Add function

src/main/java/dev/tenfont/cpmm/elements/statements/FunctionDeclarationStatement.java

@@ -5,16 +5,21 @@
 import dev.tenfont.cpmm.lang.components.Context;
 import dev.tenfont.cpmm.lang.components.Statement;
 import dev.tenfont.cpmm.lang.components.TokenType;
+import lombok.RequiredArgsConstructor;
 
+@RequiredArgsConstructor
 public class FunctionDeclarationStatement extends Statement {
+    private final BlockStatement body;
+    private String identifier;
+
     @Override
     public void execute(Interpreter interpreter) {
-        System.out.println("Function declaration statement executing test.");
     }
 
     @Override
     public boolean init(Parser parser, Context context) {
         parser.eat(TokenType.FUNCTION);
+        identifier = parser.eat(TokenType.IDENTIFIER, String.class);
         return true;
     }
 }

src/main/java/dev/tenfont/cpmm/elements/statements/IfStatement.java

@@ -6,19 +6,17 @@
 import dev.tenfont.cpmm.lang.components.Expression;
 import dev.tenfont.cpmm.lang.components.Statement;
 import dev.tenfont.cpmm.lang.components.TokenType;
+import lombok.RequiredArgsConstructor;
 
+@RequiredArgsConstructor
 public class IfStatement extends Statement {
-    private final BlockStatement blockStatement;
+    private final BlockStatement body;
     private Expression test;
 
-    public IfStatement(BlockStatement blockStatement) {
-        this.blockStatement = blockStatement;
-    }
-
     @Override
     public void execute(Interpreter interpreter) {
         var value = test.get(interpreter.getCurrentContext());
-        if (value != null && (boolean) value) blockStatement.execute(interpreter);
+        if (value != null && (boolean) value) body.execute(interpreter);
     }
 
     @Override

src/main/java/dev/tenfont/cpmm/lang/FunctionRegistry.java

@@ -0,0 +1,21 @@
+package dev.tenfont.cpmm.lang;
+
+import dev.tenfont.cpmm.lang.components.Function;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class FunctionRegistry {
+    private final Map<String, Function> map = new HashMap<>();
+
+    public boolean declareFunction(String name, Function function) {
+        if (map.containsKey(name))
+            return false;
+        map.put(name, function);
+        return true;
+    }
+
+    public boolean functionExists(String name) {
+        return map.containsKey(name);
+    }
+}

src/main/java/dev/tenfont/cpmm/lang/Parser.java

@@ -58,7 +58,6 @@ public Statement parseStatement(Context context) {
                 return this.parseBlockStatement(context);
             }
             case REVERSE -> statement = new ReverseStatement();
-            case FUNCTION -> statement = new FunctionDeclarationStatement();
             case VARIABLE_DECLARATION -> statement = new VariableDeclarationStatement();
             default -> statement = new ExpressionStatement();
         }
@@ -123,6 +122,9 @@ public Statement parseBlockStatement(Context context) {
                     statement = new IfStatement(block);
                     statement.init(this, context);
                     eat(TokenType.END_STATEMENT);
+                } case FUNCTION -> {
+                    statement.init(this, context);
+                    eat(TokenType.END_STATEMENT);
                 }
             }
         }

src/main/java/dev/tenfont/cpmm/lang/components/Context.java

@@ -1,5 +1,6 @@
 package dev.tenfont.cpmm.lang.components;
 
+import dev.tenfont.cpmm.lang.FunctionRegistry;
 import dev.tenfont.cpmm.lang.VariableMap;
 import lombok.AccessLevel;
 import lombok.Getter;
@@ -11,21 +12,23 @@
 @RequiredArgsConstructor(access = AccessLevel.PRIVATE)
 @Getter
 public class Context {
-    // TODO include optional script object, variable map and function registry
+    // TODO include optional script object
     private final @Nullable Context parentContext;
     private final VariableMap variableMap;
+    private final FunctionRegistry functionRegistry;
 
     public Context() {
         this(new VariableMap());
     }
 
     public Context(VariableMap variableMap) {
         this.parentContext = null;
+        this.functionRegistry = new FunctionRegistry();
         this.variableMap = variableMap;
     }
 
     public Context enterScope() {
-        return new Context(this, new VariableMap(variableMap));
+        return new Context(this, new VariableMap(variableMap), functionRegistry);
     }
 
     public Context exitScope() {

src/main/java/dev/tenfont/cpmm/lang/components/Function.java

@@ -0,0 +1,5 @@
+package dev.tenfont.cpmm.lang.components;
+
+public interface Function {
+    void execute(Object[] arguments);
+}

src/main/java/dev/tenfont/cpmm/lang/components/ScriptFunction.java

@@ -0,0 +1,16 @@
+package dev.tenfont.cpmm.lang.components;
+
+import dev.tenfont.cpmm.lang.Interpreter;
+import lombok.RequiredArgsConstructor;
+
+import java.util.LinkedList;
+
+@RequiredArgsConstructor
+public class ScriptFunction implements Function {
+    private final LinkedList<Statement> statements;
+
+    @Override
+    public void execute(Object[] arguments) {
+        new Interpreter(statements).execute();
+    }
+}