Added is_valid_email_address.rs

add is_valid_email_address.rs

Author: lyqio

DIRECTORY.md

@@ -314,6 +314,7 @@
     * [Burrows Wheeler Transform](https://github.com/TheAlgorithms/Rust/blob/master/src/string/burrows_wheeler_transform.rs)
     * [Duval Algorithm](https://github.com/TheAlgorithms/Rust/blob/master/src/string/duval_algorithm.rs)
     * [Hamming Distance](https://github.com/TheAlgorithms/Rust/blob/master/src/string/hamming_distance.rs)
+    * [Is Valid Email Address](https://github.com/TheAlgorithms/Rust/blob/master/src/string/is_valid_email_address.rs)
     * [Isomorphism](https://github.com/TheAlgorithms/Rust/blob/master/src/string/isomorphism.rs)
     * [Jaro Winkler Distance](https://github.com/TheAlgorithms/Rust/blob/master/src/string/jaro_winkler_distance.rs)
     * [Knuth Morris Pratt](https://github.com/TheAlgorithms/Rust/blob/master/src/string/knuth_morris_pratt.rs)

src/string/is_valid_email_address.rs

@@ -0,0 +1,112 @@
+const MAX_LOCAL_PART_LENGTH: u32 = 64;
+const MAX_DOMAIN_LENGTH: u32 = 255;
+const CHARACTERS: &str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890";
+const SYMBOLS: &str = "!#$%&'*+-/=?^_`{|}~";
+
+/// Returns true if email address is valid, otherwise returns false
+///
+/// A valid email address is made up of two parts, the local-part, and
+/// the domain.
+///
+/// The local-part may contain the following:
+///     - uppercase & lowercase latin letters
+///     - digits 0-9
+///     - characters !#$%&'*+-/=?^_`{|}~
+///     - non consecutive dots ('.') not located at start or end of local-part
+///
+/// The domain may contain the following:
+///     - uppercase & lowercase latin letters
+///     - digits 0-9
+///     - dash ('-') as long as not at start or end of domain
+///
+/// The local-part and domain must be separated by an '@'
+/// The local-part must not contain more than 64 characters
+/// The domain must not contain more than 255 characters
+pub fn is_valid_email_address(email_address: &str) -> bool {
+    let parts: Vec<String> = email_address
+        .split('@')
+        .map(|x| x.to_string())
+        .collect::<Vec<String>>();
+
+    // (1)  ensure there is only one '@' symbol in the address
+    if parts.len() != 2 {
+        return false;
+    }
+
+    let (local_part, domain): (String, String) = (parts[0].clone(), parts[1].clone());
+
+    // (2)  check that the length of the two parts are within the valid range
+    if local_part.len() > MAX_LOCAL_PART_LENGTH as usize
+        || domain.len() > MAX_DOMAIN_LENGTH as usize
+    {
+        return false;
+    }
+
+    // (3)  validate the dots in the local part
+    if local_part.starts_with('.') || local_part.ends_with('.') || local_part.contains("..") {
+        return false;
+    }
+
+    // (4)  check that the characters in the local part are valid
+    for item in local_part.chars() {
+        if !CHARACTERS.contains(item) && !SYMBOLS.contains(item) && item != '.' {
+            return false;
+        }
+    }
+
+    // (5)  check that the domain contains valid characters
+    for item in domain.chars() {
+        if !CHARACTERS.contains(item) && item != '-' && item != '.' {
+            return false;
+        }
+    }
+
+    // (6)  validate the dots in the domain
+    if domain.starts_with('.') || domain.ends_with('.') || domain.contains("..") {
+        return false;
+    }
+
+    // (7)  validate the dashes in the domain
+    if domain.starts_with('-') || domain.ends_with('-') {
+        return false;
+    }
+
+    true
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::string::is_valid_email_address::is_valid_email_address;
+
+    macro_rules! test_is_valid_email_address {
+        ($($name:ident: $inputs:expr,)*) => {
+        $(
+            #[test]
+            fn $name() {
+                let (s, expected) = $inputs;
+                assert_eq!(is_valid_email_address(s), expected);
+            }
+        )*
+        }
+    }
+
+    test_is_valid_email_address! {
+        normal_email: ("[email protected]", true),
+        email_with_dots: ("[email protected]", true),
+        dots_with_symbols: ("[email protected]", true),
+        dash_test: ("[email protected]", true),
+        short_local_part: ("[email protected]", true),
+        multiple_dash: ("[email protected]", true),
+        extreme_valid: ("longlonglonglonglonglonglonglonglonglonglonglonglonglonglonglon@example.com",true),
+        extreme_invalid: ("longlonglonglonglonglonglonglonglonglonglonglonglonglonglonglongl@example.com",false),
+        invalid_at: ("where.is.at", false),
+        multiple_ats: ("too@[email protected]", false),
+        consecutive_dots: ("[email protected]", false),
+        invalid_underscore: ("wrong@no_underscore_here", false),
+        dash_start: ("[email protected]", false),
+        dash_end: ("also-dont-put@here-", false),
+        dot_start: (".not_at_start@dont", false),
+        dot_end: ("or-at-end@here.", false),
+        dot_start_end: ("[email protected].", false),
+    }
+}

src/string/mod.rs

@@ -5,6 +5,7 @@ mod boyer_moore_search;
 mod burrows_wheeler_transform;
 mod duval_algorithm;
 mod hamming_distance;
+mod is_valid_email_address;
 mod isomorphism;
 mod jaro_winkler_distance;
 mod knuth_morris_pratt;
@@ -31,6 +32,7 @@ pub use self::burrows_wheeler_transform::{
 };
 pub use self::duval_algorithm::duval_algorithm;
 pub use self::hamming_distance::hamming_distance;
+pub use self::is_valid_email_address::is_valid_email_address;
 pub use self::isomorphism::is_isomorphic;
 pub use self::jaro_winkler_distance::jaro_winkler_distance;
 pub use self::knuth_morris_pratt::knuth_morris_pratt;