rust/src/items.rs

863 lines
33 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.
// Formatting top-level items - functions, structs, enums, traits, impls.
use {ReturnIndent, BraceStyle};
use utils::{format_mutability, format_visibility, make_indent, contains_skip, span_after,
end_typaram};
use lists::{write_list, itemize_list, ListItem, ListFormatting, SeparatorTactic, ListTactic};
use comment::FindUncommented;
use visitor::FmtVisitor;
use rewrite::Rewrite;
use config::Config;
use syntax::{ast, abi};
use syntax::codemap::{self, Span, BytePos};
use syntax::print::pprust;
use syntax::parse::token;
impl<'a> FmtVisitor<'a> {
pub fn rewrite_fn(&mut self,
indent: usize,
ident: ast::Ident,
fd: &ast::FnDecl,
explicit_self: Option<&ast::ExplicitSelf>,
generics: &ast::Generics,
unsafety: &ast::Unsafety,
constness: &ast::Constness,
abi: &abi::Abi,
vis: ast::Visibility,
span: Span)
-> String {
let newline_brace = self.newline_for_brace(&generics.where_clause);
let mut result = self.rewrite_fn_base(indent,
ident,
fd,
explicit_self,
generics,
unsafety,
constness,
abi,
vis,
span,
newline_brace);
// Prepare for the function body by possibly adding a newline and indent.
// FIXME we'll miss anything between the end of the signature and the start
// of the body, but we need more spans from the compiler to solve this.
if newline_brace {
result.push('\n');
result.push_str(&make_indent(indent));
} else {
result.push(' ');
}
result
}
pub fn rewrite_required_fn(&mut self,
indent: usize,
ident: ast::Ident,
sig: &ast::MethodSig,
span: Span)
-> String {
// Drop semicolon or it will be interpreted as comment
let span = codemap::mk_sp(span.lo, span.hi - BytePos(1));
let mut result = self.rewrite_fn_base(indent,
ident,
&sig.decl,
Some(&sig.explicit_self),
&sig.generics,
&sig.unsafety,
&sig.constness,
&sig.abi,
ast::Visibility::Inherited,
span,
false);
// Re-attach semicolon
result.push(';');
result
}
fn rewrite_fn_base(&mut self,
indent: usize,
ident: ast::Ident,
fd: &ast::FnDecl,
explicit_self: Option<&ast::ExplicitSelf>,
generics: &ast::Generics,
unsafety: &ast::Unsafety,
constness: &ast::Constness,
abi: &abi::Abi,
vis: ast::Visibility,
span: Span,
newline_brace: bool)
-> String {
// FIXME we'll lose any comments in between parts of the function decl, but anyone
// who comments there probably deserves what they get.
let where_clause = &generics.where_clause;
let mut result = String::with_capacity(1024);
// Vis unsafety abi.
result.push_str(format_visibility(vis));
if let &ast::Unsafety::Unsafe = unsafety {
result.push_str("unsafe ");
}
if let &ast::Constness::Const = constness {
result.push_str("const ");
}
if *abi != abi::Rust {
result.push_str("extern ");
result.push_str(&abi.to_string());
result.push(' ');
}
// fn foo
result.push_str("fn ");
result.push_str(&ident.to_string());
// Generics.
let generics_indent = indent + result.len();
result.push_str(&self.rewrite_generics(generics,
generics_indent,
codemap::mk_sp(span.lo,
span_for_return(&fd.output).lo)));
let ret_str = self.rewrite_return(&fd.output);
// Args.
let (one_line_budget, multi_line_budget, mut arg_indent) =
self.compute_budgets_for_args(&result, indent, ret_str.len(), newline_brace);
debug!("rewrite_fn: one_line_budget: {}, multi_line_budget: {}, arg_indent: {}",
one_line_budget, multi_line_budget, arg_indent);
// Check if vertical layout was forced by compute_budget_for_args.
if one_line_budget <= 0 {
if self.config.fn_args_paren_newline {
result.push('\n');
result.push_str(&make_indent(arg_indent));
arg_indent = arg_indent + 1; // extra space for `(`
result.push('(');
} else {
result.push_str("(\n");
result.push_str(&make_indent(arg_indent));
}
} else {
result.push('(');
}
// A conservative estimation, to goal is to be over all parens in generics
let args_start = generics.ty_params
.last()
.map(|tp| end_typaram(tp))
.unwrap_or(span.lo);
let args_span = codemap::mk_sp(span_after(codemap::mk_sp(args_start, span.hi),
"(",
self.codemap),
span_for_return(&fd.output).lo);
result.push_str(&self.rewrite_args(&fd.inputs,
explicit_self,
one_line_budget,
multi_line_budget,
arg_indent,
args_span));
result.push(')');
// Return type.
if ret_str.len() > 0 {
// If we've already gone multi-line, or the return type would push
// over the max width, then put the return type on a new line.
if result.contains("\n") ||
result.len() + indent + ret_str.len() > self.config.max_width {
let indent = match self.config.fn_return_indent {
ReturnIndent::WithWhereClause => indent + 4,
// TODO we might want to check that using the arg indent doesn't
// blow our budget, and if it does, then fallback to the where
// clause indent.
_ => arg_indent,
};
result.push('\n');
result.push_str(&make_indent(indent));
} else {
result.push(' ');
}
result.push_str(&ret_str);
// Comment between return type and the end of the decl.
let snippet_lo = fd.output.span().hi;
if where_clause.predicates.len() == 0 {
let snippet_hi = span.hi;
let snippet = self.snippet(codemap::mk_sp(snippet_lo, snippet_hi));
let snippet = snippet.trim();
if snippet.len() > 0 {
result.push(' ');
result.push_str(snippet);
}
} else {
// FIXME it would be nice to catch comments between the return type
// and the where clause, but we don't have a span for the where
// clause.
}
}
// Where clause.
result.push_str(&self.rewrite_where_clause(where_clause,
self.config,
indent,
span.hi));
result
}
fn rewrite_args(&self,
args: &[ast::Arg],
explicit_self: Option<&ast::ExplicitSelf>,
one_line_budget: usize,
multi_line_budget: usize,
arg_indent: usize,
span: Span)
-> String {
let mut arg_item_strs: Vec<_> = args.iter().map(|a| self.rewrite_fn_input(a)).collect();
// Account for sugary self.
// FIXME: the comment for the self argument is dropped. This is blocked
// on rust issue #27522.
let min_args = explicit_self.and_then(|explicit_self| {
rewrite_explicit_self(explicit_self, args)
}).map(|self_str| {
arg_item_strs[0] = self_str;
2
}).unwrap_or(1);
// Comments between args
let mut arg_items = Vec::new();
if min_args == 2 {
arg_items.push(ListItem::from_str(""));
}
// TODO if there are no args, there might still be a comment, but without
// spans for the comment or parens, there is no chance of getting it right.
// You also don't get to put a comment on self, unless it is explicit.
if args.len() >= min_args {
let comment_span_start = if min_args == 2 {
span_after(span, ",", self.codemap)
} else {
span.lo
};
let more_items = itemize_list(self.codemap,
args[min_args-1..].iter(),
")",
|arg| span_lo_for_arg(arg),
|arg| arg.ty.span.hi,
|_| String::new(),
comment_span_start,
span.hi);
arg_items.extend(more_items);
}
assert_eq!(arg_item_strs.len(), arg_items.len());
for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
item.item = arg;
}
let fmt = ListFormatting {
tactic: ListTactic::HorizontalVertical,
separator: ",",
trailing_separator: SeparatorTactic::Never,
indent: arg_indent,
h_width: one_line_budget,
v_width: multi_line_budget,
ends_with_newline: false,
};
write_list(&arg_items, &fmt)
}
fn compute_budgets_for_args(&self,
result: &str,
indent: usize,
ret_str_len: usize,
newline_brace: bool)
-> (usize, usize, usize) {
let mut budgets = None;
// Try keeping everything on the same line
if !result.contains("\n") {
// 3 = `() `, space is before ret_string
let mut used_space = indent + result.len() + ret_str_len + 3;
if !newline_brace {
used_space += 2;
}
let one_line_budget = if used_space > self.config.max_width {
0
} else {
self.config.max_width - used_space
};
// 2 = `()`
let used_space = indent + result.len() + 2;
let max_space = self.config.ideal_width + self.config.leeway;
debug!("compute_budgets_for_args: used_space: {}, max_space: {}",
used_space, max_space);
if used_space < max_space {
budgets = Some((one_line_budget,
max_space - used_space,
indent + result.len() + 1));
}
}
// Didn't work. we must force vertical layout and put args on a newline.
if let None = budgets {
let new_indent = indent + self.config.tab_spaces;
let used_space = new_indent + 2; // account for `(` and `)`
let max_space = self.config.ideal_width + self.config.leeway;
if used_space > max_space {
// Whoops! bankrupt.
// TODO take evasive action, perhaps kill the indent or something.
} else {
budgets = Some((0, max_space - used_space, new_indent));
}
}
budgets.unwrap()
}
fn newline_for_brace(&self, where_clause: &ast::WhereClause) -> bool {
match self.config.fn_brace_style {
BraceStyle::AlwaysNextLine => true,
BraceStyle::SameLineWhere if where_clause.predicates.len() > 0 => true,
_ => false,
}
}
pub fn visit_enum(&mut self,
ident: ast::Ident,
vis: ast::Visibility,
enum_def: &ast::EnumDef,
generics: &ast::Generics,
span: Span) {
let header_str = self.format_header("enum ", ident, vis);
self.buffer.push_str(&header_str);
let enum_snippet = self.snippet(span);
let body_start = span.lo + BytePos(enum_snippet.find_uncommented("{").unwrap() as u32 + 1);
let generics_str = self.format_generics(generics,
" {",
self.block_indent + self.config.tab_spaces,
codemap::mk_sp(span.lo,
body_start));
self.buffer.push_str(&generics_str);
self.last_pos = body_start;
self.block_indent += self.config.tab_spaces;
for (i, f) in enum_def.variants.iter().enumerate() {
let next_span_start: BytePos = if i == enum_def.variants.len() - 1 {
span.hi
} else {
enum_def.variants[i + 1].span.lo
};
self.visit_variant(f, i == enum_def.variants.len() - 1, next_span_start);
}
self.block_indent -= self.config.tab_spaces;
self.format_missing_with_indent(span.lo + BytePos(enum_snippet.rfind('}').unwrap() as u32));
self.buffer.push_str("}");
}
// Variant of an enum
fn visit_variant(&mut self, field: &ast::Variant, last_field: bool, next_span_start: BytePos) {
if self.visit_attrs(&field.node.attrs) {
return;
}
self.format_missing_with_indent(field.span.lo);
let result = match field.node.kind {
ast::VariantKind::TupleVariantKind(ref types) => {
let vis = format_visibility(field.node.vis);
self.buffer.push_str(vis);
let name = field.node.name.to_string();
self.buffer.push_str(&name);
let mut result = String::new();
if types.len() > 0 {
let items = itemize_list(self.codemap,
types.iter(),
")",
|arg| arg.ty.span.lo,
|arg| arg.ty.span.hi,
|arg| pprust::ty_to_string(&arg.ty),
span_after(field.span, "(", self.codemap),
next_span_start);
result.push('(');
let indent = self.block_indent
+ vis.len()
+ field.node.name.to_string().len()
+ 1; // Open paren
let comma_cost = if self.config.enum_trailing_comma {
1
} else {
0
};
let budget = self.config.ideal_width - indent - comma_cost - 1; // 1 = )
let fmt = ListFormatting {
tactic: ListTactic::HorizontalVertical,
separator: ",",
trailing_separator: SeparatorTactic::Never,
indent: indent,
h_width: budget,
v_width: budget,
ends_with_newline: true,
};
result.push_str(&write_list(&items.collect::<Vec<_>>(), &fmt));
result.push(')');
}
if let Some(ref expr) = field.node.disr_expr {
result.push_str(" = ");
let expr_snippet = self.snippet(expr.span);
result.push_str(&expr_snippet);
// Make sure we do not exceed column limit
// 4 = " = ,"
assert!(
self.config.max_width >= vis.len() + name.len() + expr_snippet.len() + 4,
"Enum variant exceeded column limit");
}
result
},
ast::VariantKind::StructVariantKind(ref struct_def) => {
// TODO Should limit the width, as we have a trailing comma
self.format_struct("",
field.node.name,
field.node.vis,
struct_def,
None,
field.span,
self.block_indent)
}
};
self.buffer.push_str(&result);
if !last_field || self.config.enum_trailing_comma {
self.buffer.push_str(",");
}
self.last_pos = field.span.hi + BytePos(1);
}
fn format_struct(&self,
item_name: &str,
ident: ast::Ident,
vis: ast::Visibility,
struct_def: &ast::StructDef,
generics: Option<&ast::Generics>,
span: Span,
offset: usize)
-> String {
let mut result = String::with_capacity(1024);
let header_str = self.format_header(item_name, ident, vis);
result.push_str(&header_str);
if struct_def.fields.len() == 0 {
result.push(';');
return result;
}
let is_tuple = match struct_def.fields[0].node.kind {
ast::StructFieldKind::NamedField(..) => false,
ast::StructFieldKind::UnnamedField(..) => true
};
let (opener, terminator) = if is_tuple {
("(", ")")
} else {
(" {", "}")
};
let generics_str = match generics {
Some(g) => self.format_generics(g,
opener,
offset + header_str.len(),
codemap::mk_sp(span.lo,
struct_def.fields[0].span.lo)),
None => opener.to_owned()
};
result.push_str(&generics_str);
let items = itemize_list(self.codemap,
struct_def.fields.iter(),
terminator,
|field| {
// Include attributes and doc comments,
// if present
if field.node.attrs.len() > 0 {
field.node.attrs[0].span.lo
} else {
field.span.lo
}
},
|field| field.node.ty.span.hi,
|field| self.format_field(field),
span_after(span, opener.trim(), self.codemap),
span.hi);
// 2 terminators and a semicolon
let used_budget = offset + header_str.len() + generics_str.len() + 3;
// Conservative approximation
let single_line_cost = (span.hi - struct_def.fields[0].span.lo).0;
let break_line = !is_tuple || generics_str.contains('\n') ||
single_line_cost as usize + used_budget > self.config.max_width;
if break_line {
let indentation = make_indent(offset + self.config.tab_spaces);
result.push('\n');
result.push_str(&indentation);
}
let tactic = if break_line {
ListTactic::Vertical
} else {
ListTactic::Horizontal
};
// 1 = ,
let budget = self.config.ideal_width - offset + self.config.tab_spaces - 1;
let fmt = ListFormatting {
tactic: tactic,
separator: ",",
trailing_separator: self.config.struct_trailing_comma,
indent: offset + self.config.tab_spaces,
h_width: self.config.max_width,
v_width: budget,
ends_with_newline: true,
};
result.push_str(&write_list(&items.collect::<Vec<_>>(), &fmt));
if break_line {
result.push('\n');
result.push_str(&make_indent(offset));
}
result.push_str(terminator);
if is_tuple {
result.push(';');
}
result
}
pub fn visit_struct(&mut self,
ident: ast::Ident,
vis: ast::Visibility,
struct_def: &ast::StructDef,
generics: &ast::Generics,
span: Span) {
let indent = self.block_indent;
let result = self.format_struct("struct ",
ident,
vis,
struct_def,
Some(generics),
span,
indent);
self.buffer.push_str(&result);
self.last_pos = span.hi;
}
fn format_header(&self, item_name: &str, ident: ast::Ident, vis: ast::Visibility) -> String {
format!("{}{}{}", format_visibility(vis), item_name, ident)
}
fn format_generics(&self,
generics: &ast::Generics,
opener: &str,
offset: usize,
span: Span)
-> String {
let mut result = self.rewrite_generics(generics, offset, span);
if generics.where_clause.predicates.len() > 0 || result.contains('\n') {
result.push_str(&self.rewrite_where_clause(&generics.where_clause,
self.config,
self.block_indent,
span.hi));
result.push_str(&make_indent(self.block_indent));
result.push('\n');
result.push_str(opener.trim());
} else {
result.push_str(opener);
}
result
}
// Field of a struct
fn format_field(&self, field: &ast::StructField) -> String {
if contains_skip(&field.node.attrs) {
return self.snippet(codemap::mk_sp(field.node.attrs[0].span.lo, field.span.hi));
}
let name = match field.node.kind {
ast::StructFieldKind::NamedField(ident, _) => Some(ident.to_string()),
ast::StructFieldKind::UnnamedField(_) => None,
};
let vis = match field.node.kind {
ast::StructFieldKind::NamedField(_, vis) |
ast::StructFieldKind::UnnamedField(vis) => format_visibility(vis)
};
let typ = pprust::ty_to_string(&field.node.ty);
let indent = self.block_indent + self.config.tab_spaces;
let mut attr_str = self.rewrite_attrs(&field.node.attrs, indent);
if attr_str.len() > 0 {
attr_str.push('\n');
attr_str.push_str(&make_indent(indent));
}
match name {
Some(name) => format!("{}{}{}: {}", attr_str, vis, name, typ),
None => format!("{}{}{}", attr_str, vis, typ)
}
}
fn rewrite_generics(&self, generics: &ast::Generics, offset: usize, span: Span) -> String {
// FIXME convert bounds to where clauses where they get too big or if
// there is a where clause at all.
let mut result = String::new();
let lifetimes: &[_] = &generics.lifetimes;
let tys: &[_] = &generics.ty_params;
if lifetimes.len() + tys.len() == 0 {
return result;
}
let budget = self.config.max_width - offset - 2;
// TODO might need to insert a newline if the generics are really long
result.push('<');
// Strings for the generics.
// 1 = <
let context = self.get_context();
// FIXME: don't unwrap
let lt_strs = lifetimes.iter().map(|lt| {
lt.rewrite(&context, budget, offset + 1).unwrap()
});
let ty_strs = tys.iter().map(|ty_param| {
ty_param.rewrite(&context, budget, offset + 1).unwrap()
});
// Extract comments between generics.
let lt_spans = lifetimes.iter().map(|l| {
let hi = if l.bounds.len() == 0 {
l.lifetime.span.hi
} else {
l.bounds[l.bounds.len() - 1].span.hi
};
codemap::mk_sp(l.lifetime.span.lo, hi)
});
let ty_spans = tys.iter().map(span_for_ty_param);
let items = itemize_list(self.codemap,
lt_spans.chain(ty_spans),
">",
|sp| sp.lo,
|sp| sp.hi,
|_| String::new(),
span_after(span, "<", self.codemap),
span.hi);
let mut items = items.collect::<Vec<_>>();
for (item, ty) in items.iter_mut().zip(lt_strs.chain(ty_strs)) {
item.item = ty;
}
let fmt = ListFormatting {
tactic: ListTactic::HorizontalVertical,
separator: ",",
trailing_separator: SeparatorTactic::Never,
indent: offset + 1,
h_width: budget,
v_width: budget,
ends_with_newline: false,
};
result.push_str(&write_list(&items, &fmt));
result.push('>');
result
}
fn rewrite_where_clause(&self,
where_clause: &ast::WhereClause,
config: &Config,
indent: usize,
span_end: BytePos)
-> String {
let mut result = String::new();
if where_clause.predicates.len() == 0 {
return result;
}
result.push('\n');
result.push_str(&make_indent(indent + config.tab_spaces));
result.push_str("where ");
let context = self.get_context();
// 6 = "where ".len()
let offset = indent + config.tab_spaces + 6;
let budget = self.config.ideal_width + self.config.leeway - offset;
let span_start = span_for_where_pred(&where_clause.predicates[0]).lo;
let items = itemize_list(self.codemap,
where_clause.predicates.iter(),
"{",
|pred| span_for_where_pred(pred).lo,
|pred| span_for_where_pred(pred).hi,
// FIXME: we should handle failure better
// this will be taken care of when write_list
// takes Rewrite object: see issue #133
|pred| pred.rewrite(&context, budget, offset).unwrap(),
span_start,
span_end);
let fmt = ListFormatting {
tactic: ListTactic::Vertical,
separator: ",",
trailing_separator: SeparatorTactic::Never,
indent: offset,
h_width: budget,
v_width: budget,
ends_with_newline: false,
};
result.push_str(&write_list(&items.collect::<Vec<_>>(), &fmt));
result
}
fn rewrite_return(&self, ret: &ast::FunctionRetTy) -> String {
match *ret {
ast::FunctionRetTy::DefaultReturn(_) => String::new(),
ast::FunctionRetTy::NoReturn(_) => "-> !".to_owned(),
ast::FunctionRetTy::Return(ref ty) => "-> ".to_owned() + &pprust::ty_to_string(ty),
}
}
// TODO we farm this out, but this could spill over the column limit, so we
// ought to handle it properly.
fn rewrite_fn_input(&self, arg: &ast::Arg) -> String {
if is_named_arg(arg) {
format!("{}: {}",
pprust::pat_to_string(&arg.pat),
pprust::ty_to_string(&arg.ty))
} else {
pprust::ty_to_string(&arg.ty)
}
}
}
fn rewrite_explicit_self(explicit_self: &ast::ExplicitSelf, args: &[ast::Arg]) -> Option<String> {
match explicit_self.node {
ast::ExplicitSelf_::SelfRegion(lt, m, _) => {
let mut_str = format_mutability(m);
match lt {
Some(ref l) => Some(format!("&{} {}self", pprust::lifetime_to_string(l), mut_str)),
None => Some(format!("&{}self", mut_str)),
}
}
ast::ExplicitSelf_::SelfExplicit(ref ty, _) => {
Some(format!("self: {}", pprust::ty_to_string(ty)))
}
ast::ExplicitSelf_::SelfValue(_) => {
assert!(args.len() >= 1, "&[ast::Arg] shouldn't be empty.");
// this hacky solution caused by absence of `Mutability` in `SelfValue`.
let mut_str = {
if let ast::Pat_::PatIdent(ast::BindingMode::BindByValue(mutability), _, _)
= args[0].pat.node {
format_mutability(mutability)
} else {
panic!("there is a bug or change in structure of AST, aborting.");
}
};
Some(format!("{}self", mut_str))
}
_ => None
}
}
fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
if is_named_arg(arg) {
arg.pat.span.lo
} else {
arg.ty.span.lo
}
}
fn is_named_arg(arg: &ast::Arg) -> bool {
if let ast::Pat_::PatIdent(_, ident, _) = arg.pat.node {
ident.node != token::special_idents::invalid
} else {
true
}
}
fn span_for_return(ret: &ast::FunctionRetTy) -> Span {
match *ret {
ast::FunctionRetTy::NoReturn(ref span) |
ast::FunctionRetTy::DefaultReturn(ref span) => span.clone(),
ast::FunctionRetTy::Return(ref ty) => ty.span,
}
}
fn span_for_ty_param(ty: &ast::TyParam) -> Span {
// Note that ty.span is the span for ty.ident, not the whole item.
let lo = ty.span.lo;
if let Some(ref def) = ty.default {
return codemap::mk_sp(lo, def.span.hi);
}
if ty.bounds.len() == 0 {
return ty.span;
}
let hi = match ty.bounds[ty.bounds.len() - 1] {
ast::TyParamBound::TraitTyParamBound(ref ptr, _) => ptr.span.hi,
ast::TyParamBound::RegionTyParamBound(ref l) => l.span.hi,
};
codemap::mk_sp(lo, hi)
}
fn span_for_where_pred(pred: &ast::WherePredicate) -> Span {
match *pred {
ast::WherePredicate::BoundPredicate(ref p) => p.span,
ast::WherePredicate::RegionPredicate(ref p) => p.span,
ast::WherePredicate::EqPredicate(ref p) => p.span,
}
}