Re: [PR] Precompile regex pattern for 'matches' operator and make it part of the lambda predicate class [incubator-kie-drools]

["Copilot (via GitHub)" <gi...@apache.org>]

Copilot commented on code in PR #6469:
URL: https://github.com/apache/incubator-kie-drools/pull/6469#discussion_r2397728169


##########
drools-model/drools-model-codegen/src/main/java/org/drools/model/codegen/execmodel/util/lambdareplace/MaterializedLambdaPredicate.java:
##########
@@ -76,6 +79,22 @@ private void createTestMethod(EnumDeclaration classDeclaration) {
         methodDeclaration.setBody(new BlockStmt(NodeList.nodeList(new ReturnStmt(clone.getExpression()))));
     }
 
+    /**
+     * recursively traverse the node tree and collect all RegexExpr
+     * @param node
+     * @return
+     */
+    private Collection<RegexExpr> collectRegexExpressions(Node node) {
+        if (node instanceof RegexExpr) {
+            return Collections.singletonList((RegexExpr) node);
+        } else {
+            return node.getChildNodes().stream()
+                    .map(this::collectRegexExpressions)
+                    .flatMap(Collection::stream)
+                    .toList();

Review Comment:
   Stream.toList() requires Java 16+. Drools builds target Java 11; this will not compile there. Replace with Collectors.toList() and add import for java.util.stream.Collectors.



##########
drools-model/drools-mvel-parser/src/main/java/org/drools/mvel/parser/ast/expr/RegexExpr.java:
##########
@@ -0,0 +1,69 @@
+/*
+ * 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.drools.mvel.parser.ast.expr;
+
+import com.github.javaparser.ast.AllFieldsConstructor;
+import com.github.javaparser.ast.Node;
+import com.github.javaparser.ast.body.FieldDeclaration;
+import com.github.javaparser.ast.expr.BinaryExpr;

Review Comment:
   Unused import: BinaryExpr is not referenced in this class. Please remove to avoid warnings.
   ```suggestion
   
   ```



##########
drools-model/drools-model-codegen/src/main/java/org/drools/model/codegen/execmodel/generator/operatorspec/RegexOperatorSpec.java:
##########
@@ -0,0 +1,120 @@
+/*
+ * 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.drools.model.codegen.execmodel.generator.operatorspec;
+
+import com.github.javaparser.ast.Modifier;
+import com.github.javaparser.ast.NodeList;
+import com.github.javaparser.ast.body.FieldDeclaration;
+import com.github.javaparser.ast.body.VariableDeclarator;
+import com.github.javaparser.ast.expr.*;
+import org.drools.model.codegen.execmodel.generator.RuleContext;
+import org.drools.model.codegen.execmodel.generator.TypedExpression;
+import org.drools.model.codegen.execmodel.generator.expressiontyper.ExpressionTyper;
+import org.drools.mvel.parser.ast.expr.PointFreeExpr;
+import org.drools.mvel.parser.ast.expr.RegexExpr;
+
+import java.util.regex.Pattern;
+
+import static org.drools.model.codegen.execmodel.generator.DrlxParseUtil.toClassOrInterfaceType;
+import static org.drools.util.StringUtils.md5Hash;
+
+public class RegexOperatorSpec extends NativeOperatorSpec {
+    public static final RegexOperatorSpec INSTANCE = new RegexOperatorSpec();
+
+    public Expression getExpression(RuleContext context, PointFreeExpr pointFreeExpr, TypedExpression left, ExpressionTyper expressionTyper) {
+        if (shouldInlineRegex(pointFreeExpr.getRight())) {
+            return super.getExpression(context, pointFreeExpr, left, expressionTyper);
+        } else {
+            // TODO(?) throw some exception instead of creating regexp_failed_to_parse expressions
+            Expression regexExpression = pointFreeExpr.getRight().getFirst()
+                    .orElse(new StringLiteralExpr("regexp_failed_to_parse"));
+
+            NameExpr regexFieldName = new NameExpr("regexp_" + md5Hash(regexExpression.toString()));
+
+            return new RegexExpr(
+                    getClassMemberFieldDeclaration(regexFieldName, regexExpression),
+                    getClassMemberInvocationExpression(pointFreeExpr, left, regexFieldName)
+            );
+        }
+    }
+
+    private EnclosedExpr getClassMemberInvocationExpression(PointFreeExpr pointFreeExpr, TypedExpression left, NameExpr regexFieldName) {
+        // we need to cast the left expression to CharSequence, otherwise it might fail in cases of missing type safety
+        // e.g. test method parameters (_this) is of a raw type Map
+        EnclosedExpr typeSafeStringToMatch = new EnclosedExpr(new CastExpr(toClassOrInterfaceType(CharSequence.class), left.getExpression()));
+
+        MethodCallExpr matchesCallExpr = new MethodCallExpr(
+                new MethodCallExpr(regexFieldName, "matcher", NodeList.nodeList(typeSafeStringToMatch)),
+                "matches"
+        );
+
+        // null string should not match
+        BinaryExpr compoundRegexCallExpr = new BinaryExpr(
+                new BinaryExpr(left.getExpression(), new NullLiteralExpr(), BinaryExpr.Operator.NOT_EQUALS),
+                pointFreeExpr.isNegated() ? new UnaryExpr(matchesCallExpr, UnaryExpr.Operator.LOGICAL_COMPLEMENT) : matchesCallExpr,
+                BinaryExpr.Operator.AND
+        );
+
+        return new EnclosedExpr(compoundRegexCallExpr);
+    }
+
+    private FieldDeclaration getClassMemberFieldDeclaration(NameExpr regexFieldName, Expression regexExpression) {
+
+        MethodCallExpr compiledRegexField = new MethodCallExpr(
+                new NameExpr(Pattern.class.getName()), "compile", NodeList.nodeList(regexExpression)
+        );
+
+        VariableDeclarator variableDeclarator = new VariableDeclarator(
+                toClassOrInterfaceType(Pattern.class),
+                regexFieldName.getName(),
+                compiledRegexField
+        );
+
+        return new FieldDeclaration(
+                NodeList.nodeList(Modifier.privateModifier(), Modifier.staticModifier(), Modifier.finalModifier()),
+                variableDeclarator
+        );
+    }
+
+    /**
+     * Recursively check if the regexPatternExpression contains a method call on the fact.
+     * If so, we consider it a dynamic regex, and cannot inline the regex expression.
+     *
+     * @param regexPatternExpression the regex pattern expression under analysis
+     * @return true if the regex pattern expression is dynamic, false otherwise
+     */
+    private boolean shouldInlineRegex(NodeList<Expression> regexPatternExpression) {
+        for (Expression expression : regexPatternExpression) {
+            if (expression instanceof MethodCallExpr methodCallExpr) {
+                boolean isInFactScope = methodCallExpr.getScope()
+                        .filter(Expression::isNameExpr)
+                        .map(Expression::asNameExpr)
+                        .map(NameExpr::getNameAsString)
+                        .filter("_this"::equals)
+                        .isPresent();
+
+                return isInFactScope || shouldInlineRegex(methodCallExpr.getArguments());
+            }
+
+            return false;
+        }
+
+        return false;
+    }

Review Comment:
   This loop returns false on the first non-MethodCallExpr, so subsequent expressions are never inspected. Move the return false outside the loop and only return true when a matching condition is found. Example fix: return true inside the if when condition matches; otherwise continue the loop; finally return false after the loop.



##########
drools-model/drools-model-codegen/src/main/java/org/drools/model/codegen/execmodel/util/lambdareplace/MaterializedLambdaPredicate.java:
##########
@@ -65,6 +64,10 @@ void createMethodsDeclaration(EnumDeclaration classDeclaration) {
     }
 
     private void createTestMethod(EnumDeclaration classDeclaration) {
+        collectRegexExpressions(lambdaExpr).stream()
+                .map(RegexExpr::getCompiledRegexMember)

Review Comment:
   [nitpick] If the same regex literal is used multiple times in a single lambda, this will add duplicate field declarations and cause a compilation error. Deduplicate by the variable name before adding, e.g., map to the VariableDeclarator name and distinct.
   ```suggestion
       private void createTestMethod(EnumDeclaration classDeclaration) {
           // Deduplicate regex member declarations by field name
           java.util.Set<String> regexMemberNames = new java.util.HashSet<>();
           collectRegexExpressions(lambdaExpr).stream()
                   .map(RegexExpr::getCompiledRegexMember)
                   .filter(member -> regexMemberNames.add(member.getVariable(0).getNameAsString()))
   ```



##########
drools-model/drools-mvel-parser/src/main/java/org/drools/mvel/parser/ast/expr/RegexExpr.java:
##########
@@ -0,0 +1,69 @@
+/*
+ * 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.drools.mvel.parser.ast.expr;
+
+import com.github.javaparser.ast.AllFieldsConstructor;
+import com.github.javaparser.ast.Node;
+import com.github.javaparser.ast.body.FieldDeclaration;
+import com.github.javaparser.ast.expr.BinaryExpr;
+import com.github.javaparser.ast.expr.EnclosedExpr;
+import com.github.javaparser.ast.expr.LiteralExpr;
+import com.github.javaparser.ast.visitor.CloneVisitor;
+import com.github.javaparser.ast.visitor.GenericVisitor;
+import com.github.javaparser.ast.visitor.VoidVisitor;
+
+public final class RegexExpr extends LiteralExpr {
+
+    private final EnclosedExpr matchesEvaluationExpr;
+    private final FieldDeclaration compiledRegexMember;
+
+    @AllFieldsConstructor
+    public RegexExpr(FieldDeclaration compiledRegexMember, EnclosedExpr matchesEvaluationExpr) {
+        super();
+
+        this.matchesEvaluationExpr = matchesEvaluationExpr;
+        this.compiledRegexMember = compiledRegexMember;
+    }

Review Comment:
   [nitpick] @AllFieldsConstructor is redundant given the explicit constructor below; if an annotation processor is enabled, this could generate a duplicate constructor. Consider removing the annotation.



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