feat: support no_std (#15)

.github/workflows/ci.yaml

@@ -18,6 +18,7 @@ jobs:
       - test-linux-aarch64
       - test-macos
       - test-windows
+      - test-no-std
       - lint
     steps:
       - run: exit 0
@@ -78,6 +79,23 @@ jobs:
           cargo check
           cargo test
 
+  test-no-std:
+    runs-on: [self-hosted, X64]
+    strategy:
+      matrix:
+        target:
+          - x86_64-unknown-none
+          - aarch64-unknown-none
+    steps:
+      - uses: actions/checkout@v3
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: rustfmt
+      - name: Check no_std
+        run: |
+          rustup target add ${{ matrix.target }}
+          cargo check --target ${{ matrix.target }} --no-default-features
+
   lint:
     runs-on: [self-hosted, X64]
 

Cargo.toml

@@ -12,19 +12,21 @@ keywords = ["string", "str", "volo"]
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-bytes = "1"
+bytes = { version = "1", default-features = false }
 serde = { version = "1", optional = true, default-features = false }
-simdutf8 = { version = "0.1", features = ["aarch64_neon"] }
+simdutf8 = { version = "0.1", default-features = false, features = [
+    "aarch64_neon",
+] }
 redis = { version = "0.26", optional = true, default-features = false }
 itoa = { version = "1", optional = true }
 ryu = { version = "1", optional = true }
 
 [features]
 default = ["std"]
-std = ["serde/std"]
-serde = ["dep:serde"]
+std = ["bytes/std", "simdutf8/std", "serde?/std"]
+serde = ["serde/alloc"]
 serde-unsafe = ["serde"]
-redis = ["dep:redis", "itoa", "ryu"]
+redis = ["std", "dep:redis", "itoa", "ryu"]
 redis-unsafe = ["redis"]
 
 [dev-dependencies]

src/lib.rs

@@ -1,16 +1,19 @@
+#![cfg_attr(not(feature = "std"), no_std)]
 #![cfg_attr(not(doctest), doc = include_str!("../README.md"))]
 
-use bytes::{Bytes, BytesMut};
-use simdutf8::basic::{from_utf8, Utf8Error};
-use std::{
-    borrow::{Borrow, Cow},
-    cmp::Ordering,
-    convert::Infallible,
-    fmt, hash, iter,
-    ops::Deref,
-    str::FromStr,
+extern crate alloc;
+
+use alloc::{
+    borrow::Cow,
+    string::{String, ToString},
     sync::Arc,
+    vec::Vec,
 };
+use bytes::{Bytes, BytesMut};
+use core::{
+    borrow::Borrow, cmp::Ordering, convert::Infallible, fmt, hash, iter, ops::Deref, str::FromStr,
+};
+use simdutf8::basic::{from_utf8, Utf8Error};
 
 /// `FastStr` is a string type that try to avoid the cost of clone.
 #[derive(Clone)]
@@ -65,7 +68,7 @@ impl FastStr {
     /// `v` must be valid UTF-8.
     #[inline]
     pub unsafe fn new_u8_slice_unchecked(v: &[u8]) -> Self {
-        let s = unsafe { std::str::from_utf8_unchecked(v) };
+        let s = unsafe { core::str::from_utf8_unchecked(v) };
         Self::new(s)
     }
 
@@ -119,7 +122,7 @@ impl FastStr {
     /// `b` must be valid UTF-8.
     #[inline]
     pub unsafe fn from_bytes_unchecked(b: Bytes) -> Self {
-        let s = std::str::from_utf8_unchecked(&b);
+        let s = core::str::from_utf8_unchecked(&b);
         if Self::can_inline(s) {
             return Self::new(s);
         }
@@ -601,7 +604,7 @@ impl Repr {
     /// The length of `s` must be <= `INLINE_CAP`.
     unsafe fn new_inline_impl(s: &str) -> Self {
         let mut buf = [0u8; INLINE_CAP];
-        std::ptr::copy_nonoverlapping(s.as_ptr(), buf.as_mut_ptr(), s.len());
+        core::ptr::copy_nonoverlapping(s.as_ptr(), buf.as_mut_ptr(), s.len());
         Self::Inline { len: s.len(), buf }
     }
 
@@ -665,11 +668,11 @@ impl Repr {
         match self {
             Self::Empty => "",
             // Safety: this is guaranteed by the user when creating the `FastStr`.
-            Self::Bytes(bytes) => unsafe { std::str::from_utf8_unchecked(bytes) },
+            Self::Bytes(bytes) => unsafe { core::str::from_utf8_unchecked(bytes) },
             Self::ArcStr(arc_str) => arc_str,
             Self::ArcString(arc_string) => arc_string,
             Self::StaticStr(s) => s,
-            Self::Inline { len, buf } => unsafe { std::str::from_utf8_unchecked(&buf[..*len]) },
+            Self::Inline { len, buf } => unsafe { core::str::from_utf8_unchecked(&buf[..*len]) },
         }
     }
 
@@ -709,7 +712,7 @@ impl Repr {
         match self {
             Self::Empty => Self::Empty,
             // Safety: this is guaranteed by the user when creating the `FastStr`.
-            Self::Bytes(bytes) => unsafe { Self::new(std::str::from_utf8_unchecked(bytes)) },
+            Self::Bytes(bytes) => unsafe { Self::new(core::str::from_utf8_unchecked(bytes)) },
             Self::ArcStr(arc_str) => Self::ArcStr(Arc::clone(arc_str)),
             Self::ArcString(arc_string) => Self::ArcString(Arc::clone(arc_string)),
             Self::StaticStr(s) => Self::StaticStr(s),
@@ -757,7 +760,7 @@ impl Repr {
                 s[sub_offset..sub_offset + sub_len].as_bytes(),
             )),
             Repr::StaticStr(s) => Self::StaticStr(unsafe {
-                std::str::from_utf8_unchecked(&s.as_bytes()[sub_offset..sub_offset + sub_len])
+                core::str::from_utf8_unchecked(&s.as_bytes()[sub_offset..sub_offset + sub_len])
             }),
             Repr::Inline { len: _, buf } => Self::Inline {
                 len: sub_len,

src/serde.rs

@@ -1,3 +1,4 @@
+use alloc::{string::String, vec::Vec};
 use core::fmt;
 
 #[cfg(not(feature = "serde-unsafe"))]