make std optional

Zentiph · Zentiph · commit ba55d4757e3d · 2025-10-29T00:36:38.000-04:00
diff --git a/Cargo.toml b/Cargo.toml
@@ -21,7 +21,16 @@ lto = "thin"
 codegen-units = 1
 
 [features]
-default = []
-srgb_lut = []               # bool
-color_double_precision = []
+default = ["std"]
+# Enable the Rust standard library. On by default for convenience.
+std = ["alloc"]
+# Things that need a heap but not full std
+alloc = []
+# Optional: serde support (works in no_std)
 serde = ["dep:serde"]
+
+# Whether to use a lookup table for srgb conversions.
+# Useful if the CPU is being used for lots of calculations rather than the GPU.
+srgb_lut = []
+# Whether to use f64s for all color conversion functions rather than f32.
+color_double_precision = []
diff --git a/src/color/mod.rs b/src/color/mod.rs
@@ -1,3 +1,5 @@
+#![cfg_attr(not(feature = "std"), no_std)]
+
 #[cfg(feature = "srgb_lut")]
 pub mod lut;
 pub mod model;
diff --git a/src/color/model.rs b/src/color/model.rs
@@ -8,6 +8,9 @@
 
 use std::fmt::{self};
 
+#[cfg(feature = "alloc")]
+extern crate alloc;
+
 use crate::color::ColorFloat;
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
@@ -290,13 +293,15 @@ impl Color {
 
     #[must_use]
     #[inline]
-    pub fn into_hex6(self) -> String {
+    #[cfg(feature = "alloc")]
+    pub fn into_hex6(self) -> alloc::string::String {
         format!("{:02x}{:02x}{:02x}", self.r, self.g, self.b)
     }
 
     #[must_use]
     #[inline]
-    pub fn into_hex8(self) -> String {
+    #[cfg(feature = "alloc")]
+    pub fn into_hex8(self) -> alloc::string::String {
         format!("{:02x}{:02x}{:02x}{:02x}", self.r, self.g, self.b, self.a)
     }
 
diff --git a/src/color/parse.rs b/src/color/parse.rs
@@ -1,6 +1,6 @@
 #![allow(dead_code)]
 
-use std::fmt;
+use core::fmt;
 
 use crate::color::model::Color;
 
@@ -16,15 +16,17 @@ pub enum ColorParseError {
 impl fmt::Display for ColorParseError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         use ColorParseError::*;
-        match self {
-            Empty => write!(f, "empty color string"),
-            InvalidLength => write!(f, "invalid hex length"),
-            InvalidHex => write!(f, "invalid hex digits"),
-            InvalidFunc => write!(f, "invalid rgb()/rgba() function"),
-            OutOfRange => write!(f, "component out of range"),
-        }
+        let msg = match self {
+            Empty => "empty color string",
+            InvalidLength => "invalid hex length",
+            InvalidHex => "invalid hex digits",
+            InvalidFunc => "invalid rgb()/rgba() function",
+            OutOfRange => "component out of range",
+        };
+        f.write_str(msg)
     }
 }
+#[cfg(feature = "std")]
 impl std::error::Error for ColorParseError {}
 
 /// Parse a hex color from a string.
@@ -219,7 +221,7 @@ pub fn parse_color(mut s: &str) -> Result<Color, ColorParseError> {
     Err(InvalidFunc)
 }
 
-impl std::str::FromStr for Color {
+impl core::str::FromStr for Color {
     type Err = ColorParseError;
     fn from_str(s: &str) -> Result<Self, Self::Err> {
         parse_color(s)

Original file line number	Diff line number	Diff line change
`@@ -1,3 +1,5 @@`
	`1`	`+#![cfg_attr(not(feature = "std"), no_std)]`
	`2`	`+`
`1`	`3`	`#[cfg(feature = "srgb_lut")]`
`2`	`4`	`pub mod lut;`
`3`	`5`	`pub mod model;`