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Fix #1021: Handle .. in tuple / tuple struct patterns #1151

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Merged
merged 1 commit into from
Sep 13, 2016
Merged

Fix #1021: Handle .. in tuple / tuple struct patterns #1151

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133 changes: 93 additions & 40 deletions src/patterns.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -13,10 +13,14 @@ use codemap::SpanUtils;
use rewrite::{Rewrite, RewriteContext};
use utils::{wrap_str, format_mutability};
use lists::{format_item_list, itemize_list};
use expr::{rewrite_unary_prefix, rewrite_pair, rewrite_tuple};
use expr::{rewrite_unary_prefix, rewrite_pair};
use types::rewrite_path;
use super::Spanned;
use comment::FindUncommented;

use syntax::ast::{BindingMode, Pat, PatKind, FieldPat};
use syntax::ast::{self, BindingMode, Pat, PatKind, FieldPat};
use syntax::ptr;
use syntax::codemap::{self, BytePos, Span};

impl Rewrite for Pat {
fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
Expand Down Expand Up @@ -60,49 +64,19 @@ impl Rewrite for Pat {
let prefix = format!("&{}", format_mutability(mutability));
rewrite_unary_prefix(context, &prefix, &**pat, width, offset)
}
// FIXME(#1021): Handle `..` in tuple / tuple struct patterns (RFC 1492)
PatKind::Tuple(ref items, dotdot_pos) => {
if dotdot_pos.is_some() {
return None;
}
rewrite_tuple(context,
items.iter().map(|x| &**x),
self.span,
width,
offset)
rewrite_tuple_pat(items, dotdot_pos, None, self.span, context, width, offset)
}
PatKind::Path(ref path) => rewrite_path(context, true, None, path, width, offset),
PatKind::TupleStruct(ref path, ref pat_vec, dotdot_pos) => {
let path_str = try_opt!(rewrite_path(context, true, None, path, width, offset));

// FIXME(#1021): Handle `..` in tuple / tuple struct patterns (RFC 1492)
match dotdot_pos {
Some(_) => Some(format!("{}(..)", path_str)),
None => {
if pat_vec.is_empty() {
Some(path_str)
} else {
// 2 = "()".len()
let width = try_opt!(width.checked_sub(path_str.len() + 2));
// 1 = "(".len()
let offset = offset + path_str.len() + 1;
let items = itemize_list(context.codemap,
pat_vec.iter(),
")",
|item| item.span.lo,
|item| item.span.hi,
|item| item.rewrite(context, width, offset),
context.codemap.span_after(self.span, "("),
self.span.hi);
Some(format!("{}({})",
path_str,
try_opt!(format_item_list(items,
width,
offset,
context.config))))
}
}
}
rewrite_tuple_pat(pat_vec,
dotdot_pos,
Some(path_str),
self.span,
context,
width,
offset)
}
PatKind::Lit(ref expr) => expr.rewrite(context, width, offset),
PatKind::Vec(ref prefix, ref slice_pat, ref suffix) => {
Expand Down Expand Up @@ -190,3 +164,82 @@ impl Rewrite for FieldPat {
}
}
}


enum TuplePatField<'a> {
Pat(&'a ptr::P<ast::Pat>),
Dotdot(Span),
}

impl<'a> Rewrite for TuplePatField<'a> {
fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
match *self {
TuplePatField::Pat(ref p) => p.rewrite(context, width, offset),
TuplePatField::Dotdot(_) => Some("..".to_string()),
}
}
}

impl<'a> Spanned for TuplePatField<'a> {
fn span(&self) -> Span {
match *self {
TuplePatField::Pat(ref p) => p.span(),
TuplePatField::Dotdot(span) => span,
}
}
}

fn rewrite_tuple_pat(pats: &[ptr::P<ast::Pat>],
dotdot_pos: Option<usize>,
path_str: Option<String>,
span: Span,
context: &RewriteContext,
width: usize,
offset: Indent)
-> Option<String> {
let mut pat_vec: Vec<_> = pats.into_iter().map(|x| TuplePatField::Pat(x)).collect();

if let Some(pos) = dotdot_pos {
let snippet = context.snippet(span);
let lo = span.lo + BytePos(snippet.find_uncommented("..").unwrap() as u32);
let span = Span {
lo: lo,
// 2 == "..".len()
hi: lo + BytePos(2),
expn_id: codemap::NO_EXPANSION,
};
let dotdot = TuplePatField::Dotdot(span);
pat_vec.insert(pos, dotdot);
}

if pat_vec.is_empty() {
path_str
} else {
// add comma if `(x,)`
let add_comma = path_str.is_none() && pat_vec.len() == 1 && dotdot_pos.is_none();

let path_len = path_str.as_ref().map(|p| p.len()).unwrap_or(0);
// 2 = "()".len(), 3 = "(,)".len()
let width = try_opt!(width.checked_sub(path_len + if add_comma { 3 } else { 2 }));
// 1 = "(".len()
let offset = offset + path_len + 1;
let items = itemize_list(context.codemap,
pat_vec.iter(),
if add_comma { ",)" } else { ")" },
|item| item.span().lo,
|item| item.span().hi,
|item| item.rewrite(context, width, offset),
context.codemap.span_after(span, "("),
span.hi - BytePos(1));

let list = try_opt!(format_item_list(items, width, offset, context.config));

match path_str {
Some(path_str) => Some(format!("{}({})", path_str, list)),
None => {
let comma = if add_comma { "," } else { "" };
Some(format!("({}{})", list, comma))
}
}
}
}
21 changes: 21 additions & 0 deletions tests/source/issue-1021.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,21 @@
fn main() {
match x {
S(true , .., true ) => (),
S(true , .. ) => (),
S(.., true ) => (),
S( .. ) => (),
S(_) => (),
S(/* .. */ .. ) => (),
S(/* .. */ .., true ) => (),
}

match y {
(true , .., true ) => (),
(true , .. ) => (),
(.., true ) => (),
( .. ) => (),
(_,) => (),
(/* .. */ .. ) => (),
(/* .. */ .., true ) => (),
}
}
27 changes: 27 additions & 0 deletions tests/target/issue-1021.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,27 @@
fn main() {
match x {
S(true, .., true) => (),
S(true, ..) => (),
S(.., true) => (),
S(..) => (),
S(_) => (),
S(// ..
..) => (),
S(// ..
..,
true) => (),
}

match y {
(true, .., true) => (),
(true, ..) => (),
(.., true) => (),
(..) => (),
(_,) => (),
(// ..
..) => (),
(// ..
..,
true) => (),
}
}