Scan simple hex value

src/syntax/scanner/number.rs

@@ -1,22 +1,63 @@
 use crate::syntax::{token::{Token, self}, utils};
 
 pub fn scan(chars: &Vec<char>, start_pos: usize) -> (Token, usize) {
+    let next_char = chars.get(start_pos);
+
+    // Try to scan a HEX value
+    if let Some(c) = next_char {
+        if *c == '0' {
+            // May be an 'x' or 'X'
+            let next_next_char = chars.get(start_pos + 1);
+            if let Some(c2) = next_next_char {
+                if *c2 == 'x' || *c2 == 'X' {
+                    return scan_hex(chars, start_pos + 2, String::from("0x"));
+                }
+            }
+        }
+    }
+
+
     scan_decimal(chars, start_pos, String::from(""))
 }
 
+/// Scans an integer.
 fn scan_decimal(chars: &Vec<char>, start_pos: usize, current: String) -> (Token, usize) {
     let next_char = chars.get(start_pos);
 
+    // If a char is found
     if let Some(c) = next_char {
-        if utils::is_digit(*c) {
-            let new_value = format!("{}{}", current, *c);
-            scan_decimal(chars, start_pos + 1, new_value)
-        } else {
-            (token::new_number(current, start_pos as i32), start_pos)
+        let c = *c;
+
+        // Scan a decimal number
+        if utils::is_digit(c) {
+            let new_value = format!("{}{}", current, c);
+            return scan_decimal(chars, start_pos + 1, new_value)
         }
-    } else {
-        (token::new_number(current, start_pos as i32), start_pos)
+   
     }
+
+    // Return the current value
+    (token::new_number(current, start_pos as i32), start_pos)
+}
+
+/// Scans a hex number. If successful, always returns '0x...', never '0X...'
+/// 
+/// `current == ""`
+/// 
+/// `start_pos` indicates the start of the hex value
+fn scan_hex(chars: &Vec<char>, start_pos: usize, current: String) -> (Token, usize) {
+    let next_char = chars.get(start_pos);
+
+    if let Some(c) = next_char {
+        let c = *c;
+
+        if utils::is_hex_digit(c) {
+            return scan_hex(chars, start_pos + 1, utils::str_append(current, c))
+        }
+    }
+
+    // Return current value
+    (token::new_number(current, start_pos as i32), start_pos)
 }
 
 
@@ -59,4 +100,36 @@ mod tests {
         assert_eq!(TokenType::Number, token.token_type);
         assert_eq!("123456", token.value);
     }
+
+    #[test]
+    fn test_hex() {
+        let input = str_to_vec("0x20");
+        let start_pos = 0;
+
+        let (token, next) = scan(&input, start_pos);
+        assert_eq!(4, next);
+        assert_eq!(TokenType::Number, token.token_type);
+        assert_eq!("0x20", token.value);
+
+
+        let input = str_to_vec("    0Xff23DA");
+        let start_pos = 4;
+
+        let (token, next) = scan(&input, start_pos);
+        assert_eq!(12, next);
+        assert_eq!(TokenType::Number, token.token_type);
+        assert_eq!("0xff23DA", token.value);
+    }
+
+    // Should not scan an incomplete hex value
+    #[test]
+    fn test_hex_2() {
+        let input = str_to_vec("0x20");
+        let start_pos = 0;
+
+        let (token, next) = scan(&input, start_pos);
+        assert_eq!(4, next);
+        assert_eq!(TokenType::Number, token.token_type);
+        assert_eq!("0x20", token.value);
+    }
 }

src/syntax/utils.rs

@@ -3,4 +3,10 @@ pub fn is_digit(c: char) -> bool {
     '0' <= c && c <= '9'
 }
 
+pub fn is_hex_digit(c: char) -> bool {
+    is_digit(c) || 'a' <= c && c <= 'f' || 'A' <= c && c <= 'F'
+}
 
+pub fn str_append(current: String, c: char) -> String {
+    format!("{}{}", current, c)
+}