fixes #866

README.md

@@ -65,6 +65,7 @@ Also I would like to know about needed examples or documentation stuff.
 
 ## Extensions in the latest SNAPSHOT version 3.1
 
+* introduced **FILTER** expression for window functions
 * allow more complex expressions for **CASE**.
 * allowed **start** as object name as column name or table name
 * introduced more positions for **!** instead of **NOT**

src/main/java/net/sf/jsqlparser/expression/AnalyticExpression.java

@@ -35,6 +35,7 @@ public class AnalyticExpression extends ASTNodeAccessImpl implements Expression
     private AnalyticType type = AnalyticType.OVER;
     private boolean distinct = false;
     private boolean ignoreNulls = false;
+    private Expression filterExpression = null;
 
     public AnalyticExpression() {
     }
@@ -82,6 +83,8 @@ public KeepExpression getKeep() {
     public void setKeep(KeepExpression keep) {
         this.keep = keep;
     }
+
+
 
     public ExpressionList getPartitionExpressionList() {
         return partitionBy.getPartitionExpressionList();
@@ -189,6 +192,12 @@ public String toString() {
             b.append(keep.toString()).append(" ");
         }
 
+        if (filterExpression != null) {
+            b.append("FILTER (WHERE ");
+            b.append(filterExpression.toString());
+            b.append(") ");
+        }
+
         switch (type) {
             case WITHIN_GROUP:
                 b.append("WITHIN GROUP");
@@ -214,4 +223,11 @@ public void setAllColumns(boolean allColumns) {
         this.allColumns = allColumns;
     }
 
+    public Expression getFilterExpression() {
+        return filterExpression;
+    }
+
+    public void setFilterExpression(Expression filterExpression) {
+        this.filterExpression = filterExpression;
+    }
 }

src/main/java/net/sf/jsqlparser/util/deparser/ExpressionDeParser.java

@@ -642,6 +642,12 @@ public void visit(AnalyticExpression aexpr) {
             keep.accept(this);
             buffer.append(" ");
         }
+
+        if (aexpr.getFilterExpression() != null) {
+            buffer.append("FILTER (WHERE ");
+            aexpr.getFilterExpression().accept(this);
+            buffer.append(") ");
+        }
 
         switch (aexpr.getType()) {
             case WITHIN_GROUP:

src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt

@@ -175,6 +175,7 @@ TOKEN: /* SQL Keywords. prefixed with K_ to avoid name clashes */
 |   <K_EXPLAIN:"EXPLAIN">
 |   <K_EXTRACT:"EXTRACT">
 |   <K_FETCH:"FETCH">
+|   <K_FILTER: "FILTER">
 |   <K_FIRST: "FIRST">
 |   <K_FALSE: "FALSE">
 |   <K_FOLLOWING: "FOLLOWING">
@@ -3115,8 +3116,12 @@ AnalyticExpression AnalyticExpression(Function function) :
     //KeepExpression keep = null;
     //boolean distinct = false;
     boolean partitionByBrackets = false;
+    Expression filter = null;
 }
 {
+
+    [ <K_FILTER> "(" <K_WHERE> filter = Expression() ")" ]
+
     (<K_OVER> {retval.setType(AnalyticType.OVER);} 
         | <K_WITHIN> <K_GROUP> {retval.setType(AnalyticType.WITHIN_GROUP);} )
 
@@ -3130,6 +3135,7 @@ AnalyticExpression AnalyticExpression(Function function) :
         retval.setPartitionExpressionList(expressionList, partitionByBrackets);
         retval.setOrderByElements(olist);
         retval.setWindowElement(windowElement);
+        retval.setFilterExpression(filter);
     }
     ")"
     {

src/test/java/net/sf/jsqlparser/statement/select/SelectTest.java

@@ -1859,6 +1859,11 @@ public void testAnalyticFunctionProblem1b() throws JSQLParserException {
     public void testAnalyticFunctionIssue670() throws JSQLParserException {
         assertSqlCanBeParsedAndDeparsed("SELECT last_value(some_column IGNORE NULLS) OVER (PARTITION BY some_other_column_1, some_other_column_2 ORDER BY some_other_column_3 ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) column_alias FROM some_table");
     }
+
+    @Test
+    public void testAnalyticFunctionFilterIssue866() throws JSQLParserException {
+        assertSqlCanBeParsedAndDeparsed("SELECT COUNT(*) FILTER (WHERE name = 'Raj') OVER (PARTITION BY name ) FROM table");
+    }
 
     @Test
     public void testFunctionLeft() throws JSQLParserException {