fix: share SET assignment parsing and support MySQL character set selection (#2661)

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

Author: minleejae

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

@@ -26,6 +26,21 @@ public final class SetStatement implements Statement {
     private String effectParameter;
     private OnOffOptions onOffOptions;
 
+    /** Assignment punctuation; NONE also supports SET options and PostgreSQL value lists. */
+    public enum AssignmentOperator {
+        NONE(""), EQUALS("="), COLON_EQUALS(":=");
+
+        private final String token;
+
+        AssignmentOperator(String token) {
+            this.token = token;
+        }
+
+        public String getToken() {
+            return token;
+        }
+    }
+
     /** SQL Server options that share the SET option [, option] ON | OFF syntax. */
     public enum OnOffOption {
         QUOTED_IDENTIFIER, CONCAT_NULL_YIELDS_NULL, CURSOR_CLOSE_ON_COMMIT, ARITHABORT, ARITHIGNORE, FMTONLY, NOCOUNT, NOEXEC, NUMERIC_ROUNDABORT, PARSEONLY, ANSI_DEFAULTS, ANSI_NULL_DFLT_OFF, ANSI_NULL_DFLT_ON, ANSI_NULLS, ANSI_PADDING, ANSI_WARNINGS, FORCEPLAN, SHOWPLAN_ALL, SHOWPLAN_TEXT, SHOWPLAN_XML, IMPLICIT_TRANSACTIONS, REMOTE_PROC_TRANSACTIONS, XACT_ABORT;
@@ -99,8 +114,12 @@ public SetStatement(Object name, ExpressionList<?> value) {
     }
 
     public void add(Object name, ExpressionList<?> value, boolean useEqual) {
+        add(name, value, useEqual ? AssignmentOperator.EQUALS : AssignmentOperator.NONE);
+    }
+
+    public void add(Object name, ExpressionList<?> value, AssignmentOperator operator) {
         onOffOptions = null;
-        values.add(new NameExpr(name, value, useEqual));
+        values.add(new NameExpr(name, value, operator));
     }
 
     public void remove(int idx) {
@@ -112,7 +131,7 @@ public int getCount() {
     }
 
     public boolean isUseEqual(int idx) {
-        return values.get(idx).useEqual;
+        return values.get(idx).isUseEqual();
     }
 
     public boolean isUseEqual() {
@@ -129,10 +148,27 @@ public SetStatement withUseEqual(int idx, boolean useEqual) {
     }
 
     public SetStatement setUseEqual(int idx, boolean useEqual) {
-        values.get(idx).useEqual = useEqual;
+        values.get(idx).setUseEqual(useEqual);
         return this;
     }
 
+    public AssignmentOperator getAssignmentOperator(int idx) {
+        return values.get(idx).operator;
+    }
+
+    public AssignmentOperator getAssignmentOperator() {
+        return getAssignmentOperator(0);
+    }
+
+    public SetStatement setAssignmentOperator(int idx, AssignmentOperator operator) {
+        values.get(idx).operator = Objects.requireNonNull(operator, "operator");
+        return this;
+    }
+
+    public SetStatement setAssignmentOperator(AssignmentOperator operator) {
+        return setAssignmentOperator(0, operator);
+    }
+
     public SetStatement withUseEqual(boolean useEqual) {
         this.setUseEqual(useEqual);
         return this;
@@ -194,7 +230,10 @@ public StringBuilder appendTo(StringBuilder builder, Consumer<Expression> expres
 
     private static void appendAssignment(StringBuilder builder, NameExpr value,
             Consumer<Expression> expressionRenderer) {
-        builder.append(value.name).append(value.useEqual ? " = " : " ");
+        builder.append(value.name).append(" ");
+        if (value.operator != AssignmentOperator.NONE) {
+            builder.append(value.operator.getToken()).append(" ");
+        }
         if (value.expressions != null) {
             for (int i = 0; i < value.expressions.size(); i++) {
                 if (i > 0) {
@@ -251,12 +290,16 @@ public SetStatement withEffectParameter(String effectParameter) {
     static class NameExpr implements Serializable {
         Object name;
         ExpressionList expressions;
-        boolean useEqual;
+        AssignmentOperator operator;
 
         public NameExpr(Object name, ExpressionList<?> expressions, boolean useEqual) {
+            this(name, expressions, useEqual ? AssignmentOperator.EQUALS : AssignmentOperator.NONE);
+        }
+
+        public NameExpr(Object name, ExpressionList<?> expressions, AssignmentOperator operator) {
             this.name = name;
             this.expressions = expressions;
-            this.useEqual = useEqual;
+            this.operator = Objects.requireNonNull(operator, "operator");
         }
 
         public Object getName() {
@@ -276,11 +319,11 @@ public void setExpressions(ExpressionList<?> expressions) {
         }
 
         public boolean isUseEqual() {
-            return useEqual;
+            return operator == AssignmentOperator.EQUALS;
         }
 
         public void setUseEqual(boolean useEqual) {
-            this.useEqual = useEqual;
+            operator = useEqual ? AssignmentOperator.EQUALS : AssignmentOperator.NONE;
         }
     }
 }

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

@@ -4491,62 +4491,60 @@ SetStatement Set(): {
 }
 
 SetStatement SetAssignments(): {
-    Object name;
-    ExpressionList expList;
-    boolean useEqual = false;
-    SetStatement set;
-    Expression exp = null;
+    SetStatement set = new SetStatement();
+    Expression exp;
     Token tk = null;
-    String effectParameter = null;
 }
 {
-    [LOOKAHEAD(3) (tk = <K_LOCAL> | tk = <K_SESSION>) {effectParameter = tk.image; } ]
+    [LOOKAHEAD(3) (tk = <K_LOCAL> | tk = <K_SESSION>) { set.setEffectParameter(tk.image); } ]
+    SetAssignment(set)
     (
-        LOOKAHEAD(2)
-        <K_DATETIMELITERAL> <K_ZONE> { name = "Time Zone"; useEqual=false; }
-        |
-        (
-            name = UserVariable() ["=" { useEqual=true; } ]
-        )
-        |
-        (
-            name = IdentifierChain()
-            ["=" { useEqual=true; } ]
-        )
-    )
-    exp=Expression()
-    {
-        expList = new ExpressionList();
-        expList.add(exp);
-        set = new SetStatement(name, expList)
-            .withUseEqual(useEqual)
-            .withEffectParameter(effectParameter);
-    }
-
-    (
-        { useEqual=false; }
         ","
-        (LOOKAHEAD(3)
-            (
-                ( LOOKAHEAD(2)
-                    <K_DATETIMELITERAL> <K_ZONE> { name = "Time Zone"; useEqual=false; }
-                    |
-                    (name = RelObjectName() ["=" { useEqual=true; } ])
-                )
-                exp=Expression()
-                {
-                    expList = new ExpressionList();
-                    expList.add(exp);
-                    set.add(name, expList, useEqual);
-                }
-            )
-            |
-            exp=Expression() { expList.add(exp); }
-         )
+        ( LOOKAHEAD(3) SetAssignment(set)
+          | exp=Expression() { set.getExpressions(set.getCount() - 1).add(exp); } )
     )*
     { return set; }
 }
 
+/** The first and subsequent assignments use identical names and operators. */
+void SetAssignment(SetStatement set):
+{
+    Object name;
+    Expression expression;
+    SetStatement.AssignmentOperator operator = SetStatement.AssignmentOperator.NONE;
+}
+{
+    (
+    LOOKAHEAD({ (getToken(1).kind == K_CHARACTER && getToken(2).kind == K_SET)
+            || (isKeywordAhead("CHARSET") && !"=".equals(getToken(2).image)
+                && !":=".equals(getToken(2).image)) }) SetCharacterSet(set)
+    |
+    ( LOOKAHEAD(2) <K_DATETIMELITERAL> <K_ZONE> { name = "Time Zone"; }
+      | name=UserVariable()
+      | name=IdentifierChain() )
+    [ "=" { operator = SetStatement.AssignmentOperator.EQUALS; }
+      | ":=" { operator = SetStatement.AssignmentOperator.COLON_EQUALS; } ]
+    expression=Expression()
+    { set.add(name, new ExpressionList<Expression>(expression), operator); }
+    )
+}
+
+/** Character set selection has a single name or DEFAULT, not an arbitrary expression. */
+void SetCharacterSet(SetStatement set):
+{
+    String name;
+    Token value;
+    Expression expression;
+}
+{
+    ( <K_CHARACTER> <K_SET> { name = "CHARACTER SET"; }
+      | <S_IDENTIFIER> { name = "CHARSET"; } )
+    ( value=<S_CHAR_LITERAL> { expression = new StringValue(value.image); }
+      | (value=<S_IDENTIFIER> | value=<S_QUOTED_IDENTIFIER> | value=<K_DEFAULT>)
+        { expression = new Column(value.image); } )
+    { set.add(name, new ExpressionList<Expression>(expression), false); }
+}
+
 SetStatement SqlServerSetOnOffOptions(): {
     SetStatement set = new SetStatement();
     List<SetStatement.OnOffOption> options = new ArrayList<SetStatement.OnOffOption>();

src/test/java/net/sf/jsqlparser/statement/MySqlSetStatementTest.java

@@ -0,0 +1,122 @@
+/*-
+ * #%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;
+
+import net.sf.jsqlparser.expression.LongValue;
+import net.sf.jsqlparser.expression.operators.relational.ExpressionList;
+import net.sf.jsqlparser.parser.AbstractJSqlParser.Dialect;
+import net.sf.jsqlparser.parser.CCJSqlParserUtil;
+import net.sf.jsqlparser.statement.SetStatement.AssignmentOperator;
+import net.sf.jsqlparser.util.deparser.ExpressionDeParser;
+import net.sf.jsqlparser.util.deparser.SelectDeParser;
+import net.sf.jsqlparser.util.deparser.StatementDeParser;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class MySqlSetStatementTest {
+    private SetStatement parse(String sql) throws Exception {
+        return (SetStatement) CCJSqlParserUtil.parse(sql, p -> p.withDialect(Dialect.MYSQL));
+    }
+
+    @ParameterizedTest
+    @ValueSource(strings = {"SET @a := 1", "SET @a=1, @b:=2", "SET @a:=1, @b=2, @c:=3",
+            "SET @@session.sql_mode := ''", "SET SESSION sql_mode = ''",
+            "SET @a = (@b := 2), @c := 3", "SET CHARACTER SET utf8mb4",
+            "SET CHARACTER SET 'utf8mb4'", "SET CHARACTER SET DEFAULT", "SET CHARSET utf8mb4",
+            "SET CHARSET DEFAULT", "SET NAMES utf8mb4 COLLATE utf8mb4_bin",
+            "SET CHARSET DEFAULT, @a=1", "SET @a=1, CHARACTER SET utf8mb4"})
+    void preservesSetSyntax(String sql) throws Exception {
+        SetStatement statement = parse(sql);
+        StringBuilder output = new StringBuilder();
+        statement.accept(new StatementDeParser(output), null);
+        assertEquals(statement.toString(), output.toString());
+        assertEquals(statement.toString(), parse(output.toString()).toString());
+    }
+
+    @Test
+    void exposesEachAssignmentAndOperator() throws Exception {
+        SetStatement statement = parse("SET @a=1, @b:=2, @c=3");
+        assertEquals(3, statement.getCount());
+        assertEquals("@b", statement.getName(1).toString());
+        assertEquals(AssignmentOperator.COLON_EQUALS, statement.getAssignmentOperator(1));
+        assertEquals(1, statement.getExpressions(1).size());
+        assertInstanceOf(LongValue.class, statement.getExpressions(1).get(0));
+        statement.setExpressions(1, new ExpressionList<>(new LongValue(9)));
+        statement.setAssignmentOperator(2, AssignmentOperator.COLON_EQUALS);
+        assertEquals("SET @a = 1, @b := 9, @c := 3", statement.toString());
+        statement.setUseEqual(1, true);
+        assertEquals(AssignmentOperator.EQUALS, statement.getAssignmentOperator(1));
+        assertTrue(statement.isUseEqual(1));
+        statement.remove(0);
+        assertEquals("SET @b = 9, @c := 3", statement.toString());
+    }
+
+    @Test
+    void exposesCharsetSelectionAlongsideAssignments() throws Exception {
+        SetStatement statement = parse("SET @a=1, CHARACTER SET utf8mb4, @b:=2");
+        assertEquals(3, statement.getCount());
+        assertEquals("CHARACTER SET", statement.getName(1));
+        assertEquals(AssignmentOperator.NONE, statement.getAssignmentOperator(1));
+        assertEquals(AssignmentOperator.COLON_EQUALS, statement.getAssignmentOperator(2));
+    }
+
+    @Test
+    void keepsNestedAssignmentInItsValue() throws Exception {
+        SetStatement statement = parse("SET @a = (@b := 2), @c := 3");
+        assertEquals(2, statement.getCount());
+        assertEquals("@a", statement.getName().toString());
+        assertEquals(1, statement.getExpressions().size());
+        assertEquals("(@b := 2)", statement.getExpressions().get(0).toString());
+    }
+
+    @Test
+    void retainsPostgresqlValueListsAndLegacyApi() throws Exception {
+        SetStatement statement = (SetStatement) CCJSqlParserUtil.parse(
+                "SET search_path = public, extensions", p -> p.withDialect(Dialect.POSTGRESQL));
+        assertEquals(1, statement.getCount());
+        assertEquals(2, statement.getExpressions().size());
+        assertEquals("SET search_path = public, extensions", statement.toString());
+        SetStatement legacy = new SetStatement("x", new ExpressionList<>(new LongValue(1)));
+        assertEquals(AssignmentOperator.EQUALS, legacy.getAssignmentOperator());
+        legacy.setUseEqual(false);
+        assertEquals("SET x 1", legacy.toString());
+        legacy.setAssignmentOperator(AssignmentOperator.COLON_EQUALS);
+        assertEquals("SET x := 1", legacy.toString());
+    }
+
+    @Test
+    void visitsAllAssignmentValues() throws Exception {
+        List<Long> values = new java.util.ArrayList<>();
+        ExpressionDeParser expressions = new ExpressionDeParser() {
+            @Override
+            public <S> StringBuilder visit(LongValue value, S context) {
+                values.add(value.getValue());
+                return getBuilder().append(value.getValue() + 10);
+            }
+        };
+        StringBuilder output = new StringBuilder();
+        parse("SET @a:=1, @b=2").accept(
+                new StatementDeParser(expressions, new SelectDeParser(), output), null);
+        assertEquals(List.of(1L, 2L), values);
+        assertEquals("SET @a := 11, @b = 12", output.toString());
+    }
+
+    @ParameterizedTest
+    @ValueSource(strings = {"SET @a :=", "SET @a := 1,", "SET CHARACTER SET",
+            "SET CHARACTER SET utf8mb4 COLLATE utf8mb4_bin", "SET CHARSET DEFAULT,"})
+    void rejectsIncompleteAssignmentsAndInvalidCharsetClauses(String sql) {
+        assertThrows(Exception.class, () -> parse(sql));
+    }
+}