sqlparser: Give CASE a higher precedence

sqlparser/lib/src/reader/parser/expressions.dart

@@ -1,6 +1,10 @@
 part of 'parser.dart';
 
-/// Parses expressions. Expressions have the following precedence:
+/// Parses expressions. Expressions have the following precedence, in descending
+/// order
+/// - primary expressions: Parenthesis, etc.
+/// - Case expressions
+/// - postfix expressions: NOT NULL, etc.
 /// - `-`, `+`, `~`, unary not
 /// - `||` (concatenation)
 /// - `*`, '/', '%'
@@ -11,40 +15,9 @@ part of 'parser.dart';
 ///   `REGEXP`
 /// - `AND`
 /// - `OR`
-/// - Case expressions
 mixin ExpressionParser on ParserBase {
   @override
   Expression expression() {
-    return _case();
-  }
-
-  Expression _case() {
-    if (_matchOne(TokenType.$case)) {
-      final caseToken = _previous;
-
-      final base = _check(TokenType.when) ? null : _or();
-      final whens = <WhenComponent>[];
-      Expression $else;
-
-      while (_matchOne(TokenType.when)) {
-        final whenToken = _previous;
-
-        final whenExpr = _or();
-        _consume(TokenType.then, 'Expected THEN');
-        final then = expression();
-        whens.add(WhenComponent(when: whenExpr, then: then)
-          ..setSpan(whenToken, _previous));
-      }
-
-      if (_matchOne(TokenType.$else)) {
-        $else = expression();
-      }
-
-      _consume(TokenType.end, 'Expected END to finish the case operator');
-      return CaseExpression(whens: whens, base: base, elseExpr: $else)
-        ..setSpan(caseToken, _previous);
-    }
-
     return _or();
   }
 
@@ -205,7 +178,7 @@ mixin ExpressionParser on ParserBase {
   }
 
   Expression _postfix() {
-    var expression = _primary();
+    var expression = _case();
 
     // todo we don't currently parse "NOT NULL" (2 tokens) because of ambiguity
     // with NOT BETWEEN / NOT IN / ... expressions
@@ -245,6 +218,36 @@ mixin ExpressionParser on ParserBase {
     return expression;
   }
 
+  Expression _case() {
+    if (_matchOne(TokenType.$case)) {
+      final caseToken = _previous;
+
+      final base = _check(TokenType.when) ? null : _primary();
+      final whens = <WhenComponent>[];
+      Expression $else;
+
+      while (_matchOne(TokenType.when)) {
+        final whenToken = _previous;
+
+        final whenExpr = _or();
+        _consume(TokenType.then, 'Expected THEN');
+        final then = expression();
+        whens.add(WhenComponent(when: whenExpr, then: then)
+          ..setSpan(whenToken, _previous));
+      }
+
+      if (_matchOne(TokenType.$else)) {
+        $else = expression();
+      }
+
+      _consume(TokenType.end, 'Expected END to finish the case operator');
+      return CaseExpression(whens: whens, base: base, elseExpr: $else)
+        ..setSpan(caseToken, _previous);
+    }
+
+    return _primary();
+  }
+
   @override
   Literal _literalOrNull() {
     final token = _peek;

sqlparser/test/parser/regression_891_test.dart

@@ -0,0 +1,82 @@
+import 'package:sqlparser/sqlparser.dart';
+import 'package:test/test.dart';
+
+import 'utils.dart';
+
+void main() {
+  final caseExpr = CaseExpression(
+    whens: [
+      WhenComponent(
+        when: BinaryExpression(
+          NumericLiteral(1, token(TokenType.numberLiteral)),
+          token(TokenType.equal),
+          ColonNamedVariable(
+            ColonVariableToken(null, ':isReviewFolderSelected'),
+          ),
+        ),
+        then: IsExpression(
+          true,
+          Reference(tableName: 'n', columnName: 'nextReviewTime'),
+          NullLiteral(token(TokenType.$null)),
+        ),
+      ),
+    ],
+    elseExpr: IsExpression(
+      false,
+      Reference(tableName: 'n', columnName: 'nextReviewTime'),
+      NullLiteral(token(TokenType.$null)),
+    ),
+  );
+
+  final folderExpr = BinaryExpression(
+    Reference(tableName: 'n', columnName: 'folderId'),
+    token(TokenType.equal),
+    ColonNamedVariable(
+      ColonVariableToken(null, ':selectedFolderId'),
+    ),
+  );
+
+  test('repro 1', () {
+    testStatement(
+      '''
+      SELECT * FROM notes n WHERE 
+        CASE 
+          WHEN 1 = :isReviewFolderSelected THEN n.nextReviewTime IS NOT NULL
+          ELSE n.nextReviewTime IS NULL
+         END
+         and n.folderId = :selectedFolderId;
+      ''',
+      SelectStatement(
+        from: TableReference('notes', 'n'),
+        columns: [StarResultColumn()],
+        where: BinaryExpression(
+          caseExpr,
+          token(TokenType.and),
+          folderExpr,
+        ),
+      ),
+    );
+  });
+
+  test('repro 2', () {
+    testStatement(
+      '''
+      SELECT * FROM notes n WHERE 
+      n.folderId = :selectedFolderId and
+      CASE 
+        WHEN 1 = :isReviewFolderSelected THEN n.nextReviewTime IS NOT NULL
+        ELSE n.nextReviewTime IS NULL
+      END;
+      ''',
+      SelectStatement(
+        from: TableReference('notes', 'n'),
+        columns: [StarResultColumn()],
+        where: BinaryExpression(
+          folderExpr,
+          token(TokenType.and),
+          caseExpr,
+        ),
+      ),
+    );
+  });
+}