serialize San,SanPlus,UciMove without alloc

Author: niklasf

.github/workflows/test.yml

@@ -14,13 +14,12 @@ jobs:
           - "nightly"
         flags:
           - ""
-          - "--features variant"
+          - "--features variant,serde"
+          - "--features nohash-hasher,variant"
           - "--features alloc"
-          - "--features serde"
+          - "--features alloc,variant,serde"
           - "--features std"
-          - "--features alloc,variant"
           - "--features std,variant,serde"
-          - "--features nohash-hasher,variant"
         include:
           - toolchain: "nightly"
             flags: "-Z minimal-versions --all-features"
@@ -53,5 +52,5 @@ jobs:
         with:
           toolchain: stable
           targets: thumbv6m-none-eabi
-      - run: cargo check --target thumbv6m-none-eabi --no-default-features --features variant,nohash-hasher
-      - run: cargo check --target thumbv6m-none-eabi --no-default-features --features alloc,variant,nohash-hasher
+      - run: cargo check --target thumbv6m-none-eabi --no-default-features --features variant,nohash-hasher,serde
+      - run: cargo check --target thumbv6m-none-eabi --no-default-features --features alloc,variant,nohash-hasher,serde

Cargo.toml

@@ -13,11 +13,11 @@ rust-version = "1.75" # remember to update test.yml
 
 [features]
 default = ["std"]
-alloc = []
+alloc = ["serde?/alloc"]
 std = ["alloc", "btoi/std", "nohash-hasher?/std"]
 variant = []
 nohash-hasher = ["dep:nohash-hasher"]
-serde = ["dep:serde", "alloc"]
+serde = ["dep:serde"]
 
 [[bench]]
 name = "benches"

src/fen.rs

@@ -580,13 +580,15 @@ impl Display for Fen {
     }
 }
 
-#[cfg(feature = "serde")]
+#[cfg(all(feature = "serde", feature = "alloc"))]
 impl serde::Serialize for Fen {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
         S: serde::Serializer,
     {
-        serializer.serialize_str(&alloc::string::ToString::to_string(self))
+        let mut s = alloc::string::String::new();
+        self.append_to_string(&mut s);
+        serializer.serialize_str(&s)
     }
 }
 
@@ -701,13 +703,15 @@ impl Display for Epd {
     }
 }
 
-#[cfg(feature = "serde")]
+#[cfg(all(feature = "serde", feature = "alloc"))]
 impl serde::Serialize for Epd {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
         S: serde::Serializer,
     {
-        serializer.serialize_str(&alloc::string::ToString::to_string(self))
+        let mut s = alloc::string::String::new();
+        self.append_to_string(&mut s);
+        serializer.serialize_str(&s)
     }
 }
 

src/san.rs

@@ -549,7 +549,10 @@ impl serde::Serialize for San {
     where
         S: serde::Serializer,
     {
-        serializer.serialize_str(&alloc::string::ToString::to_string(self))
+        // Longest syntactically valid SAN: Na1xa1=Q
+        let mut s = arrayvec::ArrayString::<8>::new();
+        let _ = self.append_to(&mut s);
+        serializer.serialize_str(&s)
     }
 }
 
@@ -725,7 +728,10 @@ impl serde::Serialize for SanPlus {
     where
         S: serde::Serializer,
     {
-        serializer.serialize_str(&alloc::string::ToString::to_string(self))
+        // Longest syntactically valid SAN with suffix: Na1xa1=Q#
+        let mut s = arrayvec::ArrayString::<9>::new();
+        let _ = self.append_to(&mut s);
+        serializer.serialize_str(&s)
     }
 }
 

src/uci.rs

@@ -138,7 +138,9 @@ impl serde::Serialize for UciMove {
     where
         S: serde::Serializer,
     {
-        serializer.serialize_str(&alloc::string::ToString::to_string(self))
+        let mut s = arrayvec::ArrayString::<5>::new();
+        let _ = self.append_to(&mut s);
+        serializer.serialize_str(&s)
     }
 }
 

src/util.rs

@@ -1,5 +1,7 @@
 use core::{convert::TryFrom as _, fmt, fmt::Write as _, num::TryFromIntError};
 
+use arrayvec::ArrayString;
+
 pub(crate) fn out_of_range_error() -> TryFromIntError {
     // This is a hack to construct TryFromIntError despite its private
     // constructor. The standard library keeps it private intentionally,
@@ -67,6 +69,17 @@ impl AppendAscii for fmt::Formatter<'_> {
     }
 }
 
+impl<const CAP: usize> AppendAscii for ArrayString<CAP> {
+    type Error = core::convert::Infallible;
+
+    fn reserve(&mut self, _additional: usize) {}
+
+    fn append_ascii(&mut self, ascii_char: char) -> Result<(), Self::Error> {
+        self.push(ascii_char);
+        Ok(())
+    }
+}
+
 #[cfg(feature = "alloc")]
 impl AppendAscii for alloc::string::String {
     type Error = core::convert::Infallible;