Add support for both preceding or both following bounds

h2/src/docsrc/help/help.csv

@@ -2551,7 +2551,7 @@ They also may require a lot of memory for large queries.
 
 "Other Grammar","Window frame","
 ROWS|RANGE|GROUP
-{windowFramePreceding|BETWEEN windowFramePreceding AND windowFrameFollowing}
+{windowFramePreceding|BETWEEN windowFrameBound AND windowFrameBound}
 [EXCLUDE {CURRENT ROW|GROUP|TIES|NO OTHERS}]
 ","
 A window frame clause.
@@ -2571,12 +2571,14 @@ UNBOUNDED PRECEDING
 CURRENT ROW
 "
 
-"Other Grammar","Window frame following","
-UNBOUNDED FOLLOWING|value FOLLOWING|CURRENT ROW
+"Other Grammar","Window frame bound","
+UNBOUNDED PRECEDING|value PRECEDING|CURRENT ROW
+    |value FOLLOWING|UNBOUNDED FOLLOWING
 ","
-A window frame following clause.
+A window frame bound clause.
 If value is specified it should be non-negative value or parameter.
 ","
+UNBOUNDED PRECEDING
 UNBOUNDED FOLLOWING
 1 FOLLOWING
 CURRENT ROW

h2/src/main/org/h2/command/Parser.java

@@ -177,7 +177,7 @@ import org.h2.expression.aggregate.JavaAggregate;
 import org.h2.expression.aggregate.Window;
 import org.h2.expression.aggregate.WindowFrame;
 import org.h2.expression.aggregate.WindowFrameBound;
-import org.h2.expression.aggregate.WindowFrameBound.WindowFrameBoundType;
+import org.h2.expression.aggregate.WindowFrameBoundType;
 import org.h2.expression.aggregate.WindowFrameExclusion;
 import org.h2.expression.aggregate.WindowFrameUnits;
 import org.h2.expression.aggregate.WindowFunction;
@@ -3105,9 +3105,9 @@ public class Parser {
         }
         WindowFrameBound starting, following;
         if (readIf("BETWEEN")) {
-            starting = readWindowFrameStarting();
+            starting = readWindowFrameRange();
             read("AND");
-            following = readWindowFrameFollowing();
+            following = readWindowFrameRange();
         } else {
             starting = readWindowFrameStarting();
             following = null;
@@ -3132,7 +3132,7 @@ public class Parser {
     private WindowFrameBound readWindowFrameStarting() {
         if (readIf("UNBOUNDED")) {
             read("PRECEDING");
-            return new WindowFrameBound(WindowFrameBoundType.UNBOUNDED, null);
+            return new WindowFrameBound(WindowFrameBoundType.UNBOUNDED_PRECEDING, null);
         }
         if (readIf("CURRENT")) {
             read("ROW");
@@ -3140,21 +3140,27 @@ public class Parser {
         }
         Expression value = readValueOrParameter();
         read("PRECEDING");
-        return new WindowFrameBound(WindowFrameBoundType.VALUE, value);
+        return new WindowFrameBound(WindowFrameBoundType.PRECEDING, value);
     }
 
-    private WindowFrameBound readWindowFrameFollowing() {
+    private WindowFrameBound readWindowFrameRange() {
         if (readIf("UNBOUNDED")) {
+            if (readIf("PRECEDING")) {
+                return new WindowFrameBound(WindowFrameBoundType.UNBOUNDED_PRECEDING, null);
+            }
             read("FOLLOWING");
-            return new WindowFrameBound(WindowFrameBoundType.UNBOUNDED, null);
+            return new WindowFrameBound(WindowFrameBoundType.UNBOUNDED_FOLLOWING, null);
         }
         if (readIf("CURRENT")) {
             read("ROW");
             return new WindowFrameBound(WindowFrameBoundType.CURRENT_ROW, null);
         }
         Expression value = readValueOrParameter();
+        if (readIf("PRECEDING")) {
+            return new WindowFrameBound(WindowFrameBoundType.PRECEDING, value);
+        }
         read("FOLLOWING");
-        return new WindowFrameBound(WindowFrameBoundType.VALUE, value);
+        return new WindowFrameBound(WindowFrameBoundType.FOLLOWING, value);
     }
 
     private Expression readValueOrParameter() {

h2/src/main/org/h2/expression/aggregate/Window.java

@@ -10,7 +10,6 @@ import java.util.ArrayList;
 import org.h2.command.dml.SelectOrderBy;
 import org.h2.engine.Session;
 import org.h2.expression.Expression;
-import org.h2.expression.aggregate.WindowFrameBound.WindowFrameBoundType;
 import org.h2.result.SortOrder;
 import org.h2.table.ColumnResolver;
 import org.h2.table.TableFilter;
@@ -66,8 +65,9 @@ public final class Window {
         this.partitionBy = partitionBy;
         this.orderBy = orderBy;
         if (frame == null) {
-            frame = new WindowFrame(WindowFrameUnits.RANGE, new WindowFrameBound(WindowFrameBoundType.UNBOUNDED, null),
-                    null, WindowFrameExclusion.EXCLUDE_NO_OTHERS);
+            frame = new WindowFrame(WindowFrameUnits.RANGE,
+                    new WindowFrameBound(WindowFrameBoundType.UNBOUNDED_PRECEDING, null), null,
+                    WindowFrameExclusion.EXCLUDE_NO_OTHERS);
         }
         this.frame = frame;
     }

h2/src/main/org/h2/expression/aggregate/WindowFrameBound.java

@@ -6,35 +6,12 @@
 package org.h2.expression.aggregate;
 
 import org.h2.expression.Expression;
-import org.h2.message.DbException;
 
 /**
  * Window frame bound.
  */
 public class WindowFrameBound {
 
-    /**
-     * Window frame bound type.
-     */
-    public enum WindowFrameBoundType {
-
-    /**
-     * UNBOUNDED PRECEDING or UNBOUNDED FOLLOWING clause.
-     */
-    UNBOUNDED,
-
-    /**
-     * CURRENT_ROW clause.
-     */
-    CURRENT_ROW,
-
-    /**
-     * PRECEDING or FOLLOWING clause.
-     */
-    VALUE;
-
-    }
-
     private final WindowFrameBoundType type;
 
     private final Expression value;
@@ -49,7 +26,7 @@ public class WindowFrameBound {
      */
     public WindowFrameBound(WindowFrameBoundType type, Expression value) {
         this.type = type;
-        if (type == WindowFrameBoundType.VALUE) {
+        if (type == WindowFrameBoundType.PRECEDING || type == WindowFrameBoundType.FOLLOWING) {
             this.value = value;
         } else {
             this.value = null;
@@ -84,16 +61,10 @@ public class WindowFrameBound {
      * @see Expression#getSQL()
      */
     public String getSQL(boolean following) {
-        switch (type) {
-        case UNBOUNDED:
-            return following ? "UNBOUNDED FOLLOWING" : "UNBOUNDED PRECEDING";
-        case CURRENT_ROW:
-            return "CURRENT ROW";
-        case VALUE:
-            return value.getSQL() + (following ? " FOLLOWING" : " PRECEDING");
-        default:
-            throw DbException.throwInternalError("type=" + type);
+        if (type == WindowFrameBoundType.PRECEDING || type == WindowFrameBoundType.FOLLOWING) {
+            return value.getSQL() + ' ' + type.getSQL();
         }
+        return type.getSQL();
     }
 
 }

h2/src/main/org/h2/expression/aggregate/WindowFrameBoundType.java

+/*
+ * Copyright 2004-2018 H2 Group. Multiple-Licensed under the MPL 2.0,
+ * and the EPL 1.0 (http://h2database.com/html/license.html).
+ * Initial Developer: H2 Group
+ */
+package org.h2.expression.aggregate;
+
+/**
+ * Window frame bound type.
+ */
+public enum WindowFrameBoundType {
+
+    /**
+     * UNBOUNDED PRECEDING clause.
+     */
+    UNBOUNDED_PRECEDING("UNBOUNDED PRECEDING"),
+
+    /**
+     * PRECEDING clause.
+     */
+    PRECEDING("PRECEDING"),
+
+    /**
+     * CURRENT_ROW clause.
+     */
+    CURRENT_ROW("CURRENT_ROW"),
+
+    /**
+     * FOLLOWING clause.
+     */
+    FOLLOWING("FOLLOWING"),
+
+    /**
+     * UNBOUNDED FOLLOWING clause.
+     */
+    UNBOUNDED_FOLLOWING("UNBOUNDED FOLLOWING");
+
+    private final String sql;
+
+    private WindowFrameBoundType(String sql) {
+        this.sql = sql;
+    }
+
+    /**
+     * Returns SQL representation.
+     *
+     * @return SQL representation.
+     * @see org.h2.expression.Expression#getSQL()
+     */
+    public String getSQL() {
+        return sql;
+    }
+
+}

h2/src/test/org/h2/test/scripts/functions/aggregate/array-agg.sql

@@ -314,5 +314,17 @@ SELECT *,
 SELECT *, ARRAY_AGG(ID) OVER (ORDER BY VALUE ROWS -1 PRECEDING) FROM TEST;
 > exception INVALID_VALUE_2
 
+SELECT *, ARRAY_AGG(ID) OVER (ORDER BY ID ROWS BETWEEN 2 PRECEDING AND 1 PRECEDING) FROM TEST FETCH FIRST 4 ROWS ONLY;
+> ID VALUE ARRAY_AGG(ID) OVER (ORDER BY ID ROWS BETWEEN 2 PRECEDING AND 1 PRECEDING)
+> -- ----- -------------------------------------------------------------------------
+> 1  1     null
+> 2  1     (1)
+> 3  5     (1, 2)
+> 4  8     (2, 3)
+> rows (ordered): 4
+
+SELECT *, ARRAY_AGG(ID) OVER (ORDER BY ID RANGE BETWEEN CURRENT ROW AND 1 PRECEDING) FROM TEST;
+> exception SYNTAX_ERROR_1
+
 DROP TABLE TEST;
 > ok