GP-5498 SymbolTable V4 schema refactor

Ghidra/Framework/DB/src/main/java/db/ConstrainedForwardRecordIterator.java

@@ -0,0 +1,79 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * 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 db;
+
+import java.io.IOException;
+import java.util.function.Function;
+
+/**
+ * {@link ConstrainedForwardRecordIterator} provides the ability to both filter and 
+ * translate records returned from an underlying {@link RecordIterator}.
+ */
+public class ConstrainedForwardRecordIterator implements RecordIterator {
+	private DBRecord nextConvertedRecord;
+
+	private final RecordIterator it;
+	private final Function<DBRecord, DBRecord> recordPredicateAndTranslate;
+
+	/**
+	 * Construct a constrained/filtered record iterator.
+	 * @param it source record iterator
+	 * @param recordPredicateAndTranslate function which enables both filtering of records
+	 * (null returned if record should be skipped) and the ability to translate the record
+	 * to an alternate table/record schema.
+	 */
+	public ConstrainedForwardRecordIterator(RecordIterator it,
+			Function<DBRecord, DBRecord> recordPredicateAndTranslate) {
+		this.it = it;
+		this.recordPredicateAndTranslate = recordPredicateAndTranslate;
+	}
+
+	@Override
+	public boolean hasPrevious() {
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public DBRecord previous() {
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public boolean delete() throws IOException {
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public boolean hasNext() throws IOException {
+		if (nextConvertedRecord != null) {
+			return true;
+		}
+		while (nextConvertedRecord == null && it.hasNext()) {
+			nextConvertedRecord = recordPredicateAndTranslate.apply(it.next());
+		}
+		return nextConvertedRecord != null;
+	}
+
+	@Override
+	public DBRecord next() throws IOException {
+		if (hasNext()) {
+			DBRecord returnedRecord = nextConvertedRecord;
+			nextConvertedRecord = null;
+			return returnedRecord;
+		}
+		return null;
+	}
+}