Add strcspn

Author: thejpster

Cargo.toml

@@ -42,6 +42,7 @@ all = [
     "strncpy",
     "strrchr",
     "strspn",
+    "strcspn",
     "strstr",
     "strtoimax",
     "strtol",
@@ -78,6 +79,7 @@ strncmp = []
 strncpy = []
 strrchr = []
 strspn = []
+strcspn = []
 strstr = []
 strtoimax = []
 strtol = []

src/lib.rs

@@ -27,6 +27,7 @@ mod strcat;
 mod strchr;
 mod strcmp;
 mod strcpy;
+mod strcspn;
 mod strlen;
 mod strncasecmp;
 mod strncmp;
@@ -73,6 +74,8 @@ pub use self::strchr::strchr;
 pub use self::strcmp::strcmp;
 #[cfg(feature = "strcpy")]
 pub use self::strcpy::strcpy;
+#[cfg(feature = "strcspn")]
+pub use self::strcspn::strcspn;
 #[cfg(feature = "strlen")]
 pub use self::strlen::strlen;
 #[cfg(feature = "strncasecmp")]

src/strcspn.rs

@@ -0,0 +1,94 @@
+//! Rust implementation of C library function `strcspn`
+//!
+//! Copyright (c) Ferrous Systems UK Ltd
+//! Licensed under the Blue Oak Model Licence 1.0.0
+
+use crate::{CChar, CInt};
+
+/// Rust implementation of C library function `strcspn`
+#[cfg_attr(feature = "strcspn", no_mangle)]
+pub unsafe extern "C" fn strcspn(s: *const CChar, charset: *const CChar) -> usize {
+	if s.is_null() {
+		return 0;
+	}
+	if charset.is_null() {
+		return 0;
+	}
+
+	let s = unsafe { core::ffi::CStr::from_ptr(s.cast()) };
+
+	let charset = unsafe { core::ffi::CStr::from_ptr(charset.cast()) };
+
+	let bytes = s.to_bytes();
+	for (idx, b) in bytes.iter().enumerate() {
+		if is_c_in_charset(*b, charset) {
+			return idx;
+		}
+	}
+
+	bytes.len()
+}
+
+fn is_c_in_charset(c: u8, charset: &core::ffi::CStr) -> bool {
+	for b in charset.to_bytes() {
+		if c == *b {
+			return true;
+		}
+	}
+	false
+}
+
+#[cfg(test)]
+mod test {
+	#[test]
+	fn complete() {
+		let charset = c"0123456789";
+		let s = c"abcdef";
+		assert_eq!(
+			unsafe { super::strcspn(s.as_ptr().cast(), charset.as_ptr().cast()) },
+			6
+		);
+	}
+
+	#[test]
+	fn subset() {
+		let charset = c"0123456789";
+		let s = c"xyz1";
+		assert_eq!(
+			unsafe { super::strcspn(s.as_ptr().cast(), charset.as_ptr().cast()) },
+			3
+		);
+	}
+
+	#[test]
+	fn none() {
+		let charset = c"0123456789";
+		let s = c"567";
+		assert_eq!(
+			unsafe { super::strcspn(s.as_ptr().cast(), charset.as_ptr().cast()) },
+			0
+		);
+	}
+
+	#[test]
+	fn empty_charset() {
+		let charset = c"";
+		let s = c"AABBCCDD";
+		assert_eq!(
+			unsafe { super::strcspn(s.as_ptr().cast(), charset.as_ptr().cast()) },
+			8
+		);
+	}
+
+	#[test]
+	fn empty_string() {
+		let charset = c"0123456789";
+		let s = c"";
+		assert_eq!(
+			unsafe { super::strcspn(s.as_ptr().cast(), charset.as_ptr().cast()) },
+			0
+		);
+	}
+}
+
+// End of file