if-ELSE!!!!

src/main/java/ch/fritteli/gombaila/domain/common/NodeStmt.java

@@ -1,4 +1,4 @@
 package ch.fritteli.gombaila.domain.common;
 
-public sealed interface NodeStmt extends Node permits NodeStmtAssign, NodeStmtExit, NodeStmtIf, NodeStmtLet, NodeStmtPrint, NodeStmtScope {
+public sealed interface NodeStmt extends Node permits NodeStmtAssign, NodeStmtExit, NodeStmtIf, NodeStmtIfElse, NodeStmtLet, NodeStmtPrint, NodeStmtScope {
 }

src/main/java/ch/fritteli/gombaila/domain/common/NodeStmtIf.java

@@ -2,6 +2,5 @@ package ch.fritteli.gombaila.domain.common;
 
 import org.jetbrains.annotations.NotNull;
 
-public record NodeStmtIf(@NotNull NodeExpr expr, @NotNull NodeStmtScope scope) implements NodeStmt {
-
+public record NodeStmtIf(@NotNull NodeExpr expr, @NotNull NodeStmtScope ifScope) implements NodeStmt {
 }

src/main/java/ch/fritteli/gombaila/domain/common/NodeStmtIfElse.java

@@ -0,0 +1,7 @@
+package ch.fritteli.gombaila.domain.common;
+
+import org.jetbrains.annotations.NotNull;
+
+public record NodeStmtIfElse(@NotNull NodeExpr expr, @NotNull NodeStmtScope ifScope,
+                             @NotNull NodeStmtScope elseScope) implements NodeStmt {
+}

src/main/java/ch/fritteli/gombaila/domain/common/TokenType.java

@@ -26,7 +26,8 @@ public enum TokenType {
     IDENTIFIER,
     // the rest
     WHITESPACE,
-    IF;
+    IF,
+    ELSE;
 
     public boolean isBinaryOperator() {
         return switch (this) {

src/main/java/ch/fritteli/gombaila/domain/generator/StmtVisitor.java

@@ -4,6 +4,7 @@ import ch.fritteli.gombaila.domain.common.NodeStmt;
 import ch.fritteli.gombaila.domain.common.NodeStmtAssign;
 import ch.fritteli.gombaila.domain.common.NodeStmtExit;
 import ch.fritteli.gombaila.domain.common.NodeStmtIf;
+import ch.fritteli.gombaila.domain.common.NodeStmtIfElse;
 import ch.fritteli.gombaila.domain.common.NodeStmtLet;
 import ch.fritteli.gombaila.domain.common.NodeStmtPrint;
 import ch.fritteli.gombaila.domain.common.NodeStmtScope;
@@ -27,6 +28,7 @@ final class StmtVisitor {
             case final NodeStmtPrint stmtPrint -> visit(stmtPrint);
             case final NodeStmtScope stmtScope -> visit(stmtScope);
             case final NodeStmtIf stmtIf -> visit(stmtIf);
+            case final NodeStmtIfElse stmtIfElse -> visit(stmtIfElse);
         }
     }
 
@@ -96,9 +98,30 @@ final class StmtVisitor {
                 "skip to %s if condition is not met".formatted(label),
                 "jz", label
         );
-        this.visit(stmt.scope());
+        this.visit(stmt.ifScope());
         this.generator.printer.label(label);
+    }
 
+    private void visit(@NotNull final NodeStmtIfElse stmt) {
+        final String afterIfLabel = this.createNextLabel();
+        final String afterElseLabel = this.createNextLabel();
+        this.generator.generateExpr(stmt.expr());
+        this.generator.pop("rax");
+        this.generator.printer.commentedLine("test the condition",
+                "test", "rax, rax");
+        this.generator.printer.commentedLine(
+                "skip to %s (else) if condition is not met".formatted(afterIfLabel),
+                "jz", afterIfLabel
+        );
+        this.visit(stmt.ifScope());
+        this.generator.printer.commentedLine(
+                "skip to %s to skip the else".formatted(afterElseLabel),
+                "jmp",
+                afterElseLabel
+        );
+        this.generator.printer.label(afterIfLabel);
+        this.visit(stmt.elseScope());
+        this.generator.printer.label(afterElseLabel);
     }
 
     private String createNextLabel() {

src/main/java/ch/fritteli/gombaila/domain/lexer/Lexer.java

@@ -80,6 +80,7 @@ public class Lexer {
             case "let" -> this.appendToken(new Token(TokenType.LET, line, column));
             case "print" -> this.appendToken(new Token(TokenType.PRINT, line, column));
             case "if" -> this.appendToken(new Token(TokenType.IF, line, column));
+            case "else" -> this.appendToken(new Token(TokenType.ELSE, line, column));
             case final String value ->
                     this.appendToken(new Token(TokenType.IDENTIFIER, Option.of(value), line, column));
         }

src/main/java/ch/fritteli/gombaila/domain/parser/Parser.java

@@ -15,6 +15,7 @@ import ch.fritteli.gombaila.domain.common.NodeStmt;
 import ch.fritteli.gombaila.domain.common.NodeStmtAssign;
 import ch.fritteli.gombaila.domain.common.NodeStmtExit;
 import ch.fritteli.gombaila.domain.common.NodeStmtIf;
+import ch.fritteli.gombaila.domain.common.NodeStmtIfElse;
 import ch.fritteli.gombaila.domain.common.NodeStmtLet;
 import ch.fritteli.gombaila.domain.common.NodeStmtPrint;
 import ch.fritteli.gombaila.domain.common.NodeStmtScope;
@@ -65,9 +66,14 @@ public class Parser {
             this.assertAndConsumeNextTokenType(TokenType.OPEN_PAREN);
             final NodeExpr expr = this.parseExpr(1);
             this.assertAndConsumeNextTokenType(TokenType.CLOSE_PAREN);
-            final NodeStmtScope scope = this.parseScope();
+            final NodeStmtScope ifScope = this.parseScope();
+            // there /could/ be an else, so let's check that
+            if (this.checkNextTokenTypeConsuming(TokenType.ELSE)) {
+                final NodeStmtScope elseScope = this.parseScope();
+                return new NodeStmtIfElse(expr, ifScope, elseScope);
+            }
             // NB: We do NOT expect a SEMI here, so we return directly.
-            return new NodeStmtIf(expr, scope);
+            return new NodeStmtIf(expr, ifScope);
         } else if (this.checkNextTokenType(TokenType.IDENTIFIER)) {
             result = this.parseStmtAssign();
         } else {

src/main/resources/gombaila/simple.gb

@@ -1,5 +1,7 @@
-let x = (10 - 2 * 3) / 2;
-if (x-2) {
-    exit (69);
+let x = 1;
+if (x) {
+    x = 99;
+} else {
+    x = 12;
 }
-exit(1);
+exit(x);