add variable declaration to parser

18 files changed, 316 insertions, 69 deletions

diff --git a/src/main/java/no/eliashaugsbakk/kompilator/IRGeneration/IRGenerator.java b/src/main/java/no/eliashaugsbakk/kompilator/IRGeneration/IRGenerator.java
index 55b349e..ffbccb6 100644
--- a/src/main/java/no/eliashaugsbakk/kompilator/IRGeneration/IRGenerator.java
+++ b/src/main/java/no/eliashaugsbakk/kompilator/IRGeneration/IRGenerator.java
@@ -6,7 +6,7 @@ import no.eliashaugsbakk.kompilator.parsing.AST;
 import no.eliashaugsbakk.kompilator.parsing.node.Program;
 import no.eliashaugsbakk.kompilator.parsing.node.expression.Expression;
 import no.eliashaugsbakk.kompilator.parsing.node.expression.FunctionCall;
-import no.eliashaugsbakk.kompilator.parsing.node.expression.StringLiteral;
+import no.eliashaugsbakk.kompilator.parsing.node.expression.literal.StringLiteral;
 import no.eliashaugsbakk.kompilator.parsing.node.statement.ExpressionStatement;
 import no.eliashaugsbakk.kompilator.parsing.node.statement.Statement;
 
diff --git a/src/main/java/no/eliashaugsbakk/kompilator/parsing/Parser.java b/src/main/java/no/eliashaugsbakk/kompilator/parsing/Parser.java
index 712df22..7f9b6c9 100644
--- a/src/main/java/no/eliashaugsbakk/kompilator/parsing/Parser.java
+++ b/src/main/java/no/eliashaugsbakk/kompilator/parsing/Parser.java
@@ -1,83 +1,255 @@
 package no.eliashaugsbakk.kompilator.parsing;
 
+import static no.eliashaugsbakk.kompilator.tokenization.TokenType.ASSIGN;
+import static no.eliashaugsbakk.kompilator.tokenization.TokenType.COLON;
+import static no.eliashaugsbakk.kompilator.tokenization.TokenType.COMMA;
 import static no.eliashaugsbakk.kompilator.tokenization.TokenType.EOF;
+import static no.eliashaugsbakk.kompilator.tokenization.TokenType.IDENTIFIER;
 import static no.eliashaugsbakk.kompilator.tokenization.TokenType.KEYWORD;
 import static no.eliashaugsbakk.kompilator.tokenization.TokenType.LPAREN;
+import static no.eliashaugsbakk.kompilator.tokenization.TokenType.NULLABLE;
 import static no.eliashaugsbakk.kompilator.tokenization.TokenType.RPAREN;
 import static no.eliashaugsbakk.kompilator.tokenization.TokenType.SEMICOLON;
-import static no.eliashaugsbakk.kompilator.tokenization.TokenType.STRING;
+import static no.eliashaugsbakk.kompilator.tokenization.TokenType.STRING_LITERAL;
+import static no.eliashaugsbakk.kompilator.tokenization.TokenType.TYPE;
 
 import java.util.ArrayList;
 import java.util.List;
 import no.eliashaugsbakk.kompilator.parsing.node.Program;
 import no.eliashaugsbakk.kompilator.parsing.node.expression.Expression;
 import no.eliashaugsbakk.kompilator.parsing.node.expression.FunctionCall;
-import no.eliashaugsbakk.kompilator.parsing.node.expression.StringLiteral;
+import no.eliashaugsbakk.kompilator.parsing.node.expression.Identifier;
+import no.eliashaugsbakk.kompilator.parsing.node.expression.literal.StringLiteral;
+import no.eliashaugsbakk.kompilator.parsing.node.statement.Assignment;
 import no.eliashaugsbakk.kompilator.parsing.node.statement.ExpressionStatement;
+import no.eliashaugsbakk.kompilator.parsing.node.statement.IdentifierDeclaration;
+import no.eliashaugsbakk.kompilator.parsing.node.statement.Statement;
 import no.eliashaugsbakk.kompilator.tokenization.Token;
 
+/*
+  The goal of parsing is to create the AST.
+  The root node is the program itself, which can only hold statements.
+
+  Statements:
+  - Is an action which executes something
+  - Has no return or implicit value
+  - Must end with a semicolon
+  - A statement may contain expressions
+  - An expression cannot contain a statement
+
+  Expressions:
+  - Returns or produces a value
+  - Does not end with a semicolon
+  - Can be nested instide other expressions or a statement
+  - Examples:
+    - Literals
+    - Identifiers
+    - Binary Operations
+    - Function calls
+ */
+
+
 public class Parser {
   private final List<Token> tokens;
-  private int position = 0;
+  private final Program rootNode;
+  private int current = 0;
 
   public Parser(List<Token> tokens) {
     this.tokens = tokens;
+    this.rootNode = new Program();
   }
 
   public AST parse() throws ParserException {
-    Program rootNode = new Program();
+    while (current < tokens.size()) {
+      Token token = tokens.get(current);
+
+      // End of File
+      if (token.type() == EOF) {
+        break;
+      }
+
+      // root node must contain only statements
+      Statement stmt = parseStatement();
+      rootNode.addStatement(stmt);
+    }
+    return new AST(rootNode);
+  }
 
-    while (position < tokens.size()) {
-      Token token = tokens.get(position);
+  private Statement parseStatement() throws ParserException {
+    // multiple statements are supported for v0.0.2;
+    // identifier declaration: x: string = "hello"; (with expression)
+    // identifier declaration: x: string; (without expression)
+    // assignment: x = "hello"; (identifier gets assigned an expression)
+    // expression statements: print(x); (function without a return value)
 
-      if (token.type() == KEYWORD) {
-        String functionName = token.value();
-        position++;
 
-        List<Expression> arguments = parseArguments();
+    // each statement must either start with a keyword or an identifier
+    Token token = tokens.get(current);
 
-        FunctionCall functionCall = new FunctionCall(functionName, arguments);
-        rootNode.addStatement(new ExpressionStatement(functionCall));
-      } else if (token.type() == EOF) {
-        break;
-      } else {
-        throw new ParserException(token.line(), token.colum(),
-            "Unexpected token: " + token.value());
-      }
+    // only keyword implemented is "skriv", so calling parseExpression right away
+    if (token.type() == KEYWORD) {
+      return parseExpressionStatement();
     }
 
-    return new AST(rootNode);
+    // must be identifier declaration or an assignment
+    else if (token.type() == IDENTIFIER) {
+      return parseIdentifierStatement();
+    }
+
+    // must be some other token which is not a statement
+    else {
+      throw new ParserException(token.line(), token.column(), "Unexpected token: " + token.value());
+    }
   }
 
-  List<Expression> parseArguments() throws ParserException {
-    List<Expression> arguments = new ArrayList<>();
+  private ExpressionStatement parseExpressionStatement() throws ParserException {
+    // this can be any expression used as a statement
+    // print(x);
+    // 5 + 6;
+    // "hello";
+
+    Expression expression = parseExpression();
+    expectSemicolon();
+    return new ExpressionStatement(expression);
+  }
+
+
+
+  private Statement parseIdentifierStatement() throws ParserException {
+    // this is either:
+    //  - declaration of a new variable with an associated value
+    //  - declaration of a new variable without an associated value
+    //  - reassigning an existing variable
+
+    /*
+    x: string?;             IDENTIFIER, COLON, TYPE, SEMICOLON
+    x: string = "string";   IDENTIFIER, COLON, TYPE, ASSIGN, STRING, SEMICOLON
+    x = "string";           IDENTIFIER, ASSIGN, STRING, SEMICOLON
+     */
+
+    String identifier = tokens.get(current).value();
+    current++;
+
+    Token next = tokens.get(current);
+
+    if (next.type() == COLON) {
+      // x: string = "hello";
+      return parseDeclaration(identifier);
+    } else if (next.type() == ASSIGN) {
+      // x = "hello";
+      return parseAssignment(identifier);
+    } else {
+      throw new ParserException(next.line(), next.column(), "Expected : or = after identifier");
+    }
+  }
 
-    if (position >= tokens.size() || tokens.get(position).type() != LPAREN) {
-      throw new ParserException(tokens.get(position).line(), tokens.get(position).colum(),
-          "Unexpected token:" + tokens.get(position).value() + "\n Expected: (");
+  private Statement parseDeclaration(String identifier) throws ParserException {
+    // x: type;
+    current++; // skip colon
+
+    Type type = parseType();
+    Expression initializer = null;
+
+    // x: type = "hello";
+    if (tokens.get(current).type() == ASSIGN) {
+      current++; // skip =
+      initializer = parseExpression();
+    }
+
+    expectSemicolon();
+    return new IdentifierDeclaration(identifier, type, initializer);
+  }
+
+  private Statement parseAssignment(String identifier) throws ParserException {
+    // x = value;
+    current++; // skip =
+
+    Expression value = parseExpression();
+    expectSemicolon();
+
+    return new Assignment(identifier, value);
+  }
+
+  private Type parseType() throws ParserException {
+    Token token = tokens.get(current);
+    if (token.type() != TYPE) {
+      throw new ParserException(token.line(), token.column(),
+          "Expected type, got: " + token.value());
     }
-    position++;
+    current++;
+
+    String typeName = token.value();
+    boolean nullable = false;
 
-    while (position < tokens.size() && tokens.get(position).type() != RPAREN) {
-      if (tokens.get(position).type() == STRING) {
-        arguments.add(new StringLiteral(tokens.get(position).value()));
+    if (current < tokens.size() && tokens.get(current).type() == NULLABLE) {
+      nullable = true;
+      current++;
+    }
+
+    return new Type(typeName, nullable);
+  }
+
+  private Expression parseExpression() throws ParserException {
+    // an expression produces a value and may contain other expressions
+    //  implemented for v0.0.2 are:
+    //  "string"    - STRING_LITERAL
+    //  my_var      - IDENTIFIER
+
+    Token token = tokens.get(current);
+    current++;
+
+    if (token.type() == STRING_LITERAL) {
+      return new StringLiteral(token.value());
+    } else if (token.type() == IDENTIFIER || token.type() == KEYWORD) {
+      // could be function call or just identifier reference
+      if (current < tokens.size() && tokens.get(current).type() == LPAREN) {
+        current--;
+        return parseFunctionCall();
       }
-      position++;
+      return new Identifier(token.value());
+    } else {
+      throw new ParserException(token.line(), token.column(),
+          "Unexpected token: " + token.value() + ". Expected an expression");
     }
+  }
+
+  private FunctionCall parseFunctionCall() throws ParserException {
+    String name = tokens.get(current).value();
+    current++;
+    List<Expression> arguments = parseFunctionArguments();
+    return new FunctionCall(name, arguments);
+  }
 
-    if (position >= tokens.size()) {
-      throw new ParserException(-1, -1, "Unexpected end of file, expected )");
+  private List<Expression> parseFunctionArguments() throws ParserException {
+    List<Expression> arguments = new ArrayList<>();
+
+    if (tokens.get(current).type() != LPAREN) {
+      throw new ParserException(tokens.get(current).line(), tokens.get(current).column(),
+          "Expected (");
     }
-    position++;
+    current++;  // skip (
+
+    while (current < tokens.size() && tokens.get(current).type() != RPAREN) {
+      arguments.add(parseExpression());  // parseExpression() increments current
 
-    if (position >= tokens.size() || tokens.get(position).type() != SEMICOLON) {
-      throw new ParserException(position < tokens.size() ? tokens.get(position).line() : -1,
-          position < tokens.size() ? tokens.get(position).colum() : -1,
-          "Unexpected token: " + (position < tokens.size() ? tokens.get(position).value() : "EOF") +
-              "\n" + "Expected: ;");
+      if (tokens.get(current).type() == COMMA) {
+        current++;  // skip comma
+      }
+    }
+
+    if (current >= tokens.size() || tokens.get(current).type() != RPAREN) {
+      throw new ParserException(tokens.get(current).line(), tokens.get(current).column(),
+          "Expected )");
     }
-    position++;
+    current++;  // skip )
 
     return arguments;
   }
+
+  private void expectSemicolon() throws ParserException {
+    if (current >= tokens.size() || tokens.get(current).type() != SEMICOLON) {
+      throw new ParserException(-1, -1, "Expected ;");
+    }
+    current++;
+  }
 }
diff --git a/src/main/java/no/eliashaugsbakk/kompilator/parsing/Type.java b/src/main/java/no/eliashaugsbakk/kompilator/parsing/Type.java
new file mode 100644
index 0000000..64305da
--- /dev/null
+++ b/src/main/java/no/eliashaugsbakk/kompilator/parsing/Type.java
@@ -0,0 +1,12 @@
+package no.eliashaugsbakk.kompilator.parsing;
+
+public class Type {
+  final String type;
+  final boolean nullable;
+
+  public Type(String type, boolean nullable) {
+    this.type = type;
+    this.nullable = nullable;
+  }
+}
+
diff --git a/src/main/java/no/eliashaugsbakk/kompilator/parsing/node/expression/Expression.java b/src/main/java/no/eliashaugsbakk/kompilator/parsing/node/expression/Expression.java
index 6ca58b2..18fc585 100644
--- a/src/main/java/no/eliashaugsbakk/kompilator/parsing/node/expression/Expression.java
+++ b/src/main/java/no/eliashaugsbakk/kompilator/parsing/node/expression/Expression.java
@@ -4,7 +4,7 @@ import no.eliashaugsbakk.kompilator.parsing.node.ASTNode;
 
 /**
  * Base class for all expression nodes.
- * An expression is a piece of code that evaluates to a value.
+ * An expression is a piece of code that evaluates to a value. (i.e., returns a value)
  * Expressions cannot stand alone as statements; they must be used within statements.
  * <p>
  * Examples:
diff --git a/src/main/java/no/eliashaugsbakk/kompilator/parsing/node/expression/Identifier.java b/src/main/java/no/eliashaugsbakk/kompilator/parsing/node/expression/Identifier.java
new file mode 100644
index 0000000..c1f475f
--- /dev/null
+++ b/src/main/java/no/eliashaugsbakk/kompilator/parsing/node/expression/Identifier.java
@@ -0,0 +1,12 @@
+package no.eliashaugsbakk.kompilator.parsing.node.expression;
+
+/**
+ * Resolves to a variable's value
+ */
+public class Identifier extends Expression {
+  final String name;
+
+  public Identifier(String name) {
+    this.name = name;
+  }
+}
diff --git a/src/main/java/no/eliashaugsbakk/kompilator/parsing/node/expression/StringLiteral.java b/src/main/java/no/eliashaugsbakk/kompilator/parsing/node/expression/literal/StringLiteral.java
index 67ce405..82402ed 100644
--- a/src/main/java/no/eliashaugsbakk/kompilator/parsing/node/expression/StringLiteral.java
+++ b/src/main/java/no/eliashaugsbakk/kompilator/parsing/node/expression/literal/StringLiteral.java
@@ -1,4 +1,6 @@
-package no.eliashaugsbakk.kompilator.parsing.node.expression;
+package no.eliashaugsbakk.kompilator.parsing.node.expression.literal;
+
+import no.eliashaugsbakk.kompilator.parsing.node.expression.Expression;
 
 /**
  * Represents a string literal expression (e.g., "Hello, World").
diff --git a/src/main/java/no/eliashaugsbakk/kompilator/parsing/node/statement/Assignment.java b/src/main/java/no/eliashaugsbakk/kompilator/parsing/node/statement/Assignment.java
new file mode 100644
index 0000000..a54a891
--- /dev/null
+++ b/src/main/java/no/eliashaugsbakk/kompilator/parsing/node/statement/Assignment.java
@@ -0,0 +1,13 @@
+package no.eliashaugsbakk.kompilator.parsing.node.statement;
+
+import no.eliashaugsbakk.kompilator.parsing.node.expression.Expression;
+
+public class Assignment extends Statement {
+  final String identifier;
+  final Expression expression;
+
+  public Assignment(String identifier, Expression expression) {
+    this.identifier = identifier;
+    this.expression = expression;
+  }
+}
diff --git a/src/main/java/no/eliashaugsbakk/kompilator/parsing/node/statement/ExpressionStatement.java b/src/main/java/no/eliashaugsbakk/kompilator/parsing/node/statement/ExpressionStatement.java
index 64bc0a8..b810a04 100644
--- a/src/main/java/no/eliashaugsbakk/kompilator/parsing/node/statement/ExpressionStatement.java
+++ b/src/main/java/no/eliashaugsbakk/kompilator/parsing/node/statement/ExpressionStatement.java
@@ -2,6 +2,11 @@ package no.eliashaugsbakk.kompilator.parsing.node.statement;
 
 import no.eliashaugsbakk.kompilator.parsing.node.expression.Expression;
 
+/**
+ * A statement which holds an expression.
+ * print("hello"); does not have a return value; it is a statement, but it is also
+ *    function call.
+ */
 public class ExpressionStatement extends Statement {
   public Expression expression;
   public ExpressionStatement(Expression expression) {
diff --git a/src/main/java/no/eliashaugsbakk/kompilator/parsing/node/statement/IdentifierDeclaration.java b/src/main/java/no/eliashaugsbakk/kompilator/parsing/node/statement/IdentifierDeclaration.java
new file mode 100644
index 0000000..e7db477
--- /dev/null
+++ b/src/main/java/no/eliashaugsbakk/kompilator/parsing/node/statement/IdentifierDeclaration.java
@@ -0,0 +1,22 @@
+package no.eliashaugsbakk.kompilator.parsing.node.statement;
+
+import no.eliashaugsbakk.kompilator.parsing.Type;
+import no.eliashaugsbakk.kompilator.parsing.node.expression.Expression;
+
+public class IdentifierDeclaration extends Statement {
+  // identifier name: [my_var]: type = 4;
+  final String identifier;
+
+  // identifier type: my_var: [type] = 4;
+  final Type type;
+
+  // identifier initialization:  my_var: type [4];
+  // may be null: my_var: type?;
+  final Expression expression; // may be null: x: int?;
+
+  public IdentifierDeclaration(String identifier, Type type, Expression expression) {
+    this.identifier = identifier;
+    this.type = type;
+    this.expression = expression;
+  }
+}
diff --git a/src/main/java/no/eliashaugsbakk/kompilator/parsing/node/statement/Statement.java b/src/main/java/no/eliashaugsbakk/kompilator/parsing/node/statement/Statement.java
index fc52f9a..aed21ad 100644
--- a/src/main/java/no/eliashaugsbakk/kompilator/parsing/node/statement/Statement.java
+++ b/src/main/java/no/eliashaugsbakk/kompilator/parsing/node/statement/Statement.java
@@ -5,9 +5,11 @@ import no.eliashaugsbakk.kompilator.parsing.node.ASTNode;
 /**
  * Base class for all statement nodes.
  * A statement is a top-level line of code that performs an action.
+ * No return value.
  * <p>
  * Examples:
  * - print("Hello");  (function call statement)
+ * x my_value = my_func("Hello"); (not a statement - it has a return value)
  * - var x: int = 5;  (variable declaration statement)
  * - if (x > 0) { }   (conditional statement)
  */
diff --git a/src/main/java/no/eliashaugsbakk/kompilator/semanticAnalysis/Analyzer.java b/src/main/java/no/eliashaugsbakk/kompilator/semanticAnalysis/Analyzer.java
index 9452fc1..b7cc7af 100644
--- a/src/main/java/no/eliashaugsbakk/kompilator/semanticAnalysis/Analyzer.java
+++ b/src/main/java/no/eliashaugsbakk/kompilator/semanticAnalysis/Analyzer.java
@@ -6,7 +6,7 @@ import no.eliashaugsbakk.kompilator.parsing.AST;
 import no.eliashaugsbakk.kompilator.parsing.node.Program;
 import no.eliashaugsbakk.kompilator.parsing.node.expression.Expression;
 import no.eliashaugsbakk.kompilator.parsing.node.expression.FunctionCall;
-import no.eliashaugsbakk.kompilator.parsing.node.expression.StringLiteral;
+import no.eliashaugsbakk.kompilator.parsing.node.expression.literal.StringLiteral;
 import no.eliashaugsbakk.kompilator.parsing.node.statement.ExpressionStatement;
 import no.eliashaugsbakk.kompilator.parsing.node.statement.Statement;
 
diff --git a/src/main/java/no/eliashaugsbakk/kompilator/tokenization/Lexer.java b/src/main/java/no/eliashaugsbakk/kompilator/tokenization/Lexer.java
index c185650..53c7b53 100644
--- a/src/main/java/no/eliashaugsbakk/kompilator/tokenization/Lexer.java
+++ b/src/main/java/no/eliashaugsbakk/kompilator/tokenization/Lexer.java
@@ -6,15 +6,17 @@ import static no.eliashaugsbakk.kompilator.tokenization.LexerState.IN_TYPE;
 import static no.eliashaugsbakk.kompilator.tokenization.LexerState.IN_WORD;
 import static no.eliashaugsbakk.kompilator.tokenization.LexerState.NORMAL;
 import static no.eliashaugsbakk.kompilator.tokenization.TokenType.ASSIGN;
+import static no.eliashaugsbakk.kompilator.tokenization.TokenType.COMMA;
 import static no.eliashaugsbakk.kompilator.tokenization.TokenType.EOF;
 import static no.eliashaugsbakk.kompilator.tokenization.TokenType.IDENTIFIER;
 import static no.eliashaugsbakk.kompilator.tokenization.TokenType.KEYWORD;
 import static no.eliashaugsbakk.kompilator.tokenization.TokenType.LPAREN;
+import static no.eliashaugsbakk.kompilator.tokenization.TokenType.NULLABLE;
 import static no.eliashaugsbakk.kompilator.tokenization.TokenType.RPAREN;
 import static no.eliashaugsbakk.kompilator.tokenization.TokenType.SEMICOLON;
-import static no.eliashaugsbakk.kompilator.tokenization.TokenType.STRING;
+import static no.eliashaugsbakk.kompilator.tokenization.TokenType.STRING_LITERAL;
 import static no.eliashaugsbakk.kompilator.tokenization.TokenType.TYPE;
-import static no.eliashaugsbakk.kompilator.tokenization.TokenType.TYPE_DECLARATION;
+import static no.eliashaugsbakk.kompilator.tokenization.TokenType.COLON;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -47,12 +49,11 @@ public class Lexer {
       }
 
       current = input.charAt(position);
-      if (!Character.isWhitespace(current)) {
-
+      if (state == IN_STRING) {
+        inString();
+      } else if (!Character.isWhitespace(current)) {
         if (state == IN_WORD) {
           inWord();
-        } else if (state == IN_STRING) {
-          inString();
         } else if (state == IN_TYPE) {
           inType();
         }
@@ -76,7 +77,7 @@ public class Lexer {
       wordBuffer.append(current);
 
     } else if (current == ':') {
-      tokens.add(new Token(TYPE_DECLARATION, ":", line, column));
+      tokens.add(new Token(COLON, ":", line, column));
       state = IN_TYPE;
 
     } else if (current == '=') {
@@ -87,11 +88,18 @@ public class Lexer {
       tokens.add(new Token(RPAREN, Character.toString(current), line, column));
     } else if (current == ';') {
       tokens.add(new Token(SEMICOLON, Character.toString(current), line, column));
+    } else if (current == ',') {
+      tokens.add(new Token(COMMA, Character.toString(current), line, column));
     }
   }
 
   private void inType() {
-    if (current == '=' || current == ';') {
+    if (current == '?') {
+      state = NORMAL;
+      tokens.add(new Token(TYPE, wordBuffer.toString(), line, column - wordBuffer.length()));
+      tokens.add(new Token(NULLABLE, "?", line, column));
+      clearWordBuffer();
+    } else if (current == '=' || current == ';') {
       state = NORMAL;
       tokens.add(new Token(TYPE, wordBuffer.toString(), line, column - wordBuffer.length()));
       clearWordBuffer();
@@ -101,11 +109,10 @@ public class Lexer {
   }
 
   private void inString() {
-    if (current == '"') {
-      position++; // skip closing "
+    if (current == '"') { // closing " gets skipped implicitly
       current = input.charAt(position);
       state = NORMAL;
-      tokens.add(new Token(STRING, wordBuffer.toString(), line, column));
+      tokens.add(new Token(STRING_LITERAL, wordBuffer.toString(), line, column));
       wordBuffer.delete(0, wordBuffer.length());
     } else {
       wordBuffer.append(current);
diff --git a/src/main/java/no/eliashaugsbakk/kompilator/tokenization/Token.java b/src/main/java/no/eliashaugsbakk/kompilator/tokenization/Token.java
index 09c5d83..1cab703 100644
--- a/src/main/java/no/eliashaugsbakk/kompilator/tokenization/Token.java
+++ b/src/main/java/no/eliashaugsbakk/kompilator/tokenization/Token.java
@@ -1,4 +1,4 @@
 package no.eliashaugsbakk.kompilator.tokenization;
 
-public record Token(TokenType type, String value, int line, int colum) {
+public record Token(TokenType type, String value, int line, int column) {
 }
diff --git a/src/main/java/no/eliashaugsbakk/kompilator/tokenization/TokenType.java b/src/main/java/no/eliashaugsbakk/kompilator/tokenization/TokenType.java
index 1d6382e..3a1d4ba 100644
--- a/src/main/java/no/eliashaugsbakk/kompilator/tokenization/TokenType.java
+++ b/src/main/java/no/eliashaugsbakk/kompilator/tokenization/TokenType.java
@@ -3,12 +3,14 @@ package no.eliashaugsbakk.kompilator.tokenization;
 public enum TokenType {
   KEYWORD,          // print, var, if, while, function, etc.
   IDENTIFIER,       // variable_1
-  STRING,           // "Hello, World!"
-  TYPE_DECLARATION, // : (x[:] int = ...)
-  TYPE,             // String, i32, i16?, my_type, ... (? makes nullable)
+  STRING_LITERAL,   // "Hello, World!"
+  COLON,            // : (x[:] int = ...)
+  TYPE,             // string, i32, i16?, my_type, ... (? makes nullable)
   ASSIGN,           // =
+  NULLABLE,    // ? (x = string?;)
   LPAREN,           // (
   RPAREN,           // )
   SEMICOLON,        // ;
+  COMMA,            // ,
   EOF               // End of File
 }
diff --git a/src/test/java/no/eliashaugsbakk/kompilator/IRGeneration/IRGeneratorTest.java b/src/test/java/no/eliashaugsbakk/kompilator/IRGeneration/IRGeneratorTest.java
index 16ebc73..fdaab26 100644
--- a/src/test/java/no/eliashaugsbakk/kompilator/IRGeneration/IRGeneratorTest.java
+++ b/src/test/java/no/eliashaugsbakk/kompilator/IRGeneration/IRGeneratorTest.java
@@ -6,7 +6,7 @@ import java.util.List;
 import no.eliashaugsbakk.kompilator.parsing.AST;
 import no.eliashaugsbakk.kompilator.parsing.node.Program;
 import no.eliashaugsbakk.kompilator.parsing.node.expression.FunctionCall;
-import no.eliashaugsbakk.kompilator.parsing.node.expression.StringLiteral;
+import no.eliashaugsbakk.kompilator.parsing.node.expression.literal.StringLiteral;
 import no.eliashaugsbakk.kompilator.parsing.node.statement.ExpressionStatement;
 import org.junit.jupiter.api.Test;
 
diff --git a/src/test/java/no/eliashaugsbakk/kompilator/parsing/ParserTest.java b/src/test/java/no/eliashaugsbakk/kompilator/parsing/ParserTest.java
index ac31dfc..fcd47c7 100644
--- a/src/test/java/no/eliashaugsbakk/kompilator/parsing/ParserTest.java
+++ b/src/test/java/no/eliashaugsbakk/kompilator/parsing/ParserTest.java
@@ -4,13 +4,13 @@ import static no.eliashaugsbakk.kompilator.tokenization.TokenType.KEYWORD;
 import static no.eliashaugsbakk.kompilator.tokenization.TokenType.LPAREN;
 import static no.eliashaugsbakk.kompilator.tokenization.TokenType.RPAREN;
 import static no.eliashaugsbakk.kompilator.tokenization.TokenType.SEMICOLON;
-import static no.eliashaugsbakk.kompilator.tokenization.TokenType.STRING;
+import static no.eliashaugsbakk.kompilator.tokenization.TokenType.STRING_LITERAL;
 import static org.junit.jupiter.api.Assertions.*;
 
 import java.util.List;
 import no.eliashaugsbakk.kompilator.parsing.node.Program;
 import no.eliashaugsbakk.kompilator.parsing.node.expression.FunctionCall;
-import no.eliashaugsbakk.kompilator.parsing.node.expression.StringLiteral;
+import no.eliashaugsbakk.kompilator.parsing.node.expression.literal.StringLiteral;
 import no.eliashaugsbakk.kompilator.parsing.node.statement.ExpressionStatement;
 import no.eliashaugsbakk.kompilator.tokenization.Token;
 import org.junit.jupiter.api.Test;
@@ -22,7 +22,7 @@ class ParserTest {
     List<Token> tokens = List.of(
         new Token(KEYWORD, "print", 1, 0),
         new Token(LPAREN, "(", 1, 5),
-        new Token(STRING, "Hello", 1, 6),
+        new Token(STRING_LITERAL, "Hello", 1, 6),
         new Token(RPAREN, ")", 1, 13),
         new Token(SEMICOLON, ";", 1, 14)
     );
@@ -49,7 +49,7 @@ class ParserTest {
     List<Token> tokens = List.of(
         new Token(KEYWORD, "print", 1, 0),
         new Token(LPAREN, "(", 1, 5),
-        new Token(STRING, "Hello", 1, 6),
+        new Token(STRING_LITERAL, "Hello", 1, 6),
         new Token(RPAREN, ")", 1, 13)
     );
 
@@ -60,7 +60,7 @@ class ParserTest {
   void missingParenthesisThrows() {
     List<Token> tokens = List.of(
         new Token(KEYWORD, "print", 1, 0),
-        new Token(STRING, "Hello", 1, 5),
+        new Token(STRING_LITERAL, "Hello", 1, 5),
         new Token(RPAREN, ")", 1, 12),
         new Token(SEMICOLON, ";", 1, 13)
     );
diff --git a/src/test/java/no/eliashaugsbakk/kompilator/semanticAnalysis/AnalyzerTest.java b/src/test/java/no/eliashaugsbakk/kompilator/semanticAnalysis/AnalyzerTest.java
index e6cdafa..13827e4 100644
--- a/src/test/java/no/eliashaugsbakk/kompilator/semanticAnalysis/AnalyzerTest.java
+++ b/src/test/java/no/eliashaugsbakk/kompilator/semanticAnalysis/AnalyzerTest.java
@@ -6,7 +6,7 @@ import java.util.List;
 import no.eliashaugsbakk.kompilator.parsing.AST;
 import no.eliashaugsbakk.kompilator.parsing.node.Program;
 import no.eliashaugsbakk.kompilator.parsing.node.expression.FunctionCall;
-import no.eliashaugsbakk.kompilator.parsing.node.expression.StringLiteral;
+import no.eliashaugsbakk.kompilator.parsing.node.expression.literal.StringLiteral;
 import no.eliashaugsbakk.kompilator.parsing.node.statement.ExpressionStatement;
 import org.junit.jupiter.api.Test;
 
diff --git a/src/test/java/no/eliashaugsbakk/kompilator/tokenization/LexerTest.java b/src/test/java/no/eliashaugsbakk/kompilator/tokenization/LexerTest.java
index 4b7fd46..85241ef 100644
--- a/src/test/java/no/eliashaugsbakk/kompilator/tokenization/LexerTest.java
+++ b/src/test/java/no/eliashaugsbakk/kompilator/tokenization/LexerTest.java
@@ -5,7 +5,7 @@ import static no.eliashaugsbakk.kompilator.tokenization.TokenType.KEYWORD;
 import static no.eliashaugsbakk.kompilator.tokenization.TokenType.LPAREN;
 import static no.eliashaugsbakk.kompilator.tokenization.TokenType.RPAREN;
 import static no.eliashaugsbakk.kompilator.tokenization.TokenType.SEMICOLON;
-import static no.eliashaugsbakk.kompilator.tokenization.TokenType.STRING;
+import static no.eliashaugsbakk.kompilator.tokenization.TokenType.STRING_LITERAL;
 import static org.junit.jupiter.api.Assertions.*;
 
 import java.util.List;
@@ -22,15 +22,13 @@ class LexerTest {
     Lexer lexer = new Lexer(input);
     List<Token> tokens = lexer.tokenize();
 
-    // tokens.forEach(t-> IO.println(t.type + " : " + t.value));
-
     assertSame(KEYWORD, tokens.getFirst().type());
     assertEquals(1, tokens.get(0).line());
-    assertEquals(1, tokens.get(0).colum());
+    assertEquals(1, tokens.get(0).column());
 
     assertSame(LPAREN, tokens.get(1).type());
 
-    assertSame(STRING, tokens.get(2).type());
+    assertSame(STRING_LITERAL, tokens.get(2).type());
     assertTrue(tokens.get(2).value().contains("Hello, World"));
 
     assertSame(RPAREN, tokens.get(3).type());