JEXL-252, JEXL-250: added safe navigation and string interpolation to…

… identifier resolution
apache · Feb 5, 2018 · dffcc16 · dffcc16
1 parent 2996187
commit dffcc16
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Showing 10 changed files with 245 additions and 13 deletions.
diff --git a/RELEASE-NOTES.txt b/RELEASE-NOTES.txt
@@ -25,9 +25,22 @@ Release 3.2
 
 Version 3.2 is a minor release.
 
+What's new in 3.2:
+==================
+
+* Interpolated strings in identifiers, as in x.`${prefix}_${suffix}` that in many cases would be equivalent to
+  x[prefix + '_' + suffix] or x[`${prefix}_${suffix}`].
+* Safe-navigation operator '?.' allowing lenient handling of non-existent or null properties so that an expression
+  like 'x?.y?.z' would behave as 'x.y.z' in nominal execution and return null instead of throwing an exception in error
+  cases.
+* A set of syntactic restrictions can be applied to scripts ranging from not allowing side-effects to not allowing
+  loops enabling fine control over what end-users may be able to enter as expressions/scripts.
+
 New Features in 3.2:
 ====================
 
+* JEXL-252:      Allow for interpolated strings to be used in property access operators
+* JEXL-250:      Safe navigation operator
 * JEXL-248:      Allow range subexpression as an array property assignment identifier
 * JEXL-243:      Allow restricting available features in Script/Expressions
 * JEXL-238:      Restrict getLiteralClass to a Number for NumberLiterals

diff --git a/src/main/java/org/apache/commons/jexl3/internal/Debugger.java b/src/main/java/org/apache/commons/jexl3/internal/Debugger.java
@@ -611,13 +611,20 @@ protected Object visit(ASTIdentifier node, Object data) {
 
     @Override
     protected Object visit(ASTIdentifierAccess node, Object data) {
-        builder.append(".");
+        builder.append(node.isSafe() ? "?." : ".");
         String image = node.getName();
-        if (needQuotes(image)) {
+        if (node.isExpression()) {
+            builder.append('`');
+            builder.append(image.replace("`", "\\`"));
+            builder.append('`');
+        } else if (needQuotes(image)) {
             // quote it
-            image = "'" + image.replace("'", "\\'") + "'";
+            builder.append('\'');
+            builder.append(image.replace("'", "\\'"));
+            builder.append('\'');
+        } else {
+            builder.append(image);
         }
-        builder.append(image);
         return data;
     }
 

diff --git a/src/main/java/org/apache/commons/jexl3/internal/Interpreter.java b/src/main/java/org/apache/commons/jexl3/internal/Interpreter.java
@@ -59,6 +59,7 @@
 import org.apache.commons.jexl3.parser.ASTGTNode;
 import org.apache.commons.jexl3.parser.ASTIdentifier;
 import org.apache.commons.jexl3.parser.ASTIdentifierAccess;
+import org.apache.commons.jexl3.parser.ASTIdentifierAccessJxlt;
 import org.apache.commons.jexl3.parser.ASTIfStatement;
 import org.apache.commons.jexl3.parser.ASTJexlLambda;
 import org.apache.commons.jexl3.parser.ASTJexlScript;
@@ -1000,9 +1001,34 @@ protected boolean isLocalVariable(ASTReference node, int which) {
                 && ((ASTIdentifier) node.jjtGetChild(which)).getSymbol() >= 0);
     }
 
+    /**
+     * Evaluates an access identifier based on the 2 main implementations;
+     * static (name or numbered identifier) or dynamic (jxlt).
+     * @param node the identifier access node
+     * @return the evaluated identifier
+     */
+    private Object evalIdentifier(ASTIdentifierAccess node) {
+        if (node instanceof ASTIdentifierAccessJxlt) {
+            ASTIdentifierAccessJxlt accessJxlt = (ASTIdentifierAccessJxlt) node;
+            TemplateEngine.TemplateExpression expr = (TemplateEngine.TemplateExpression) accessJxlt.getExpression();
+            if (expr == null) {
+                TemplateEngine jxlt = jexl.jxlt();
+                expr = jxlt.parseExpression(node.jexlInfo(), node.getName(), frame != null ? frame.getScope() : null);
+                accessJxlt.setExpression(expr);
+            }
+            if (expr != null) {
+                return expr.evaluate(frame, context);
+            }
+            throw new JexlException.Property(node, node.getName());
+        } else {
+            return node.getIdentifier();
+        }
+    }
+
     @Override
     protected Object visit(ASTIdentifierAccess node, Object data) {
-        return data != null ? getAttribute(data, node.getIdentifier(), node) : null;
+        Object id = evalIdentifier(node);
+        return data != null ? getAttribute(data, id, node) : null;
     }
 
     @Override
@@ -1245,7 +1271,7 @@ protected Object executeAssign(JexlNode node, JexlOperator assignop, Object data
         Object property = null;
         JexlNode propertyNode = left.jjtGetChild(last);
         if (propertyNode instanceof ASTIdentifierAccess) {
-            property = ((ASTIdentifierAccess) propertyNode).getIdentifier();
+            property = evalIdentifier((ASTIdentifierAccess) propertyNode);
             // deal with antish variable
             if (ant != null && object == null) {
                 if (last > 0) {
@@ -1774,8 +1800,13 @@ protected Object getAttribute(Object object, Object attribute, JexlNode node) {
         }
         // lets fail
         if (node != null) {
-            String attrStr = attribute != null ? attribute.toString() : null;
-            return unsolvableProperty(node, attrStr, xcause);
+            boolean safe = (node instanceof ASTIdentifierAccess) && ((ASTIdentifierAccess) node).isSafe();
+            if (safe) {
+                return null;
+            } else {
+                String attrStr = attribute != null ? attribute.toString() : null;
+                return unsolvableProperty(node, attrStr, xcause);
+            }
         } else {
             // direct call
             String error = "unable to get object property"

diff --git a/src/main/java/org/apache/commons/jexl3/parser/ASTIdentifierAccess.java b/src/main/java/org/apache/commons/jexl3/parser/ASTIdentifierAccess.java
@@ -16,10 +16,11 @@
  */
 package org.apache.commons.jexl3.parser;
 
+
 /**
  * Identifiers, variables and registers.
  */
-public final class ASTIdentifierAccess extends JexlNode {
+public class ASTIdentifierAccess extends JexlNode {
     private String name = null;
     private Integer identifier = null;
 
@@ -36,6 +37,22 @@ void setIdentifier(String id) {
         identifier = parseIdentifier(id);
     }
 
+    /**
+     * Whether this is a dot or a question-mark-dot aka safe-navigation access.
+     * @return true is ?., false if .
+     */
+    public boolean isSafe() {
+        return false;
+    }
+
+    /**
+     * Whether this is a Jxlt based identifier.
+     * @return true if `..${...}...`, false otherwise
+     */
+    public boolean isExpression() {
+        return false;
+    }
+
     /**
      * Parse an identifier which must be of the form:
      * 0|([1-9][0-9]*)

diff --git a/src/main/java/org/apache/commons/jexl3/parser/ASTIdentifierAccessJxlt.java b/src/main/java/org/apache/commons/jexl3/parser/ASTIdentifierAccessJxlt.java
@@ -0,0 +1,49 @@
+/*
+ * 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
+ *
+ *      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 org.apache.commons.jexl3.parser;
+
+import org.apache.commons.jexl3.JxltEngine;
+
+/**
+ * x.`expr`.
+ */
+public class ASTIdentifierAccessJxlt extends ASTIdentifierAccess {
+    protected JxltEngine.Expression jxltExpr;
+
+    ASTIdentifierAccessJxlt(int id) {
+        super(id);
+    }
+
+    ASTIdentifierAccessJxlt(Parser p, int id) {
+        super(p, id);
+    }
+
+    @Override
+    public boolean isExpression() {
+        return true;
+    }
+
+    public void setExpression(JxltEngine.Expression tp) {
+        jxltExpr = tp;
+    }
+
+    public JxltEngine.Expression getExpression() {
+        return jxltExpr;
+    }
+
+}
diff --git a/src/main/java/org/apache/commons/jexl3/parser/ASTIdentifierAccessSafe.java b/src/main/java/org/apache/commons/jexl3/parser/ASTIdentifierAccessSafe.java
@@ -0,0 +1,37 @@
+/*
+ * 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
+ *
+ *      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 org.apache.commons.jexl3.parser;
+
+/**
+ * x?.identifier .
+ */
+public class ASTIdentifierAccessSafe extends ASTIdentifierAccess {
+    ASTIdentifierAccessSafe(int id) {
+        super(id);
+    }
+
+    ASTIdentifierAccessSafe(Parser p, int id) {
+        super(p, id);
+    }
+
+    @Override
+    public boolean isSafe() {
+        return true;
+    }
+
+}
diff --git a/src/main/java/org/apache/commons/jexl3/parser/ASTIdentifierAccessSafeJxlt.java b/src/main/java/org/apache/commons/jexl3/parser/ASTIdentifierAccessSafeJxlt.java
@@ -0,0 +1,37 @@
+/*
+ * 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
+ *
+ *      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 org.apache.commons.jexl3.parser;
+
+/**
+ * x?.`expr` .
+ */
+public class ASTIdentifierAccessSafeJxlt extends ASTIdentifierAccessJxlt {
+    ASTIdentifierAccessSafeJxlt(int id) {
+        super(id);
+    }
+
+    ASTIdentifierAccessSafeJxlt(Parser p, int id) {
+        super(p, id);
+    }
+
+    @Override
+    public boolean isSafe() {
+        return true;
+    }
+
+}
diff --git a/src/main/java/org/apache/commons/jexl3/parser/Parser.jjt b/src/main/java/org/apache/commons/jexl3/parser/Parser.jjt
@@ -147,6 +147,7 @@ TOKEN_MGR_DECLS : {
     | < COLON : ":" >
     | < COMMA : "," >
     | < DOT : "." > { pushDot(); } /* Lexical state is now DOT_ID */
+    | < QDOT : "?." > { pushDot(); } /* Lexical state is now DOT_ID */
     | < ELIPSIS : "..." >
 }
 
@@ -259,7 +260,7 @@ TOKEN_MGR_DECLS : {
 {
   < JXLT_LITERAL:
     "`" (~["`","\\"] | "\\" ~["\u0000"])* "`"
-  >
+  > { popDot(); } /* Revert state to default if was DOT_ID. */
 }
 
 /***************************************
@@ -793,15 +794,25 @@ void Lambda() #JexlLambda() :
  *     References
  ***************************************/
 
-void IdentifierAccess() :
+void IdentifierAccess() #void :
 {
     Token t;
 }
 {
     <DOT> (
-        t=<DOT_IDENTIFIER> { jjtThis.setIdentifier(t.image); }
+        t=<DOT_IDENTIFIER> { jjtThis.setIdentifier(t.image); } #IdentifierAccess
+    |
+        t=<STRING_LITERAL> { jjtThis.setIdentifier(Parser.buildString(t.image, true)); } #IdentifierAccess
+    |
+        t=<JXLT_LITERAL> { jjtThis.setIdentifier(Parser.buildString(t.image, true)); } #IdentifierAccessJxlt
+    )
+    |
+    <QDOT> (
+        t=<DOT_IDENTIFIER> { jjtThis.setIdentifier(t.image); } #IdentifierAccessSafe
     |
-        t=<STRING_LITERAL> { jjtThis.setIdentifier(Parser.buildString(t.image, true)); }
+        t=<STRING_LITERAL> { jjtThis.setIdentifier(Parser.buildString(t.image, true)); } #IdentifierAccessSafe
+    |
+        t=<JXLT_LITERAL> { jjtThis.setIdentifier(Parser.buildString(t.image, true)); } #IdentifierAccessSafeJxlt
     )
 }
 
@@ -815,6 +826,8 @@ void MemberAccess() #void : {}
     LOOKAHEAD(<LBRACKET>) ArrayAccess()
     |
     LOOKAHEAD(<DOT>) IdentifierAccess()
+    |
+    LOOKAHEAD(<QDOT>) IdentifierAccess()
 }
 
 void ReferenceExpression() #MethodNode(>1) : {}

diff --git a/src/site/xdoc/changes.xml b/src/site/xdoc/changes.xml
@@ -26,6 +26,12 @@
     </properties>
     <body>
         <release version="3.2" date="unreleased">
+            <action dev="henrib" type="add" issue="JEXL-252" due-to="Dmitri Blinov">
+                Allow for interpolated strings to be used in property access operators
+            </action>
+            <action dev="henrib" type="add" issue="JEXL-250" due-to="Dmitri Blinov">
+                Safe navigation operator
+            </action>
             <action dev="henrib" type="add" issue="JEXL-248" due-to="Dmitri Blinov">
                 Allow range subexpression as an array property assignment identifier
             </action>

diff --git a/src/test/java/org/apache/commons/jexl3/IssuesTest200.java b/src/test/java/org/apache/commons/jexl3/IssuesTest200.java
@@ -341,4 +341,26 @@ public void test245() throws Exception {
             }
         }
     }
+
+    @Test
+    public void test252() throws Exception {
+        MapContext ctx = new MapContext();
+        JexlEngine engine = new JexlBuilder().strict(true).silent(false).create();
+        String stmt = "(x, dflt)->{ x?.class1 ?? dflt }";
+        JexlScript script = engine.createScript(stmt);
+        Object result = script.execute(ctx, "querty", "default");
+        Assert.assertEquals("default", result);
+        try {
+        stmt = "(x, al, dflt)->{  x.`c${al}ss` ?? dflt }";
+        script = engine.createScript(stmt);
+        result = script.execute(ctx, "querty", "la", "default");
+        Assert.assertEquals(stmt.getClass(), result);
+        stmt = "(x, al, dflt)->{  x?.`c${al}ss` ?? dflt }";
+        script = engine.createScript(stmt);
+        result = script.execute(ctx, "querty", "la", "default");
+        Assert.assertEquals(stmt.getClass(), result);
+        } catch(JexlException xany) {
+            String xanystr = xany.toString();
+        }
+    }
 }