identifiers: Move session ID validation out of separate validation crate

crates/ruma-common/src/identifiers/session_id.rs

@@ -2,11 +2,42 @@
 
 use ruma_macros::IdZst;
 
+use super::IdParseError;
+
 /// A session ID.
 ///
 /// Session IDs in Matrix are opaque character sequences of `[0-9a-zA-Z.=_-]`. Their length must
 /// must not exceed 255 characters.
 #[repr(transparent)]
 #[derive(PartialEq, Eq, PartialOrd, Ord, Hash, IdZst)]
-#[ruma_id(validate = ruma_identifiers_validation::session_id::validate)]
+#[ruma_id(validate = validate_session_id)]
 pub struct SessionId(str);
+
+const fn validate_session_id(s: &str) -> Result<(), IdParseError> {
+    if s.len() > 255 {
+        return Err(IdParseError::MaximumLengthExceeded);
+    } else if contains_invalid_byte(s.as_bytes()) {
+        return Err(IdParseError::InvalidCharacters);
+    } else if s.is_empty() {
+        return Err(IdParseError::Empty);
+    }
+
+    Ok(())
+}
+
+const fn contains_invalid_byte(mut bytes: &[u8]) -> bool {
+    // non-const form:
+    //
+    // bytes.iter().all(|b| b.is_ascii_alphanumeric() || b".=_-".contains(&b))
+    loop {
+        if let Some((byte, rest)) = bytes.split_first() {
+            if byte.is_ascii_alphanumeric() || matches!(byte, b'.' | b'=' | b'_' | b'-') {
+                bytes = rest;
+            } else {
+                break true;
+            }
+        } else {
+            break false;
+        }
+    }
+}

crates/ruma-identifiers-validation/src/lib.rs

@@ -12,7 +12,6 @@ pub mod room_id;
 pub mod room_id_or_alias_id;
 pub mod room_version_id;
 pub mod server_name;
-pub mod session_id;
 pub mod user_id;
 pub mod voip_version_id;
 

crates/ruma-identifiers-validation/src/session_id.rs

@@ -1,13 +0,0 @@
-use crate::Error;
-
-pub fn validate(s: &str) -> Result<(), Error> {
-    if s.len() > 255 {
-        return Err(Error::MaximumLengthExceeded);
-    } else if !s.bytes().all(|b| b.is_ascii_alphanumeric() || b".=_-".contains(&b)) {
-        return Err(Error::InvalidCharacters);
-    } else if s.is_empty() {
-        return Err(Error::Empty);
-    }
-
-    Ok(())
-}