initial work for DateAdd function

git-svn-id: https://svn.code.sf.net/p/jackcess/code/jackcess/trunk@1212 f203690c-595d-4dc9-a70b-905162fa7fd2

src/main/java/com/healthmarketscience/jackcess/impl/expr/DefaultDateFunctions.java

@@ -157,6 +157,49 @@ public class DefaultDateFunctions
     }
   });
 
+  public static final Function DATEADD = registerFunc(new Func3("DateAdd") {
+    @Override
+    protected Value eval3(EvalContext ctx,
+                          Value param1, Value param2, Value param3) {
+      if(param3.isNull()) {
+        return ValueSupport.NULL_VAL;
+      }
+
+      String intv = param1.getAsString(ctx).trim();
+      int val = param2.getAsLongInt(ctx);
+
+      int result = -1;
+      Calendar cal = nonNullToCalendar(ctx, param3);
+
+      // FIXME
+      if(intv.equalsIgnoreCase(INTV_YEAR)) {
+        cal.add(Calendar.YEAR, val);
+      } else if(intv.equalsIgnoreCase(INTV_QUARTER)) {
+        cal.add(Calendar.MONTH, val * 3);
+      } else if(intv.equalsIgnoreCase(INTV_MONTH)) {
+        cal.add(Calendar.MONTH, val);
+      } else if(intv.equalsIgnoreCase(INTV_DAY_OF_YEAR)) {
+        cal.add(Calendar.DAY_OF_YEAR, val);
+      } else if(intv.equalsIgnoreCase(INTV_DAY)) {
+        cal.add(Calendar.DAY_OF_YEAR, val);
+      } else if(intv.equalsIgnoreCase(INTV_WEEKDAY)) {
+        cal.add(Calendar.DAY_OF_WEEK, val);
+      } else if(intv.equalsIgnoreCase(INTV_WEEK)) {
+        cal.add(Calendar.WEEK_OF_YEAR, val);
+      } else if(intv.equalsIgnoreCase(INTV_HOUR)) {
+        cal.add(Calendar.HOUR, val);
+      } else if(intv.equalsIgnoreCase(INTV_MINUTE)) {
+        cal.add(Calendar.MINUTE, val);
+      } else if(intv.equalsIgnoreCase(INTV_SECOND)) {
+        cal.add(Calendar.SECOND, val);
+      } else {
+        throw new EvalException("Invalid interval " + intv);
+      }
+
+      return ValueSupport.toValue(cal);
+    }
+  });
+
   public static final Function NOW = registerFunc(new Func0("Now") {
     @Override
     protected Value eval0(EvalContext ctx) {

src/main/java/com/healthmarketscience/jackcess/impl/expr/ExpressionTokenizer.java

@@ -54,6 +54,9 @@ class ExpressionTokenizer
   private static final char EQUALS_CHAR = '=';
 
   // access times are based on this date (not the UTC base)
+  static final int BASE_DATE_YEAR = 1899;
+  static final int BASE_DATE_MONTH = 12;
+  static final int BASE_DATE_DAY = 30;
   private static final String BASE_DATE_PREFIX = "1899/12/30 ";
   private static final String BASE_DATE_FMT_PREFIX = "yyyy/M/d ";
 

src/main/java/com/healthmarketscience/jackcess/impl/expr/ValueSupport.java

@@ -18,10 +18,11 @@ package com.healthmarketscience.jackcess.impl.expr;
 
 import java.math.BigDecimal;
 import java.text.DateFormat;
+import java.util.Calendar;
 import java.util.Date;
 
-import com.healthmarketscience.jackcess.expr.LocaleContext;
 import com.healthmarketscience.jackcess.expr.EvalException;
+import com.healthmarketscience.jackcess.expr.LocaleContext;
 import com.healthmarketscience.jackcess.expr.Value;
 import com.healthmarketscience.jackcess.impl.ColumnImpl;
 
@@ -91,6 +92,23 @@ public class ValueSupport
                        ColumnImpl.fromDateDouble(dd, ctx.getCalendar())));
   }
 
+  public static Value toValue(Calendar cal) {
+    boolean hasTime = ((cal.get(Calendar.HOUR) != 0) ||
+                       (cal.get(Calendar.MINUTE) != 0) ||
+                       (cal.get(Calendar.SECOND) == 0));
+
+    boolean hasDate =
+      ((cal.get(Calendar.YEAR) != ExpressionTokenizer.BASE_DATE_YEAR) ||
+       ((cal.get(Calendar.MONTH) + 1) != ExpressionTokenizer.BASE_DATE_MONTH) ||
+       (cal.get(Calendar.DAY_OF_MONTH) == ExpressionTokenizer.BASE_DATE_DAY));
+
+    Value.Type type = (hasDate ?
+                       (hasTime ? Value.Type.DATE_TIME : Value.Type.DATE) :
+                       Value.Type.TIME);
+
+    return new DateTimeValue(type, cal.getTime());
+  }
+
   public static Value toValue(Value.Type type, Date d) {
     return new DateTimeValue(type, d);
   }