Documented expr.* packages.

Converted some tabs into spaces.

git-svn-id: http://google-refine.googlecode.com/svn/trunk@332 7d457c2a-affb-35e4-300a-418c747d4874

src/main/java/com/metaweb/gridworks/expr/EvalError.java

@@ -8,6 +8,12 @@ import org.json.JSONWriter;
 
 import com.metaweb.gridworks.Jsonizable;
 
+/**
+ * An error that occurs during the evaluation of an Evaluable. Errors are values, too
+ * because they can be stored in cells just like strings, numbers, etc. Errors are not
+ * thrown because an error might occupy just one element in an array and doesn't need
+ * to make the whole array erroneous.
+ */
 public class EvalError implements Serializable, Jsonizable {
     private static final long serialVersionUID = -102681220092874080L;
     

src/main/java/com/metaweb/gridworks/expr/Evaluable.java

@@ -2,6 +2,15 @@ package com.metaweb.gridworks.expr;
 
 import java.util.Properties;
 
+/**
+ * Interface for evaluable expressions in any arbitrary language.
+ */
 public interface Evaluable {
+    /**
+     * Evaluate this expression in the given environment (bindings).
+     * 
+     * @param bindings
+     * @return
+     */
     public Object evaluate(Properties bindings);
 }

src/main/java/com/metaweb/gridworks/expr/ExpressionUtils.java

@@ -65,9 +65,11 @@ public class ExpressionUtils {
     
     static public boolean sameValue(Object v1, Object v2) {
         if (v1 == null) {
-    		return (v2 == null) || (v2 instanceof String && ((String) v2).length() == 0);
+            return (v2 == null)
+                    || (v2 instanceof String && ((String) v2).length() == 0);
         } else if (v2 == null) {
-    		return (v1 == null) || (v1 instanceof String && ((String) v1).length() == 0);
+            return (v1 == null)
+                    || (v1 instanceof String && ((String) v1).length() == 0);
         } else {
             return v1.equals(v2);
         }

src/main/java/com/metaweb/gridworks/expr/HasFields.java

@@ -2,6 +2,10 @@ package com.metaweb.gridworks.expr;
 
 import java.util.Properties;
 
+/**
+ * Interface for objects that have named fields, which can be retrieved using the 
+ * dot notation or the bracket notation, e.g., cells.Country, cells["Type of Disaster"].
+ */
 public interface HasFields {
     public Object getField(String name, Properties bindings);
 }

src/main/java/com/metaweb/gridworks/expr/JythonHasFieldsWrapper.java

@@ -5,11 +5,11 @@ import java.util.Properties;
 import org.python.core.PyObject;
 import org.python.core.PyString;
 
-
 public class JythonHasFieldsWrapper extends PyObject {
     private static final long serialVersionUID = -1275353513262385099L;
 
     public HasFields _obj;
+
     private Properties _bindings;
 
     public JythonHasFieldsWrapper(HasFields obj, Properties bindings) {

src/main/java/com/metaweb/gridworks/expr/MetaParser.java

@@ -8,6 +8,15 @@ import clojure.lang.IFn;
 import com.metaweb.gridworks.gel.Parser;
 
 abstract public class MetaParser {
+    /**
+     * Parse an expression that might have a language prefix into an Evaluable.
+     * Expressions without valid prefixes or without any prefix are assumed to be
+     * GEL expressions.
+     * 
+     * @param s
+     * @return
+     * @throws ParsingException
+     */
     static public Evaluable parse(String s) throws ParsingException {
         String language = "gel";
         

src/main/java/com/metaweb/gridworks/expr/functions/Type.java

@@ -1,6 +1,7 @@
 package com.metaweb.gridworks.expr.functions;
 
 import java.util.Calendar;
+import java.util.Date;
 import java.util.List;
 import java.util.Properties;
 
@@ -20,18 +21,21 @@ public class Type implements Function {
             if (v != null) {
                 if (v instanceof String) {
                     return "string";
-                } else if (v instanceof Calendar) {
+                } else if (v instanceof Calendar || v instanceof Date) {
                     return "date";
                 } else if (v instanceof Number) {
                     return "number";
                 } else if (v.getClass().isArray() || v instanceof List<?>) {
                     return "array";
+                } else if (v instanceof EvalError) {
+                    return "error";
                 } else {
                     return v.getClass().getName();
                 }
             }
+            return "undefined";
         }
-        return new EvalError(ControlFunctionRegistry.getFunctionName(this) + " expects a parameter");
+        return new EvalError(ControlFunctionRegistry.getFunctionName(this) + " expects one argument");
     }
 
     public void write(JSONWriter writer, Properties options)