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Fix bug in padding unicode, #17105. #17145

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Merged
merged 1 commit into from
Sep 12, 2014
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Fix bug in padding unicode, #17105. #17145

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4 changes: 2 additions & 2 deletions src/libcore/fmt/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -476,7 +476,7 @@ impl<'a> Formatter<'a> {

let mut prefixed = false;
if self.flags & (1 << (FlagAlternate as uint)) != 0 {
prefixed = true; width += prefix.len();
prefixed = true; width += prefix.char_len();
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Could you add a test for this change as well?

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Do you have a recommendation as to how to test that? There isn't a trait for which # will print unicode, so I'd have to have access to the internal function to test it, which isn't possible from here, I don't think.

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The pad_integral function is a public function, and you could implement Show for a custom newtype which invokes pad_integral with a unicode prefix.

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I added the custom Show function.

One question, when it runs format!("{:#4}", C) with C being declared, struct C;, is that printing an object of type C or is it printing the type C without creating an object?

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When you have struct C; it's both a value and a type, so the expression C constructs a value of type C

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After looking back at the tutorial, I noticed this is just a special case of Point { x: 1, y: 2 }, being used to create a Point.

}

// Writes the sign if it exists, and then the prefix if it was requested
Expand Down Expand Up @@ -562,7 +562,7 @@ impl<'a> Formatter<'a> {
// If we're under both the maximum and the minimum width, then fill
// up the minimum width with the specified string + some alignment.
Some(width) => {
self.with_padding(width - s.len(), rt::AlignLeft, |me| {
self.with_padding(width - s.char_len(), rt::AlignLeft, |me| {
me.buf.write(s.as_bytes())
})
}
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8 changes: 8 additions & 0 deletions src/test/run-pass/ifmt.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@ use std::str;

struct A;
struct B;
struct C;

impl fmt::Signed for A {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
Expand All @@ -36,6 +37,11 @@ impl fmt::Signed for B {
f.write("adios".as_bytes())
}
}
impl fmt::Show for C {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.pad_integral(true, "☃", "123".as_bytes())
}
}

macro_rules! t(($a:expr, $b:expr) => { assert_eq!($a.as_slice(), $b) })

Expand Down Expand Up @@ -81,13 +87,15 @@ pub fn main() {
t!(format!("{} {0}", "a"), "a a");
t!(format!("{foo_bar}", foo_bar=1i), "1");
t!(format!("{:d}", 5i + 5i), "10");
t!(format!("{:#4}", C), "☃123");

let a: &fmt::Show = &1i;
t!(format!("{}", a), "1");

// Formatting strings and their arguments
t!(format!("{:s}", "a"), "a");
t!(format!("{:4s}", "a"), "a ");
t!(format!("{:4s}", "☃"), "☃ ");
t!(format!("{:>4s}", "a"), " a");
t!(format!("{:<4s}", "a"), "a ");
t!(format!("{:^5s}", "a"), " a ");
Expand Down