fixes #1429

Author: Tobias Warneke

README.md

@@ -56,6 +56,9 @@ Also I would like to know about needed examples or documentation stuff.
 
 ## Extensions in the latest SNAPSHOT version 4.3
 
+* moved to JUnit 5 as a test framework
+* added **IGNORE NULLS** to window functions
+
 Additionally, we have fixed many errors and improved the code quality and the test coverage.
 
 ## Extensions of JSqlParser releases

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

@@ -36,7 +36,8 @@ public class AnalyticExpression extends ASTNodeAccessImpl implements Expression
     private AnalyticType type = AnalyticType.OVER;
     private boolean distinct = false;
     private boolean unique = false;
-    private boolean ignoreNulls = false;
+    private boolean ignoreNulls = false;            //IGNORE NULLS inside function parameters
+    private boolean ignoreNullsOutside = false;     //IGNORE NULLS outside function parameters
     private Expression filterExpression = null;
     private WindowElement windowElement = null;
     private List<OrderByElement> funcOrderBy = null;
@@ -178,6 +179,14 @@ public void setIgnoreNulls(boolean ignoreNulls) {
         this.ignoreNulls = ignoreNulls;
     }
 
+    public boolean isIgnoreNullsOutside() {
+        return ignoreNullsOutside;
+    }
+
+    public void setIgnoreNullsOutside(boolean ignoreNullsOutside) {
+        this.ignoreNullsOutside = ignoreNullsOutside;
+    }
+
     @Override
     @SuppressWarnings({"PMD.CyclomaticComplexity", "PMD.NPathComplexity", "PMD.MissingBreakInSwitch"})
     public String toString() {
@@ -220,6 +229,10 @@ public String toString() {
             }
         }
 
+        if (isIgnoreNullsOutside()) {
+            b.append("IGNORE NULLS ");
+        }
+        
         switch (type) {
             case FILTER_ONLY:
                 return b.toString();

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

@@ -674,6 +674,10 @@ public void visit(AnalyticExpression aexpr) {
                 buffer.append(" ");
             }
         }
+        
+        if (aexpr.isIgnoreNullsOutside()) {
+            buffer.append("IGNORE NULLS ");
+        }
 
         switch (aexpr.getType()) {
             case FILTER_ONLY:

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

@@ -4184,7 +4184,7 @@ void windowFun(AnalyticExpression retval):{
          WindowElement windowElement = null;
          boolean partitionByBrackets = false;
 } {
-    (<K_OVER> {retval.setType(AnalyticType.OVER);}
+    ([<K_IGNORE> <K_NULLS> { retval.setIgnoreNullsOutside(true); } ] <K_OVER> {retval.setType(AnalyticType.OVER);}
         | <K_WITHIN> <K_GROUP> {retval.setType(AnalyticType.WITHIN_GROUP);} )
 
     "("

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

@@ -4972,4 +4972,9 @@ public void testLogicalExpressionSelectItemIssue1381() throws JSQLParserExceptio
     public void testKeywordAtIssue1414() throws JSQLParserException {
         assertSqlCanBeParsedAndDeparsed("SELECT * FROM table1 at");
     }
+    
+    @Test
+    public void testIgnoreNullsForWindowFunctionsIssue1429() throws JSQLParserException {
+        assertSqlCanBeParsedAndDeparsed("SELECT lag(mydata) IGNORE NULLS OVER (ORDER BY sortorder) AS previous_status FROM mytable");
+    }
 }