36abfe5dc2
This removes usage of: * PathExt * split_last * split_last_mut * catch_panic The catch_panic one was a little tricky as the ident interner needed to be cloned across threads (a little unsafely), but it should otherwise be good to go.
231 lines
9 KiB
Rust
231 lines
9 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 and method calls.
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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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use Indent;
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use rewrite::{Rewrite, RewriteContext};
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use utils::first_line_width;
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use expr::rewrite_call;
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use config::BlockIndentStyle;
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use syntax::{ast, ptr};
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use syntax::codemap::{mk_sp, Span};
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use syntax::print::pprust;
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pub fn rewrite_chain(mut expr: &ast::Expr,
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context: &RewriteContext,
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width: usize,
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offset: Indent)
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-> Option<String> {
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let total_span = expr.span;
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let mut subexpr_list = vec![expr];
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while let Some(subexpr) = pop_expr_chain(expr) {
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subexpr_list.push(subexpr);
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expr = subexpr;
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}
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let parent_block_indent = match context.config.chain_base_indent {
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BlockIndentStyle::Visual => offset,
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BlockIndentStyle::Inherit => context.block_indent,
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BlockIndentStyle::Tabbed => context.block_indent.block_indent(context.config),
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};
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let parent_context = &RewriteContext { block_indent: parent_block_indent, ..*context };
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let parent = subexpr_list.pop().unwrap();
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let parent_rewrite = try_opt!(expr.rewrite(parent_context, width, offset));
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let (indent, extend) = if !parent_rewrite.contains('\n') && is_continuable(parent) ||
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parent_rewrite.len() <= context.config.tab_spaces {
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(offset + Indent::new(0, parent_rewrite.len()), true)
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} else if is_block_expr(parent, &parent_rewrite) {
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(parent_block_indent, false)
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} else {
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(offset + Indent::new(context.config.tab_spaces, 0), false)
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};
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let max_width = try_opt!((width + offset.width()).checked_sub(indent.width()));
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let mut rewrites = try_opt!(subexpr_list.iter()
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.rev()
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.map(|e| {
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rewrite_chain_expr(e,
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total_span,
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context,
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max_width,
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indent)
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})
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.collect::<Option<Vec<_>>>());
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// Total of all items excluding the last.
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let almost_total = rewrites[..rewrites.len() - 1]
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.iter()
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.fold(0, |a, b| a + first_line_width(b)) +
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parent_rewrite.len();
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let total_width = almost_total + first_line_width(rewrites.last().unwrap());
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let veto_single_line = if context.config.take_source_hints && subexpr_list.len() > 1 {
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// Look at the source code. Unless all chain elements start on the same
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// line, we won't consider putting them on a single line either.
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let first_line_no = context.codemap.lookup_char_pos(subexpr_list[0].span.lo).line;
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subexpr_list[1..]
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.iter()
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.any(|ex| context.codemap.lookup_char_pos(ex.span.hi).line != first_line_no)
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} else {
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false
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};
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let fits_single_line = !veto_single_line &&
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match subexpr_list[0].node {
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ast::Expr_::ExprMethodCall(ref method_name, ref types, ref expressions)
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if context.config.chains_overflow_last => {
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let len = rewrites.len();
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let (init, last) = rewrites.split_at_mut(len - 1);
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let last = &mut last[0];
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if init.iter().all(|s| !s.contains('\n')) && total_width <= width {
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let last_rewrite = width.checked_sub(almost_total)
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.and_then(|inner_width| {
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rewrite_method_call(method_name.node,
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types,
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expressions,
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total_span,
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context,
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inner_width,
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offset + almost_total)
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});
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match last_rewrite {
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Some(mut string) => {
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::std::mem::swap(&mut string, last);
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true
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}
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None => false,
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}
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} else {
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false
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}
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}
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_ => total_width <= width && rewrites.iter().all(|s| !s.contains('\n')),
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};
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let connector = if fits_single_line && !parent_rewrite.contains('\n') {
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String::new()
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} else {
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format!("\n{}", indent.to_string(context.config))
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};
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let first_connector = if extend {
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""
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} else {
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&connector[..]
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};
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Some(format!("{}{}{}",
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parent_rewrite,
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first_connector,
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rewrites.join(&connector)))
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}
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// States whether an expression's last line exclusively consists of closing
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// parens, braces and brackets in its idiomatic formatting.
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fn is_block_expr(expr: &ast::Expr, repr: &str) -> bool {
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match expr.node {
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ast::Expr_::ExprStruct(..) |
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ast::Expr_::ExprWhile(..) |
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ast::Expr_::ExprWhileLet(..) |
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ast::Expr_::ExprIf(..) |
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ast::Expr_::ExprIfLet(..) |
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ast::Expr_::ExprBlock(..) |
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ast::Expr_::ExprLoop(..) |
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ast::Expr_::ExprForLoop(..) |
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ast::Expr_::ExprMatch(..) => repr.contains('\n'),
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ast::Expr_::ExprParen(ref expr) |
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ast::Expr_::ExprBinary(_, _, ref expr) |
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ast::Expr_::ExprIndex(_, ref expr) |
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ast::Expr_::ExprUnary(_, ref expr) => is_block_expr(expr, repr),
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_ => false,
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}
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}
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fn pop_expr_chain<'a>(expr: &'a ast::Expr) -> Option<&'a ast::Expr> {
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match expr.node {
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ast::Expr_::ExprMethodCall(_, _, ref expressions) => {
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Some(&expressions[0])
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}
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ast::Expr_::ExprTupField(ref subexpr, _) |
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ast::Expr_::ExprField(ref subexpr, _) => {
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Some(subexpr)
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}
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_ => None,
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}
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}
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fn rewrite_chain_expr(expr: &ast::Expr,
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span: Span,
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context: &RewriteContext,
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width: usize,
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offset: Indent)
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-> Option<String> {
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match expr.node {
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ast::Expr_::ExprMethodCall(ref method_name, ref types, ref expressions) => {
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let inner = &RewriteContext { block_indent: offset, ..*context };
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rewrite_method_call(method_name.node,
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types,
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expressions,
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span,
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inner,
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width,
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offset)
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}
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ast::Expr_::ExprField(_, ref field) => {
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Some(format!(".{}", field.node))
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}
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ast::Expr_::ExprTupField(_, ref field) => {
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Some(format!(".{}", field.node))
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}
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_ => unreachable!(),
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}
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}
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// Determines we can continue formatting a given expression on the same line.
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fn is_continuable(expr: &ast::Expr) -> bool {
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match expr.node {
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ast::Expr_::ExprPath(..) => true,
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_ => false,
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}
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}
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fn rewrite_method_call(method_name: ast::Ident,
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types: &[ptr::P<ast::Ty>],
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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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width: usize,
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offset: Indent)
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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.iter().map(|ty| pprust::ty_to_string(ty)).collect::<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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let span = mk_sp(args[0].span.hi, span.hi);
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rewrite_call(context, &callee_str, &args[1..], span, width, offset)
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}
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