use macros::convert_try_mac;
use rewrite::{Rewrite, RewriteContext};
use shape::Shape;
-use utils::{
- first_line_width, last_line_extendable, last_line_width, mk_sp, trimmed_last_line_width,
- wrap_str,
-};
+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 std::iter;
use syntax::codemap::Span;
use syntax::{ast, ptr};
pub fn rewrite_chain(expr: &ast::Expr, context: &RewriteContext, shape: Shape) -> Option<String> {
debug!("rewrite_chain {:?}", shape);
- let total_span = expr.span;
- let (parent, subexpr_list) = make_subexpr_list(expr, context);
+ let chain = Chain::from_ast(expr, context);
+ // 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)));
+ }
+
+ match context.config.indent_style() {
+ IndentStyle::Block => rewrite_chain_block(chain, context, shape),
+ IndentStyle::Visual => rewrite_chain_visual(chain, context, shape),
+ }
+}
+
+// An expression plus trailing `?`s to be formatted together.
+#[derive(Debug)]
+struct ChainItem {
+ expr: ast::Expr,
+ tries: usize,
+}
+
+#[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);
+
+ // Un-parse the expression tree into ChainItems
+ let mut children = vec![];
+ let mut sub_tries = 0;
+ loop {
+ if subexpr_list.is_empty() {
+ break;
+ }
+
+ let subexpr = subexpr_list.pop().unwrap();
+ match subexpr.node {
+ ast::ExprKind::Try(_) => sub_tries += 1,
+ _ => {
+ children.push(ChainItem {
+ expr: subexpr.clone(),
+ tries: sub_tries,
+ });
+ sub_tries = 0;
+ }
+ }
+ }
- // Bail out if the chain is just try sugar, i.e., an expression followed by
- // any number of `?`s.
- if chain_only_try(&subexpr_list) {
- return rewrite_try(&parent, subexpr_list.len(), context, shape);
+ Chain {
+ parent: children.remove(0),
+ children,
+ }
}
- let suffix_try_num = subexpr_list.iter().take_while(|e| is_try(e)).count();
- let prefix_try_num = subexpr_list.iter().rev().take_while(|e| is_try(e)).count();
+}
+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()`.
- let parent_shape = if is_block_expr(context, &parent, "\n") {
- match context.config.indent_style() {
- IndentStyle::Visual => shape.visual_indent(0),
- IndentStyle::Block => shape,
+ // 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));
+ }
+ None => break,
+ }
+
+ root_ends_with_block = is_block_expr(context, &item.expr, &root_rewrite);
+
+ children = &children[1..];
+ if children.is_empty() {
+ return Some(root_rewrite);
+ }
+ }
+
+ // Separate out the last item in the chain for special treatment below.
+ let last = &children[children.len() - 1];
+ children = &children[..children.len() - 1];
+
+ // 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());
+ rewrites.push(root_rewrite);
+ let mut is_block_like = Vec::with_capacity(children.len());
+ 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)?
+ };
+
+ // 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
+ // })
+ // ```
+
+ 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;
+ } 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;
+ }
+ }
+ }
+ }
}
+ }
+
+ 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)));
+
+ // 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 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;
+ }
+ child_shape.indent.to_string_with_newline(context.config)
+ };
+
+ let result = join_rewrites(&rewrites, &is_block_like, &connector);
+ Some(result)
+}
+
+fn rewrite_chain_visual(mut chain: Chain, context: &RewriteContext, shape: Shape) -> Option<String> {
+ let last = chain.children.pop().unwrap();
+
+ // 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 parent_rewrite = parent
+ let parent_rewrite = chain.parent.expr
.rewrite(context, parent_shape)
- .map(|parent_rw| parent_rw + &"?".repeat(prefix_try_num))?;
+ .map(|parent_rw| parent_rw + &"?".repeat(chain.parent.tries))?;
let parent_rewrite_contains_newline = parent_rewrite.contains('\n');
- let is_small_parent = parent_rewrite.len() <= context.config.tab_spaces();
+
+ let other_child_shape = shape.visual_indent(0).with_max_width(context.config);
// Decide how to layout the rest of the chain. `extend` is true if we can
// put the first non-parent item on the same line as the parent.
- let (nested_shape, extend) = if !parent_rewrite_contains_newline && is_continuable(&parent) {
- (
- chain_indent(context, shape.add_offset(parent_rewrite.len())),
- context.config.indent_style() == IndentStyle::Visual || is_small_parent,
- )
- } else if is_block_expr(context, &parent, &parent_rewrite) {
- match context.config.indent_style() {
- // Try to put the first child on the same line with parent's last line
- IndentStyle::Block => (parent_shape.block_indent(context.config.tab_spaces()), true),
- // The parent is a block, so align the rest of the chain with the closing
- // brace.
- IndentStyle::Visual => (parent_shape, false),
- }
- } else {
- (
- chain_indent(context, shape.add_offset(parent_rewrite.len())),
- false,
- )
- };
-
- let other_child_shape = nested_shape.with_max_width(context.config);
+ let extend = !parent_rewrite_contains_newline && is_continuable(&chain.parent.expr);
let first_child_shape = if extend {
let overhead = last_line_width(&parent_rewrite);
- let offset = trimmed_last_line_width(&parent_rewrite) + prefix_try_num;
- match context.config.indent_style() {
- IndentStyle::Visual => parent_shape.offset_left(overhead)?,
- IndentStyle::Block => parent_shape.offset_left(offset)?,
- }
+ parent_shape.offset_left(overhead)?
} else {
other_child_shape
};
first_child_shape, other_child_shape
);
- let child_shape_iter = Some(first_child_shape)
- .into_iter()
- .chain(iter::repeat(other_child_shape));
- let subexpr_num = subexpr_list.len();
- let last_subexpr = &subexpr_list[suffix_try_num];
- let subexpr_list = &subexpr_list[suffix_try_num..subexpr_num - prefix_try_num];
- let iter = subexpr_list.iter().skip(1).rev().zip(child_shape_iter);
- let mut rewrites = iter.map(|(e, shape)| rewrite_chain_subexpr(e, total_span, context, shape))
- .collect::<Option<Vec<_>>>()?;
+ let mut rewrites: Vec<String> = Vec::with_capacity(chain.children.len());
+ for (i, item) in chain.children.iter().enumerate() {
+ let shape = if i == 0 {
+ first_child_shape
+ } else {
+ other_child_shape
+ };
+ let rewrite = rewrite_chain_subexpr(&item.expr, context, shape)?;
+ rewrites.push(format!("{}{}", rewrite, "?".repeat(item.tries)));
+ }
// Total of all items excluding the last.
- let extend_last_subexpr = if is_small_parent {
- rewrites.len() == 1 && last_line_extendable(&rewrites[0])
- } else {
- rewrites.is_empty() && last_line_extendable(&parent_rewrite)
- };
- let almost_total = if extend_last_subexpr {
- last_line_width(&parent_rewrite)
- } else {
- rewrites.iter().fold(0, |a, b| a + b.len()) + parent_rewrite.len()
- } + suffix_try_num;
+ let almost_total = rewrites.iter().fold(0, |a, b| a + b.len()) + parent_rewrite.len() + last.tries;
let one_line_budget = if rewrites.is_empty() {
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 last_shape = if rewrites.is_empty() {
- first_child_shape
- } else {
- other_child_shape
- }.sub_width(shape.rhs_overhead(context.config) + suffix_try_num)?;
+ let last_shape =
+ other_child_shape.sub_width(shape.rhs_overhead(context.config) + last.tries)?;
// 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:
// })
// ```
- // `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_subexpr {
+ 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.
- parent_shape.offset_left(almost_total).map(|shape| {
- if let Some(rw) = rewrite_chain_subexpr(last_subexpr, total_span, context, shape) {
+ 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 expect the last child.
+ // 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 fits_single_line = almost_total + first_line_width(&rw) <= one_line_budget;
- if fits_single_line && line_count >= 5 {
- (Some(rw), true)
+ 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_last() {
- Some(ref new_rw) if !fits_single_line => (Some(new_rw.clone()), false),
+ 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 => {
- (Some(rw), fits_single_line)
+ 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;
}
- new_rw @ Some(..) => (new_rw, false),
- _ => (Some(rw), fits_single_line),
}
}
- } else {
- (rewrite_last(), false)
}
- })?
- } else {
- (rewrite_last(), false)
- };
+ }
+ }
+
+ 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 && !parent_rewrite_contains_newline {
if *context.force_one_line_chain.borrow() {
return None;
}
- nested_shape.indent.to_string_with_newline(context.config)
+ other_child_shape.indent.to_string_with_newline(context.config)
};
- let first_connector = if is_small_parent || fits_single_line
- || last_line_extendable(&parent_rewrite)
- || context.config.indent_style() == IndentStyle::Visual
- {
- ""
- } else {
- &connector
- };
-
- let result = if is_small_parent && rewrites.len() > 1 {
- let second_connector = if fits_single_line || rewrites[1] == "?"
- || last_line_extendable(&rewrites[0])
- || context.config.indent_style() == IndentStyle::Visual
- {
- ""
- } else {
- &connector
- };
- format!(
- "{}{}{}{}{}",
- parent_rewrite,
- first_connector,
- rewrites[0],
- second_connector,
- join_rewrites(&rewrites[1..], &connector)
- )
- } else {
- format!(
- "{}{}{}",
- parent_rewrite,
- first_connector,
- join_rewrites(&rewrites, &connector)
- )
- };
- let result = format!("{}{}", result, "?".repeat(suffix_try_num));
- if context.config.indent_style() == IndentStyle::Visual {
- wrap_str(result, context.config.max_width(), shape)
- } else {
- Some(result)
- }
+ let result = format!("{}{}{}",
+ parent_rewrite,
+ join_rewrites_vis(&rewrites, &connector),
+ "?".repeat(last.tries),
+ );
+ wrap_str(result, context.config.max_width(), shape)
}
-// True if the chain is only `?`s.
-fn chain_only_try(exprs: &[ast::Expr]) -> bool {
- exprs.iter().all(|e| {
- if let ast::ExprKind::Try(_) = e.node {
- true
- } else {
- false
+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();
+
+ for (rewrite, prev_is_block_like) in rewrite_iter.zip(is_block_like.iter()) {
+ if rewrite != "?" && !prev_is_block_like {
+ result.push_str(connector);
}
- })
-}
+ result.push_str(&rewrite);
+ }
-fn rewrite_try(
- expr: &ast::Expr,
- try_count: usize,
- context: &RewriteContext,
- shape: Shape,
-) -> Option<String> {
- let sub_expr = expr.rewrite(context, shape.sub_width(try_count)?)?;
- Some(format!("{}{}", sub_expr, "?".repeat(try_count)))
+ result
}
-fn join_rewrites(rewrites: &[String], connector: &str) -> String {
+fn join_rewrites_vis(rewrites: &[String], connector: &str) -> String {
let mut rewrite_iter = rewrites.iter();
let mut result = rewrite_iter.next().unwrap().clone();
// 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::Mac(..)
+ | ast::ExprKind::Call(..)
+ | ast::ExprKind::MethodCall(..) => {
context.use_block_indent() && repr.contains('\n')
}
ast::ExprKind::Struct(..)
ast::ExprKind::Paren(ref expr)
| ast::ExprKind::Binary(_, _, ref expr)
| ast::ExprKind::Index(_, ref expr)
- | ast::ExprKind::Unary(_, ref expr) => is_block_expr(context, expr, repr),
+ | 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,
}
}
-// Returns the root of the chain and a Vec of the prefixes of the rest of the chain.
-// E.g., for input `a.b.c` we return (`a`, [`a.b.c`, `a.b`])
-fn make_subexpr_list(expr: &ast::Expr, context: &RewriteContext) -> (ast::Expr, Vec<ast::Expr>) {
+// 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()];
while let Some(subexpr) = pop_expr_chain(subexpr_list.last().unwrap(), context) {
subexpr_list.push(subexpr.clone());
}
- let parent = subexpr_list.pop().unwrap();
- (parent, subexpr_list)
-}
-
-fn chain_indent(context: &RewriteContext, shape: Shape) -> Shape {
- match context.config.indent_style() {
- IndentStyle::Visual => shape.visual_indent(0),
- IndentStyle::Block => shape
- .block_indent(context.config.tab_spaces())
- .with_max_width(context.config),
- }
+ subexpr_list
}
// Returns the expression's subexpression, if it exists. When the subexpr
// `.c`.
fn rewrite_chain_subexpr(
expr: &ast::Expr,
- span: Span,
context: &RewriteContext,
shape: Shape,
) -> Option<String> {
match expr.node {
ast::ExprKind::MethodCall(ref segment, ref expressions) => {
- let types = match segment.parameters {
+ let types = match segment.args {
Some(ref params) => match **params {
- ast::PathParameters::AngleBracketed(ref data) => &data.types[..],
+ ast::GenericArgs::AngleBracketed(ref data) => &data.args[..],
_ => &[],
},
_ => &[],
};
- rewrite_method_call(segment.ident, types, expressions, span, context, shape)
+ 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) {
}
}
-fn is_try(expr: &ast::Expr) -> bool {
- match expr.node {
- ast::ExprKind::Try(..) => true,
- _ => false,
- }
-}
-
fn rewrite_method_call(
method_name: ast::Ident,
- types: &[ptr::P<ast::Ty>],
+ types: &[ast::GenericArg],
args: &[ptr::P<ast::Expr>],
span: Span,
context: &RewriteContext,
.map(|ty| ty.rewrite(context, shape))
.collect::<Option<Vec<_>>>()?;
- let type_str =
- if context.config.spaces_within_parens_and_brackets() && !type_list.is_empty() {
- format!("::< {} >", type_list.join(", "))
- } else {
- format!("::<{}>", type_list.join(", "))
- };
+ let type_str = format!("::<{}>", type_list.join(", "));
- (types.last().unwrap().span.hi(), type_str)
+ (types.last().unwrap().span().hi(), type_str)
};
let callee_str = format!(".{}{}", method_name, type_str);
projects / rust.git / blobdiff