[empire-db] branch master updated: EMPIREDB-304 addes useful functions for enum decoding

[doebele]

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doebele pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/empire-db.git


The following commit(s) were added to refs/heads/master by this push:
     new af7f2af  EMPIREDB-304 addes useful functions for enum decoding
af7f2af is described below

commit af7f2afaff399183e8a195aebe6d1a7054c5c283
Author: Rainer Döbele <doeb...@apache.org>
AuthorDate: Mon Jan 27 16:34:25 2020 +0100

    EMPIREDB-304
    addes useful functions for enum decoding
---
 .../main/java/org/apache/empire/db/DBColumn.java   | 25 ++++++++++
 .../java/org/apache/empire/db/DBColumnExpr.java    | 53 ++++++++++++++++++++++
 2 files changed, 78 insertions(+)

diff --git a/empire-db/src/main/java/org/apache/empire/db/DBColumn.java 
b/empire-db/src/main/java/org/apache/empire/db/DBColumn.java
index 95b88b5..fe6ca70 100644
--- a/empire-db/src/main/java/org/apache/empire/db/DBColumn.java
+++ b/empire-db/src/main/java/org/apache/empire/db/DBColumn.java
@@ -407,6 +407,31 @@ public abstract class DBColumn extends DBColumnExpr
     }
 
     /**
+     * Creates and returns a sql-expression that maps enum values by name or 
ordinal to their string representation 
+     * 
+     * @return a DBDecodeExpr object
+     */
+    public DBColumnExpr decodeEnum()
+    {
+        return super.decodeEnum(getEnumType(), null, 
getDataType().isNumeric());
+    }
+
+    /**
+     * Creates and returns a sql-expression that maps enum values from name to 
ordinal
+     * 
+     * @return a DBDecodeExpr object
+     */
+    public DBColumnExpr decodeSort(boolean defaultToEnd)
+    {
+        if (getDataType().isNumeric())
+        {
+            log.warn("Unnecessary decode for numeric column");
+            return this;
+        }
+        return super.decodeSort(getEnumType(), defaultToEnd);
+    }
+    
+    /**
      * Creates and returns a new DBSetExpr object.
      *
      * @see org.apache.empire.db.expr.set.DBSetExpr
diff --git a/empire-db/src/main/java/org/apache/empire/db/DBColumnExpr.java 
b/empire-db/src/main/java/org/apache/empire/db/DBColumnExpr.java
index 61e6492..d8b850d 100644
--- a/empire-db/src/main/java/org/apache/empire/db/DBColumnExpr.java
+++ b/empire-db/src/main/java/org/apache/empire/db/DBColumnExpr.java
@@ -20,6 +20,7 @@ package org.apache.empire.db;
 
 import java.util.Collection;
 import java.util.HashMap;
+import java.util.LinkedHashMap;
 import java.util.Map;
 
 import org.apache.empire.commons.Attributes;
@@ -41,6 +42,7 @@ import org.apache.empire.db.expr.column.DBValueExpr;
 import org.apache.empire.db.expr.compare.DBCompareColExpr;
 import org.apache.empire.db.expr.compare.DBCompareExpr;
 import org.apache.empire.db.expr.order.DBOrderByExpr;
+import org.apache.empire.exceptions.InvalidArgumentException;
 import org.w3c.dom.Element;
 
 
@@ -1077,6 +1079,57 @@ public abstract class DBColumnExpr extends DBExpr
     }
 
     /**
+     * Creates and returns a sql-expression that maps enum values by name or 
ordinal to their string representation 
+     * 
+     * @param enumType an enumType to decode 
+     * @param otherwise the value to take if no key matches the given 
expression
+     * @param byOrdinal if true then the ordinal of the enum will be decoded 
otherwise the name
+     * @return a DBDecodeExpr object
+     */
+    public DBColumnExpr decodeEnum(Class<Enum<?>> enumType, Object otherwise, 
boolean byOrdinal)
+    {
+        if (enumType==null || !enumType.isEnum())
+            throw new InvalidArgumentException("enumType", enumType);
+        // create map
+        Enum<?>[] items = enumType.getEnumConstants();
+        Map<Object, String> enumMap = new LinkedHashMap<Object, 
String>(items.length);
+        for (int i=0; i<items.length; i++)
+        {   // key: ordinal (for numeric columns) or name (for CHAR columns)
+            Object key = (byOrdinal ? items[i].ordinal() : items[i].name());
+            enumMap.put(key, items[i].toString());
+        }
+        // Create the decode function
+        return new DBDecodeExpr(this, enumMap, otherwise, DataType.VARCHAR);
+    }
+
+    /**
+     * Creates and returns a sql-expression that maps enum values from name to 
ordinal
+     * This is useful for sorting.
+     * e.g. cmd.orderBy(SOME_EXPR.decodeSort(MyEnum.class, true) 
+     * 
+     * @param enumType an enumType to decode 
+     * @param defaultToEnd true if non matching values (e.g. NULL) should be 
assigned the highest number, otherwise they get the lowest number
+     * @return a DBDecodeExpr object
+     */
+    public DBColumnExpr decodeSort(Class<Enum<?>> enumType, boolean 
defaultToEnd)
+    {
+        if (enumType==null || !enumType.isEnum())
+            throw new InvalidArgumentException("enumType", enumType);
+        // create map
+        Enum<?>[] items = enumType.getEnumConstants();
+        Map<String, Integer> enumMap = new LinkedHashMap<String, 
Integer>(items.length);
+        int sortOffset = (defaultToEnd ? 0 : 1);
+        for (int i=0; i<items.length; i++)
+        {   
+            int sortValue = items[i].ordinal();
+            enumMap.put(items[i].name(), sortValue + sortOffset);
+        }
+        // Create the decode function
+        int defaultValue = (defaultToEnd ? items.length : 0);
+        return new DBDecodeExpr(this, enumMap, defaultValue, DataType.INTEGER);
+    }
+    
+    /**
      * Creates and returns a sql-expression that compares the current column 
expression with 
      * a list of values and returns the corresponding alternative value.<BR>
      *