Fix[2306] - Adds support for Trino UDF

src/main/java/net/sf/jsqlparser/parser/ParserKeywordsUtils.java

@@ -124,6 +124,7 @@ public class ParserKeywordsUtils {
             {"PRIOR", RESTRICTED_ALIAS},
             {"PROCEDURE", RESTRICTED_ALIAS},
             {"PUBLIC", RESTRICTED_ALIAS},
+            {"RETURNS", RESTRICTED_JSQLPARSER},
             {"RETURNING", RESTRICTED_JSQLPARSER},
             {"RIGHT", RESTRICTED_SQL2016},
             {"SAMPLE", RESTRICTED_ALIAS},

src/main/java/net/sf/jsqlparser/statement/select/WithFunctionDeclaration.java

@@ -0,0 +1,107 @@
+/*-
+ * #%L
+ * JSQLParser library
+ * %%
+ * Copyright (C) 2004 - 2025 JSQLParser
+ * %%
+ * Dual licensed under GNU LGPL 2.1 or Apache License 2.0
+ * #L%
+ */
+package net.sf.jsqlparser.statement.select;
+
+import net.sf.jsqlparser.expression.Expression;
+
+import java.io.Serializable;
+import java.util.List;
+
+public class WithFunctionDeclaration implements Serializable {
+    private String functionName;
+    private List<WithFunctionParameter> parameters;
+    private String returnType;
+    private Expression returnExpression;
+
+    public WithFunctionDeclaration() {}
+
+    public WithFunctionDeclaration(String functionName, List<WithFunctionParameter> parameters,
+            String returnType, Expression returnExpression) {
+        this.functionName = functionName;
+        this.parameters = parameters;
+        this.returnType = returnType;
+        this.returnExpression = returnExpression;
+    }
+
+    public String getFunctionName() {
+        return functionName;
+    }
+
+    public void setFunctionName(String functionName) {
+        this.functionName = functionName;
+    }
+
+    public List<WithFunctionParameter> getParameters() {
+        return parameters;
+    }
+
+    public void setParameters(List<WithFunctionParameter> parameters) {
+        this.parameters = parameters;
+    }
+
+    public String getReturnType() {
+        return returnType;
+    }
+
+    public void setReturnType(String returnType) {
+        this.returnType = returnType;
+    }
+
+    public Expression getReturnExpression() {
+        return returnExpression;
+    }
+
+    public void setReturnExpression(Expression returnExpression) {
+        this.returnExpression = returnExpression;
+    }
+
+    public WithFunctionDeclaration withFunctionName(String functionName) {
+        this.setFunctionName(functionName);
+        return this;
+    }
+
+    public WithFunctionDeclaration withParameters(List<WithFunctionParameter> parameters) {
+        this.setParameters(parameters);
+        return this;
+    }
+
+    public WithFunctionDeclaration withReturnType(String returnType) {
+        this.setReturnType(returnType);
+        return this;
+    }
+
+    public WithFunctionDeclaration withReturnExpression(Expression returnExpression) {
+        this.setReturnExpression(returnExpression);
+        return this;
+    }
+
+    public StringBuilder appendTo(StringBuilder builder) {
+        builder
+                .append("FUNCTION ")
+                .append(functionName)
+                .append("(");
+        for (int i = 0; parameters != null && i < parameters.size(); i++) {
+            if (i > 0) {
+                builder.append(", ");
+            }
+            parameters.get(i).appendTo(builder);
+        }
+        return builder
+                .append(") RETURNS ")
+                .append(returnType)
+                .append(" RETURN ")
+                .append(returnExpression);
+    }
+
+    @Override
+    public String toString() {
+        return appendTo(new StringBuilder()).toString();
+    }
+}

src/main/java/net/sf/jsqlparser/statement/select/WithFunctionParameter.java

@@ -0,0 +1,59 @@
+/*-
+ * #%L
+ * JSQLParser library
+ * %%
+ * Copyright (C) 2004 - 2025 JSQLParser
+ * %%
+ * Dual licensed under GNU LGPL 2.1 or Apache License 2.0
+ * #L%
+ */
+package net.sf.jsqlparser.statement.select;
+
+import java.io.Serializable;
+
+public class WithFunctionParameter implements Serializable {
+    private String name;
+    private String type; // e.g., INT
+
+    public WithFunctionParameter() {}
+
+    public WithFunctionParameter(String name, String type) {
+        this.name = name;
+        this.type = type;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public WithFunctionParameter withName(String name) {
+        this.name = name;
+        return this;
+    }
+
+    public String getType() {
+        return type;
+    }
+
+    public void setType(String type) {
+        this.type = type;
+    }
+
+    public WithFunctionParameter withType(String type) {
+        this.type = type;
+        return this;
+    }
+
+    public StringBuilder appendTo(StringBuilder builder) {
+        return builder.append(name).append(" ").append(type);
+    }
+
+    @Override
+    public String toString() {
+        return appendTo(new StringBuilder()).toString();
+    }
+}

src/main/java/net/sf/jsqlparser/statement/select/WithItem.java

@@ -27,6 +27,7 @@ public class WithItem<K extends ParenthesedStatement> implements Serializable {
     private K statement;
     private Alias alias;
     private List<SelectItem<?>> withItemList;
+    private WithFunctionDeclaration withFunctionDeclaration;
     private boolean recursive = false;
     private boolean usingNot = false;
     private boolean materialized = false;
@@ -121,28 +122,46 @@ public void setWithItemList(List<SelectItem<?>> withItemList) {
         this.withItemList = withItemList;
     }
 
+    public WithFunctionDeclaration getWithFunctionDeclaration() {
+        return withFunctionDeclaration;
+    }
+
+    public void setWithFunctionDeclaration(WithFunctionDeclaration withFunctionDeclaration) {
+        this.withFunctionDeclaration = withFunctionDeclaration;
+    }
+
+    public WithItem<K> withWithFunctionDeclaration(
+            WithFunctionDeclaration withFunctionDeclaration) {
+        this.setWithFunctionDeclaration(withFunctionDeclaration);
+        return this;
+    }
+
     @Override
     public String toString() {
         StringBuilder builder = new StringBuilder();
-        builder.append(recursive ? "RECURSIVE " : "");
-        if (alias != null) {
-            builder.append(alias.getName());
-        }
-        if (withItemList != null) {
-            builder.append("(");
-            int size = withItemList.size();
-            for (int i = 0; i < size; i++) {
-                builder.append(withItemList.get(i)).append(i < size - 1 ? "," : "");
+        if (withFunctionDeclaration != null) {
+            builder.append(withFunctionDeclaration);
+        } else {
+            builder.append(recursive ? "RECURSIVE " : "");
+            if (alias != null) {
+                builder.append(alias.getName());
             }
-            builder.append(")");
-        }
-        builder.append(" AS ");
-        if (materialized) {
-            builder.append(usingNot
-                    ? "NOT MATERIALIZED "
-                    : "MATERIALIZED ");
+            if (withItemList != null) {
+                builder.append("(");
+                int size = withItemList.size();
+                for (int i = 0; i < size; i++) {
+                    builder.append(withItemList.get(i)).append(i < size - 1 ? "," : "");
+                }
+                builder.append(")");
+            }
+            builder.append(" AS ");
+            if (materialized) {
+                builder.append(usingNot
+                        ? "NOT MATERIALIZED "
+                        : "MATERIALIZED ");
+            }
+            builder.append(statement);
         }
-        builder.append(statement);
         return builder.toString();
     }
 

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

@@ -717,23 +717,27 @@ public <S> StringBuilder visit(SetOperationList list, S context) {
 
     @Override
     public <S> StringBuilder visit(WithItem<?> withItem, S context) {
-        if (withItem.isRecursive()) {
-            builder.append("RECURSIVE ");
-        }
-        builder.append(withItem.getAlias().getName());
-        if (withItem.getWithItemList() != null) {
-            builder.append(" ")
-                    .append(PlainSelect.getStringList(withItem.getWithItemList(), true, true));
-        }
-        builder.append(" AS ");
-        if (withItem.isMaterialized()) {
-            builder.append(withItem.isUsingNot()
-                    ? "NOT MATERIALIZED "
-                    : "MATERIALIZED ");
-        }
-        StatementDeParser statementDeParser =
-                new StatementDeParser((ExpressionDeParser) expressionVisitor, this, builder);
-        statementDeParser.deParse(withItem.getParenthesedStatement());
+        if (withItem.getWithFunctionDeclaration() == null) {
+            if (withItem.isRecursive()) {
+                builder.append("RECURSIVE ");
+            }
+            builder.append(withItem.getAlias().getName());
+            if (withItem.getWithItemList() != null) {
+                builder.append(" ")
+                        .append(PlainSelect.getStringList(withItem.getWithItemList(), true, true));
+            }
+            builder.append(" AS ");
+            if (withItem.isMaterialized()) {
+                builder.append(withItem.isUsingNot()
+                        ? "NOT MATERIALIZED "
+                        : "MATERIALIZED ");
+            }
+            StatementDeParser statementDeParser =
+                    new StatementDeParser((ExpressionDeParser) expressionVisitor, this, builder);
+            statementDeParser.deParse(withItem.getParenthesedStatement());
+        } else {
+            builder.append(withItem.getWithFunctionDeclaration().toString());
+        }
         return builder;
     }