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Add hexadecimal formatting of integers with fmt::Debug

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This can be used for integers within a larger types which implements Debug
(possibly through derive) but not fmt::UpperHex or fmt::LowerHex.

```rust
assert!(format!("{:02x?}", b"Foo\0") == "[46, 6f, 6f, 00]");
assert!(format!("{:02X?}", b"Foo\0") == "[46, 6F, 6F, 00]");
```

RFC: https://github.com/rust-lang/rfcs/pull/2226
This commit is contained in:
Simon Sapin
2018-03-13 14:08:15 +01:00
parent 883e74645d
commit 4897935e86
5 changed files with 42 additions and 4 deletions
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22
src/libfmt_macros/lib.rs
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@@ -108,6 +108,10 @@ pub enum Flag {
/// For numbers, this means that the number will be padded with zeroes,
/// and the sign (`+` or `-`) will precede them.
FlagSignAwareZeroPad,
/// For Debug / `?`, format integers in lower-case hexadecimal.
FlagDebugLowerHex,
/// For Debug / `?`, format integers in upper-case hexadecimal.
FlagDebugUpperHex,
}
/// A count is used for the precision and width parameters of an integer, and
@@ -377,8 +381,22 @@ impl<'a> Parser<'a> {
spec.precision = self.count();
}
}
// Finally the actual format specifier
if self.consume('?') {
// Optional radix followed by the actual format specifier
if self.consume('x') {
if self.consume('?') {
spec.flags |= 1 << (FlagDebugLowerHex as u32);
spec.ty = "?";
} else {
spec.ty = "x";
}
} else if self.consume('X') {
if self.consume('?') {
spec.flags |= 1 << (FlagDebugUpperHex as u32);
spec.ty = "?";
} else {
spec.ty = "X";
}
} else if self.consume('?') {
spec.ty = "?";
} else {
spec.ty = self.word();