-/// Collect operands that appears in the given binary operator in the opposite order.
-/// e.g. `collect_binary_items(e, ||)` for `a && b || c || d` returns `[d, c, a && b]`.
-fn collect_binary_items<'a>(mut expr: &'a ast::Expr, binop: ast::BinOp) -> Vec<&'a ast::Expr> {
- let mut result = vec![];
- let mut prev_lhs = None;
- loop {
- match expr.node {
- ast::ExprKind::Binary(inner_binop, ref lhs, ref rhs)
- if inner_binop.node == binop.node =>
- {
- result.push(&**rhs);
- expr = lhs;
- prev_lhs = Some(lhs);
- }
- _ => {
- if let Some(lhs) = prev_lhs {
- result.push(lhs);
- }
- break;
- }
- }
- }
- result
-}
-
-/// Rewrites a binary expression whose operands fits within a single line.
-fn rewrite_simple_binaries(
- context: &RewriteContext,
- expr: &ast::Expr,
- shape: Shape,
- op: ast::BinOp,
-) -> Option<String> {
- let op_str = context.snippet(op.span);
-
- // 2 = spaces around a binary operator.
- let sep_overhead = op_str.len() + 2;
- let nested_overhead = sep_overhead - 1;
-
- let nested_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);
- let nested_shape = match context.config.binop_separator() {
- SeparatorPlace::Back => nested_shape.sub_width(nested_overhead)?,
- SeparatorPlace::Front => nested_shape.offset_left(nested_overhead)?,
- };
-
- let opt_rewrites: Option<Vec<_>> = collect_binary_items(expr, op)
- .iter()
- .rev()
- .map(|e| e.rewrite(context, nested_shape))
- .collect();
- if let Some(rewrites) = opt_rewrites {
- if rewrites.iter().all(|e| ::utils::is_single_line(e)) {
- let total_width = rewrites.iter().map(|s| s.len()).sum::<usize>()
- + sep_overhead * (rewrites.len() - 1);
-
- let sep_str = if total_width <= shape.width {
- format!(" {} ", op_str)
- } else {
- let indent_str = nested_shape.indent.to_string_with_newline(context.config);
- match context.config.binop_separator() {
- SeparatorPlace::Back => format!(" {}{}", op_str.trim_right(), indent_str),
- SeparatorPlace::Front => format!("{}{} ", indent_str, op_str.trim_left()),
- }
- };
-
- return wrap_str(rewrites.join(&sep_str), context.config.max_width(), shape);
- }
- }
-
- None
-}
-
-#[derive(new, Clone, Copy)]
-pub struct PairParts<'a> {
- prefix: &'a str,
- infix: &'a str,
- suffix: &'a str,
-}
-
-pub fn rewrite_pair<LHS, RHS>(
- lhs: &LHS,
- rhs: &RHS,
- pp: PairParts,
- context: &RewriteContext,
- shape: Shape,
- separator_place: SeparatorPlace,
-) -> Option<String>
-where
- LHS: Rewrite,
- RHS: Rewrite,
-{
- let lhs_overhead = match separator_place {
- SeparatorPlace::Back => shape.used_width() + pp.prefix.len() + pp.infix.trim_right().len(),
- SeparatorPlace::Front => shape.used_width(),
- };
- let lhs_shape = Shape {
- width: context.budget(lhs_overhead),
- ..shape
- };
- let lhs_result = lhs.rewrite(context, lhs_shape)
- .map(|lhs_str| format!("{}{}", pp.prefix, lhs_str))?;
-
- // Try to put both lhs and rhs on the same line.
- let rhs_orig_result = shape
- .offset_left(last_line_width(&lhs_result) + pp.infix.len())
- .and_then(|s| s.sub_width(pp.suffix.len()))
- .and_then(|rhs_shape| rhs.rewrite(context, rhs_shape));
- if let Some(ref rhs_result) = rhs_orig_result {
- // If the length of the lhs is equal to or shorter than the tab width or
- // the rhs looks like block expression, we put the rhs on the same
- // line with the lhs even if the rhs is multi-lined.
- let allow_same_line = lhs_result.len() <= context.config.tab_spaces()
- || rhs_result
- .lines()
- .next()
- .map(|first_line| first_line.ends_with('{'))
- .unwrap_or(false);
- if !rhs_result.contains('\n') || allow_same_line {
- let one_line_width = last_line_width(&lhs_result)
- + pp.infix.len()
- + first_line_width(rhs_result)
- + pp.suffix.len();
- if one_line_width <= shape.width {
- return Some(format!(
- "{}{}{}{}",
- lhs_result, pp.infix, rhs_result, pp.suffix
- ));
- }
- }
- }
-
- // We have to use multiple lines.
- // Re-evaluate the rhs because we have more space now:
- let mut rhs_shape = match context.config.indent_style() {
- IndentStyle::Visual => shape
- .sub_width(pp.suffix.len() + pp.prefix.len())?
- .visual_indent(pp.prefix.len()),
- IndentStyle::Block => {
- // Try to calculate the initial constraint on the right hand side.
- let rhs_overhead = shape.rhs_overhead(context.config);
- Shape::indented(shape.indent.block_indent(context.config), context.config)
- .sub_width(rhs_overhead)?
- }
- };
- let infix = match separator_place {
- SeparatorPlace::Back => pp.infix.trim_right(),
- SeparatorPlace::Front => pp.infix.trim_left(),
- };
- if separator_place == SeparatorPlace::Front {
- rhs_shape = rhs_shape.offset_left(infix.len())?;
- }
- let rhs_result = rhs.rewrite(context, rhs_shape)?;
- let indent_str = rhs_shape.indent.to_string_with_newline(context.config);
- let infix_with_sep = match separator_place {
- SeparatorPlace::Back => format!("{}{}", infix, indent_str),
- SeparatorPlace::Front => format!("{}{}", indent_str, infix),
- };
- Some(format!(
- "{}{}{}{}",
- lhs_result, infix_with_sep, rhs_result, pp.suffix
- ))
-}
-