1.支持index模式取MAP节点，用于支持特殊符号节点名，例如req['content-type']，中括号中仅支持字符串格式，例如req[content-type]仍然按数组格式进行解析。

2.提供表达式变量分析工具，ELUtils.getVariants，将表达式传入后分析出该表达式的变量列表
3.修复根节点为数组时解析失败的问题，现在this[xxx]可以正确被识别为数组
4.优化了表达式方法调用选取重载方法的方式
5.修复了多维度数组的赋值和取值问题

Author: FanJiaRui

src/main/java/org/fanjr/simplify/el/ELExecutor.java

@@ -743,7 +743,11 @@ private static NodeInvoker resolveNode(char[] chars, int start, int end) {
                 throw new ElException("解析错误！错误的节点:" + nodeName);
             } else {
                 int lastArrayIndex = findLastCharToken(chars, '[', start, end - 1, false);
-                NodeInvoker parent = resolveNode(chars, start, lastArrayIndex);
+                NodeInvoker parent = null;
+                if (start != lastArrayIndex) {
+                    // 没有上一级，可能是多维数组
+                    parent = resolveNode(chars, start, lastArrayIndex);
+                }
                 ELInvoker indexEl = resolve(chars, lastArrayIndex + 1, end - 1);
                 if (indexEl instanceof StringInvoker) {
                     return IndexMapNodeInvoker.newInstance(nodeName, parent, (String) indexEl.invoke(null));

src/main/java/org/fanjr/simplify/el/invoker/node/IndexMapNodeInvoker.java

@@ -27,6 +27,15 @@ public static IndexMapNodeInvoker newInstance(String nodeName, NodeInvoker super
         return new IndexMapNodeInvoker(nodeName, superNode, indexNodeName);
     }
 
+    @Override
+    public void setParentNodeInvoker(NodeInvoker parentNodeInvoker) {
+        if (this.parentNodeInvoker == null) {
+            this.parentNodeInvoker = parentNodeInvoker;
+        } else {
+            this.parentNodeInvoker.setParentNodeInvoker(parentNodeInvoker);
+        }
+    }
+
     @Override
     Object getValueByParent(Object ctx, NodeHolder parentNode) {
         String nodeName = this.indexNodeName;

src/main/java/org/fanjr/simplify/el/invoker/node/IndexNodeInvoker.java

@@ -8,7 +8,6 @@
 
 import java.lang.reflect.Array;
 import java.util.List;
-import java.util.stream.Stream;
 
 /**
  * @author fanjr@vip.qq.com
@@ -30,7 +29,11 @@ public static IndexNodeInvoker newInstance(String nodeName, NodeInvoker superNod
 
     @Override
     public void setParentNodeInvoker(NodeInvoker parentNodeInvoker) {
-        this.parentNodeInvoker.setParentNodeInvoker(parentNodeInvoker);
+        if (this.parentNodeInvoker == null) {
+            this.parentNodeInvoker = parentNodeInvoker;
+        } else {
+            this.parentNodeInvoker.setParentNodeInvoker(parentNodeInvoker);
+        }
     }
 
     private int getIndex(Object ctx) {

src/test/java/unit/ElTest.java

@@ -107,7 +107,13 @@ public void baseTest() {
         Assertions.assertEquals("t1", ELExecutor.eval("a.b.c.d=='1234567890'?'t1':'t2'", context, String.class));
         Assertions.assertEquals("t1", ELExecutor.eval("a.b.c.d=='1234567890'?\"t1\":\"t2\"", context, String.class));
         Assertions.assertEquals("true", ELExecutor.eval("a.b.c.boo=true", context, String.class));
+        Assertions.assertEquals("true", ELExecutor.eval("a.b.c.boo", context, String.class));
+        Assertions.assertEquals("true", ELExecutor.eval("a.b.c['boo']", context, String.class));
+        Assertions.assertEquals("true", ELExecutor.eval("a.b.['c']['boo']", context, String.class));
+        Assertions.assertEquals("true", ELExecutor.eval("a.['b']['c'].boo", context, String.class));
         Assertions.assertEquals("true", ELExecutor.eval("a.b.c.arr[3][1]=true", context, String.class));
+        Assertions.assertEquals("true", ELExecutor.eval("a.b.c.arr[3][1]", context, String.class));
+        Assertions.assertEquals("true", ELExecutor.eval("a.b.c.['arr'][3][1]", context, String.class));
         Assertions.assertEquals("1", ELExecutor.eval("a.index=1", context, String.class));
         Assertions.assertEquals("{\"d\":\"", ELExecutor.eval("a.b.c.toString().substring(\"0\",6)", context, String.class));
         Assertions.assertEquals("{\"c\":{\"d\":\"1234567890\",\"boo\":true,\"arr\":[null,null,null,[null,true]]}}", ELExecutor.eval("a.b", context, String.class));
@@ -124,6 +130,7 @@ public void baseTest() {
         Assertions.assertEquals("6", ELExecutor.eval("a.index = (a.index + 5)", context, String.class));
         Assertions.assertEquals("11", ELExecutor.eval("+ a.index += 5", context, String.class));
         Assertions.assertEquals("11", ELExecutor.eval("a.index2[a.index] = a.index", context, String.class));
+        Assertions.assertEquals("true", ELExecutor.eval("a.index2[a.index] == a.index", context, String.class));
         Assertions.assertEquals("6", ELExecutor.eval("a.index = (a.index - 5)", context, String.class));
         Assertions.assertEquals("1", ELExecutor.eval("a.index -= 5", context, String.class));
         Assertions.assertEquals("1", ELExecutor.eval("a.index2[this.a.index] = a.index", context, String.class));