/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    *
    *      https://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.commons.jexl3;
  
  import static org.apache.commons.jexl3.introspection.JexlPermissions.RESTRICTED;
  import static org.apache.commons.jexl3.introspection.JexlPermissions.UNRESTRICTED;
  import static org.junit.jupiter.api.Assertions.assertArrayEquals;
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertFalse;
  import static org.junit.jupiter.api.Assertions.assertInstanceOf;
  import static org.junit.jupiter.api.Assertions.assertNotNull;
  import static org.junit.jupiter.api.Assertions.assertNull;
  import static org.junit.jupiter.api.Assertions.assertThrows;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  import static org.junit.jupiter.api.Assertions.fail;
  
  import java.io.Closeable;
  import java.io.File;
  import java.io.StringWriter;
  import java.lang.reflect.Method;
  import java.math.BigDecimal;
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import java.util.Objects;
  import java.util.concurrent.atomic.AtomicLong;
  
  import org.apache.commons.jexl3.internal.Debugger;
  import org.apache.commons.jexl3.internal.Engine32;
  import org.apache.commons.jexl3.internal.Scope;
  import org.apache.commons.jexl3.internal.TemplateEngine;
  import org.apache.commons.jexl3.introspection.JexlPermissions;
  import org.apache.commons.jexl3.introspection.JexlSandbox;
  import org.apache.commons.jexl3.parser.ASTJexlScript;
  import org.apache.commons.jexl3.parser.JexlScriptParser;
  import org.apache.commons.jexl3.parser.Parser;
  import org.apache.commons.jexl3.parser.StringProvider;
  import org.junit.jupiter.api.Assertions;
  import org.junit.jupiter.api.Test;
  
  /**
   * Test cases for reported issue between JEXL-300 and JEXL-399.
   */
  public class Issues400Test {
  
      public static class VinzCaller {
          private final JexlContext context;
  
          VinzCaller(final JexlContext context) {
              this.context = context;
          }
  
          public Object execute(final JexlScript script) {
              return script.execute(context);
          }
      }
  
      public static class VinzContext extends MapContext {
          public String member(final String m, final String u) {
              return m + '.' + u;
          }
      }
  
      /**
       * Any function in a context can be used as a method of its first parameter. Overloads are respected.
       */
      public static class XuContext extends MapContext {
  
          public String join(final int[] list, final String str) {
              return join(Arrays.stream(list).iterator(), str);
          }
  
          public String join(final Iterable<?> list, final String str) {
              return join(list.iterator(), str);
          }
  
          public String join(final Iterator<?> iterator, final String str) {
              if (!iterator.hasNext()) {
                  return "";
              }
              final StringBuilder strb = new StringBuilder(256);
              strb.append(iterator.next().toString());
             while (iterator.hasNext()) {
                 strb.append(str);
                 strb.append(Objects.toString(iterator.next(), "?"));
             }
             return strb.toString();
         }
     }
 
     private static void run404(final JexlEngine jexl, final String src, final Object... a) {
         final JexlScript script = jexl.createScript(src, "a", "b");
         if (!src.endsWith(";")) {
             assertEquals(script.getSourceText(), script.getParsedText());
         }
         final Object result = script.execute(null, a);
         assertEquals(42, result);
     }
 
     @Test
     void test402() {
         final JexlContext jc = new MapContext();
         // @formatter:off
       final String[] sources = {
         "if (true) { return }",
         "if (true) { 3; return }",
         "(x->{ 3; return })()"
       };
       // @formatter:on
         final JexlEngine jexl = new JexlBuilder().create();
         for (final String source : sources) {
             final JexlScript e = jexl.createScript(source);
             final Object o = e.execute(jc);
             assertNull(o);
         }
     }
 
     @Test
     void test403() {
         // @formatter:off
         final String[] strings = {
             "  map1.`${item.a}` = 1;\n",
             "  map1[`${item.a}`] = 1;\n",
             "  map1[item.a] = 1;\n"
          };
         // @formatter:on
         for (final String setmap : strings) {
             // @formatter:off
             final String src = "var a = {'a': 1};\n" +
                 "var list = [a, a];\n" +
                 "let map1 = {:};\n" +
                 "for (let item : list) {\n" +
                 setmap +
                 "}\n " +
                 "map1";
             // @formatter:on
             final JexlEngine jexl = new JexlBuilder().cache(64).create();
             final JexlScript script = jexl.createScript(src);
             for (int i = 0; i < 2; ++i) {
                 final Object result = script.execute(null);
                 assertInstanceOf(Map.class, result);
                 final Map<?, ?> map = (Map<?, ?>) result;
                 assertEquals(1, map.size());
                 final Object val = jexl.createScript("m -> m[1]").execute(null, map);
                 assertEquals(1, val);
             }
         }
     }
 
     @Test
     void test404a() {
         final JexlEngine jexl = new JexlBuilder().cache(64).strict(true).safe(false).create();
         Map<String, Object> a = Collections.singletonMap("b", 42);
         // access is constant
         for (final String src : new String[]{"a.b", "a?.b", "a['b']", "a?['b']", "a?.`b`"}) {
             run404(jexl, src, a);
             run404(jexl, src + ";", a);
         }
         // access is variable
         for (final String src : new String[]{"a[b]", "a?[b]", "a?.`${b}`"}) {
             run404(jexl, src, a, "b");
             run404(jexl, src + ";", a, "b");
         }
         // add a 3rd access
         final Map<String, Object> b = Collections.singletonMap("c", 42);
         a = Collections.singletonMap("b", b);
         for (final String src : new String[]{"a[b].c", "a?[b]?['c']", "a?.`${b}`.c"}) {
             run404(jexl, src, a, "b");
         }
     }
 
     @Test
     void test404b() {
         // @formatter:off
       final JexlEngine jexl = new JexlBuilder()
           .cache(64)
           .strict(true)
           .safe(false)
           .create();
       // @formatter:on
         final Map<String, Object> b = Collections.singletonMap("c", 42);
         final Map<String, Object> a = Collections.singletonMap("b", b);
         JexlScript script;
         Object result;
         script = jexl.createScript("a?['B']?['C']", "a");
         result = script.execute(null, a);
         assertEquals(script.getSourceText(), script.getParsedText());
         assertNull(result);
         script = jexl.createScript("a?['b']?['C']", "a");
         assertEquals(script.getSourceText(), script.getParsedText());
         result = script.execute(null, a);
         assertNull(result);
         script = jexl.createScript("a?['b']?['c']", "a");
         assertEquals(script.getSourceText(), script.getParsedText());
         result = script.execute(null, a);
         assertEquals(42, result);
         script = jexl.createScript("a?['B']?['C']?: 1042", "a");
         assertEquals(script.getSourceText(), script.getParsedText());
         result = script.execute(null, a);
         assertEquals(1042, result);
         // can still do ternary, note the space between ? and [
         script = jexl.createScript("a? ['B']:['C']", "a");
         result = script.execute(null, a);
         assertArrayEquals(new String[]{"B"}, (String[]) result);
         script = jexl.createScript("a?['b'] ?: ['C']", "a");
         result = script.execute(null, a);
         assertEquals(b, result);
         script = jexl.createScript("a?['B'] ?: ['C']", "a");
         result = script.execute(null, a);
         assertArrayEquals(new String[]{"C"}, (String[]) result);
     }
 
     @Test
     void test406a() {
         // @formatter:off
         final JexlEngine jexl = new JexlBuilder()
             .cache(64)
             .strict(true)
             .safe(false)
             .create();
         // @formatter:on
 
         final JexlContext context = new XuContext();
         // @formatter:off
         final List<String> list = Arrays.asList(
             "[1, 2, 3, 4, ...].join('-')", // List<Integer>
             "[1, 2, 3, 4,].join('-')", // int[]
             "(1 .. 4).join('-')", // iterable<Integer>
             "join([1, 2, 3, 4, ...], '-')",
             "join([1, 2, 3, 4], '-')",
             "join((1 .. 4), '-')");
         // @formatter:on
         for (final String src : list) {
             final JexlScript script = jexl.createScript(src);
             final Object result = script.execute(context);
             assertEquals("1-2-3-4", result, src);
         }
 
         final String src0 = "x.join('*')";
         final JexlScript script0 = jexl.createScript(src0, "x");
         final String src1 = "join(x, '*')";
         final JexlScript script1 = jexl.createScript(src1, "x");
         for (final Object x : Arrays.asList(Arrays.asList(1, 2, 3, 4), new int[]{1, 2, 3, 4})) {
             Object result = script0.execute(context, x);
             assertEquals("1*2*3*4", result, src0);
             result = script1.execute(context, x);
             assertEquals("1*2*3*4", result, src1);
         }
     }
 
     @Test
     void test407() {
         // Java version
         final double r = 99.0d + 7.82d - 99.0d - 7.82d;
         assertEquals(0d, r, 8.e-15); // Not zero, IEEE 754
         // jexl
         final JexlEngine jexl = new JexlBuilder().create();
         final JexlScript script = jexl.createScript("a + b - a - b", "a", "b");
         // using doubles, same as Java
         Number result = (Number) script.execute(null, 99.0d, 7.82d);
         assertEquals(0d, result.doubleValue(), 8.e-15);
         // using BigdDecimal, more precise, still not zero
         result = (Number) script.execute(null, new BigDecimal("99.0"), new BigDecimal("7.82"));
         assertEquals(0d, result.doubleValue(), 3.e-32);
     }
 
     @Test
     void test412() {
         final Map<Object, Object> ctl = new HashMap<>();
         ctl.put("one", 1);
         ctl.put("two", 2);
         final String fnsrc0 = "function f(x) { x }\n" + "let one = 'one', two = 'two';\n";
         // @formatter:off
         final List<String> list = Arrays.asList(
             "{ one : f(1), two:f(2) }",
             "{ one: f(1), two: f(2) }",
             "{ one: f(1), two:f(2) }",
             "{ one :f(1), two:f(2) }");
         // @formatter:on
         for (final String map0 : list) {
             final String fnsrc = fnsrc0 + map0;
             final JexlContext jc = new MapContext();
             final JexlEngine jexl = new JexlBuilder().create();
             final JexlScript e = jexl.createScript(fnsrc);
             final Object o = e.execute(jc);
             assertInstanceOf(Map.class, o);
             final Map<?, ?> map = (Map<?, ?>) o;
             assertEquals(map, ctl);
         }
     }
 
     @Test
     void test413a() {
         final JexlBuilder builder = new JexlBuilder();
         final JexlEngine jexl = builder.create();
         final JexlScript script = jexl.createScript("var c = 42; var f = y -> c += y; f(z)", "z");
         final Number result = (Number) script.execute(null, 12);
         assertEquals(54, result);
     }
 
     @Test
     void test413b() {
         final JexlBuilder builder = new JexlBuilder();
         final JexlOptions options = builder.options();
         options.setConstCapture(true);
         options.setLexical(true);
         final JexlEngine jexl = builder.create();
         final JexlScript script = jexl.createScript("var c = 42; var f = y -> c += y; f(z)", "z");
         final JexlException.Variable xvar = assertThrows(JexlException.Variable.class,
             () -> script.execute(null, 12), "c should be const");
         assertEquals("c", xvar.getVariable());
     }
 
     @Test
     void test413c() {
         final JexlBuilder builder = new JexlBuilder();
         final JexlEngine jexl = builder.create();
         final String pragma = "#pragma jexl.options '+constCapture'\n"
             + "var c = 42; var f = y -> c += y; f(z)";
         final JexlScript script = jexl.createScript(pragma, "z");
         final JexlException.Variable xvar = assertThrows(
             JexlException.Variable.class, () -> script.execute(null, 12), "c should be const");
         assertEquals("c", xvar.getVariable());
     }
 
     @Test
     void test413d() {
         final JexlBuilder builder = new JexlBuilder().features(new JexlFeatures().constCapture(true));
         final JexlEngine jexl = builder.create();
         final JexlException.Parsing xparse = assertThrows(JexlException.Parsing.class,
             () -> jexl.createScript("var c = 42; var f = y -> c += y; f(z)", "z"),
             "c should be const");
         assertTrue(xparse.getMessage().contains("const"));
     }
 
     @Test
     void test415() {
         final JexlBuilder builder = new JexlBuilder().features(new JexlFeatures().constCapture(true));
         final JexlEngine jexl = builder.create();
         JexlScript script;
         Object result;
         script = jexl.createScript("`#${c}`", "c");
         result = script.execute(null, 42);
         assertEquals("#42", result.toString());
         script = jexl.createScript("`$${c}`", "c");
         result = script.execute(null, 42);
         assertEquals("$42", result.toString());
         script = jexl.createScript("`$#{c}`", "c");
         result = script.execute(null, 42);
         assertEquals("$42", result.toString());
         script = jexl.createScript("`##{c}`", "c");
         result = script.execute(null, 42);
         assertEquals("#42", result.toString());
         script = jexl.createScript("`--##{c}`", "c");
         result = script.execute(null, 42);
         assertEquals("--#42", result.toString());
     }
 
     @Test
     void test419() throws NoSuchMethodException {
         // check RESTRICTED permissions denies call to System::currentTimeMillis()
         final Method currentTimeMillis = System.class.getMethod("currentTimeMillis");
         assertFalse(RESTRICTED.allow(currentTimeMillis));
         // compose using a positive class permission to allow just System::currentTimeMillis()
         final JexlPermissions permissions = RESTRICTED.compose("java.lang { +System { currentTimeMillis(); } }");
         // check no side effect on compose
         assertTrue(permissions.allow(currentTimeMillis));
         assertFalse(RESTRICTED.allow(currentTimeMillis));
 
         // An engine with the System class as namespace and the positive permissions
         final JexlEngine jexl = new JexlBuilder()
             .namespaces(Collections.singletonMap("sns", System.class))
             .permissions(permissions)
             .create();
 
         final AtomicLong result = new AtomicLong();
         assertEquals(0, result.get());
         final long now = System.currentTimeMillis();
         // calling System::currentTimeMillis() is allowed and behaves as expected
         jexl.createScript("result.set(sns:currentTimeMillis())", "result").execute(null, result);
         assertTrue(result.get() >= now);
 
         // we still cant call anything else
         final JexlScript script = jexl.createScript("sns:gc()");
         final JexlException.Method method = assertThrows(JexlException.Method.class, () -> script.execute(null));
         assertEquals("gc", method.getMethod());
 
     }
 
     @Test
     void testDocBreakContinue() {
         final JexlBuilder builder = new JexlBuilder().features(new JexlFeatures().constCapture(true));
         final JexlEngine jexl = builder.create();
         JexlScript script;
         Object result;
         // @formatter:off
         final String srcContinue = "let text = '';\n" +
             "for (let i : (4..2)) { if (i == 3) continue; text += i; }\n" +
             "text;";
         // @formatter:on
         script = jexl.createScript(srcContinue);
         result = script.execute(null);
         assertEquals("42", result);
         // @formatter:off
         final String srcBreak = "let i = 33;\n" +
             "while (i < 66) { if (i == 42) { break; } i += 1; }\n" +
             "i;";
         // @formatter:on
         script = jexl.createScript(srcBreak);
         result = script.execute(null);
         assertEquals(42, result);
     }
 
     @Test
     void testNamespaceVsTernary0() {
         final VinzContext ctxt = new VinzContext();
         ctxt.set("Users", "USERS");
         final JexlEngine jexl = new JexlBuilder().safe(false).strict(true).silent(false).create();
         // @formatter:off
         JexlScript script = jexl.createScript("() -> {\n"
             + "  var fn = (user) -> {\n"
             + "     user ? user : member(Users, 'user');\n"
             + "  }\n"
             + "}");
         // @formatter:on
         Object r = script.execute(ctxt);
         assertNotNull(r);
         script = (JexlScript) r;
         r = script.execute(ctxt);
         assertEquals("USERS.user", r);
     }
 
     @Test
     void testNamespaceVsTernary1() {
         final VinzContext ctxt = new VinzContext();
         ctxt.set("Users", "USERS");
         ctxt.set("vinz", new VinzCaller(ctxt));
         final JexlEngine jexl = new JexlBuilder().safe(false).strict(true).silent(false).create();
         // @formatter:off
         final JexlScript script = jexl.createScript(
             "vinz.execute(() -> {\n"
             + "  var test = 42;\n"
             + "  var user = useTest ? test : member(Users, 'user');\n"
             + "})\n" , "useTest");
         // @formatter:on
         Object r = script.execute(ctxt, false);
         assertNotNull(r);
         assertEquals("USERS.user", r);
         r = script.execute(ctxt, true);
         assertNotNull(r);
         assertEquals(42, r);
     }
 
     public static class Ns429 {
         public int f(final int x) {
             return x * 10000 + 42;
         }
     }
 
     @Test
     void test429a() {
         final MapContext ctxt = new MapContext();
         final JexlFeatures features = JexlFeatures.createDefault();
         final JexlEngine jexl = new JexlBuilder().features(features).safe(false).strict(true).silent(false).create();
         final JexlScript f = jexl.createScript("x -> x");
         ctxt.set("f", f);
         String src = "#pragma jexl.namespace.b " + Ns429.class.getName() + "\n" + "b ? b : f(2);";
         JexlScript script = jexl.createScript(src, "b");
         assertEquals(1, (int) script.execute(ctxt, 1));
 
         src = "#pragma jexl.namespace.b " + Ns429.class.getName() + "\n" + "b ? b:f(2) : 1;";
         script = jexl.createScript(src, "b");
         assertEquals(20042, (int) script.execute(ctxt, 1));
     }
 
     @Test
     void test429b() {
         final MapContext ctxt = new MapContext();
         ctxt.set("b", 1);
         final JexlFeatures features = JexlFeatures.createDefault();
         features.namespaceIdentifier(true);
         final JexlEngine jexl = new JexlBuilder().features(features).safe(false).strict(true).silent(false).create();
         final JexlScript f = jexl.createScript("x -> x");
         ctxt.set("f", f);
         String src = "#pragma jexl.namespace.b " + Ns429.class.getName() + "\n" + "b ? b : f(2);";
         JexlScript script = jexl.createScript(src);
         assertEquals(1, (int) script.execute(ctxt));
 
         src = "#pragma jexl.namespace.b " + Ns429.class.getName() + "\n" + "b ? b:f(2) : 1;";
         script = jexl.createScript(src);
         assertEquals(20042, (int) script.execute(ctxt));
     }
 
     @Test
     void test431a() {
         final JexlEngine jexl = new JexlBuilder().create();
         final String src = "let x = 0; try { x += 19 } catch (let error) { return 169 } "
             + "try { x += 23 } catch (let error) { return 169 }";
         final JexlScript script = jexl.createScript(src);
         assertNotNull(script);
         final Object result = script.execute(null);
         assertEquals(42, result);
     }
 
     Closeable foo() {
         return null;
     }
 
     @Test
     void test431b() {
         final JexlEngine jexl = new JexlBuilder().create();
         final String src = "let x = 0; try(let error) { x += 19 } catch (let error) { return 169 } "
             + "try { x += 23 } catch (let error) { return 169 }";
         final JexlScript script = jexl.createScript(src);
         assertNotNull(script);
         final Object result = script.execute(null);
         assertEquals(42, result);
     }
 
     @Test
     void test431c() {
         final JexlEngine jexl = new JexlBuilder().create();
         final String src = "let xx = 0; try { xx += 19 } catch (let xx) { return 169 }";
         try {
             final JexlScript script = jexl.createScript(src);
             fail("xx is already defined in scope");
         } catch (final JexlException.Parsing parsing) {
             assertTrue(parsing.getDetail().contains("xx"));
         }
     }
 
     @Test
     void test433() {
         final JexlEngine jexl = new JexlBuilder().create();
         final String src = "let condition = true; if (condition) { return; }";
         final JexlScript script = jexl.createScript(src);
         assertNotNull(script);
         final Object result = script.execute(null);
         assertNull(result);
         final Debugger debugger = new Debugger();
         assertTrue(debugger.debug(script));
         final String dbgStr = debugger.toString();
         assertTrue(JexlTestCase.equalsIgnoreWhiteSpace(src, dbgStr));
     }
 
     @Test
     void test434() {
         final JexlEngine jexl = new JexlBuilder().safe(false).strict(true).create();
         final String src = "let foo = null; let value = foo?[bar]";
         final JexlScript script = jexl.createScript(src);
         assertNotNull(script);
         final Object result = script.execute(null);
         assertNull(result);
     }
 
     public static class Arithmetic435 extends JexlArithmetic {
         public Arithmetic435(final boolean strict) {
             super(strict);
         }
 
         public Object empty(final String type) {
             if ("list".equals(type)) {
                 return Collections.emptyList();
             }
             return null;
         }
     }
 
     @Test
     void test435() {
         final JexlArithmetic arithmetic = new Arithmetic435(true);
         final JexlEngine jexl = new JexlBuilder().arithmetic(arithmetic).create();
         final String src = "empty('list')";
         final JexlScript script = jexl.createScript(src);
         assertNotNull(script);
         final Object result = script.execute(null);
         assertInstanceOf(List.class, result);
     }
 
     @Test
     void test436a() {
         final String[] srcs = {"let i = null; ++i", "let i; ++i;", "let i; i--;", "let i; i++;"};
         run436(null, srcs);
     }
 
     @Test
     void test436b() {
         final String[] srcs = {"var i = null; ++i", "var i; ++i;", "var i; i--;", "var i; i++;"};
         run436(null, srcs);
     }
 
     @Test
     void test436c() {
         final JexlContext ctxt = new MapContext();
         ctxt.set("i", null);
         final String[] srcs = {"++i", "++i;", "i--;", "i++;"};
         run436(null, srcs);
     }
 
     void run436(final JexlContext ctxt, final String[] srcs) {
         final JexlEngine jexl = new JexlBuilder().create();
         for (final String src : srcs) {
             final JexlScript script = jexl.createScript(src);
             assertThrows(JexlException.Operator.class, () -> script.execute(ctxt));
         }
     }
 
     @Test
     void test437a() {
         final JexlEngine jexl = new JexlBuilder().create();
         final String src = "let values = [...]\n"
             + "function append(const value) {\n"
             + "  values.add(value)\n"
             + "}\n"
             + "\n"
             + "append(1)\n"
             + "append(2)\n"
             + "return values ";
         final JexlScript script = jexl.createScript(src);
         assertNotNull(script);
         final Object result = script.execute(null);
         assertInstanceOf(List.class, result);
         final List<?> values = (List<?>) result;
         assertEquals(2, values.size());
     }
 
     @Test
     void test437b() {
         final JexlFeatures features = JexlFeatures.createDefault().ambiguousStatement(true);
         assertTrue(features.supportsAmbiguousStatement());
         final JexlEngine jexl = new JexlBuilder().features(features).create();
         final String src = "let values = [...]"
             + "function append(const value) {"
             + "  values.add(value)"
             + "}"
             + "append(1)"
             + "append(2)"
             + "return values ";
         final JexlScript script = jexl.createScript(src);
         assertNotNull(script);
         final Object result = script.execute(null);
         assertInstanceOf(List.class, result);
         final List<?> values = (List<?>) result;
         assertEquals(2, values.size());
     }
 
     /**
      * The set of characters that may be followed by a '='.
      */
     static final char[] EQ_FRIEND;
 
     static {
         final char[] eq = {'!', ':', '<', '>', '^', '|', '&', '+', '-', '/', '*', '~', '='};
         Arrays.sort(eq);
         EQ_FRIEND = eq;
     }
 
     /**
      * Transcodes a SQL-inspired expression to a JEXL expression.
      *
      * @param expr the expression to transcode
      * @return the resulting expression
      */
     private static String transcodeSQLExpr(final CharSequence expr) {
         final StringBuilder strb = new StringBuilder(expr.length());
         final int end = expr.length();
         char previous = 0;
         for (int i = 0; i < end; ++i) {
             final char c = expr.charAt(i);
             if (previous == '<') {
                 // previous char a '<' now followed by '>'
                 if (c == '>') {
                     // replace '<>' with '!='
                     strb.append("!=");
                     previous = c;
                     continue;
                 }
                 strb.append('<');
             }
             if (c != '<') {
                 if (c == '=') {
                     // replace '=' with '==' when it does not follow a 'friend'
                     if (Arrays.binarySearch(EQ_FRIEND, previous) >= 0) {
                         strb.append(c);
                     } else {
                         strb.append("==");
                     }
                 } else {
                     strb.append(c);
                     if (c == '"' || c == '\'') {
                         // read string, escape '\'
                         boolean escape = false;
                         for (i += 1; i < end; ++i) {
                             final char ec = expr.charAt(i);
                             strb.append(ec);
                             if (ec == '\\') {
                                 escape = !escape;
                             } else if (escape) {
                                 escape = false;
                             } else if (ec == c) {
                                 break;
                             }
                         }
                     }
                 }
             }
             previous = c;
         }
         return strb.toString();
     }
 
     public static class SQLParser implements JexlScriptParser {
         final Parser parser;
 
         public SQLParser() {
             parser = new Parser(new StringProvider(";"));
         }
 
         @Override
         public ASTJexlScript parse(final JexlInfo info, final JexlFeatures features, final String src, final Scope scope) {
             return parser.parse(info, features, transcodeSQLExpr(src), scope);
         }
 
         @Override
         public ASTJexlScript jxltParse(final JexlInfo info, final JexlFeatures features, final String src, final Scope scope) {
             return new Parser(parser).parse(info, features, transcodeSQLExpr(src), scope);
         }
     }
 
 
     @Test
     void testSQLTranspose() {
         final String[] e = {"a<>b", "a = 2", "a.b.c <> '1<>0'"};
         final String[] j = {"a!=b", "a == 2", "a.b.c != '1<>0'"};
         for (int i = 0; i < e.length; ++i) {
             final String je = transcodeSQLExpr(e[i]);
             Assertions.assertEquals(j[i], je);
         }
     }
 
     @Test
     void testSQLNoChange() {
         final String[] e = {"a <= 2", "a >= 2", "a := 2", "a + 3 << 4 > 5",};
         for (final String element : e) {
             final String je = transcodeSQLExpr(element);
             Assertions.assertEquals(element, je);
         }
     }
 
     @Test
     void test438() {// no local, no lambda, no loops, no-side effects
         final JexlFeatures f = new JexlFeatures()
             .localVar(false)
             .lambda(false)
             .loops(false)
             .sideEffect(false)
             .sideEffectGlobal(false);
         final JexlBuilder builder = new JexlBuilder().parserFactory(SQLParser::new).cache(32).features(f);
         final JexlEngine sqle = builder.create();
         Assertions.assertTrue((boolean) sqle.createScript("a <> 25", "a").execute(null, 24));
         Assertions.assertFalse((boolean) sqle.createScript("a <> 25", "a").execute(null, 25));
         Assertions.assertFalse((boolean) sqle.createScript("a = 25", "a").execute(null, 24));
         Assertions.assertTrue((boolean) sqle.createScript("a != 25", "a").execute(null, 24));
         Assertions.assertTrue((boolean) sqle.createScript("a = 25", "a").execute(null, 25));
         Assertions.assertFalse((boolean) sqle.createScript("a != 25", "a").execute(null, 25));
     }
 
     @Test
     void testIssue441() {
         final JexlEngine jexl = new JexlBuilder().create();
         String ctl = "\nab\nc`d\n";
         final JexlExpression e = jexl.createExpression("`\nab\nc\\`d\n`");
         Object o = e.evaluate(null);
         Assertions.assertEquals(ctl, o);
 
         final JexlContext context = new MapContext();
         context.set("name", "Hello");
         final String code = "return `${name + '\\n' + name}`;";
         final JexlScript script = jexl.createScript(code);
         o = script.execute(context);
         ctl = "Hello\nHello";
         Assertions.assertEquals(ctl, o);
     }
 
     @Test
     void testIssue442() {
         final JexlEngine jexl = new JexlBuilder().create();
         final JexlContext context = new MapContext();
         final String code = "var x = 'hello';\n" + "function test(z) {\n" +
             //"x + ' ' + z\n"+
             "`${x} ${z}`;\n" + "}\n" + "test('world');";
         final JexlScript script = jexl.createScript(code);
         final Object result = script.execute(context);
         Assertions.assertEquals("hello world", result);
     }
 
 
     @Test
     void testIssue447() {
         final JexlEngine jexl = new JexlBuilder().create();
         final String src = "const c = `${a}\n?= ${b}`; "
             + "function foo(const left, const right) { `${left}\n?== ${right}` } "
             + "c+foo(a, b)";
         final JexlScript script = jexl.createScript(src, "a", "b");
         final Object result = script.execute(null, "a", "b");
         Assertions.assertEquals("a\n?= ba\n?== b", result);
         String[] locals = script.getLocalVariables();
         Assertions.assertArrayEquals(new String[]{"c", "foo"}, locals);
         final String TEST447 = "src/test/scripts/test447.jexl";
         final File src447 = new File(TEST447);
         final JexlScript script447 = jexl.createScript(src447);
         final Object result447 = script447.execute(null);
         Assertions.assertInstanceOf(List.class, result447);
         @SuppressWarnings("unchecked") final List<Boolean> list = (List<Boolean>) result447;
         for (final Boolean item : list) {
             Assertions.assertTrue(item);
         }
     }
 
     public static class BrkContext extends MapContext {
         public BrkContext() {
             super();
             set("SYSTEM", System.class);
             set("UNRESTRICTED", UNRESTRICTED);
         }
 
         public static Object brk(Object debug) {
             return debug;
         }
 
     }
 
     @Test
     void test450a() {
         JexlEngine jexl0 = new JexlBuilder().silent(false).permissions(JexlPermissions.RESTRICTED).create();
         assertThrows(JexlException.Method.class,
             () -> jexl0.newInstance("org.apache.commons.jexl3.internal.introspection.Uberspect", null, null),
             "should not be able to create Uberspect with RESTRICTED");
         JexlPermissions perm = new JexlPermissions.ClassPermissions(
             org.apache.commons.jexl3.internal.introspection.Uberspect.class);
         JexlEngine jexl1 = new JexlBuilder().silent(false).permissions(perm).create();
         assertNotNull(jexl1.newInstance(
             "org.apache.commons.jexl3.internal.introspection.Uberspect", null, null),
             "should able to create Uberspect with Uberspect permission");
 
     }
 
     @Test
     void test450b() {
         // cannot load System with RESTRICTED
         assertThrows(JexlException.Method.class, () -> run450b(JexlPermissions.RESTRICTED),
             "should not be able to load System with RESTRICTED");
         // can load System with UNRESTRICTED
         assertEquals(java.lang.System.class, run450b(UNRESTRICTED));
         // need to explicitly allow Uberspect and the current class loader to load System
         JexlPermissions perm = new JexlPermissions.ClassPermissions(
             getClass().getClassLoader().getClass(),
             org.apache.commons.jexl3.internal.introspection.Uberspect.class);
         assertEquals(java.lang.System.class, run450b(perm));
     }
 
     private static Object run450b(JexlPermissions perm) {
         JexlEngine jexl = new JexlBuilder().silent(false).permissions(perm).create();
         String uscript = "new('org.apache.commons.jexl3.internal.introspection.Uberspect', "
             + "null, null, perm).getClassLoader().loadClass('java.lang.System')";
         JexlScript u0 = jexl.createScript(uscript, "perm");
         return u0.execute(null, perm);
     }
 
     @Test
     void test450c() {
         // can reach and invoke System::currentTimeMillis with UNRESTRICTED
         assertNotNull(run450c(UNRESTRICTED));
         // need explicit permissions to ClassPermissions and Uberspect to reach and invoke
         // System::currentTimeMillis
         JexlPermissions perm = new JexlPermissions.ClassPermissions(
             JexlPermissions.ClassPermissions.class,
             org.apache.commons.jexl3.internal.introspection.Uberspect.class);
         assertNotNull(run450c(perm));
         // cannot reach and invoke System::currentTimeMillis with RESTRICTED
         assertThrows(JxltEngine.Exception.class, () -> run450c(JexlPermissions.RESTRICTED),
             "should not be able to load System with RESTRICTED");
     }
 
     private static Object run450c(JexlPermissions perm) {
         JexlBuilder builder = new JexlBuilder().silent(false).permissions(perm);
         Object result = new TemplateEngine(new Engine32(builder), false, 2, '$', '#')
             .createExpression(
                 "${x = new ('org.apache.commons.jexl3.internal.introspection.Uberspect', "
                 + "null, null, UNRESTRICTED);"
                 + "sys = x?.getClassLoader()?.loadClass('java.lang.System') ?: SYSTEM;"
                 + "p = new('org.apache.commons.jexl3.introspection.JexlPermissions$ClassPermissions', [sys]);"
                 + "c = new('org.apache.commons.jexl3.internal.introspection.Uberspect', null, null, p);"
                 + "z = c.getMethod(sys,'currentTimeMillis').invoke(x,null);}")
             .evaluate(new BrkContext());
         return result;
     }
 
     @Test
     void test450() {
         assertNotNull(run450(JexlPermissions.UNRESTRICTED),
             "should be able to reach and invoke System::currentTimeMillis with UNRESTRICTED");
         assertNotNull(
             run450(new JexlPermissions.ClassPermissions(
                 org.apache.commons.jexl3.internal.TemplateEngine.class)),
             "should be able to reach and invoke System::currentTimeMillis with TemplateEngine permission");
         assertThrows(JexlException.Method.class, () -> run450(RESTRICTED),
             "should not be able to reach and invoke System::currentTimeMillis with RESTRICTED");
     }
 
     public static class Engine33 extends Engine32 {
         public Engine33() {
             this(createBuilder());
         }
 
         public Engine33(JexlBuilder builder) {
             super(builder);
         }
 
         static JexlBuilder createBuilder() {
             JexlPermissions perm = new JexlPermissions.ClassPermissions(
                 Issues400Test.class.getClassLoader().getClass(),
                 JexlPermissions.ClassPermissions.class,
                 org.apache.commons.jexl3.internal.TemplateEngine.class,
                 org.apache.commons.jexl3.internal.introspection.Uberspect.class);
             return new JexlBuilder().safe(false).silent(false).permissions(perm);
         }
     }
 
     private static Object run450(JexlPermissions perm) {
         JexlEngine jexl = new JexlBuilder().silent(false).strict(true).safe(false)
             .permissions(perm).create();
         String script = "new('org.apache.commons.jexl3.internal.TemplateEngine',"
             + "new('org.apache.commons.jexl3.Issues400Test$Engine33'),false,256,"
             + "'$'.charAt(0),'#'.charAt(0))"
             + ".createExpression("
             + "\"#{x = new ('org.apache.commons.jexl3.internal.introspection.Uberspect', null, null);"
             + "sys = x?.getClassLoader().loadClass('java.lang.System') ?: SYSTEM;"
             + "p = new('org.apache.commons.jexl3.introspection.JexlPermissions$ClassPermissions', [sys]);"
             + "c = new('org.apache.commons.jexl3.internal.introspection.Uberspect', null, null, p);"
             + "z = c.getMethod(sys,'currentTimeMillis').invoke(x,null);}\")"
             + ".evaluate(new('org.apache.commons.jexl3.Issues400Test$BrkContext'))";
         return jexl.createScript(script).execute(null);
     }
 
     @Test
     void test451() {
         JexlEngine jexl = new JexlBuilder().create();
         assertEquals("42", jexl.createScript("o.toString()", "o").execute(null, "42"));
         JexlPermissions perms = RESTRICTED.compose("java.lang { +Class { getSimpleName(); } }");
         JexlSandbox sandbox = new JexlSandbox(false, true);
         sandbox.permissions(Object.class.getName(), true, true, false, false);
         sandbox.allow(String.class.getName()).execute("toString");
         final JexlEngine jexl451 = new JexlBuilder().safe(false).silent(false).permissions(perms).sandbox(sandbox).create();
         // sandbox allows String::toString
         assertEquals("42", jexl451.createScript("o.toString()", "o").execute(null, "42"));
         // sandbox forbids getClass
         assertThrows(JexlException.Method.class, () -> jexl451.createScript("oo.getClass()", "oo").execute(null, "42"));
         // sandbox allows reading properties, permissions allow getClass
         assertEquals(String.class, jexl451.createScript("o.class", "o").execute(null, "42"));
         // sandbox allows reading properties, permissions allow getSimpleName
         assertEquals("Object", jexl451.createScript("o.class.simpleName", "o").execute(null, new Object()));
         // sandbox allows reading properties, permissions forbids getClassLoader
         assertThrows(JexlException.Property.class,
             () -> jexl451.createScript("o.class.classLoader", "o").execute(null, new Object()));
     }
 
     @Test
     void testIssue455a() {
         final JexlEngine jexl = new JexlBuilder().create();
         String code = "name -> `${name +\n\t\f\r name}`";
         JexlScript script = jexl.createScript(code);
         Object o = script.execute(null, "Hello");
         String ctl = "HelloHello";
         Assertions.assertEquals(ctl, o);
     }
 
     @Test
     void testIssue455b() {
         final JexlEngine jexl = new JexlBuilder().create();
         String code = "name -> `${name}\n${name}`;";
         JexlScript script = jexl.createScript(code);
         Object o = script.execute(null, "Hello");
         String ctl = "Hello\nHello";
         Assertions.assertEquals(ctl, o);
     }
 
     @Test
     void testIssue455c() {
         final JexlEngine jexl = new JexlBuilder().create();
         final JexlContext context = new MapContext();
         context.set("name", "Hello");
         final JxltEngine jxlt = jexl.createJxltEngine();
         final JxltEngine.Template template = jxlt.createTemplate("<b>\n\t${name\n\t+\r\f name}\n</b>");
         final StringWriter writer = new StringWriter();
         template.evaluate(context, writer);
         assertEquals("<b>\n\tHelloHello\n</b>", writer.toString());
     }
 
     @Test
     void testIssue455d() {
         final JexlEngine jexl = new JexlBuilder().create();
         // 'ref' contains 'greeting' which is the name of the variable to expand
         String code = "`#{${\nref\t}}\n#{${\rref\f}}`;";
         JexlScript script = jexl.createScript(code, "ref", "greeting");
         Object o = script.execute(null, "greeting", "Hello");
         String ctl = "Hello\nHello";
         Assertions.assertEquals(ctl, o);
     }
 
     @Test
     void testIssue455e() {
         final JexlEngine jexl = new JexlBuilder().create();
         // Evaluate nested immediate inside deferred at runtime using a parameterized script
         final String src = "(name, suffix) -> `#{name} Hello ${name} ! #{suffix}`";
         final JexlScript script = jexl.createScript(src);
         final Object result = script.execute(null, "World", "~");
         Assertions.assertEquals("World Hello World ! ~", result);
     }
 
     @Test
     void testIssue455f() {
         final JexlEngine jexl = new JexlBuilder().create();
         // Evaluate nested immediate inside deferred at runtime using a parameterized script
         final String src = "(name, suffix) -> `#{name + ' Hello'} ${name + ' !'} #{suffix}`";
         final JexlScript script = jexl.createScript(src);
         final Object result = script.execute(null, "World", "~");
         Assertions.assertEquals("World Hello World ! ~", result);
     }
 
     @Test
     void testIssue455g() {
         final JexlEngine jexl = new JexlBuilder().create();
         final JxltEngine jxlt = jexl.createJxltEngine();
         final JxltEngine.Template template = jxlt.createTemplate("${name} #{suffix}", "name", "suffix");
         final StringWriter writer = new StringWriter();
         // prepare requires immediate arguments; evaluate needs deferred arguments
         template.prepare(null, "World", null).evaluate(null, writer, null, "~");
         Assertions.assertEquals("World ~", writer.toString());
     }
 
     @Test
     void testIssue455h() {
         final JexlEngine jexl = new JexlBuilder().create();
         final JxltEngine jxlt = jexl.createJxltEngine();
         final JxltEngine.Template template = jxlt.createTemplate("#{name + ' Hello'} ${name + ' !'} #{suffix}", "name", "suffix");
         final StringWriter writer = new StringWriter();
         // Prepare only the immediate name argument; evaluate needs both deferred arguments - name and suffix
         template.prepare(null, "World").evaluate(null, writer, "World", "~");
         Assertions.assertEquals("World Hello World ! ~", writer.toString());
     }
 
 }