feat(lexer): Scan alphanumeric

src/lexer/Lexer.kt

@@ -9,25 +9,25 @@ class Lexer(private val source: String) {
 
     fun scan(): List<Token> {
         while (hasNext()) {
-            val token = scanToken()
-            tokens += token
+            tokens += scanToken()
         }
 
+        position.length = 0
         tokens += Token(TokenType.EOF, position)
 
         return tokens
     }
 
     private fun scanToken(): Token {
-        val c = peek()
-        val token = when (c) {
-            '.' -> Token(TokenType.DOT, position)
-            else -> throw Error("Unknown symbol: $c", position)
-        }
+        val char: Char = peek()
 
-        offset++
-        position.column++
-        return token
+        position.length = 1
+
+        return when {
+            char == '.' -> scanDot()
+            char.isLetterOrDigit() -> scanAlphanumeric()
+            else -> throw Error("Unknown symbol: $char", position)
+        }
     }
 
     private fun hasNext(): Boolean {
@@ -41,4 +41,27 @@ class Lexer(private val source: String) {
 
         return source[offset]
     }
+
+    // Scanners
+
+    private fun scanDot(): Token {
+        val token = Token(TokenType.DOT, position)
+        offset++
+        position.column++
+        return token
+    }
+
+    private fun scanAlphanumeric(): Token {
+        val token = Token(TokenType.ALPHANUMERIC, position)
+        offset++
+        position.column++
+
+        while (hasNext() && peek().isLetterOrDigit()) {
+            offset++
+            position.column++
+            position.length++
+        }
+
+        return token
+    }
 }