Fix issue in parsing TRY_CAST() function (#1391)

* Fix issue in parsing TRY_CAST() function

* Fix issue in parsing TRY_CAST() function

* Add parser, deparser, validator and vistior implementation for try_cast function

* Update toString() method of TryCastExpression class

Author: prashantcsutar

pom.xml

@@ -43,6 +43,12 @@
         	<version>5.8.1</version>
         	<scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <version>5.7.1</version>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>org.mockito</groupId>
             <artifactId>mockito-core</artifactId>

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

@@ -115,6 +115,8 @@ public interface ExpressionVisitor {
 
     void visit(CastExpression cast);
 
+    void visit(TryCastExpression cast);
+
     void visit(Modulo modulo);
 
     void visit(AnalyticExpression aexpr);

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

@@ -304,6 +304,11 @@ public void visit(CastExpression expr) {
         expr.getLeftExpression().accept(this);
     }
 
+    @Override
+    public void visit(TryCastExpression expr) {
+        expr.getLeftExpression().accept(this);
+    }
+
     @Override
     public void visit(Modulo expr) {
         visitBinaryExpression(expr);

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

@@ -0,0 +1,95 @@
+/*-
+ * #%L
+ * JSQLParser library
+ * %%
+ * Copyright (C) 2004 - 2019 JSQLParser
+ * %%
+ * Dual licensed under GNU LGPL 2.1 or Apache License 2.0
+ * #L%
+ */
+package net.sf.jsqlparser.expression;
+
+import net.sf.jsqlparser.parser.ASTNodeAccessImpl;
+import net.sf.jsqlparser.statement.create.table.ColDataType;
+
+public class TryCastExpression extends ASTNodeAccessImpl implements Expression {
+
+    private Expression leftExpression;
+    private ColDataType type;
+    private RowConstructor rowConstructor;
+    private boolean useCastKeyword = true;
+
+    public RowConstructor getRowConstructor() {
+        return rowConstructor;
+    }
+
+    public void setRowConstructor(RowConstructor rowConstructor) {
+        this.rowConstructor = rowConstructor;
+        this.type = null;
+    }
+
+    public TryCastExpression withRowConstructor(RowConstructor rowConstructor) {
+        setRowConstructor(rowConstructor);
+        return this;
+    }
+
+    public ColDataType getType() {
+        return type;
+    }
+
+    public void setType(ColDataType type) {
+        this.type = type;
+        this.rowConstructor = null;
+    }
+
+    public Expression getLeftExpression() {
+        return leftExpression;
+    }
+
+    public void setLeftExpression(Expression expression) {
+        leftExpression = expression;
+    }
+
+    @Override
+    public void accept(ExpressionVisitor expressionVisitor) {
+        expressionVisitor.visit(this);
+    }
+
+    public boolean isUseCastKeyword() {
+        return useCastKeyword;
+    }
+
+    public void setUseCastKeyword(boolean useCastKeyword) {
+        this.useCastKeyword = useCastKeyword;
+    }
+
+    @Override
+    public String toString() {
+        if (useCastKeyword) {
+            return rowConstructor!=null
+              ? "TRY_CAST(" + leftExpression + " AS " + rowConstructor.toString() + ")"
+              : "TRY_CAST(" + leftExpression + " AS " + type.toString() + ")";
+        } else {
+            return leftExpression + "::" + type.toString();
+        }
+    }
+
+    public TryCastExpression withType(ColDataType type) {
+        this.setType(type);
+        return this;
+    }
+
+    public TryCastExpression withUseCastKeyword(boolean useCastKeyword) {
+        this.setUseCastKeyword(useCastKeyword);
+        return this;
+    }
+
+    public TryCastExpression withLeftExpression(Expression leftExpression) {
+        this.setLeftExpression(leftExpression);
+        return this;
+    }
+
+    public <E extends Expression> E getLeftExpression(Class<E> type) {
+        return type.cast(getLeftExpression());
+    }
+}

src/main/java/net/sf/jsqlparser/util/TablesNamesFinder.java

@@ -462,6 +462,11 @@ public void visit(CastExpression cast) {
         cast.getLeftExpression().accept(this);
     }
 
+    @Override
+    public void visit(TryCastExpression cast) {
+        cast.getLeftExpression().accept(this);
+    }
+
     @Override
     public void visit(Modulo modulo) {
         visitBinaryExpression(modulo);

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

@@ -599,6 +599,21 @@ public void visit(CastExpression cast) {
         }
     }
 
+    @Override
+    public void visit(TryCastExpression cast) {
+        if (cast.isUseCastKeyword()) {
+            buffer.append("TRY_CAST(");
+            cast.getLeftExpression().accept(this);
+            buffer.append(" AS ");
+            buffer.append( cast.getRowConstructor()!=null ? cast.getRowConstructor() : cast.getType() );
+            buffer.append(")");
+        } else {
+            cast.getLeftExpression().accept(this);
+            buffer.append("::");
+            buffer.append(cast.getType());
+        }
+    }
+
     @Override
     public void visit(Modulo modulo) {
         visitBinaryExpression(modulo, " % ");

src/main/java/net/sf/jsqlparser/util/validation/validator/ExpressionValidator.java

@@ -348,6 +348,11 @@ public void visit(CastExpression cast) {
         cast.getLeftExpression().accept(this);
     }
 
+    @Override
+    public void visit(TryCastExpression cast) {
+        cast.getLeftExpression().accept(this);
+    }
+
     @Override
     public void visit(Modulo modulo) {
         visitBinaryExpression(modulo, " % ");

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

@@ -153,7 +153,8 @@ TOKEN: /* SQL Keywords. prefixed with K_ to avoid name clashes */
 |   <K_CASCADE: "CASCADE">
 |   <K_CASE:"CASE">
 |   <K_CASEWHEN:"CASEWHEN">  /* H2 casewhen function */
-|   <K_CAST:"CAST">
+|   <K_CAST: "CAST">
+|   <K_TRY_CAST: "TRY_CAST">
 |   <K_CHARACTER:"CHARACTER">
 |   <K_CHANGE:"CHANGE">
 |   <K_CHECK:"CHECK">
@@ -1635,7 +1636,7 @@ String RelObjectNameWithoutValue() :
     (tk=<S_IDENTIFIER> | tk=<S_QUOTED_IDENTIFIER> 
       | tk=<K_ALGORITHM> | tk=<K_AT>
       | tk=<K_BYTE> | tk=<K_CHAR> | tk=<K_CHANGE> | tk=<K_CHARACTER>
-      | tk=<K_CAST> | tk=<K_COMMENT> | tk=<K_COSTS> | tk=<K_DISABLE> | tk=<K_DESC>
+      | tk=<K_CAST> | tk =<K_TRY_CAST> | tk=<K_COMMENT> | tk=<K_COSTS> | tk=<K_DISABLE> | tk=<K_DESC>
       | tk=<K_DO> | tk=<K_EXTRACT> | tk=<K_FILTER> | tk=<K_FIRST> | tk=<K_FOLLOWING> | tk=<K_JSON>
       | tk=<K_LAST> | tk=<K_LEADING> | tk=<K_MATERIALIZED> | tk=<K_NULLS> | tk=<K_PARTITION> | tk=<K_RANGE>
       | tk=<K_ROW> | tk=<K_ROWS> | tk=<K_SIBLINGS> | tk=<K_XML>
@@ -3692,6 +3693,8 @@ Expression PrimaryExpression() #PrimaryExpression:
 
         | LOOKAHEAD(2) retval=CastExpression()
 
+        | LOOKAHEAD(2) retval=TryCastExpression()
+
         //| LOOKAHEAD(2) retval=RowConstructor()
 
         // support timestamp expressions
@@ -4303,6 +4306,31 @@ CastExpression CastExpression():
     }
 }
 
+TryCastExpression TryCastExpression():
+{
+    TryCastExpression retval = new TryCastExpression();
+    ColDataType type = null;
+    RowConstructor rowConstructor = null;
+    Expression expression = null;
+    boolean    useCastKeyword;
+}
+{
+    <K_TRY_CAST>
+    "("
+    expression=SimpleExpression()
+    <K_AS> { retval.setUseCastKeyword(true); }
+    (
+        LOOKAHEAD(3) rowConstructor = RowConstructor() { retval.setRowConstructor(rowConstructor); }
+        | type=ColDataType() { retval.setType(type); }
+    )
+    ")"
+
+    {
+        retval.setLeftExpression(expression);
+        return retval;
+    }
+}
+
 Expression CaseWhenExpression() #CaseWhenExpression:
 {
     CaseExpression caseExp = new CaseExpression();

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

@@ -1756,6 +1756,32 @@ public void testCastTypeProblem2() throws JSQLParserException {
         assertSqlCanBeParsedAndDeparsed(stmt);
     }
 
+    @Test
+    public void testTryCast() throws JSQLParserException {
+        String stmt = "SELECT TRY_CAST(a AS varchar) FROM tabelle1";
+        assertSqlCanBeParsedAndDeparsed(stmt);
+        stmt = "SELECT CAST(a AS varchar2) FROM tabelle1";
+        assertSqlCanBeParsedAndDeparsed(stmt);
+    }
+
+    @Test
+    public void testTryCastInTryCast() throws JSQLParserException {
+        String stmt = "SELECT TRY_CAST(TRY_CAST(a AS numeric) AS varchar) FROM tabelle1";
+        assertSqlCanBeParsedAndDeparsed(stmt);
+    }
+
+    @Test
+    public void testTryCastInTryCast2() throws JSQLParserException {
+        String stmt = "SELECT TRY_CAST('test' + TRY_CAST(assertEqual AS numeric) AS varchar) FROM tabelle1";
+        assertSqlCanBeParsedAndDeparsed(stmt);
+    }
+
+    @Test
+    public void testTryCastTypeProblem() throws JSQLParserException {
+        String stmt = "SELECT TRY_CAST(col1 AS varchar (256)) FROM tabelle1";
+        assertSqlCanBeParsedAndDeparsed(stmt);
+    }
+
     @Test
     public void testMySQLHintStraightJoin() throws JSQLParserException {
         String stmt = "SELECT col FROM tbl STRAIGHT_JOIN tbl2 ON tbl.id = tbl2.id";