// 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 and method calls.
-//
-// 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.
+/// 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 Indent;
+use Shape;
use rewrite::{Rewrite, RewriteContext};
-use utils::first_line_width;
+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(mut expr: &ast::Expr,
- context: &RewriteContext,
- width: usize,
- offset: Indent)
- -> Option<String> {
+pub fn rewrite_chain(expr: &ast::Expr, context: &RewriteContext, shape: Shape) -> Option<String> {
+ debug!("rewrite_chain {:?}", shape);
let total_span = expr.span;
- let mut subexpr_list = vec![expr];
+ 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);
+ }
- while let Some(subexpr) = pop_expr_chain(expr) {
- subexpr_list.push(subexpr);
- expr = subexpr;
+ // 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));
- let parent_block_indent = match context.config.chain_base_indent {
- BlockIndentStyle::Visual => offset,
- BlockIndentStyle::Inherit => context.block_indent,
- BlockIndentStyle::Tabbed => context.block_indent.block_indent(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('\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)
};
- let parent_context = &RewriteContext { block_indent: parent_block_indent, ..*context };
- let parent = subexpr_list.pop().unwrap();
- let parent_rewrite = try_opt!(expr.rewrite(parent_context, width, offset));
- let (indent, extend) = if !parent_rewrite.contains('\n') && is_continuable(parent) ||
- parent_rewrite.len() <= context.config.tab_spaces {
- (offset + Indent::new(0, parent_rewrite.len()), true)
- } else if is_block_expr(parent, &parent_rewrite) {
- (parent_block_indent, false)
+
+ let max_width = try_opt!((shape.width + shape.indent.width() + shape.offset)
+ .checked_sub(nested_shape.indent.width() +
+ nested_shape.offset));
+
+ 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 {
- (offset + Indent::new(context.config.tab_spaces, 0), false)
+ other_child_shape
};
+ debug!("child_shapes {:?} {:?}",
+ first_child_shape,
+ other_child_shape);
- let max_width = try_opt!((width + offset.width()).checked_sub(indent.width()));
- let mut rewrites = try_opt!(subexpr_list.iter()
- .rev()
- .map(|e| {
- rewrite_chain_expr(e,
- total_span,
- context,
- max_width,
- indent)
- })
- .collect::<Option<Vec<_>>>());
+ 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 total_width = almost_total + first_line_width(rewrites.last().unwrap());
- let veto_single_line = if context.config.take_source_hints && subexpr_list.len() > 1 {
+ 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));
false
};
- let fits_single_line = !veto_single_line &&
- match subexpr_list[0].node {
- ast::Expr_::ExprMethodCall(ref method_name, ref types, ref expressions)
- if context.config.chains_overflow_last => {
- let len = rewrites.len();
- let (init, last) = rewrites.split_at_mut(len - 1);
- let last = &mut last[0];
-
- if init.iter().all(|s| !s.contains('\n')) && total_width <= width {
- let last_rewrite = width.checked_sub(almost_total)
- .and_then(|inner_width| {
- rewrite_method_call(method_name.node,
- types,
- expressions,
- total_span,
- context,
- inner_width,
- offset + almost_total)
- });
- match last_rewrite {
- Some(mut string) => {
- ::std::mem::swap(&mut string, last);
- true
- }
- None => false,
+ 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)
}
- } else {
- false
+ _ => !last[0].contains('\n'),
}
}
- _ => total_width <= width && rewrites.iter().all(|s| !s.contains('\n')),
- };
+ }
let connector = if fits_single_line && !parent_rewrite.contains('\n') {
+ // Yay, we can put everything on one line.
String::new()
} else {
- format!("\n{}", indent.to_string(context.config))
+ // Use new lines.
+ format!("\n{}", nested_shape.indent.to_string(context.config))
};
- let first_connector = if extend {
+ 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.
+// parens, braces, and brackets in its idiomatic formatting.
fn is_block_expr(expr: &ast::Expr, repr: &str) -> bool {
match expr.node {
- ast::Expr_::ExprStruct(..) |
- ast::Expr_::ExprWhile(..) |
- ast::Expr_::ExprWhileLet(..) |
- ast::Expr_::ExprIf(..) |
- ast::Expr_::ExprIfLet(..) |
- ast::Expr_::ExprBlock(..) |
- ast::Expr_::ExprLoop(..) |
- ast::Expr_::ExprForLoop(..) |
- ast::Expr_::ExprMatch(..) => repr.contains('\n'),
- ast::Expr_::ExprParen(ref expr) |
- ast::Expr_::ExprBinary(_, _, ref expr) |
- ast::Expr_::ExprIndex(_, ref expr) |
- ast::Expr_::ExprUnary(_, ref expr) => is_block_expr(expr, repr),
+ 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,
}
}
-fn pop_expr_chain<'a>(expr: &'a ast::Expr) -> Option<&'a ast::Expr> {
- match expr.node {
- ast::Expr_::ExprMethodCall(_, _, ref expressions) => {
- Some(&expressions[0])
+// 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
}
- ast::Expr_::ExprTupField(ref subexpr, _) |
- ast::Expr_::ExprField(ref subexpr, _) => {
- Some(subexpr)
+ } 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 rewrite_chain_expr(expr: &ast::Expr,
- span: Span,
- context: &RewriteContext,
- width: usize,
- offset: Indent)
- -> Option<String> {
+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::Expr_::ExprMethodCall(ref method_name, ref types, ref expressions) => {
- let inner = &RewriteContext { block_indent: offset, ..*context };
- rewrite_method_call(method_name.node,
- types,
- expressions,
- span,
- inner,
- width,
- offset)
+ 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::Expr_::ExprField(_, ref field) => {
- Some(format!(".{}", field.node))
+ ast::ExprKind::TupField(_, ref field) => {
+ let s = format!(".{}", field.node);
+ if s.len() <= shape.width {
+ Some(s)
+ } else {
+ None
+ }
}
- ast::Expr_::ExprTupField(_, ref field) => {
- Some(format!(".{}", field.node))
+ ast::ExprKind::Try(_) => {
+ if shape.width >= 1 {
+ Some("?".into())
+ } else {
+ None
+ }
}
_ => unreachable!(),
}
}
-// Determines we can continue formatting a given expression on the same line.
+// Determines if we can continue formatting a given expression on the same line.
fn is_continuable(expr: &ast::Expr) -> bool {
match expr.node {
- ast::Expr_::ExprPath(..) => true,
+ ast::ExprKind::Path(..) => true,
_ => false,
}
}
args: &[ptr::P<ast::Expr>],
span: Span,
context: &RewriteContext,
- width: usize,
- offset: Indent)
+ shape: Shape)
-> Option<String> {
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<_>>();
+ 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,
- format!("::<{}>", type_list.join(", ")))
+ (types.last()
+ .unwrap()
+ .span
+ .hi,
+ type_str)
};
let callee_str = format!(".{}{}", method_name, type_str);
let span = mk_sp(lo, span.hi);
- rewrite_call(context, &callee_str, &args[1..], span, width, offset)
+ rewrite_call(context, &callee_str, &args[1..], span, shape)
}
projects / rust.git / blobdiff