improved sql parser.

2023-03-04 19:17:16 +00:00 · 2017-08-24 10:40:09 +08:00
parent 0c46c2a165
commit 026295ddbd
41 changed files with 565 additions and 186 deletions
@@ -0,0 +1,91 @@
+/*
+ * Copyright 1999-2017 Alibaba Group Holding Ltd.
+ *
+ * Licensed 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
+ *
+ *      http://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 com.alibaba.druid.sql;
+
+import com.alibaba.druid.sql.ast.SQLExpr;
+import com.alibaba.druid.sql.ast.expr.*;
+
+import java.util.List;
+
+public class SQLTransformUtils {
+    public static SQLExpr transformDecode(SQLMethodInvokeExpr x) {
+        if (x == null) {
+            return null;
+        }
+
+        if (!"decode".equalsIgnoreCase(x.getMethodName())) {
+            throw new IllegalArgumentException(x.getMethodName());
+        }
+
+        List<SQLExpr> parameters = x.getParameters();
+        SQLCaseExpr caseExpr = new SQLCaseExpr();
+        caseExpr.setParent(x.getParent());
+        caseExpr.setValueExpr(parameters.get(0));
+
+        if (parameters.size() == 4) {
+            SQLExpr param1 = parameters.get(1);
+
+            x.setMethodName("if");
+
+            SQLBinaryOpExpr condition;
+            if (param1 instanceof SQLNullExpr) {
+                condition = new SQLBinaryOpExpr(parameters.get(0), SQLBinaryOperator.Is, param1);
+            } else {
+                condition = new SQLBinaryOpExpr(parameters.get(0), SQLBinaryOperator.Equality, param1);
+            }
+            condition.setParent(x);
+            parameters.set(0, condition);
+            parameters.set(1, parameters.get(2));
+            parameters.set(2, parameters.get(3));
+            parameters.remove(3);
+            return x;
+        }
+
+        for (int i = 1; i + 1 < parameters.size(); i += 2) {
+            SQLCaseExpr.Item item = new SQLCaseExpr.Item();
+            SQLExpr conditionExpr = parameters.get(i);
+
+            item.setConditionExpr(conditionExpr);
+
+            SQLExpr valueExpr = parameters.get(i + 1);
+
+            if (valueExpr instanceof SQLMethodInvokeExpr) {
+                SQLMethodInvokeExpr methodInvokeExpr = (SQLMethodInvokeExpr) valueExpr;
+                if ("decode".equalsIgnoreCase(methodInvokeExpr.getMethodName())) {
+                    valueExpr = transformDecode(methodInvokeExpr);
+                }
+            }
+
+            item.setValueExpr(valueExpr);
+            caseExpr.addItem(item);
+        }
+
+        if (parameters.size() % 2 == 0) {
+            SQLExpr defaultExpr = parameters.get(parameters.size() - 1);
+
+            if (defaultExpr instanceof SQLMethodInvokeExpr) {
+                SQLMethodInvokeExpr methodInvokeExpr = (SQLMethodInvokeExpr) defaultExpr;
+                if ("decode".equalsIgnoreCase(methodInvokeExpr.getMethodName())) {
+                    defaultExpr = transformDecode(methodInvokeExpr);
+                }
+            }
+
+            caseExpr.setElseExpr(defaultExpr);
+        }
+
+        return caseExpr;
+    }
+}