1 files changed, 70 insertions, 0 deletions
diff --git a/javaparser-core/src/main/java/com/github/javaparser/ast/validator/chunks/CommonValidators.java b/javaparser-core/src/main/java/com/github/javaparser/ast/validator/chunks/CommonValidators.java
new file mode 100644
index 000000000..5e5b7919e
--- /dev/null
+++ b/javaparser-core/src/main/java/com/github/javaparser/ast/validator/chunks/CommonValidators.java
@@ -0,0 +1,70 @@
+package com.github.javaparser.ast.validator.chunks;
+
+import com.github.javaparser.ast.NodeList;
+import com.github.javaparser.ast.body.ClassOrInterfaceDeclaration;
+import com.github.javaparser.ast.body.InitializerDeclaration;
+import com.github.javaparser.ast.expr.*;
+import com.github.javaparser.ast.validator.SimpleValidator;
+import com.github.javaparser.ast.validator.SingleNodeTypeValidator;
+import com.github.javaparser.ast.validator.TreeVisitorValidator;
+import com.github.javaparser.ast.validator.Validators;
+import com.github.javaparser.metamodel.NodeMetaModel;
+import com.github.javaparser.metamodel.PropertyMetaModel;
+
+import java.util.Optional;
+
+/**
+ * Contains validations that are valid for every Java version.
+ */
+public class CommonValidators extends Validators {
+    public CommonValidators() {
+        super(
+                new SimpleValidator<>(ClassOrInterfaceDeclaration.class,
+                        n -> !n.isInterface() && n.getExtendedTypes().size() > 1,
+                        (n, reporter) -> reporter.report(n.getExtendedTypes(1), "A class cannot extend more than one other class.")
+                ),
+                new SimpleValidator<>(ClassOrInterfaceDeclaration.class,
+                        n -> n.isInterface() && !n.getImplementedTypes().isEmpty(),
+                        (n, reporter) -> reporter.report(n.getImplementedTypes(0), "An interface cannot implement other interfaces.")
+                ),
+                new SingleNodeTypeValidator<>(ClassOrInterfaceDeclaration.class, (n, reporter) -> {
+                    if (n.isInterface()) {
+                        n.getMembers().forEach(mem -> {
+                            if (mem instanceof InitializerDeclaration) {
+                                reporter.report(mem, "An interface cannot have initializers.");
+                            }
+                        });
+                    }
+                }
+                ),
+                new SingleNodeTypeValidator<>(AssignExpr.class, (n, reporter) -> {
+                    // https://docs.oracle.com/javase/specs/jls/se8/html/jls-15.html#jls-15.26
+                    Expression target = n.getTarget();
+                    while (target instanceof EnclosedExpr) {
+                        target = ((EnclosedExpr) target).getInner();
+                    }
+                    if (target instanceof NameExpr
+                            || target instanceof ArrayAccessExpr
+                            || target instanceof FieldAccessExpr) {
+                        return;
+                    }
+                    reporter.report(n.getTarget(), "Illegal left hand side of an assignment.");
+                }
+                ),
+                new TreeVisitorValidator((node, problemReporter) -> {
+                    NodeMetaModel mm = node.getMetaModel();
+                    for (PropertyMetaModel ppm : mm.getAllPropertyMetaModels()) {
+                        if (ppm.isNonEmpty()) {
+                            if (ppm.isNodeList()) {
+                                NodeList value = (NodeList) ppm.getValue(node);
+                                if (value.isEmpty()) {
+                                    problemReporter.report(node, "%s.%s can not be empty.", mm.getTypeName(), ppm.getName());
+                                }
+                            }
+                            // No need to check empty strings, it should be impossible to set them to ""
+                        }
+                    }
+                })
+        );
+    }
+}