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Merged
Halifuda merged 1 commit into from
Apr 18, 2025
Merged

Remove unnecessary alloc usage #1

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4 changes: 4 additions & 0 deletions Cargo.toml
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Expand Up @@ -22,6 +22,10 @@ bench = false # ignoring libtest check, so criterion cmd options can be used.
[dev-dependencies]
criterion = { version = "0.4", features = ["html_reports"] }

[features]
default = ["alloc"]
alloc = []

[[example]]
name = "bitmap-base"
[[example]]
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2 changes: 2 additions & 0 deletions README.md
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Expand Up @@ -67,6 +67,8 @@
the map is relatively small like 8 or 16 bits,
you can put it on stack safely. If it is larger like 256 or
1024 bits, you may want to put it on heap.

The alloc feature which is enabled by default is only used for formatting.

## Examples

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54 changes: 53 additions & 1 deletion src/bitmap/fmt.rs
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@@ -1,9 +1,59 @@
//! Implementations of formating methods for `Bitmap`, including [`Debug`].

#[cfg(feature = "alloc")]
use alloc::{string::{String, ToString}, format};

use crate::bitmap::*;

#[cfg(not(feature = "alloc"))]
impl<const BYTES: usize> core::fmt::Display for Bitmap<BYTES> {
/// Formats a bitmap. Only shows the last 2 bytes if the bitmap is longer.
/// The bytes will be separated by space `' '`.
///
/// The bits will be arranged from right to left. If the bitmap is longer than
/// 2 bytes, a `"..."` will show on the left.
/// On the very left, a bracket tells the bit length of the map (in a form
/// like `"[N bits]"`). A space `' '` will be between the bit contents and this
/// bracket.
///
/// # Examples
/// ```
/// use cbitmap::bitmap::*;
///
/// let mut map: Bitmap<3> = 0.into();
/// map.set(0);
/// map.set(8);
/// let str = &format!("{map}");
/// assert_eq!(str, "[24 bits] ...00000001 00000001");
/// ```
fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
write!(f, "[{} bits] ", BYTES * 8)?;
let size = 2.min(BYTES);
if BYTES > size {
write!(f, "...")?;
}
for i in 0..size {
if i > 0 {
write!(f, " ")?;
}
write!(f, "{:08b}", self.__copy_u8(size - i - 1))?;
}
Ok(())
}
}

#[cfg(not(feature = "alloc"))]
impl<const BYTES: usize> core::fmt::Debug for Bitmap<BYTES> {
fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
f.debug_struct("Bitmap")
.field("#bytes", &BYTES)
.field("#bits", &(BYTES * 8))
.field("bits", &self.bits)
.finish()
}
}

#[cfg(feature = "alloc")]
impl<const BYTES: usize> core::fmt::Display for Bitmap<BYTES> {
/// Formats a bitmap. Only shows the last 2 bytes if the bitmap is longer.
/// The bytes will be separated by space `' '`.
Expand Down Expand Up @@ -41,6 +91,7 @@ impl<const BYTES: usize> core::fmt::Display for Bitmap<BYTES> {
}
}

#[cfg(feature = "alloc")]
impl<const BYTES: usize> core::fmt::Debug for Bitmap<BYTES> {
fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
let mut contents = String::new();
Expand All @@ -63,6 +114,7 @@ impl<const BYTES: usize> core::fmt::Debug for Bitmap<BYTES> {
}
}

#[cfg(feature = "alloc")]
impl<const BYTES: usize> Bitmap<BYTES> {
/// Format a range of bits into a [`Option<String>`].
///
Expand Down Expand Up @@ -117,4 +169,4 @@ impl<const BYTES: usize> Bitmap<BYTES> {

Some(contents)
}
}
}
1 change: 1 addition & 0 deletions src/lib.rs
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Expand Up @@ -166,6 +166,7 @@
//! not `BitRef` due to a similar issue.
#![no_std]

#[cfg(feature = "alloc")]
extern crate alloc;

mod tools;
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