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Documented the history package.

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git-svn-id: http://google-refine.googlecode.com/svn/trunk@334 7d457c2a-affb-35e4-300a-418c747d4874
This commit is contained in:
David Huynh 2010-03-22 18:19:31 +00:00
parent ec0110d65b
commit 1d20b33cf1
4 changed files with 50 additions and 16 deletions
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7
src/main/java/com/metaweb/gridworks/history/Change.java
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@ -6,6 +6,13 @@ import java.util.Properties;
import com.metaweb.gridworks.model.Project;
/**
* Interface for a concrete change to a project's data. A change should consist
* of new values already computed. When apply() is called, the change should not
* spend any more time computing anything. It should simply save existing values
* and swap in new values. Similarly, when revert() is called, the change
* should only swap old values back in.
*/
public interface Change {
public void apply(Project project);
public void revert(Project project);

34
src/main/java/com/metaweb/gridworks/history/History.java
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@ -17,6 +17,13 @@ import com.metaweb.gridworks.Jsonizable;
import com.metaweb.gridworks.ProjectManager;
import com.metaweb.gridworks.model.Project;
/**
* Track done and undone changes. Done changes can be undone; undone changes can be redone.
* Each change is actually not tracked directly but through a history entry. The history
* entry stores only the metadata, while the change object stores the actual data. Thus
* the history entries are much smaller and can be kept in memory, while the change objects
* are only loaded into memory on demand.
*/
public class History implements Jsonizable {
static public Change readOneChange(LineNumberReader reader) throws Exception {
/* String version = */ reader.readLine();
@ -45,8 +52,8 @@ public class History implements Jsonizable {
}
protected long _projectID;
protected List<HistoryEntry> _pastEntries;
protected List<HistoryEntry> _futureEntries;
protected List<HistoryEntry> _pastEntries; // done changes, can be undone
protected List<HistoryEntry> _futureEntries; // undone changes, can be redone
public History(Project project) {
_projectID = project.id;
@ -55,15 +62,23 @@ public class History implements Jsonizable {
}
public void addEntry(HistoryEntry entry) {
for (HistoryEntry entry2 : _futureEntries) {
entry2.delete();
}
entry.apply(ProjectManager.singleton.getProject(_projectID));
_pastEntries.add(entry);
_futureEntries.clear();
setModified();
// Any new change will clear all future entries.
List<HistoryEntry> futureEntries = _futureEntries;
_futureEntries = new ArrayList<HistoryEntry>();
for (HistoryEntry entry2 : futureEntries) {
try {
// remove residual data on disk
entry2.delete();
} catch (Exception e) {
e.printStackTrace();
}
}
}
protected void setModified() {
@ -80,6 +95,7 @@ public class History implements Jsonizable {
public void undoRedo(long lastDoneEntryID) {
if (lastDoneEntryID == 0) {
// undo all the way back to the start of the project
undo(_pastEntries.size());
} else {
for (int i = 0; i < _pastEntries.size(); i++) {
@ -121,12 +137,12 @@ public class History implements Jsonizable {
entry.revert(project);
setModified();
times--;
_pastEntries.remove(_pastEntries.size() - 1);
_futureEntries.add(0, entry);
}
setModified();
}
protected void redo(int times) {
@ -137,12 +153,12 @@ public class History implements Jsonizable {
entry.apply(project);
setModified();
times--;
_pastEntries.add(entry);
_futureEntries.remove(0);
}
setModified();
}
public void write(JSONWriter writer, Properties options)

17
src/main/java/com/metaweb/gridworks/history/HistoryEntry.java
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@ -24,13 +24,20 @@ import com.metaweb.gridworks.model.Project;
import com.metaweb.gridworks.operations.OperationRegistry;
import com.metaweb.gridworks.util.ParsingUtilities;
/**
* This is the metadata of a Change. It's small, so we can load it in order to
* obtain information about a change without actually loading the change.
*/
public class HistoryEntry implements Jsonizable {
final public long id;
final public long projectID;
final public String description;
final public AbstractOperation operation;
final public Date time;
final public long id;
final public long projectID;
final public String description;
final public Date time;
// the abstract operation, if any, that results in the change
final public AbstractOperation operation;
// the actual change, loaded on demand
transient protected Change _change;
public HistoryEntry(Project project, String description, AbstractOperation operation, Change change) {

8
src/main/java/com/metaweb/gridworks/history/HistoryProcess.java
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@ -9,10 +9,14 @@ import com.metaweb.gridworks.model.Project;
import com.metaweb.gridworks.process.Process;
import com.metaweb.gridworks.process.ProcessManager;
/**
* The process for undoing or redoing. This involves calling apply() and revert()
* on changes.
*/
public class HistoryProcess extends Process {
final protected Project _project;
final protected long _lastDoneID;
final protected String _description;
final protected long _lastDoneID;
final protected String _description;
protected boolean _done = false;