From ba94812596fcfd81e9eedf28086c818a8df49727 Mon Sep 17 00:00:00 2001
From: Peter Thomas <ptrthomas@gmail.com>
Date: Fri, 17 May 2024 11:04:31 +0530
Subject: [PATCH] support do-while syntax #1

---
 .../java/io/karatelabs/js/Interpreter.java    | 24 ++++++++++++++++++-
 .../main/java/io/karatelabs/js/Parser.java    | 13 ++++++++++
 .../src/main/java/io/karatelabs/js/Type.java  |  1 +
 .../test/java/io/karatelabs/js/EvalTest.java  |  6 +++++
 4 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/karate-js/src/main/java/io/karatelabs/js/Interpreter.java b/karate-js/src/main/java/io/karatelabs/js/Interpreter.java
index bcfd689..d8cc373 100644
--- a/karate-js/src/main/java/io/karatelabs/js/Interpreter.java
+++ b/karate-js/src/main/java/io/karatelabs/js/Interpreter.java
@@ -617,9 +617,10 @@ private static Object evalVarStmt(Node node, Context context) {
     private static Object evalWhileStmt(Node node, Context context) {
         Context whileContext = new Context(context);
         Node whileBody = node.children.get(node.children.size() - 1);
+        Node whileExpr = node.children.get(2);
         Object whileResult = null;
         while (true) {
-            Object whileCondition = eval(node.children.get(2), whileContext);
+            Object whileCondition = eval(whileExpr, whileContext);
             if (!Terms.isTruthy(whileCondition)) {
                 break;
             }
@@ -632,6 +633,25 @@ private static Object evalWhileStmt(Node node, Context context) {
         return whileResult;
     }
 
+    private static Object evalDoWhileStmt(Node node, Context context) {
+        Context doContext = new Context(context);
+        Node doBody = node.children.get(1);
+        Node doExpr = node.children.get(4);
+        Object doResult = null;
+        while (true) {
+            doResult = eval(doBody, doContext);
+            if (doContext.isStopped()) {
+                context.updateFrom(doContext);
+                break;
+            }
+            Object doCondition = eval(doExpr, doContext);
+            if (!Terms.isTruthy(doCondition)) {
+                break;
+            }
+        }
+        return doResult;
+    }
+
     public static Object eval(Node node, Context context) {
         context.currentNode = node;
         switch (node.type) {
@@ -714,6 +734,8 @@ public static Object eval(Node node, Context context) {
                 return evalVarStmt(node, context);
             case WHILE_STMT:
                 return evalWhileStmt(node, context);
+            case DO_WHILE_STMT:
+                return evalDoWhileStmt(node, context);
             default:
                 throw new RuntimeException(node.toStringError("eval - unexpected node"));
         }
diff --git a/karate-js/src/main/java/io/karatelabs/js/Parser.java b/karate-js/src/main/java/io/karatelabs/js/Parser.java
index b9f022a..3b65473 100644
--- a/karate-js/src/main/java/io/karatelabs/js/Parser.java
+++ b/karate-js/src/main/java/io/karatelabs/js/Parser.java
@@ -303,6 +303,7 @@ private boolean statement(boolean mandatory) {
         result = result || try_stmt();
         result = result || for_stmt();
         result = result || while_stmt();
+        result = result || do_while_stmt();
         result = result || switch_stmt();
         result = result || (break_stmt() && eos());
         result = result || (delete_stmt() && eos());
@@ -431,6 +432,18 @@ private boolean while_stmt() {
         return exit();
     }
 
+    private boolean do_while_stmt() {
+        if (!enter(Type.DO_WHILE_STMT, Token.DO)) {
+            return false;
+        }
+        statement(true);
+        consume(Token.WHILE);
+        consume(Token.L_PAREN);
+        expr(-1, true);
+        consume(Token.R_PAREN);
+        return exit();
+    }
+
     private boolean switch_stmt() {
         if (!enter(Type.SWITCH_STMT, Token.SWITCH)) {
             return false;
diff --git a/karate-js/src/main/java/io/karatelabs/js/Type.java b/karate-js/src/main/java/io/karatelabs/js/Type.java
index 5c05ae3..601f4a3 100644
--- a/karate-js/src/main/java/io/karatelabs/js/Type.java
+++ b/karate-js/src/main/java/io/karatelabs/js/Type.java
@@ -37,6 +37,7 @@ public enum Type {
     THROW_STMT,
     FOR_STMT,
     WHILE_STMT,
+    DO_WHILE_STMT,
     SWITCH_STMT,
     CASE_BLOCK,
     DEFAULT_BLOCK,
diff --git a/test-core/src/test/java/io/karatelabs/js/EvalTest.java b/test-core/src/test/java/io/karatelabs/js/EvalTest.java
index a137f63..b375637 100644
--- a/test-core/src/test/java/io/karatelabs/js/EvalTest.java
+++ b/test-core/src/test/java/io/karatelabs/js/EvalTest.java
@@ -544,6 +544,12 @@ void testWhileLoop() {
         assertEquals(5, get("a"));
     }
 
+    @Test
+    void testDoWhileLoop() {
+        eval("a = 0; do { a++ } while (a <= 5)");
+        assertEquals(6, get("a"));
+    }
+
     @Test
     void testTernary() {
         eval("a = true ? 1 : 2");