Implement RFC style for match
Put the opening brace of match arm's body on the next line if the pattern has guard and consists of multi lines.
This commit is contained in:
Seiichi Uchida
parent
de403f4f65
commit
0a2567db93
141
src/expr.rs
141
src/expr.rs
@ -1549,45 +1549,6 @@ fn arm_comma(config: &Config, body: &ast::Expr) -> &'static str {
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}
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}
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fn rewrite_match_pattern(
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context: &RewriteContext,
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pats: &Vec<ptr::P<ast::Pat>>,
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guard: &Option<ptr::P<ast::Expr>>,
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shape: Shape,
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) -> Option<String> {
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// Patterns
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// 5 = ` => {`
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let pat_shape = try_opt!(shape.sub_width(5));
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let pat_strs = try_opt!(
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pats.iter()
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.map(|p| p.rewrite(context, pat_shape))
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.collect::<Option<Vec<_>>>()
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);
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let items: Vec<_> = pat_strs.into_iter().map(ListItem::from_str).collect();
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let tactic = definitive_tactic(&items, ListTactic::HorizontalVertical, pat_shape.width);
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let fmt = ListFormatting {
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tactic: tactic,
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separator: " |",
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trailing_separator: SeparatorTactic::Never,
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shape: pat_shape,
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ends_with_newline: false,
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config: context.config,
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};
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let pats_str = try_opt!(write_list(&items, &fmt));
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// Guard
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let guard_str = try_opt!(rewrite_guard(
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context,
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guard,
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shape,
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trimmed_last_line_width(&pats_str),
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));
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Some(format!("{}{}", pats_str, guard_str))
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}
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fn rewrite_match_arms(
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context: &RewriteContext,
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arms: &[ast::Arm],
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@ -1677,6 +1638,45 @@ fn rewrite_match_arm(context: &RewriteContext, arm: &ast::Arm, shape: Shape) ->
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rewrite_match_body(context, &arm.body, &pats_str, shape, arm.guard.is_some())
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}
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fn rewrite_match_pattern(
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context: &RewriteContext,
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pats: &Vec<ptr::P<ast::Pat>>,
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guard: &Option<ptr::P<ast::Expr>>,
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shape: Shape,
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) -> Option<String> {
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// Patterns
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// 5 = ` => {`
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let pat_shape = try_opt!(shape.sub_width(5));
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let pat_strs = try_opt!(
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pats.iter()
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.map(|p| p.rewrite(context, pat_shape))
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.collect::<Option<Vec<_>>>()
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);
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let items: Vec<_> = pat_strs.into_iter().map(ListItem::from_str).collect();
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let tactic = definitive_tactic(&items, ListTactic::HorizontalVertical, pat_shape.width);
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let fmt = ListFormatting {
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tactic: tactic,
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separator: " |",
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trailing_separator: SeparatorTactic::Never,
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shape: pat_shape,
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ends_with_newline: false,
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config: context.config,
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};
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let pats_str = try_opt!(write_list(&items, &fmt));
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// Guard
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let guard_str = try_opt!(rewrite_guard(
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context,
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guard,
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shape,
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trimmed_last_line_width(&pats_str),
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));
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Some(format!("{}{}", pats_str, guard_str))
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}
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fn rewrite_match_body(
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context: &RewriteContext,
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body: &ptr::P<ast::Expr>,
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@ -1699,39 +1699,46 @@ fn rewrite_match_body(
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let comma = arm_comma(&context.config, body);
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let alt_block_sep = String::from("\n") + &shape.indent.block_only().to_string(context.config);
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let alt_block_sep = alt_block_sep.as_str();
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let is_block = if let ast::ExprKind::Block(..) = body.node {
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true
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let (is_block, is_empty_block) = if let ast::ExprKind::Block(ref block) = body.node {
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(true, is_empty_block(block, context.codemap))
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} else {
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false
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(false, false)
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};
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let combine_orig_body = |body_str: &str| {
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let block_sep = match context.config.control_brace_style() {
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ControlBraceStyle::AlwaysNextLine if is_block => alt_block_sep,
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_ if has_guard && pats_str.contains('\n') && is_block && body_str != "{}" => {
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alt_block_sep
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}
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_ => " ",
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};
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Some(format!("{} =>{}{}{}", pats_str, block_sep, body_str, comma))
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};
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let forbid_same_line = has_guard && pats_str.contains('\n') && !is_empty_block;
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let next_line_indent = if is_block {
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shape.indent
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} else {
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shape.indent.block_indent(context.config)
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};
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let combine_next_line_body = |body_str: &str| {
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let indent_str = shape
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.indent
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.block_indent(context.config)
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.to_string(context.config);
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if is_block {
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return Some(format!(
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"{} =>\n{}{}",
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pats_str,
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next_line_indent.to_string(context.config),
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body_str
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));
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}
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let indent_str = shape.indent.to_string(context.config);
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let nested_indent_str = next_line_indent.to_string(context.config);
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let (body_prefix, body_suffix) = if context.config.wrap_match_arms() {
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let comma = if context.config.match_block_trailing_comma() {
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","
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} else {
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""
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};
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(
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"{",
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format!("\n{}}}{}", shape.indent.to_string(context.config), comma),
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)
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("{", format!("\n{}}}{}", indent_str, comma))
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} else {
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("", String::from(","))
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};
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@ -1739,8 +1746,9 @@ fn rewrite_match_body(
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let block_sep = match context.config.control_brace_style() {
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ControlBraceStyle::AlwaysNextLine => format!("{}{}\n", alt_block_sep, body_prefix),
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_ if body_prefix.is_empty() => "\n".to_owned(),
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_ => " ".to_owned() + body_prefix + "\n",
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} + &indent_str;
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_ if forbid_same_line => format!("{}{}\n", alt_block_sep, body_prefix),
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_ => format!(" {}\n", body_prefix),
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} + &nested_indent_str;
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Some(format!(
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"{} =>{}{}{}",
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@ -1753,19 +1761,20 @@ fn rewrite_match_body(
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// Let's try and get the arm body on the same line as the condition.
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// 4 = ` => `.len()
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let orig_arm_shape = shape
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let orig_body_shape = shape
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.offset_left(extra_offset(&pats_str, shape) + 4)
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.and_then(|shape| shape.sub_width(comma.len()));
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let orig_body = if let Some(arm_shape) = orig_arm_shape {
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let orig_body = if let Some(body_shape) = orig_body_shape {
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let rewrite = nop_block_collapse(
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format_expr(body, ExprType::Statement, context, arm_shape),
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arm_shape.width,
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format_expr(body, ExprType::Statement, context, body_shape),
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body_shape.width,
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);
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match rewrite {
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Some(ref body_str)
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if ((!body_str.contains('\n')) && first_line_width(body_str) <= arm_shape.width) ||
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is_block =>
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if !forbid_same_line &&
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(is_block ||
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(!body_str.contains('\n') && body_str.len() <= body_shape.width)) =>
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{
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return combine_orig_body(body_str);
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}
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@ -1774,18 +1783,20 @@ fn rewrite_match_body(
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} else {
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None
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};
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let orig_budget = orig_arm_shape.map_or(0, |shape| shape.width);
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let orig_budget = orig_body_shape.map_or(0, |shape| shape.width);
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// Try putting body on the next line and see if it looks better.
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let next_line_body_shape =
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Shape::indented(shape.indent.block_indent(context.config), context.config);
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let next_line_body_shape = Shape::indented(next_line_indent, context.config);
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let next_line_body = nop_block_collapse(
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format_expr(body, ExprType::Statement, context, next_line_body_shape),
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next_line_body_shape.width,
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);
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match (orig_body, next_line_body) {
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(Some(ref orig_str), Some(ref next_line_str))
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if prefer_next_line(orig_str, next_line_str) => combine_next_line_body(next_line_str),
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if forbid_same_line || prefer_next_line(orig_str, next_line_str) =>
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{
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combine_next_line_body(next_line_str)
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}
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(Some(ref orig_str), _) if extend && first_line_width(orig_str) <= orig_budget => {
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combine_orig_body(orig_str)
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}
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