// 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 (?).
+///
+/// Instead of walking these subexpressions one-by-one, as is our usual strategy
+/// for expression formatting, we collect maximal sequences of these expressions
+/// and handle them simultaneously.
+///
+/// Whenever possible, the entire chain is put on a single line. If that fails,
+/// we put each subexpression on a separate, much like the (default) function
+/// argument function argument strategy.
+///
+/// Depends on config options: `chain_indent` is the indent to use for
+/// blocks in the parent/root/base of the chain (and the rest of the chain's
+/// alignment).
+/// E.g., `let foo = { aaaa; bbb; ccc }.bar.baz();`, we would layout for the
+/// following values of `chain_indent`:
+/// Visual:
+/// ```
+/// let foo = {
+/// aaaa;
+/// bbb;
+/// ccc
+/// }
+/// .bar
+/// .baz();
+/// ```
+/// Inherit:
+/// ```
+/// let foo = {
+/// aaaa;
+/// bbb;
+/// ccc
+/// }
+/// .bar
+/// .baz();
+/// ```
+/// Tabbed:
+/// ```
+/// let foo = {
+/// aaaa;
+/// bbb;
+/// ccc
+/// }
+/// .bar
+/// .baz();
+/// ```
+///
+/// If the first item in the chain is a block expression, we align the dots with
+/// the braces.
+/// Visual:
+/// ```
+/// let a = foo.bar
+/// .baz()
+/// .qux
+/// ```
+/// Inherit:
+/// ```
+/// let a = foo.bar
+/// .baz()
+/// .qux
+/// ```
+/// Tabbed:
+/// ```
+/// let a = foo.bar
+/// .baz()
+/// .qux
+/// ```
+
+use Shape;
use rewrite::{Rewrite, RewriteContext};
-use utils::{span_after, make_indent, extra_offset};
+use utils::{wrap_str, first_line_width, last_line_width};
use expr::rewrite_call;
+use config::BlockIndentStyle;
+use macros::convert_try_mac;
+use std::iter;
use syntax::{ast, ptr};
use syntax::codemap::{mk_sp, Span};
-use syntax::print::pprust;
-
-pub fn rewrite_chain(orig_expr: &ast::Expr,
- context: &RewriteContext,
- width: usize,
- offset: usize)
- -> Option<String> {
- let mut expr = orig_expr;
- let mut rewrites = Vec::new();
- let indent = offset + context.config.tab_spaces;
- let max_width = try_opt!(context.config.max_width.checked_sub(indent));
-
- loop {
- match expr.node {
- ast::Expr_::ExprMethodCall(ref method_name, ref types, ref expressions) => {
- // FIXME: a lot of duplication between this and the
- // rewrite_method_call in expr.rs.
- let new_span = mk_sp(expressions[0].span.hi, expr.span.hi);
- let lo = span_after(new_span, "(", context.codemap);
- let new_span = mk_sp(lo, expr.span.hi);
-
- let rewrite = rewrite_method_call(method_name.node,
- types,
- &expressions[1..],
- new_span,
- context,
- max_width,
- indent);
- rewrites.push(try_opt!(rewrite));
- expr = &expressions[0];
- }
- ast::Expr_::ExprField(ref subexpr, ref field) => {
- expr = subexpr;
- rewrites.push(format!(".{}", field.node));
- }
- ast::Expr_::ExprTupField(ref subexpr, ref field) => {
- expr = subexpr;
- rewrites.push(format!(".{}", field.node));
- }
- _ => break,
- }
+
+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);
+
+ // 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);
}
- let parent_rewrite = try_opt!(expr.rewrite(context, width, offset));
-
- // TODO: add exception for when rewrites.len() == 1
- if rewrites.len() == 1 {
- let extra_offset = extra_offset(&parent_rewrite, offset);
- let max_width = try_opt!(width.checked_sub(extra_offset));
- // FIXME: massive duplication
- let rerewrite = match orig_expr.node {
- ast::Expr_::ExprMethodCall(ref method_name, ref types, ref expressions) => {
- let new_span = mk_sp(expressions[0].span.hi, orig_expr.span.hi);
- let lo = span_after(new_span, "(", context.codemap);
- let new_span = mk_sp(lo, orig_expr.span.hi);
-
- rewrite_method_call(method_name.node,
- types,
- &expressions[1..],
- new_span,
- context,
- max_width,
- offset + extra_offset)
- }
- ast::Expr_::ExprField(_, ref field) => {
- Some(format!(".{}", field.node))
- }
- ast::Expr_::ExprTupField(_, ref field) => {
- Some(format!(".{}", field.node))
- }
- _ => unreachable!(),
+ // Parent is the first item in the chain, e.g., `foo` in `foo.bar.baz()`.
+ let mut parent_shape = shape;
+ if is_block_expr(&parent, "\n") {
+ parent_shape = chain_indent(context, shape);
+ }
+ let parent_rewrite = try_opt!(parent.rewrite(context, parent_shape));
+
+ // 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('\n') && is_continuable(&parent) {
+ let nested_shape = if let ast::ExprKind::Try(..) = subexpr_list.last().unwrap().node {
+ parent_shape.block_indent(context.config.tab_spaces)
+ } else {
+ chain_indent(context, shape.add_offset(parent_rewrite.len()))
};
+ (nested_shape, true)
+ } else if is_block_expr(&parent, &parent_rewrite) {
+ // The parent is a block, so align the rest of the chain with the closing
+ // brace.
+ (parent_shape, false)
+ } else if parent_rewrite.contains('\n') {
+ (chain_indent(context,
+ parent_shape.block_indent(context.config.tab_spaces)),
+ false)
+ } else {
+ (shape.block_indent(context.config.tab_spaces), false)
+ };
- return Some(format!("{}{}", parent_rewrite, try_opt!(rerewrite)));
- }
+ let max_width = try_opt!((shape.width + shape.indent.width() + shape.offset)
+ .checked_sub(nested_shape.indent.width() +
+ nested_shape.offset));
- let total_width = rewrites.iter().fold(0, |a, b| a + b.len()) + parent_rewrite.len();
+ let other_child_shape = Shape { width: max_width, ..nested_shape };
+ let first_child_shape = if extend {
+ let mut shape = try_opt!(parent_shape.shrink_left(last_line_width(&parent_rewrite)));
+ match context.config.chain_indent {
+ BlockIndentStyle::Visual => other_child_shape,
+ BlockIndentStyle::Tabbed => {
+ shape.offset = shape.offset.checked_sub(context.config.tab_spaces).unwrap_or(0);
+ shape.indent.block_indent += context.config.tab_spaces;
+ shape
+ }
+ }
+ } else {
+ other_child_shape
+ };
+ debug!("child_shapes {:?} {:?}",
+ first_child_shape,
+ other_child_shape);
- let connector = if total_width <= width && rewrites.iter().all(|s| !s.contains('\n')) {
- String::new()
+ let child_shape_iter =
+ Some(first_child_shape).into_iter().chain(::std::iter::repeat(other_child_shape)
+ .take(subexpr_list.len() - 1));
+ let iter = subexpr_list.iter().rev().zip(child_shape_iter);
+ let mut rewrites =
+ try_opt!(iter.map(|(e, shape)| rewrite_chain_subexpr(e, total_span, context, shape))
+ .collect::<Option<Vec<_>>>());
+
+ // Total of all items excluding the last.
+ let almost_total = rewrites[..rewrites.len() - 1].iter().fold(0, |a, b| {
+ a + first_line_width(b)
+ }) + parent_rewrite.len();
+
+ let veto_single_line = if subexpr_list.len() > context.config.chain_one_line_max - 1 {
+ // -1 above because subexpr_list does not include the parent.
+ true
+ } else if context.config.take_source_hints && subexpr_list.len() > 1 {
+ // Look at the source code. Unless all chain elements start on the same
+ // line, we won't consider putting them on a single line either.
+ let last_span = context.snippet(mk_sp(subexpr_list[1].span.hi, total_span.hi));
+ let first_span = context.snippet(subexpr_list[1].span);
+ let last_iter = last_span.chars().take_while(|c| c.is_whitespace());
+
+ first_span.chars().chain(last_iter).any(|c| c == '\n')
} else {
- format!("\n{}", make_indent(indent))
+ false
};
- // FIXME: don't do this. There's a more efficient way. VecDeque?
- rewrites.reverse();
+ let mut fits_single_line = !veto_single_line && almost_total <= shape.width;
+ if fits_single_line {
+ let len = rewrites.len();
+ let (init, last) = rewrites.split_at_mut(len - 1);
+ fits_single_line = init.iter().all(|s| !s.contains('\n'));
+
+ if fits_single_line {
+ fits_single_line = match expr.node {
+ ref e @ ast::ExprKind::MethodCall(..) => {
+ rewrite_method_call_with_overflow(e,
+ &mut last[0],
+ almost_total,
+ total_span,
+ context,
+ shape)
+ }
+ _ => !last[0].contains('\n'),
+ }
+ }
+ }
- // Put the first link on the same line as parent, if it fits.
- let first_connector = if parent_rewrite.len() + rewrites[0].len() <= width &&
- !rewrites[0].contains('\n') ||
- parent_rewrite.len() <= context.config.tab_spaces {
+ let connector = if fits_single_line && !parent_rewrite.contains('\n') {
+ // Yay, we can put everything on one line.
+ String::new()
+ } else {
+ // Use new lines.
+ format!("\n{}", nested_shape.indent.to_string(context.config))
+ };
+
+ let first_connector = if extend || subexpr_list.is_empty() {
+ ""
+ } else if let ast::ExprKind::Try(_) = subexpr_list[0].node {
""
} else {
- &connector[..]
+ &*connector
};
- Some(format!("{}{}{}", parent_rewrite, first_connector, rewrites.join(&connector)))
+ wrap_str(format!("{}{}{}",
+ parent_rewrite,
+ first_connector,
+ join_rewrites(&rewrites, &subexpr_list, &connector)),
+ 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
+ })
+}
+
+pub fn rewrite_try(expr: &ast::Expr,
+ try_count: usize,
+ context: &RewriteContext,
+ shape: Shape)
+ -> Option<String> {
+ let sub_expr = try_opt!(expr.rewrite(context, try_opt!(shape.sub_width(try_count))));
+ Some(format!("{}{}",
+ sub_expr,
+ iter::repeat("?").take(try_count).collect::<String>()))
+}
+
+fn join_rewrites(rewrites: &[String], subexps: &[ast::Expr], connector: &str) -> String {
+ let mut rewrite_iter = rewrites.iter();
+ let mut result = rewrite_iter.next().unwrap().clone();
+ let mut subexpr_iter = subexps.iter().rev();
+ subexpr_iter.next();
+
+ for (rewrite, expr) in rewrite_iter.zip(subexpr_iter) {
+ match expr.node {
+ ast::ExprKind::Try(_) => (),
+ _ => result.push_str(connector),
+ };
+ result.push_str(&rewrite[..]);
+ }
+
+ result
+}
+
+// States whether an expression's last line exclusively consists of closing
+// parens, braces, and brackets in its idiomatic formatting.
+fn is_block_expr(expr: &ast::Expr, repr: &str) -> bool {
+ match expr.node {
+ 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) => is_block_expr(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>) {
+ 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.chain_indent {
+ BlockIndentStyle::Visual => shape.visual_indent(0),
+ BlockIndentStyle::Tabbed => shape.block_indent(context.config.tab_spaces),
+ }
+}
+
+fn rewrite_method_call_with_overflow(expr_kind: &ast::ExprKind,
+ last: &mut String,
+ almost_total: usize,
+ total_span: Span,
+ context: &RewriteContext,
+ shape: Shape)
+ -> bool {
+ if let &ast::ExprKind::MethodCall(ref method_name, ref types, ref expressions) = expr_kind {
+ let shape = match shape.shrink_left(almost_total) {
+ Some(b) => b,
+ None => return false,
+ };
+ let mut last_rewrite = rewrite_method_call(method_name.node,
+ types,
+ expressions,
+ total_span,
+ context,
+ shape);
+
+ if let Some(ref mut s) = last_rewrite {
+ ::std::mem::swap(s, last);
+ true
+ } else {
+ false
+ }
+ } else {
+ unreachable!();
+ }
+}
+
+// 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::TupField(ref subexpr, _) |
+ ast::ExprKind::Field(ref subexpr, _) |
+ ast::ExprKind::Try(ref subexpr) => Some(convert_try(subexpr, context)),
+ _ => None,
+ }
+}
+
+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()
+ }
+ }
+ _ => 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,
+ span: Span,
+ context: &RewriteContext,
+ shape: Shape)
+ -> Option<String> {
+ match expr.node {
+ ast::ExprKind::MethodCall(ref method_name, ref types, ref expressions) => {
+ rewrite_method_call(method_name.node, types, expressions, span, context, shape)
+ }
+ ast::ExprKind::Field(_, ref field) => {
+ let s = format!(".{}", field.node);
+ if s.len() <= shape.width {
+ Some(s)
+ } else {
+ None
+ }
+ }
+ ast::ExprKind::TupField(_, ref field) => {
+ let s = format!(".{}", field.node);
+ if s.len() <= shape.width {
+ Some(s)
+ } else {
+ None
+ }
+ }
+ ast::ExprKind::Try(_) => {
+ if shape.width >= 1 {
+ Some("?".into())
+ } else {
+ None
+ }
+ }
+ _ => unreachable!(),
+ }
+}
+
+// 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 rewrite_method_call(method_name: ast::Ident,
args: &[ptr::P<ast::Expr>],
span: Span,
context: &RewriteContext,
- width: usize,
- offset: usize)
+ shape: Shape)
-> Option<String> {
- let type_str = if types.is_empty() {
- String::new()
+ let (lo, type_str) = if types.is_empty() {
+ (args[0].span.hi, String::new())
} else {
- let type_list = types.iter().map(|ty| pprust::ty_to_string(ty)).collect::<Vec<_>>();
- format!("::<{}>", type_list.join(", "))
+ let type_list: Vec<_> =
+ try_opt!(types.iter().map(|ty| ty.rewrite(context, shape)).collect());
+
+ let type_str = if context.config.spaces_within_angle_brackets && type_list.len() > 0 {
+ format!("::< {} >", type_list.join(", "))
+ } else {
+ format!("::<{}>", type_list.join(", "))
+ };
+
+ (types.last()
+ .unwrap()
+ .span
+ .hi,
+ type_str)
};
let callee_str = format!(".{}{}", method_name, type_str);
- let inner_context = &RewriteContext {
- block_indent: offset,
- ..*context
- };
+ let span = mk_sp(lo, span.hi);
- rewrite_call(inner_context, &callee_str, args, span, width, offset)
+ rewrite_call(context, &callee_str, &args[1..], span, shape)
}
projects / rust.git / blobdiff