rust/src/types.rs
2017-05-03 11:26:25 +09:00

736 lines
31 KiB
Rust

// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use std::ops::Deref;
use std::iter::ExactSizeIterator;
use syntax::abi;
use syntax::ast::{self, Mutability, FunctionRetTy};
use syntax::codemap::{self, Span, BytePos};
use syntax::print::pprust;
use syntax::symbol::keywords;
use {Shape, Spanned};
use codemap::SpanUtils;
use lists::{format_item_list, itemize_list, format_fn_args};
use rewrite::{Rewrite, RewriteContext};
use utils::{extra_offset, format_mutability, colon_spaces, wrap_str};
use expr::{rewrite_unary_prefix, rewrite_pair, rewrite_tuple};
use config::TypeDensity;
use itertools::Itertools;
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub enum PathContext {
Expr,
Type,
Import,
}
// Does not wrap on simple segments.
pub fn rewrite_path(context: &RewriteContext,
path_context: PathContext,
qself: Option<&ast::QSelf>,
path: &ast::Path,
shape: Shape)
-> Option<String> {
let skip_count = qself.map_or(0, |x| x.position);
let mut result = if path.is_global() && qself.is_none() &&
path_context != PathContext::Import {
"::".to_owned()
} else {
String::new()
};
let mut span_lo = path.span.lo;
if let Some(qself) = qself {
result.push('<');
if context.config.spaces_within_angle_brackets {
result.push_str(" ")
}
let fmt_ty = try_opt!(qself.ty.rewrite(context, shape));
result.push_str(&fmt_ty);
if skip_count > 0 {
result.push_str(" as ");
if path.is_global() && path_context != PathContext::Import {
result.push_str("::");
}
let extra_offset = extra_offset(&result, shape);
// 3 = ">::".len()
let shape = try_opt!(try_opt!(shape.shrink_left(extra_offset)).sub_width(3));
result = try_opt!(rewrite_path_segments(PathContext::Type,
result,
path.segments.iter().take(skip_count),
span_lo,
path.span.hi,
context,
shape));
}
if context.config.spaces_within_angle_brackets {
result.push_str(" ")
}
result.push_str(">::");
span_lo = qself.ty.span.hi + BytePos(1);
}
rewrite_path_segments(path_context,
result,
path.segments.iter().skip(skip_count),
span_lo,
path.span.hi,
context,
shape)
}
fn rewrite_path_segments<'a, I>(path_context: PathContext,
mut buffer: String,
iter: I,
mut span_lo: BytePos,
span_hi: BytePos,
context: &RewriteContext,
shape: Shape)
-> Option<String>
where I: Iterator<Item = &'a ast::PathSegment>
{
let mut first = true;
let shape = shape.visual_indent(0);
for segment in iter {
// Indicates a global path, shouldn't be rendered.
if segment.identifier.name == keywords::CrateRoot.name() {
continue;
}
if first {
first = false;
} else {
buffer.push_str("::");
}
let extra_offset = extra_offset(&buffer, shape);
let new_shape = try_opt!(shape.shrink_left(extra_offset));
let segment_string = try_opt!(rewrite_segment(path_context,
segment,
&mut span_lo,
span_hi,
context,
new_shape));
buffer.push_str(&segment_string);
}
Some(buffer)
}
#[derive(Debug)]
enum SegmentParam<'a> {
LifeTime(&'a ast::Lifetime),
Type(&'a ast::Ty),
Binding(&'a ast::TypeBinding),
}
impl<'a> SegmentParam<'a> {
fn get_span(&self) -> Span {
match *self {
SegmentParam::LifeTime(lt) => lt.span,
SegmentParam::Type(ty) => ty.span,
SegmentParam::Binding(binding) => binding.span,
}
}
}
impl<'a> Rewrite for SegmentParam<'a> {
fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
match *self {
SegmentParam::LifeTime(lt) => lt.rewrite(context, shape),
SegmentParam::Type(ty) => ty.rewrite(context, shape),
SegmentParam::Binding(binding) => {
let mut result = match context.config.type_punctuation_density {
TypeDensity::Wide => format!("{} = ", binding.ident),
TypeDensity::Compressed => format!("{}=", binding.ident),
};
let budget = try_opt!(shape.width.checked_sub(result.len()));
let rewrite =
try_opt!(binding
.ty
.rewrite(context,
Shape::legacy(budget, shape.indent + result.len())));
result.push_str(&rewrite);
Some(result)
}
}
}
}
// Formats a path segment. There are some hacks involved to correctly determine
// the segment's associated span since it's not part of the AST.
//
// The span_lo is assumed to be greater than the end of any previous segment's
// parameters and lesser or equal than the start of current segment.
//
// span_hi is assumed equal to the end of the entire path.
//
// When the segment contains a positive number of parameters, we update span_lo
// so that invariants described above will hold for the next segment.
fn rewrite_segment(path_context: PathContext,
segment: &ast::PathSegment,
span_lo: &mut BytePos,
span_hi: BytePos,
context: &RewriteContext,
shape: Shape)
-> Option<String> {
let ident_len = segment.identifier.to_string().len();
let shape = try_opt!(shape.shrink_left(ident_len));
let params = if let Some(ref params) = segment.parameters {
match **params {
ast::PathParameters::AngleBracketed(ref data) if !data.lifetimes.is_empty() ||
!data.types.is_empty() ||
!data.bindings.is_empty() => {
let param_list = data.lifetimes
.iter()
.map(SegmentParam::LifeTime)
.chain(data.types.iter().map(|x| SegmentParam::Type(&*x)))
.chain(data.bindings.iter().map(|x| SegmentParam::Binding(&*x)))
.collect::<Vec<_>>();
let next_span_lo = param_list.last().unwrap().get_span().hi + BytePos(1);
let list_lo = context
.codemap
.span_after(codemap::mk_sp(*span_lo, span_hi), "<");
let separator = if path_context == PathContext::Expr {
"::"
} else {
""
};
// 1 for <
let extra_offset = 1 + separator.len();
// 1 for >
// TODO bad visual indent
let list_shape = try_opt!(try_opt!(shape.shrink_left(extra_offset)).sub_width(1))
.visual_indent(0);
let items = itemize_list(context.codemap,
param_list.into_iter(),
">",
|param| param.get_span().lo,
|param| param.get_span().hi,
|seg| seg.rewrite(context, list_shape),
list_lo,
span_hi);
let list_str = try_opt!(format_item_list(items, list_shape, context.config));
// Update position of last bracket.
*span_lo = next_span_lo;
if context.config.spaces_within_angle_brackets && list_str.len() > 0 {
format!("{}< {} >", separator, list_str)
} else {
format!("{}<{}>", separator, list_str)
}
}
ast::PathParameters::Parenthesized(ref data) => {
let output = match data.output {
Some(ref ty) => FunctionRetTy::Ty(ty.clone()),
None => FunctionRetTy::Default(codemap::DUMMY_SP),
};
try_opt!(format_function_type(data.inputs.iter().map(|x| &**x),
&output,
false,
data.span,
context,
shape))
}
_ => String::new(),
}
} else {
String::new()
};
Some(format!("{}{}", segment.identifier, params))
}
fn format_function_type<'a, I>(inputs: I,
output: &FunctionRetTy,
variadic: bool,
span: Span,
context: &RewriteContext,
shape: Shape)
-> Option<String>
where I: ExactSizeIterator,
<I as Iterator>::Item: Deref,
<I::Item as Deref>::Target: Rewrite + Spanned + 'a
{
// Code for handling variadics is somewhat duplicated for items, but they
// are different enough to need some serious refactoring to share code.
enum ArgumentKind<T>
where T: Deref,
<T as Deref>::Target: Rewrite + Spanned
{
Regular(Box<T>),
Variadic(BytePos),
}
let variadic_arg = if variadic {
let variadic_start = context.codemap.span_before(span, "...");
Some(ArgumentKind::Variadic(variadic_start))
} else {
None
};
// 2 for ()
let budget = try_opt!(shape.width.checked_sub(2));
// 1 for (
let offset = shape.indent + 1;
let list_lo = context.codemap.span_after(span, "(");
let items = itemize_list(context.codemap,
// FIXME Would be nice to avoid this allocation,
// but I couldn't get the types to work out.
inputs
.map(|i| ArgumentKind::Regular(Box::new(i)))
.chain(variadic_arg),
")",
|arg| match *arg {
ArgumentKind::Regular(ref ty) => ty.span().lo,
ArgumentKind::Variadic(start) => start,
},
|arg| match *arg {
ArgumentKind::Regular(ref ty) => ty.span().hi,
ArgumentKind::Variadic(start) => start + BytePos(3),
},
|arg| match *arg {
ArgumentKind::Regular(ref ty) => {
ty.rewrite(context, Shape::legacy(budget, offset))
}
ArgumentKind::Variadic(_) => Some("...".to_owned()),
},
list_lo,
span.hi);
let list_str = try_opt!(format_fn_args(items, Shape::legacy(budget, offset), context.config));
let output = match *output {
FunctionRetTy::Ty(ref ty) => {
let budget = try_opt!(shape.width.checked_sub(4));
let type_str = try_opt!(ty.rewrite(context, Shape::legacy(budget, offset + 4)));
format!(" -> {}", type_str)
}
FunctionRetTy::Default(..) => String::new(),
};
let infix = if !output.is_empty() && output.len() + list_str.len() > shape.width {
format!("\n{}", (offset - 1).to_string(context.config))
} else {
String::new()
};
Some(if context.config.spaces_within_parens {
format!("( {} ){}{}", list_str, infix, output)
} else {
format!("({}){}{}", list_str, infix, output)
})
}
fn type_bound_colon(context: &RewriteContext) -> &'static str {
colon_spaces(context.config.space_before_bound,
context.config.space_after_bound_colon)
}
impl Rewrite for ast::WherePredicate {
fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
// TODO: dead spans?
let result = match *self {
ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate {
ref bound_lifetimes,
ref bounded_ty,
ref bounds,
..
}) => {
let type_str = try_opt!(bounded_ty.rewrite(context, shape));
let colon = type_bound_colon(context);
if !bound_lifetimes.is_empty() {
let lifetime_str: String = try_opt!(bound_lifetimes.iter()
.map(|lt| lt.rewrite(context, shape))
.intersperse(Some(", ".to_string()))
.collect());
let joiner = match context.config.type_punctuation_density {
TypeDensity::Compressed => "+",
TypeDensity::Wide => " + ",
};
// 6 = "for<> ".len()
let used_width = lifetime_str.len() + type_str.len() + colon.len() + 6;
let budget = try_opt!(shape.width.checked_sub(used_width));
let bounds_str: String = try_opt!(bounds.iter()
.map(|ty_bound| {
ty_bound.rewrite(context,
Shape::legacy(budget,
shape.indent + used_width))
})
.intersperse(Some(joiner.to_string()))
.collect());
if context.config.spaces_within_angle_brackets && lifetime_str.len() > 0 {
format!("for< {} > {}{}{}",
lifetime_str,
type_str,
colon,
bounds_str)
} else {
format!("for<{}> {}{}{}", lifetime_str, type_str, colon, bounds_str)
}
} else {
let joiner = match context.config.type_punctuation_density {
TypeDensity::Compressed => "+",
TypeDensity::Wide => " + ",
};
let used_width = type_str.len() + colon.len();
let budget = try_opt!(shape.width.checked_sub(used_width));
let bounds_str: String = try_opt!(bounds.iter()
.map(|ty_bound| {
ty_bound.rewrite(context,
Shape::legacy(budget,
shape.indent + used_width))
})
.intersperse(Some(joiner.to_string()))
.collect());
format!("{}{}{}", type_str, colon, bounds_str)
}
}
ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate {
ref lifetime,
ref bounds,
..
}) => {
try_opt!(rewrite_bounded_lifetime(lifetime, bounds.iter(), context, shape))
}
ast::WherePredicate::EqPredicate(ast::WhereEqPredicate {
ref lhs_ty,
ref rhs_ty,
..
}) => {
let lhs_ty_str = try_opt!(lhs_ty.rewrite(context, shape));
// 3 = " = ".len()
let used_width = 3 + lhs_ty_str.len();
let budget = try_opt!(shape.width.checked_sub(used_width));
let rhs_ty_str = try_opt!(rhs_ty.rewrite(context,
Shape::legacy(budget,
shape.indent + used_width)));
format!("{} = {}", lhs_ty_str, rhs_ty_str)
}
};
wrap_str(result, context.config.max_width, shape)
}
}
impl Rewrite for ast::LifetimeDef {
fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
rewrite_bounded_lifetime(&self.lifetime, self.bounds.iter(), context, shape)
}
}
fn rewrite_bounded_lifetime<'b, I>(lt: &ast::Lifetime,
bounds: I,
context: &RewriteContext,
shape: Shape)
-> Option<String>
where I: ExactSizeIterator<Item = &'b ast::Lifetime>
{
let result = try_opt!(lt.rewrite(context, shape));
if bounds.len() == 0 {
Some(result)
} else {
let appendix: Vec<_> = try_opt!(bounds
.into_iter()
.map(|b| b.rewrite(context, shape))
.collect());
let colon = type_bound_colon(context);
let joiner = match context.config.type_punctuation_density {
TypeDensity::Compressed => "+",
TypeDensity::Wide => " + ",
};
let result = format!("{}{}{}", result, colon, appendix.join(joiner));
wrap_str(result, context.config.max_width, shape)
}
}
impl Rewrite for ast::TyParamBound {
fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
match *self {
ast::TyParamBound::TraitTyParamBound(ref tref, ast::TraitBoundModifier::None) => {
tref.rewrite(context, shape)
}
ast::TyParamBound::TraitTyParamBound(ref tref, ast::TraitBoundModifier::Maybe) => {
let budget = try_opt!(shape.width.checked_sub(1));
Some(format!("?{}",
try_opt!(tref.rewrite(context,
Shape::legacy(budget, shape.indent + 1)))))
}
ast::TyParamBound::RegionTyParamBound(ref l) => l.rewrite(context, shape),
}
}
}
impl Rewrite for ast::Lifetime {
fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
wrap_str(pprust::lifetime_to_string(self),
context.config.max_width,
shape)
}
}
impl Rewrite for ast::TyParamBounds {
fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
let joiner = match context.config.type_punctuation_density {
TypeDensity::Compressed => "+",
TypeDensity::Wide => " + ",
};
let strs: Vec<_> = try_opt!(self.iter().map(|b| b.rewrite(context, shape)).collect());
wrap_str(strs.join(joiner), context.config.max_width, shape)
}
}
impl Rewrite for ast::TyParam {
fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
let mut result = String::with_capacity(128);
result.push_str(&self.ident.to_string());
if !self.bounds.is_empty() {
if context.config.space_before_bound {
result.push_str(" ");
}
result.push_str(":");
if context.config.space_after_bound_colon {
result.push_str(" ");
}
let joiner = match context.config.type_punctuation_density {
TypeDensity::Compressed => "+",
TypeDensity::Wide => " + ",
};
let bounds: String =
try_opt!(self.bounds
.iter()
.map(|ty_bound| ty_bound.rewrite(context, shape))
.intersperse(Some(joiner.to_string()))
.collect());
result.push_str(&bounds);
}
if let Some(ref def) = self.default {
let eq_str = match context.config.type_punctuation_density {
TypeDensity::Compressed => "=",
TypeDensity::Wide => " = ",
};
result.push_str(eq_str);
let budget = try_opt!(shape.width.checked_sub(result.len()));
let rewrite = try_opt!(def.rewrite(context,
Shape::legacy(budget, shape.indent + result.len())));
result.push_str(&rewrite);
}
wrap_str(result, context.config.max_width, shape)
}
}
impl Rewrite for ast::PolyTraitRef {
fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
if !self.bound_lifetimes.is_empty() {
let lifetime_str: String = try_opt!(self.bound_lifetimes
.iter()
.map(|lt| lt.rewrite(context, shape))
.intersperse(Some(", ".to_string()))
.collect());
// 6 is "for<> ".len()
let extra_offset = lifetime_str.len() + 6;
let max_path_width = try_opt!(shape.width.checked_sub(extra_offset));
let path_str = try_opt!(self.trait_ref
.rewrite(context,
Shape::legacy(max_path_width,
shape.indent + extra_offset)));
Some(if context.config.spaces_within_angle_brackets && lifetime_str.len() > 0 {
format!("for< {} > {}", lifetime_str, path_str)
} else {
format!("for<{}> {}", lifetime_str, path_str)
})
} else {
self.trait_ref.rewrite(context, shape)
}
}
}
impl Rewrite for ast::TraitRef {
fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
rewrite_path(context, PathContext::Type, None, &self.path, shape)
}
}
impl Rewrite for ast::Ty {
fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
match self.node {
ast::TyKind::TraitObject(ref bounds) => bounds.rewrite(context, shape),
ast::TyKind::Ptr(ref mt) => {
let prefix = match mt.mutbl {
Mutability::Mutable => "*mut ",
Mutability::Immutable => "*const ",
};
rewrite_unary_prefix(context, prefix, &*mt.ty, shape, self.span)
}
ast::TyKind::Rptr(ref lifetime, ref mt) => {
let mut_str = format_mutability(mt.mutbl);
let mut_len = mut_str.len();
Some(match *lifetime {
Some(ref lifetime) => {
let lt_budget = try_opt!(shape.width.checked_sub(2 + mut_len));
let lt_str = try_opt!(lifetime.rewrite(context,
Shape::legacy(lt_budget,
shape.indent +
2 +
mut_len)));
let lt_len = lt_str.len();
let budget = try_opt!(shape.width.checked_sub(2 + mut_len + lt_len));
format!("&{} {}{}",
lt_str,
mut_str,
try_opt!(mt.ty
.rewrite(context,
Shape::legacy(budget,
shape.indent + 2 +
mut_len +
lt_len))))
}
None => {
let budget = try_opt!(shape.width.checked_sub(1 + mut_len));
format!("&{}{}",
mut_str,
try_opt!(mt.ty
.rewrite(context,
Shape::legacy(budget,
shape.indent + 1 +
mut_len))))
}
})
}
// FIXME: we drop any comments here, even though it's a silly place to put
// comments.
ast::TyKind::Paren(ref ty) => {
let budget = try_opt!(shape.width.checked_sub(2));
ty.rewrite(context, Shape::legacy(budget, shape.indent + 1))
.map(|ty_str| if context.config.spaces_within_parens {
format!("( {} )", ty_str)
} else {
format!("({})", ty_str)
})
}
ast::TyKind::Slice(ref ty) => {
let budget = if context.config.spaces_within_square_brackets {
try_opt!(shape.width.checked_sub(4))
} else {
try_opt!(shape.width.checked_sub(2))
};
ty.rewrite(context, Shape::legacy(budget, shape.indent + 1))
.map(|ty_str| if context.config.spaces_within_square_brackets {
format!("[ {} ]", ty_str)
} else {
format!("[{}]", ty_str)
})
}
ast::TyKind::Tup(ref items) => {
rewrite_tuple(context, items.iter().map(|x| &**x), self.span, shape)
}
ast::TyKind::Path(ref q_self, ref path) => {
rewrite_path(context, PathContext::Type, q_self.as_ref(), path, shape)
}
ast::TyKind::Array(ref ty, ref repeats) => {
let use_spaces = context.config.spaces_within_square_brackets;
let lbr = if use_spaces { "[ " } else { "[" };
let rbr = if use_spaces { " ]" } else { "]" };
rewrite_pair(&**ty, &**repeats, lbr, "; ", rbr, context, shape)
}
ast::TyKind::Infer => {
if shape.width >= 1 {
Some("_".to_owned())
} else {
None
}
}
ast::TyKind::BareFn(ref bare_fn) => rewrite_bare_fn(bare_fn, self.span, context, shape),
ast::TyKind::Never => Some(String::from("!")),
ast::TyKind::Mac(..) => None,
ast::TyKind::ImplicitSelf => Some(String::from("")),
ast::TyKind::ImplTrait(ref it) => {
it.rewrite(context, shape)
.map(|it_str| format!("impl {}", it_str))
}
ast::TyKind::Typeof(..) => unreachable!(),
}
}
}
fn rewrite_bare_fn(bare_fn: &ast::BareFnTy,
span: Span,
context: &RewriteContext,
shape: Shape)
-> Option<String> {
let mut result = String::with_capacity(128);
if !bare_fn.lifetimes.is_empty() {
result.push_str("for<");
// 6 = "for<> ".len(), 4 = "for<".
// This doesn't work out so nicely for mutliline situation with lots of
// rightward drift. If that is a problem, we could use the list stuff.
result.push_str(&try_opt!(bare_fn
.lifetimes
.iter()
.map(|l| {
l.rewrite(context,
Shape::legacy(try_opt!(shape.width.checked_sub(6)), shape.indent + 4))
})
.intersperse(Some(", ".to_string()))
.collect::<Option<String>>()));
result.push_str("> ");
}
result.push_str(::utils::format_unsafety(bare_fn.unsafety));
if bare_fn.abi != abi::Abi::Rust {
result.push_str(&::utils::format_abi(bare_fn.abi, context.config.force_explicit_abi));
}
result.push_str("fn");
let budget = try_opt!(shape.width.checked_sub(result.len()));
let indent = shape.indent + result.len();
let rewrite = try_opt!(format_function_type(bare_fn.decl.inputs.iter(),
&bare_fn.decl.output,
bare_fn.decl.variadic,
span,
context,
Shape::legacy(budget, indent)));
result.push_str(&rewrite);
Some(result)
}