// 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.
+/// 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
/// we put each subexpression on a separate, much like the (default) function
/// argument function argument strategy.
///
-/// Depends on config options: `chain_base_indent` is the indent to use for
-/// blocks in the parent/root/base of the chain.
+/// 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_base_indent`:
+/// following values of `chain_indent`:
/// Visual:
/// ```
/// let foo = {
/// .baz();
/// ```
///
-/// `chain_indent` dictates how the rest of the chain is aligned.
/// If the first item in the chain is a block expression, we align the dots with
/// the braces.
/// Visual:
/// .baz()
/// .qux
/// ```
-/// `chains_overflow_last` applies only to chains where the last item is a
-/// method call. Usually, any line break in a chain sub-expression causes the
-/// whole chain to be split with newlines at each `.`. With `chains_overflow_last`
-/// true, then we allow the last method call to spill over multiple lines without
-/// forcing the rest of the chain to be split.
-
-use Indent;
+use Shape;
use rewrite::{Rewrite, RewriteContext};
-use utils::{wrap_str, 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};
-
-pub fn rewrite_chain(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 (parent, subexpr_list) = make_subexpr_list(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);
+ }
// Parent is the first item in the chain, e.g., `foo` in `foo.bar.baz()`.
- let parent_block_indent = chain_base_indent(context, offset);
- let parent_context = &RewriteContext { block_indent: parent_block_indent, ..*context };
- let parent_rewrite = try_opt!(parent.rewrite(parent_context, width, offset));
+ 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 (indent, extend) = if !parent_rewrite.contains('\n') && is_continuable(parent) ||
- parent_rewrite.len() <= context.config.tab_spaces {
- // Try and put at least the first two items on the same line.
- (chain_indent(context, offset + Indent::new(0, parent_rewrite.len())), true)
- } else if is_block_expr(parent, &parent_rewrite) {
+ 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_block_indent, false)
+ (parent_shape, false)
} else if parent_rewrite.contains('\n') {
- (chain_indent(context, parent_block_indent.block_indent(context.config)), false)
+ (chain_indent(context,
+ parent_shape.block_indent(context.config.tab_spaces)),
+ false)
} else {
- (chain_indent_newline(context, offset + Indent::new(0, parent_rewrite.len())), false)
+ (shape.block_indent(context.config.tab_spaces), false)
};
- 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_subexpr(e, total_span, context, max_width, indent))
- .collect::<Option<Vec<_>>>());
+ 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 {
+ other_child_shape
+ };
+ debug!("child_shapes {:?} {:?}",
+ first_child_shape,
+ other_child_shape);
+
+ 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 mut fits_single_line = !veto_single_line && total_width <= width;
+ 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);
if fits_single_line {
fits_single_line = match expr.node {
- ref e @ ast::ExprKind::MethodCall(..) if context.config.chains_overflow_last => {
+ ref e @ ast::ExprKind::MethodCall(..) => {
rewrite_method_call_with_overflow(e,
&mut last[0],
almost_total,
- width,
total_span,
context,
- offset)
+ shape)
}
_ => !last[0].contains('\n'),
}
String::new()
} else {
// Use new lines.
- format!("\n{}", indent.to_string(context.config))
+ 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
};
wrap_str(format!("{}{}{}",
parent_rewrite,
first_connector,
- rewrites.join(&connector)),
+ join_rewrites(&rewrites, &subexpr_list, &connector)),
context.config.max_width,
- width,
- offset)
+ 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
// 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(mut expr: &ast::Expr) -> (&ast::Expr, Vec<&ast::Expr>) {
- fn pop_expr_chain(expr: &ast::Expr) -> Option<&ast::Expr> {
- match expr.node {
- ast::ExprKind::MethodCall(_, _, ref expressions) => Some(&expressions[0]),
- ast::ExprKind::TupField(ref subexpr, _) |
- ast::ExprKind::Field(ref subexpr, _) => Some(subexpr),
- _ => None,
- }
- }
-
- let mut subexpr_list = vec![expr];
+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(expr) {
- subexpr_list.push(subexpr);
- expr = subexpr;
+ 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_base_indent(context: &RewriteContext, offset: Indent) -> Indent {
- match context.config.chain_base_indent {
- BlockIndentStyle::Visual => offset,
- BlockIndentStyle::Inherit => context.block_indent,
- BlockIndentStyle::Tabbed => context.block_indent.block_indent(context.config),
- }
-}
-
-fn chain_indent(context: &RewriteContext, offset: Indent) -> Indent {
- match context.config.chain_indent {
- BlockIndentStyle::Visual => offset,
- BlockIndentStyle::Inherit => context.block_indent,
- BlockIndentStyle::Tabbed => context.block_indent.block_indent(context.config),
- }
-}
-
-// Ignores visual indenting because this function should be called where it is
-// not possible to use visual indentation because we are starting on a newline.
-fn chain_indent_newline(context: &RewriteContext, _offset: Indent) -> Indent {
+fn chain_indent(context: &RewriteContext, shape: Shape) -> Shape {
match context.config.chain_indent {
- BlockIndentStyle::Inherit => context.block_indent,
- BlockIndentStyle::Visual | BlockIndentStyle::Tabbed => {
- context.block_indent.block_indent(context.config)
- }
+ 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,
- width: usize,
total_span: Span,
context: &RewriteContext,
- offset: Indent)
+ shape: Shape)
-> bool {
if let &ast::ExprKind::MethodCall(ref method_name, ref types, ref expressions) = expr_kind {
- let budget = match width.checked_sub(almost_total) {
+ let shape = match shape.shrink_left(almost_total) {
Some(b) => b,
None => return false,
};
expressions,
total_span,
context,
- budget,
- offset + almost_total);
+ shape);
if let Some(ref mut s) = last_rewrite {
::std::mem::swap(s, last);
}
}
+// 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,
- width: usize,
- offset: Indent)
+ shape: Shape)
-> Option<String> {
match expr.node {
ast::ExprKind::MethodCall(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)
+ rewrite_method_call(method_name.node, types, expressions, span, context, shape)
}
ast::ExprKind::Field(_, ref field) => {
let s = format!(".{}", field.node);
- if s.len() <= width {
+ if s.len() <= shape.width {
Some(s)
} else {
None
}
ast::ExprKind::TupField(_, ref field) => {
let s = format!(".{}", field.node);
- if s.len() <= width {
+ if s.len() <= shape.width {
Some(s)
} else {
None
}
}
+ ast::ExprKind::Try(_) => {
+ if shape.width >= 1 {
+ Some("?".into())
+ } else {
+ None
+ }
+ }
_ => unreachable!(),
}
}
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: Vec<_> = try_opt!(types.iter()
- .map(|ty| ty.rewrite(context, width, offset))
- .collect());
+ 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