project 4 skeleton

2024-03-27 10:18:16 -04:00
parent 1bf1e773a5
commit 4321264563
96 changed files with 5772 additions and 0 deletions
@@ -0,0 +1,92 @@
+package relop;
+
+import global.RID;
+import heap.HeapFile;
+import heap.HeapScan;
+
+/**
+ * Wrapper for heap file scan, the most basic access method. This "iterator"
+ * version takes schema into consideration and generates real tuples.
+ */
+public class FileScan extends Iterator {
+	
+	private HeapFile file = null; // needed for restart(), getFile();
+	private HeapScan scan = null;
+	private RID rid = null;
+	private boolean isOpen;
+
+  /**
+   * Constructs a file scan, given the schema and heap file.
+   */
+  public FileScan(Schema aSchema, HeapFile aFile) {
+	this.schema = aSchema;
+	this.file = aFile;
+	this.scan = file.openScan();
+	this.rid = new RID();
+	isOpen = true;
+  }
+
+  /**
+   * Gives a one-line explanation of the iterator, repeats the call on any
+   * child iterators, and increases the indent depth along the way.
+   */
+  public void explain(int depth) {
+	  for(int i = 0; i < depth; i++){
+		  System.out.printf("    ");
+	  }
+	  System.out.printf("FileScan\n");
+  }
+
+  /**
+   * Restarts the iterator, i.e. as if it were just constructed.
+   */
+  public void restart() {
+	  scan.close();
+	  scan = file.openScan();
+	  //rid = new RID();
+  }
+
+  /**
+   * Returns true if the iterator is open; false otherwise.
+   */
+  public boolean isOpen() {
+	  return isOpen;
+  }
+
+  /**
+   * Closes the iterator, releasing any resources (i.e. pinned pages).
+   */
+  public void close() {
+	  scan.close();
+	  isOpen = false;
+  }
+
+  /**
+   * Returns true if there are more tuples, false otherwise.
+   */
+  public boolean hasNext() {
+	  return scan.hasNext();
+  }
+
+  /**
+   * Gets the next tuple in the iteration.
+   * 
+   * @throws IllegalStateException if no more tuples
+   */
+  public Tuple getNext() {
+	  return new Tuple(schema, scan.getNext(rid));
+  }
+
+  /**
+   * Gets the RID of the last tuple returned.
+   */
+  public RID getLastRID() {
+	  return rid;
+  }
+  
+  // getter; added so HashJoin doesn't have to copy the file;
+  public HeapFile getFile(){
+	  return file;
+  }
+
+} // public class FileScan extends Iterator