impl FromStr

Author: tomtomwombat

README.md

@@ -53,63 +53,17 @@ ptr --> <var int length> <data>
 
 ![string_memory](https://github.com/user-attachments/assets/25f5acf8-9a3e-4a4c-b2f1-b2fb972cc9c8)
 
-## Measured from System Memory
+## Memory Usage Comparison (RSS per String)
 
-### 0..=4
-```text,ignore
-Crate, len 0..=4   |      RSS (B) |  Virtual (B)
--------------------|--------------|-------------
-std                |         36.9 |         38.4
-smol_str           |         24.0 |         24.0
-compact_str        |         24.0 |         24.0
-compact_string     |         24.1 |         26.2
-cold-string        |          8.0 |          8.0
-```
-
-### 0..=8
-```text,ignore
-Crate, len 0..=8   |      RSS (B) |  Virtual (B)
--------------------|--------------|-------------
-std                |         38.4 |         40.0
-smol_str           |         24.0 |         24.0
-compact_str        |         24.0 |         24.0
-compact_string     |         25.8 |         27.8
-cold-string        |         11.2 |         11.7
-```
-
-### 0..=16
-```text,ignore
-Crate, len 0..=16  |      RSS (B) |  Virtual (B)
--------------------|--------------|-------------
-std                |         46.8 |         48.6
-smol_str           |         24.0 |         24.1
-compact_str        |         24.0 |         24.0
-compact_string     |         32.6 |         34.9
-cold-string        |         24.9 |         26.7
-```
-
-### 0..=32
-```text,ignore
-Crate, len 0..=32  |      RSS (B) |  Virtual (B)
--------------------|--------------|-------------
-std                |         55.3 |         57.4
-smol_str           |         41.1 |         42.1
-compact_str        |         35.4 |         36.6
-compact_string     |         40.5 |         42.9
-cold-string        |         36.5 |         38.8
-```
-
-### 0..=64
-```text,ignore
-Crate, len 0..=64  |      RSS (B) |  Virtual (B)
--------------------|--------------|-------------
-std                |         71.4 |         73.7
-smol_str           |         72.2 |         74.3
-compact_str        |         61.0 |         63.3
-compact_string     |         56.5 |         59.1
-cold-string        |         53.5 |         56.3
-```
+| Crate | 0–4 chars | 0–8 chars | 0–16 chars | 0–32 chars | 0–64 chars |
+| :--- | :---: | :---: | :---: | :---: | :---: |
+| `std` | 36.9 B | 38.4 B | 46.8 B | 55.3 B | 71.4 B |
+| `smol_str` | 24.0 B | 24.0 B | 24.0 B | 41.1 B | 72.2 B |
+| `compact_str` | 24.0 B | 24.0 B | 24.0 B | 35.4 B | 61.0 B |
+| `compact_string` | 24.1 B | 25.8 B | 32.6 B | 40.5 B | 56.5 B |
+| **`cold-string`** | **8.0 B** | **11.2 B** | **24.9 B** | **36.5 B** | **53.5 B** |
 
+**Note:** Columns represent string length (bytes/chars). Values represent average Resident Set Size (RSS) in bytes per string instance. Measurements taken with 10M iterations.
 
 ## License
 

src/lib.rs

@@ -373,6 +373,13 @@ impl AsRef<[u8]> for ColdString {
     }
 }
 
+impl alloc::str::FromStr for ColdString {
+    type Err = core::convert::Infallible;
+    fn from_str(s: &str) -> Result<ColdString, Self::Err> {
+        Ok(ColdString::new(s))
+    }
+}
+
 #[cfg(feature = "serde")]
 impl serde::Serialize for ColdString {
     fn serialize<S: serde::Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {

tests/memory.rs

@@ -1,13 +1,13 @@
 #![allow(unsafe_op_in_unsafe_fn)]
 
+use std::alloc::{GlobalAlloc, Layout, System};
+use std::fmt::Debug;
 use std::io::Write;
-use std::iter::repeat_with;
+use std::str::FromStr;
+use std::sync::atomic::{AtomicUsize, Ordering};
 use std::time::Instant;
 use sysinfo::Pid;
 
-use std::alloc::{GlobalAlloc, Layout, System};
-use std::sync::atomic::{AtomicUsize, Ordering};
-
 #[global_allocator]
 static A: CountingAlloc = CountingAlloc;
 
@@ -27,18 +27,22 @@ unsafe impl GlobalAlloc for CountingAlloc {
     }
 }
 
-fn random_string<T: TryFrom<String>>(min: usize, max: usize) -> T
+fn random_string<T: FromStr>(min: usize, max: usize) -> T
 where
-    <T as TryFrom<String>>::Error: std::fmt::Debug,
+    <T as FromStr>::Err: Debug,
 {
     let len = fastrand::usize(min..=max);
-    let s: String = repeat_with(fastrand::alphanumeric).take(len).collect();
-    s.try_into().unwrap()
+    let mut scratch = [0u8; 128];
+    for i in 0..len {
+        scratch[i] = fastrand::alphanumeric() as u8;
+    }
+    let s = unsafe { std::str::from_utf8_unchecked(&scratch[..len]) };
+    s.parse().unwrap()
 }
 
-fn allocator_memory<T: TryFrom<String>>(name: &str)
+fn allocator_memory<T: FromStr>(name: &str)
 where
-    <T as TryFrom<String>>::Error: std::fmt::Debug,
+    <T as FromStr>::Err: Debug,
 {
     const SIZE: usize = 48;
     const TRIALS: usize = 100;
@@ -69,9 +73,9 @@ where
     );
 }
 
-fn system_memory<T: TryFrom<String>>(name: &str, min: usize, max: usize)
+fn system_memory<T: FromStr>(name: &str, min: usize, max: usize)
 where
-    <T as TryFrom<String>>::Error: std::fmt::Debug,
+    <T as FromStr>::Err: Debug,
 {
     let mut sys = sysinfo::System::new_all();
     let pid = Pid::from(std::process::id() as usize);