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Merge pull request #347 from scyptnex/issue339-match_block_collapse

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match arms collapse for issue #339
This commit is contained in:
Nick Cameron 2015-09-24 12:28:35 +12:00
commit e176dc97fe
4 changed files with 181 additions and 50 deletions
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116
src/expr.rs
View file

@ -320,6 +320,17 @@ fn rewrite_closure(capture: ast::CaptureClause,
Some(format!("{} {}", prefix, try_opt!(body_rewrite)))
}
fn nop_block_collapse(block_str: Option<String>) -> Option<String> {
block_str.map(|block_str| {
if block_str.starts_with("{") &&
(block_str[1..].find(|c: char| !c.is_whitespace()).unwrap() == block_str.len() - 2) {
"{}".to_owned()
} else {
block_str.to_owned()
}
})
}
impl Rewrite for ast::Block {
fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
let user_str = context.snippet(self.span);
@ -620,6 +631,51 @@ fn is_simple_block(block: &ast::Block, codemap: &CodeMap) -> bool {
!contains_comment(&snippet)
}
// inter-match-arm-comment-rules:
// - all comments following a match arm before the start of the next arm
// are about the second arm
fn rewrite_match_arm_comment(context: &RewriteContext,
missed_str: &str,
width: usize,
arm_indent: Indent,
arm_indent_str: &str)
-> String {
// The leading "," is not part of the arm-comment
let missed_str = match missed_str.find_uncommented(",") {
Some(n) => &missed_str[n+1..],
None => &missed_str[..],
};
// Nor the trailing "}" which closes the match
let missed_str = match missed_str.find_uncommented("}") {
Some(n) => &missed_str[..n-1],
None => &missed_str[..],
};
let mut result = String::new();
// any text not preceeded by a newline is pushed unmodified to the block
let first_brk = missed_str.find(|c: char| c == '\n').unwrap_or(0);
result.push_str(&missed_str[..first_brk]);
let missed_str = &missed_str[first_brk..]; // If missed_str had one newline, it starts with it
let first = missed_str.find(|c: char| !c.is_whitespace()).unwrap_or(missed_str.len());
if missed_str[..first].chars().filter(|c| c == &'\n').count() >= 2 {
// Excessive vertical whitespace before comment should be preserved
// TODO handle vertical whitespace better
result.push('\n');
}
let missed_str = missed_str[first..].trim();
if !missed_str.is_empty() {
result.push('\n');
result.push_str(arm_indent_str);
result.push_str(&rewrite_comment(&missed_str,
false,
width,
arm_indent,
context.config));
}
return result;
}
fn rewrite_match(context: &RewriteContext,
cond: &ast::Expr,
arms: &[ast::Arm],
@ -647,32 +703,15 @@ fn rewrite_match(context: &RewriteContext,
for (i, arm) in arms.iter().enumerate() {
// Make sure we get the stuff between arms.
let missed_str = if i == 0 {
context.snippet(mk_sp(open_brace_pos + BytePos(1), arm_start_pos(arm)))
context.snippet(mk_sp(open_brace_pos, arm_start_pos(arm)))
} else {
context.snippet(mk_sp(arm_end_pos(&arms[i-1]), arm_start_pos(arm)))
};
let missed_str = match missed_str.find_uncommented(",") {
Some(n) => &missed_str[n+1..],
None => &missed_str[..],
};
// first = first non-whitespace byte index.
let first = missed_str.find(|c: char| !c.is_whitespace()).unwrap_or(missed_str.len());
if missed_str[..first].chars().filter(|c| c == &'\n').count() >= 2 {
// There were multiple line breaks which got trimmed to nothing
// that means there should be some vertical white space. Lets
// replace that with just one blank line.
result.push('\n');
}
let missed_str = missed_str.trim();
if !missed_str.is_empty() {
result.push('\n');
result.push_str(&arm_indent_str);
result.push_str(&rewrite_comment(&missed_str,
false,
width,
arm_indent,
context.config));
}
result.push_str(&rewrite_match_arm_comment(context,
&missed_str,
width,
arm_indent,
&arm_indent_str));
result.push('\n');
result.push_str(&arm_indent_str);
@ -688,26 +727,11 @@ fn rewrite_match(context: &RewriteContext,
}
}
let last_comment = context.snippet(mk_sp(arm_end_pos(&arms[arms.len() - 1]), span.hi));
let last_comment = match last_comment.find_uncommented(",") {
Some(n) => &last_comment[n+1..],
None => &last_comment[..],
};
let last_comment = match last_comment.find_uncommented("}") {
Some(n) => &last_comment[..n-1],
None => &last_comment[..],
};
let last_comment = last_comment.trim();
result.push_str(&rewrite_match_arm_comment(context,
&last_comment,
width, arm_indent,
&arm_indent_str));
result.push('\n');
if last_comment.len() > 0 {
result.push_str(&arm_indent_str);
result.push_str(&rewrite_comment(&last_comment,
false,
width,
arm_indent,
context.config));
result.push('\n');
}
result.push_str(&(context.block_indent + context.overflow_indent).to_string(context.config));
result.push('}');
Some(result)
@ -817,7 +841,9 @@ impl Rewrite for ast::Arm {
// 4 = ` => `.len()
if context.config.max_width > line_start + comma.len() + 4 {
let budget = context.config.max_width - line_start - comma.len() - 4;
if let Some(ref body_str) = body.rewrite(context, budget, line_indent + 4) {
if let Some(ref body_str) = nop_block_collapse(body.rewrite(context,
budget,
line_indent + 4)) {
if first_line_width(body_str) <= budget {
return Some(format!("{}{} => {}{}",
attr_str.trim_left(),
@ -835,7 +861,9 @@ impl Rewrite for ast::Arm {
}
let body_budget = try_opt!(width.checked_sub(context.config.tab_spaces));
let body_str = try_opt!(body.rewrite(context, body_budget, context.block_indent));
let body_str = try_opt!(nop_block_collapse(body.rewrite(context,
body_budget,
context.block_indent)));
Some(format!("{}{} =>\n{}{},",
attr_str.trim_left(),
pats_str,

58
tests/source/expr.rs
View file

@ -140,6 +140,64 @@ fn matches() {
}
}
fn issue339() {
match a {
b => {}
c => { }
d => {
}
e => {
}
// collapsing here is safe
ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff => {
}
// collapsing here exceeds line length
ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffg => {
}
h => { // comment above block
}
i => {
} // comment below block
j => {
// comment inside block
}
j2 => {
// comments inside...
} // ... and after
// TODO uncomment when vertical whitespace is handled better
// k => {
//
// // comment with WS above
// }
// l => {
// // comment with ws below
//
// }
m => {
} n => { } o =>
{
}
p => { // Dont collapse me
} q => { } r =>
{
}
s => 0, // s comment
// t comment
t => 1,
u => 2,
// TODO uncomment when block-support exists
// v => {
// } /* funky block
// * comment */
// final comment
}
}
fn arrays() {
let x = [0,
1,

54
tests/target/expr.rs
View file

@ -169,13 +169,59 @@ fn issue184(source: &str) {
fn matches() {
match 1 {
1 => 1,
// foo
1 => 1, // foo
2 => 2,
// bar
3 => 3,
_ => 0,
// baz
_ => 0, // baz
}
}
fn issue339() {
match a {
b => {}
c => {}
d => {}
e => {}
// collapsing here is safe
ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff => {}
// collapsing here exceeds line length
ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffg => {
}
h => { // comment above block
}
i => {} // comment below block
j => {
// comment inside block
}
j2 => {
// comments inside...
} // ... and after
// TODO uncomment when vertical whitespace is handled better
// k => {
//
// // comment with WS above
// }
// l => {
// // comment with ws below
//
// }
m => {}
n => {}
o => {}
p => { // Dont collapse me
}
q => {}
r => {}
s => 0, // s comment
// t comment
t => 1,
u => 2,
// TODO uncomment when block-support exists
// v => {
// } /* funky block
// * comment */
// final comment
}
}

3
tests/target/match.rs
View file

@ -38,8 +38,7 @@ fn foo() {
_ => {}
ast::PathParameters::AngleBracketedParameters(ref data) if data.lifetimes.len() > 0 ||
data.types.len() > 0 ||
data.bindings.len() > 0 => {
}
data.bindings.len() > 0 => {}
}
let whatever = match something {