fix: end column DEFAULT values before a top-level COLLATE

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

@@ -224,20 +224,46 @@ public class CCJSqlParser extends AbstractJSqlParser<CCJSqlParser> {
      */
     private boolean isSliceColonAhead() {
         Token colon = getToken(1);
-        if (subscriptOpenings.isEmpty() || !":".equals(colon.image)) {
-            return false;
-        }
-        int depth = 0;
-        for (Token t = subscriptOpenings.peek().next; t != null && t != colon; t = t.next) {
-            if (t.kind == K_CASE || "(".equals(t.image) || "[".equals(t.image)
-                    || "{".equals(t.image)) {
-                depth++;
-            } else if (t.kind == K_END || ")".equals(t.image) || "]".equals(t.image)
-                    || "}".equals(t.image)) {
-                depth--;
+        return !subscriptOpenings.isEmpty() && ":".equals(colon.image)
+                && TokenNesting.isTopLevelFrom(subscriptOpenings.peek().next, colon);
+    }
+
+    /**
+     * Token nesting checks shared by the lookaheads above and below. A nested class keeps its
+     * branches out of CCJSqlParser.class, whose constant pool is close to what JaCoCo can still
+     * instrument.
+     */
+    private static final class TokenNesting {
+        private TokenNesting() {}
+
+        /**
+         * Whether the target is not nested in brackets, braces, parentheses or a CASE expression
+         * opened from the first token on.
+         */
+        static boolean isTopLevelFrom(Token first, Token target) {
+            int depth = 0;
+            for (Token t = first; t != null && t != target; t = t.next) {
+                if (t.kind == K_CASE || "(".equals(t.image) || "[".equals(t.image)
+                        || "{".equals(t.image)) {
+                    depth++;
+                } else if (t.kind == K_END || ")".equals(t.image) || "]".equals(t.image)
+                        || "}".equals(t.image)) {
+                    depth--;
+                }
             }
+            return depth == 0;
         }
-        return depth == 0;
+    }
+
+    // first tokens of the enclosing column DEFAULT values: a COLLATE at their top level is the
+    // column's own attribute, as in MySQL's column_attribute and PostgreSQL's ColQualList
+    private final Deque<Token> columnDefaultStarts = new ArrayDeque<Token>();
+
+    /** Whether the pending COLLATE follows an unparenthesized column DEFAULT value. */
+    private boolean isColumnCollateAhead() {
+        Token collate = getToken(1);
+        return !columnDefaultStarts.isEmpty() && collate.kind == K_COLLATE
+                && TokenNesting.isTopLevelFrom(columnDefaultStarts.peek(), collate);
     }
 
     private Expression createOutputArgument(Expression argument) throws ParseException {
@@ -13149,7 +13175,7 @@ Expression PrimaryExpression() #PrimaryExpression:
     )
 
     [
-        LOOKAHEAD(2) <K_COLLATE> (token=<S_CHAR_LITERAL> | token=<S_QUOTED_IDENTIFIER> | token=<S_IDENTIFIER>) { retval = new CollateExpression(retval, token.image); }
+        LOOKAHEAD(2, { !isColumnCollateAhead() }) <K_COLLATE> (token=<S_CHAR_LITERAL> | token=<S_QUOTED_IDENTIFIER> | token=<S_IDENTIFIER>) { retval = new CollateExpression(retval, token.image); }
     ]
 
     [
@@ -16389,14 +16415,33 @@ ColumnOption ColumnDefinitionOption(): {
         LOOKAHEAD(<K_DEFAULT>) <K_DEFAULT> { option = ColumnOption.raw("DEFAULT"); }
         // Db2 permits an omitted default value. Keep these implicit defaults raw.
         [ LOOKAHEAD(2, { !(getToken(1).kind == K_NOT && getToken(2).kind == K_NULL) })
-            defaultExpression=Expression() { option = ColumnOption.defaultValue(defaultExpression); } ]
+            defaultExpression=ColumnDefaultValue() { option = ColumnOption.defaultValue(defaultExpression); } ]
         |
         parameter=ColumnDefinitionParameter()
         { option = ColumnOption.raw(parameter); }
     )
     { return option; }
 }
 
+/**
+ * An explicit column DEFAULT value. MySQL's DEFAULT literal and PostgreSQL's DEFAULT b_expr exclude
+ * COLLATE, so the value ends before a COLLATE at its top level, which is the column's own
+ * attribute. A COLLATE inside parentheses, function arguments or CASE stays in the expression.
+ */
+Expression ColumnDefaultValue():
+{
+    Expression expression;
+}
+{
+    { columnDefaultStarts.push(getToken(1)); }
+    try {
+        expression=Expression()
+    } finally {
+        columnDefaultStarts.pop();
+    }
+    { return expression; }
+}
+
 GeneratedColumnDefinition GeneratedColumnDefinition():
 {
     Expression expression;

src/site/sphinx/usage.rst

@@ -935,6 +935,18 @@ Charset remains in ``ColDataType.getCharacterSet()``; column collation is in its
 COLLATE option. Consumers can map both directly without reconstructing tokens.
 StringValue comment bodies retain their SQL escape representation.
 
+A column DEFAULT value ends before a COLLATE at its top level, which becomes the
+column's COLLATE option: MySQL's DEFAULT literal and PostgreSQL's DEFAULT ``b_expr``
+do not include COLLATE. A COLLATE inside parentheses, function arguments or a CASE
+expression stays in the default expression. ``SET DEFAULT`` actions and CREATE
+DOMAIN keep an expression COLLATE.
+
+Migration: ``DEFAULT 'N' COLLATE utf8mb4_bin`` in a column definition previously
+produced one DEFAULT option holding a ``CollateExpression``. It now produces a
+DEFAULT option with ``'N'`` and a COLLATE option with ``getCollation()``;
+``getColumnSpecs()`` returns ``[DEFAULT, 'N', COLLATE, utf8mb4_bin]``. SQL output
+is unchanged.
+
 MySQL column attributes have their own kinds: ``SRID`` (``getSrid()``),
 ``COLUMN_FORMAT`` (``getColumnFormat()``: FIXED, DYNAMIC or DEFAULT), and
 ``ENGINE_ATTRIBUTE``/``SECONDARY_ENGINE_ATTRIBUTE`` (``getEngineAttribute()``

src/test/java/net/sf/jsqlparser/statement/create/ColumnDefaultExpressionTest.java

@@ -9,36 +9,48 @@
  */
 package net.sf.jsqlparser.statement.create;
 
+import static net.sf.jsqlparser.test.TestUtils.assertSqlCanBeParsedAndDeparsed;
 import static net.sf.jsqlparser.util.validation.ValidationTestAsserts.validateNotAllowed;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertInstanceOf;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertThrows;
-
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
+import java.util.function.Consumer;
+import java.util.stream.Stream;
 import net.sf.jsqlparser.JSQLParserException;
+import net.sf.jsqlparser.expression.CollateExpression;
 import net.sf.jsqlparser.expression.Expression;
 import net.sf.jsqlparser.expression.ExpressionVisitorAdapter;
 import net.sf.jsqlparser.expression.LongValue;
+import net.sf.jsqlparser.expression.StringValue;
+import net.sf.jsqlparser.expression.operators.relational.ParenthesedExpressionList;
+import net.sf.jsqlparser.parser.AbstractJSqlParser.Dialect;
+import net.sf.jsqlparser.parser.CCJSqlParser;
 import net.sf.jsqlparser.parser.CCJSqlParserUtil;
 import net.sf.jsqlparser.parser.feature.Feature;
-import net.sf.jsqlparser.util.validation.feature.FeaturesAllowed;
-import net.sf.jsqlparser.parser.AbstractJSqlParser.Dialect;
 import net.sf.jsqlparser.statement.Statement;
 import net.sf.jsqlparser.statement.StatementVisitorAdapter;
 import net.sf.jsqlparser.statement.alter.Alter;
+import net.sf.jsqlparser.statement.alter.AlterDomain;
+import net.sf.jsqlparser.statement.alter.AlterRelation;
+import net.sf.jsqlparser.statement.create.domain.CreateDomain;
 import net.sf.jsqlparser.statement.create.table.ColumnDefinition;
 import net.sf.jsqlparser.statement.create.table.ColumnOption;
 import net.sf.jsqlparser.statement.create.table.CreateTable;
 import net.sf.jsqlparser.statement.select.SelectVisitorAdapter;
 import net.sf.jsqlparser.util.deparser.ExpressionDeParser;
 import net.sf.jsqlparser.util.deparser.SelectDeParser;
 import net.sf.jsqlparser.util.deparser.StatementDeParser;
+import net.sf.jsqlparser.util.validation.feature.FeaturesAllowed;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
 import org.junit.jupiter.params.provider.ValueSource;
 
 class ColumnDefaultExpressionTest {
@@ -161,6 +173,94 @@ void neighboringAndLegacyColumnOptionsStillRoundTrip(String sql) throws JSQLPars
         assertRoundTrip(CCJSqlParserUtil.parse(sql));
     }
 
+    @ParameterizedTest
+    @ValueSource(
+            strings = {"CREATE TABLE t (c VARCHAR(30) ", "ALTER TABLE t ADD COLUMN c VARCHAR(30) ",
+                    "ALTER TABLE t MODIFY COLUMN c VARCHAR(30) ",
+                    "ALTER TABLE t CHANGE COLUMN old_c c VARCHAR(30) "})
+    void collateAfterDefaultIsAColumnAttribute(String prefix) throws JSQLParserException {
+        String sql = prefix + "NOT NULL DEFAULT 'N' COLLATE utf8mb4_unicode_ci COMMENT 'flag'"
+                + (prefix.startsWith("CREATE") ? ")" : "");
+        List<Consumer<CCJSqlParser>> configurations = Arrays.asList(parser -> {
+        }, parser -> parser.withDialect(Dialect.MYSQL));
+        for (Consumer<CCJSqlParser> configuration : configurations) {
+            Statement statement = assertSqlCanBeParsedAndDeparsed(sql, true, configuration);
+            ColumnDefinition column = firstColumn(statement);
+            assertThat(column.getColumnOptions()).extracting(ColumnOption::getKind)
+                    .containsExactly(ColumnOption.Kind.NULLABILITY, ColumnOption.Kind.DEFAULT,
+                            ColumnOption.Kind.COLLATE, ColumnOption.Kind.COMMENT);
+            assertInstanceOf(StringValue.class, defaultOption(column).getDefaultExpression());
+            assertEquals("utf8mb4_unicode_ci", column.getColumnOptions().get(2).getCollation());
+            assertThat(column.getColumnSpecs()).containsExactly("NOT", "NULL", "DEFAULT", "'N'",
+                    "COLLATE", "utf8mb4_unicode_ci", "COMMENT", "'flag'");
+            assertRoundTrip(statement);
+        }
+    }
+
+    static Stream<Arguments> defaultValuesBeforeCollate() {
+        return Stream.of(Arguments.of(Dialect.MYSQL, "_utf8mb4'N'", "utf8mb4_bin"),
+                Arguments.of(Dialect.MYSQL, "'N'", "'utf8mb4_bin'"),
+                Arguments.of(Dialect.MYSQL, "1", "utf8mb4_bin"),
+                Arguments.of(Dialect.MYSQL, "-1", "utf8mb4_bin"),
+                Arguments.of(Dialect.POSTGRESQL, "'a' || 'b'", "\"C\""),
+                Arguments.of(Dialect.POSTGRESQL, "lower('A' COLLATE \"C\")", "\"C\""),
+                Arguments.of(Dialect.POSTGRESQL, "CASE WHEN true THEN 'a' END", "\"C\""),
+                Arguments.of(Dialect.POSTGRESQL, "'x'::text", "\"C\""),
+                Arguments.of(Dialect.POSTGRESQL, "'x'", "pg_catalog.\"default\""));
+    }
+
+    @ParameterizedTest
+    @MethodSource("defaultValuesBeforeCollate")
+    void defaultValueEndsBeforeTopLevelCollate(Dialect dialect, String value, String collation)
+            throws JSQLParserException {
+        String definition = " VARCHAR(30) DEFAULT " + value + " COLLATE " + collation + " NOT NULL";
+        String alter = dialect == Dialect.MYSQL ? "ALTER TABLE t MODIFY COLUMN c"
+                : "ALTER TABLE t ADD COLUMN c";
+        for (String sql : Arrays.asList("CREATE TABLE t (c" + definition + ")",
+                alter + definition)) {
+            ColumnDefinition column = firstColumn(assertSqlCanBeParsedAndDeparsed(sql, true,
+                    parser -> parser.withDialect(dialect)));
+            assertThat(column.getColumnOptions()).extracting(ColumnOption::getKind)
+                    .containsExactly(ColumnOption.Kind.DEFAULT, ColumnOption.Kind.COLLATE,
+                            ColumnOption.Kind.NULLABILITY);
+            assertEquals(value, defaultOption(column).getDefaultExpression().toString());
+            assertEquals(collation, column.getColumnOptions().get(1).getCollation());
+        }
+    }
+
+    @Test
+    void parenthesizedCollateStaysInTheDefaultValue() throws JSQLParserException {
+        ColumnDefinition column = firstColumn(assertSqlCanBeParsedAndDeparsed(
+                "ALTER TABLE t MODIFY COLUMN c VARCHAR(3) DEFAULT ('N' COLLATE utf8mb4_bin) NOT NULL",
+                true, parser -> parser.withDialect(Dialect.MYSQL)));
+        assertThat(column.getColumnOptions()).extracting(ColumnOption::getKind)
+                .containsExactly(ColumnOption.Kind.DEFAULT, ColumnOption.Kind.NULLABILITY);
+        Expression value = defaultOption(column).getDefaultExpression();
+        assertInstanceOf(ParenthesedExpressionList.class, value);
+        assertInstanceOf(CollateExpression.class, ((ParenthesedExpressionList<?>) value).get(0));
+    }
+
+    @Test
+    void setDefaultAndDomainDefaultsKeepTheExpressionCollate() throws JSQLParserException {
+        // PostgreSQL's SET DEFAULT takes an a_expr, which includes COLLATE. CREATE DOMAIN is
+        // unchanged.
+        Consumer<CCJSqlParser> postgres = parser -> parser.withDialect(Dialect.POSTGRESQL);
+        Alter table = (Alter) assertSqlCanBeParsedAndDeparsed(
+                "ALTER TABLE t ALTER COLUMN c SET DEFAULT 'x' COLLATE \"C\"", true, postgres);
+        assertInstanceOf(CollateExpression.class, table.getAlterExpressions().get(0)
+                .getColumnDefaults().get(0).getDefaultExpression());
+        AlterRelation view = (AlterRelation) assertSqlCanBeParsedAndDeparsed(
+                "ALTER VIEW v ALTER COLUMN c SET DEFAULT 'x' COLLATE \"C\"", true, postgres);
+        assertInstanceOf(CollateExpression.class,
+                view.getActions().get(0).getDefaultExpression());
+        AlterDomain alterDomain = (AlterDomain) assertSqlCanBeParsedAndDeparsed(
+                "ALTER DOMAIN d SET DEFAULT 'x' COLLATE \"C\"", true, postgres);
+        assertInstanceOf(CollateExpression.class, alterDomain.getDefaultExpression());
+        CreateDomain createDomain = (CreateDomain) assertSqlCanBeParsedAndDeparsed(
+                "CREATE DOMAIN d AS text DEFAULT 'x' COLLATE \"C\"", true, postgres);
+        assertInstanceOf(CollateExpression.class, createDomain.getDefaultExpression());
+    }
+
     @ParameterizedTest
     @ValueSource(strings = {"CREATE TABLE t (a INT DEFAULT (1 + 2",
             "CREATE TABLE t (a INT DEFAULT (1 +))",