feat: parse PostgreSQL CREATE CAST, CREATE TRANSFORM, CREATE CONVERSION and ALTER CONVERSION (#2918)

CREATE CAST (source AS target) WITH FUNCTION f(args) | WITHOUT FUNCTION |
WITH INOUT [AS ASSIGNMENT | AS IMPLICIT], CREATE [OR REPLACE] TRANSFORM
FOR type LANGUAGE lang (FROM SQL WITH FUNCTION f, TO SQL WITH FUNCTION g),
CREATE [DEFAULT] CONVERSION name FOR 'enc' TO 'enc' FROM function and
ALTER CONVERSION name RENAME TO | OWNER TO | SET SCHEMA were unsupported
statements.

They parse to CreateCast, CreateTransform, CreateConversion and
AlterConversion. A cast and a transform are named by the CastSignature
and TransformSignature of DROP CAST and DROP TRANSFORM, and functions
are RoutineReference objects, read by the existing productions. The
statements are wired into the deparser, visitors, table finder,
validation (createCast, createTransform, createConversion and
alterConversion, enabled for PostgreSQL) and feature analysis.

With the PostgreSQL dialect these words start only these statements, so
forms the server reports as syntax errors are parse errors. In another
dialect and without one, a statement is read this way when it has
PostgreSQL's form, and statements of other products that start with the
same words, such as CREATE CAST (a AS b) WITH SPECIFIC FUNCTION f, stay
unsupported statements.

Signed-off-by: minleejae <mmj9808@gmail.com>

Author: minleejae

README.md

@@ -167,6 +167,7 @@ and missing syntax gets added on demand — [open an issue](https://github.com/J
 | **MySQL utility statements** | `EXPLAIN`/`DESCRIBE [ANALYZE] FORMAT = …` · `EXPLAIN FOR CONNECTION` · `DESCRIBE t col` · `PREPARE … FROM` · `EXECUTE … USING` · `DROP PREPARE` · `DO` |
 | **PostgreSQL administration** | `CREATE`/`ALTER EVENT TRIGGER` · `REINDEX` · `SECURITY LABEL` |
 | **PostgreSQL types and rules** | `CREATE TYPE` (shell, composite, enum, range and base types) · `ALTER TYPE` · `CREATE RULE` · `ALTER RULE` |
+| **PostgreSQL casts, transforms and conversions** | `CREATE CAST` · `DROP CAST` · `CREATE [OR REPLACE] TRANSFORM` · `DROP TRANSFORM` · `CREATE [DEFAULT] CONVERSION` · `ALTER CONVERSION` |
 | **PostgreSQL operators and aggregates** | `CREATE`/`ALTER OPERATOR` · `CREATE`/`ALTER OPERATOR CLASS` · `CREATE`/`ALTER OPERATOR FAMILY` · `CREATE`/`ALTER AGGREGATE` |
 | **Informix constraints** | `ALTER TABLE … ADD CONSTRAINT` with trailing constraint names for primary, unique, foreign and check constraints; enable with `parser.withDialect(Dialect.INFORMIX)` |
 | **Salesforce SOQL** | `INCLUDES` · `EXCLUDES` |

src/main/java/net/sf/jsqlparser/parser/feature/Feature.java

@@ -1036,6 +1036,30 @@ public enum Feature {
      * @see net.sf.jsqlparser.statement.alter.AlterRule
      */
     alterRule,
+    /**
+     * PostgreSQL "CREATE CAST" statement is allowed
+     *
+     * @see net.sf.jsqlparser.statement.create.cast.CreateCast
+     */
+    createCast,
+    /**
+     * PostgreSQL "CREATE TRANSFORM" statement is allowed
+     *
+     * @see net.sf.jsqlparser.statement.create.transform.CreateTransform
+     */
+    createTransform,
+    /**
+     * PostgreSQL "CREATE CONVERSION" statement is allowed
+     *
+     * @see net.sf.jsqlparser.statement.create.conversion.CreateConversion
+     */
+    createConversion,
+    /**
+     * PostgreSQL "ALTER CONVERSION" statement is allowed
+     *
+     * @see net.sf.jsqlparser.statement.alter.AlterConversion
+     */
+    alterConversion,
     /**
      * PostgreSQL "CREATE OPERATOR" statement is allowed
      *

src/main/java/net/sf/jsqlparser/statement/StatementFeatureVisitor.java

@@ -45,6 +45,10 @@
 import net.sf.jsqlparser.statement.alter.AlterOperatorFamily;
 import net.sf.jsqlparser.statement.alter.AlterAggregate;
 import net.sf.jsqlparser.statement.alter.AlterRule;
+import net.sf.jsqlparser.statement.create.cast.CreateCast;
+import net.sf.jsqlparser.statement.create.transform.CreateTransform;
+import net.sf.jsqlparser.statement.create.conversion.CreateConversion;
+import net.sf.jsqlparser.statement.alter.AlterConversion;
 import net.sf.jsqlparser.statement.alter.AlterServer;
 import net.sf.jsqlparser.statement.alter.AlterSession;
 import net.sf.jsqlparser.statement.alter.AlterStatistics;
@@ -1631,21 +1635,41 @@ public <S> Void visit(AlterRule statement, S context) {
         return schemaOnly();
     }
 
+    @Override
+    public <S> Void visit(CreateCast statement, S context) {
+        return schemaOnly();
+    }
+
     @Override
     public <S> Void visit(CreateOperator statement, S context) {
         return schemaOnly();
     }
 
+    @Override
+    public <S> Void visit(CreateTransform statement, S context) {
+        return schemaOnly();
+    }
+
     @Override
     public <S> Void visit(CreateOperatorClass statement, S context) {
         return schemaOnly();
     }
 
+    @Override
+    public <S> Void visit(CreateConversion statement, S context) {
+        return schemaOnly();
+    }
+
     @Override
     public <S> Void visit(CreateOperatorFamily statement, S context) {
         return schemaOnly();
     }
 
+    @Override
+    public <S> Void visit(AlterConversion statement, S context) {
+        return schemaOnly();
+    }
+
     @Override
     public <S> Void visit(CreateAggregate statement, S context) {
         return schemaOnly();

src/main/java/net/sf/jsqlparser/statement/StatementVisitor.java

@@ -33,6 +33,10 @@
 import net.sf.jsqlparser.statement.alter.AlterOperatorFamily;
 import net.sf.jsqlparser.statement.alter.AlterAggregate;
 import net.sf.jsqlparser.statement.alter.AlterRule;
+import net.sf.jsqlparser.statement.create.cast.CreateCast;
+import net.sf.jsqlparser.statement.create.transform.CreateTransform;
+import net.sf.jsqlparser.statement.create.conversion.CreateConversion;
+import net.sf.jsqlparser.statement.alter.AlterConversion;
 import net.sf.jsqlparser.statement.alter.AlterRoutine;
 import net.sf.jsqlparser.statement.alter.AlterTrigger;
 import net.sf.jsqlparser.statement.alter.AlterPolicy;
@@ -1262,6 +1266,38 @@ default void visit(AlterRule statement) {
         visit(statement, null);
     }
 
+    default <S> T visit(CreateCast statement, S context) {
+        return null;
+    }
+
+    default void visit(CreateCast statement) {
+        visit(statement, null);
+    }
+
+    default <S> T visit(CreateTransform statement, S context) {
+        return null;
+    }
+
+    default void visit(CreateTransform statement) {
+        visit(statement, null);
+    }
+
+    default <S> T visit(CreateConversion statement, S context) {
+        return null;
+    }
+
+    default void visit(CreateConversion statement) {
+        visit(statement, null);
+    }
+
+    default <S> T visit(AlterConversion statement, S context) {
+        return null;
+    }
+
+    default void visit(AlterConversion statement) {
+        visit(statement, null);
+    }
+
     default <S> T visit(CreateOperator statement, S context) {
         return null;
     }

src/main/java/net/sf/jsqlparser/statement/StatementVisitorAdapter.java

@@ -11,6 +11,10 @@
 
 import net.sf.jsqlparser.statement.alter.AlterRelation;
 import net.sf.jsqlparser.statement.alter.AlterRule;
+import net.sf.jsqlparser.statement.create.cast.CreateCast;
+import net.sf.jsqlparser.statement.create.transform.CreateTransform;
+import net.sf.jsqlparser.statement.create.conversion.CreateConversion;
+import net.sf.jsqlparser.statement.alter.AlterConversion;
 import net.sf.jsqlparser.statement.alter.AlterTablespace;
 import net.sf.jsqlparser.statement.alter.AlterPolicy;
 import net.sf.jsqlparser.statement.alter.AlterRoutine;
@@ -1294,4 +1298,24 @@ public <S> T visit(AlterRule statement, S context) {
         fromItemVisitor.visitFromItem(statement.getTable(), context);
         return null;
     }
+
+    @Override
+    public <S> T visit(CreateCast statement, S context) {
+        return null;
+    }
+
+    @Override
+    public <S> T visit(CreateTransform statement, S context) {
+        return null;
+    }
+
+    @Override
+    public <S> T visit(CreateConversion statement, S context) {
+        return null;
+    }
+
+    @Override
+    public <S> T visit(AlterConversion statement, S context) {
+        return null;
+    }
 }

src/main/java/net/sf/jsqlparser/statement/alter/AlterConversion.java

@@ -0,0 +1,130 @@
+/*-
+ * #%L
+ * JSQLParser library
+ * %%
+ * Copyright (C) 2004 - 2026 JSQLParser
+ * %%
+ * Dual licensed under GNU LGPL 2.1 or Apache License 2.0
+ * #L%
+ */
+package net.sf.jsqlparser.statement.alter;
+
+import net.sf.jsqlparser.parser.ASTNodeAccessImpl;
+import net.sf.jsqlparser.statement.Statement;
+import net.sf.jsqlparser.statement.StatementVisitor;
+
+/**
+ * PostgreSQL
+ * {@code ALTER CONVERSION name {RENAME TO new_name | OWNER TO role | SET SCHEMA schema}}. Names
+ * retain SQL identifier quoting.
+ */
+public class AlterConversion extends ASTNodeAccessImpl implements Statement {
+    public enum Action {
+        RENAME, OWNER, SET_SCHEMA
+    }
+
+    private String name;
+    private Action action;
+    private String newName;
+    private String owner;
+    private String schemaName;
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public AlterConversion withName(String name) {
+        setName(name);
+        return this;
+    }
+
+    public Action getAction() {
+        return action;
+    }
+
+    public void setAction(Action action) {
+        this.action = action;
+    }
+
+    public AlterConversion withAction(Action action) {
+        setAction(action);
+        return this;
+    }
+
+    public String getNewName() {
+        return newName;
+    }
+
+    public void setNewName(String newName) {
+        this.newName = newName;
+    }
+
+    public AlterConversion withNewName(String newName) {
+        setNewName(newName);
+        return this;
+    }
+
+    /**
+     * The new owner: a role name, {@code CURRENT_ROLE}, {@code CURRENT_USER} or
+     * {@code SESSION_USER}.
+     *
+     * @return the owner of {@code OWNER TO}
+     */
+    public String getOwner() {
+        return owner;
+    }
+
+    public void setOwner(String owner) {
+        this.owner = owner;
+    }
+
+    public AlterConversion withOwner(String owner) {
+        setOwner(owner);
+        return this;
+    }
+
+    public String getSchemaName() {
+        return schemaName;
+    }
+
+    public void setSchemaName(String schemaName) {
+        this.schemaName = schemaName;
+    }
+
+    public AlterConversion withSchemaName(String schemaName) {
+        setSchemaName(schemaName);
+        return this;
+    }
+
+    public StringBuilder appendTo(StringBuilder builder) {
+        builder.append("ALTER CONVERSION ").append(name);
+        switch (action) {
+            case RENAME:
+                builder.append(" RENAME TO ").append(newName);
+                break;
+            case OWNER:
+                builder.append(" OWNER TO ").append(owner);
+                break;
+            case SET_SCHEMA:
+                builder.append(" SET SCHEMA ").append(schemaName);
+                break;
+            default:
+                throw new IllegalStateException("Unknown conversion action: " + action);
+        }
+        return builder;
+    }
+
+    @Override
+    public String toString() {
+        return appendTo(new StringBuilder()).toString();
+    }
+
+    @Override
+    public <T, S> T accept(StatementVisitor<T> statementVisitor, S context) {
+        return statementVisitor.visit(this, context);
+    }
+}