(subexpr) = convert_try_mac(mac, context) {
- subexpr
- } else {
- expr.clone()
- }
+impl<'a> ChainFormatterVisual<'a> {
+ fn new(chain: &'a Chain) -> ChainFormatterVisual<'a> {
+ ChainFormatterVisual {
+ shared: ChainFormatterShared::new(chain),
+ offset: 0,
}
- _ => expr.clone(),
}
}
-// Rewrite the last element in the chain `expr`. E.g., given `a.b.c` we rewrite
-// `.c`.
-fn rewrite_chain_subexpr(
- expr: &ast::Expr,
- context: &RewriteContext,
- shape: Shape,
-) -> Option<String> {
- let rewrite_element = |expr_str: String| {
- if expr_str.len() <= shape.width {
- Some(expr_str)
+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 {
- None
- }
- };
-
- match expr.node {
- ast::ExprKind::MethodCall(ref segment, ref expressions) => {
- let types = match segment.args {
- Some(ref params) => match **params {
- ast::GenericArgs::AngleBracketed(ref data) => &data.args[..],
- _ => &[],
- },
- _ => &[],
- };
- rewrite_method_call(segment.ident, types, expressions, expr.span, context, shape)
- }
- ast::ExprKind::Field(ref nested, ref field) => {
- let space = if is_tup_field_access(expr) && is_tup_field_access(nested) {
- " "
- } else {
- ""
- };
- rewrite_element(format!("{}.{}", space, field.name))
- }
- ast::ExprKind::Try(_) => rewrite_element(String::from("?")),
- _ => unreachable!(),
- }
-}
+ 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;
+ }
+ }
-fn is_tup_field_access(expr: &ast::Expr) -> bool {
- match expr.node {
- ast::ExprKind::Field(_, ref field) => {
- field.name.to_string().chars().all(|c| c.is_digit(10))
+ self.shared.children = &self.shared.children[1..];
}
- _ => false,
+
+ self.shared.rewrites.push(root_rewrite);
+ Some(())
}
-}
-// Determines if we can continue formatting a given expression on the same line.
-fn is_continuable(expr: &ast::Expr) -> bool {
- match expr.node {
- ast::ExprKind::Path(..) => true,
- _ => false,
+ 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 rewrite_method_call(
- method_name: ast::Ident,
- types: &[ast::GenericArg],
- args: &[ptr::P<ast::Expr>],
- span: Span,
- context: &RewriteContext,
- shape: Shape,
-) -> Option<String> {
- let (lo, type_str) = if types.is_empty() {
- (args[0].span.hi(), String::new())
- } else {
- let type_list = types
- .iter()
- .map(|ty| ty.rewrite(context, shape))
- .collect::<Option<Vec<_>>>()?;
+ 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(())
+ }
- let type_str = format!("::<{}>", type_list.join(", "));
+ fn format_last_child(
+ &mut self,
+ context: &RewriteContext<'_>,
+ shape: Shape,
+ child_shape: Shape,
+ ) -> Option<()> {
+ self.shared
+ .format_last_child(false, context, shape, child_shape)
+ }
- (types.last().unwrap().span().hi(), type_str)
- };
+ fn join_rewrites(&self, context: &RewriteContext<'_>, child_shape: Shape) -> Option<String> {
+ self.shared.join_rewrites(context, child_shape)
+ }
- let callee_str = format!(".{}{}", method_name, type_str);
- let span = mk_sp(lo, span.hi());
+ fn pure_root(&mut self) -> Option<String> {
+ self.shared.pure_root()
+ }
+}
- rewrite_call(context, &callee_str, &args[1..], span, shape)
+/// Removes try operators (`?`s) that appear in the given string. If removing
+/// them leaves an empty line, remove that line as well unless it is the first
+/// line (we need the first newline for detecting pre/post comment).
+fn trim_tries(s: &str) -> String {
+ let mut result = String::with_capacity(s.len());
+ let mut line_buffer = String::with_capacity(s.len());
+ for (kind, rich_char) in CharClasses::new(s.chars()) {
+ match rich_char.get_char() {
+ '\n' => {
+ if result.is_empty() || !line_buffer.trim().is_empty() {
+ result.push_str(&line_buffer);
+ result.push('\n')
+ }
+ line_buffer.clear();
+ }
+ '?' if kind == FullCodeCharKind::Normal => continue,
+ c => line_buffer.push(c),
+ }
+ }
+ if !line_buffer.trim().is_empty() {
+ result.push_str(&line_buffer);
+ }
+ result
}
projects / rust.git / blobdiff