Array literals with zero or one element were not be parsed correctly.

h2/src/docsrc/help/help.csv

@@ -1506,11 +1506,14 @@ ID=1 AND NAME='Hi'
 "
 
 "Other Grammar","Array","
-( expression [,...] )
+( [ expression, [ expression [,...] ] ] )
 ","
-An array of values.
+An array of values. An empty array is '()'. Trailing commas are ignored.
+An array with one element must contain a comma to be parsed as an array.
 ","
 (1, 2)
+(1, )
+()
 "
 
 "Other Grammar","Boolean","

h2/src/docsrc/html/changelog.html

@@ -18,7 +18,10 @@ Change Log
 <h1>Change Log</h1>
 
 <h2>Next Version (unreleased)</h2>
-<ul><li>Issue 290: Conditions using subqueries were sometimes evaluated before much simpler conditions,
+<ul><li>Array literals with zero or one element were not be parsed correctly.
+    Now trailing commas are ignored (as in Java). Expressions of the form '(1)' are still parsed as the value 1.
+    An empty array is '()'. An array with one element must contain a comma to be parsed as an array, as in '(1,)'. 
+</li><li>Issue 290: Conditions using subqueries were sometimes evaluated before much simpler conditions,
     which was very bad for performance. This includes subqueries returning a value, EXISTS subqueries,
     and IN(SELECT ..) subqueries.
 </li><li>Issue 288: Some queries with right outer joins or nested joins could throw a NullPointerException.

h2/src/docsrc/html/roadmap.html

@@ -561,6 +561,7 @@ See also <a href="build.html#providing_patches">Providing Patches</a>.
 </li><li>Optimization for large lists for column IN(1, 2, 3, 4,...) - currently an list is used, could potentially use a hash set
     (maybe only for a part of the values - the ones that can be evaluated).
 </li><li>Compatibility for ARRAY data type (Oracle: VARRAY(n) of VARCHAR(m); HSQLDB: VARCHAR(n) ARRAY; Postgres: VARCHAR(n)[]).
+</li><li>PostgreSQL compatible array literal syntax: ARRAY[['breakfast', 'consulting'], ['meeting', 'lunch']]
 </li></ul>
 
 <h2>Not Planned</h2>

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

@@ -2482,19 +2482,28 @@ public class Parser {
             break;
         case OPEN:
             read();
+            if (readIf(")")) {
+                r = ExpressionList.EMPTY;
+            } else {
                 r = readExpression();
                 if (readIf(",")) {
                     ArrayList<Expression> list = New.arrayList();
                     list.add(r);
-                do {
+                    while (!readIf(")")) {
                         r = readExpression();
                         list.add(r);
-                } while (readIf(","));
+                        if (!readIf(",")) {
+                            read(")");
+                            break;
+                        }
+                    }
                     Expression[] array = new Expression[list.size()];
                     list.toArray(array);
                     r = new ExpressionList(array);
-            }
+                } else {
                     read(")");
+                }
+            }
             break;
         case TRUE:
             read();

h2/src/main/org/h2/expression/ExpressionList.java

@@ -20,6 +20,8 @@ import org.h2.value.ValueArray;
  */
 public class ExpressionList extends Expression {
 
+    public static final ExpressionList EMPTY = new ExpressionList(new Expression[0]);
+
     private Expression[] list;
 
     public ExpressionList(Expression[] list) {
@@ -83,6 +85,9 @@ public class ExpressionList extends Expression {
             buff.appendExceptFirst(", ");
             buff.append(e.getSQL());
         }
+        if (list.length == 1) {
+            buff.append(',');
+        }
         return buff.append(')').toString();
     }
 

h2/src/main/org/h2/value/ValueArray.java

@@ -15,6 +15,9 @@ import org.h2.util.StatementBuilder;
  * Implementation of the ARRAY data type.
  */
 public class ValueArray extends Value {
+
+    private static final ValueArray EMPTY = new ValueArray(new Value[0]);
+
     private final Value[] values;
     private int hash;
 
@@ -30,7 +33,7 @@ public class ValueArray extends Value {
      * @return the value
      */
     public static ValueArray get(Value[] list) {
-        return new ValueArray(list);
+        return list.length == 0 ? EMPTY : new ValueArray(list);
     }
 
     public int hashCode() {
@@ -104,6 +107,9 @@ public class ValueArray extends Value {
             buff.appendExceptFirst(", ");
             buff.append(v.getSQL());
         }
+        if (values.length == 1) {
+            buff.append(',');
+        }
         return buff.append(')').toString();
     }
 

h2/src/test/org/h2/test/test-1.3.txt

 --- special grammar and test cases ---------------------------------------------------------------------------------------------
+select () empty;
+> EMPTY
+> -----
+> ()
+> rows: 1
+
+select (1,) one_element;
+> ONE_ELEMENT
+> -----------
+> (1)
+> rows: 1
+
+select (1) one;
+> ONE
+> ---
+> 1
+> rows: 1
+
 create table test(id int);
 > ok