Override hashCode and operator == in common expressions

moor/lib/src/runtime/query_builder/expressions/bools.dart

@@ -55,4 +55,12 @@ class _NotExpression extends Expression<bool, BoolType> {
     context.buffer.write('NOT ');
     writeInner(context, inner);
   }
+
+  @override
+  int get hashCode => inner.hashCode << 1;
+
+  @override
+  bool operator ==(other) {
+    return other is _NotExpression && other.inner == inner;
+  }
 }

moor/lib/src/runtime/query_builder/expressions/comparable.dart

@@ -104,4 +104,17 @@ class _BetweenExpression extends Expression<bool, BoolType> {
     context.buffer.write(' AND ');
     writeInner(context, higher);
   }
+
+  @override
+  int get hashCode => $mrjf($mrjc(target.hashCode,
+      $mrjc(lower.hashCode, $mrjc(higher.hashCode, not.hashCode))));
+
+  @override
+  bool operator ==(other) {
+    return other is _BetweenExpression &&
+        other.target == target &&
+        other.not == not &&
+        other.lower == lower &&
+        other.higher == higher;
+  }
 }

moor/lib/src/runtime/query_builder/expressions/custom.dart

@@ -16,4 +16,14 @@ class CustomExpression<D, S extends SqlType<D>> extends Expression<D, S> {
 
   @override
   void writeInto(GenerationContext context) => context.buffer.write(content);
+
+  @override
+  int get hashCode => content.hashCode * 3;
+
+  @override
+  bool operator ==(other) {
+    return other.runtimeType == runtimeType &&
+        // ignore: test_types_in_equals
+        (other as CustomExpression).content == content;
+  }
 }

moor/lib/src/runtime/query_builder/expressions/datetimes.dart

@@ -103,4 +103,14 @@ class _StrftimeSingleFieldExpression extends Expression<int, IntType> {
     date.writeInto(context);
     context.buffer.write(', "unixepoch") AS INTEGER)');
   }
+
+  @override
+  int get hashCode => $mrjf($mrjc(format.hashCode, date.hashCode));
+
+  @override
+  bool operator ==(other) {
+    return other is _StrftimeSingleFieldExpression &&
+        other.format == format &&
+        other.date == date;
+  }
 }

moor/lib/src/runtime/query_builder/expressions/expression.dart

@@ -1,5 +1,7 @@
 part of '../query_builder.dart';
 
+const _equality = ListEquality();
+
 /// Any sql expression that evaluates to some generic value. This does not
 /// include queries (which might evaluate to multiple values) but individual
 /// columns, functions and operators.
@@ -38,13 +40,13 @@ abstract class Expression<D, T extends SqlType<D>> implements Component {
   /// An expression that is true if `this` resolves to any of the values in
   /// [values].
   Expression<bool, BoolType> isIn(Iterable<D> values) {
-    return _InExpression(this, values, false);
+    return _InExpression(this, values.toList(), false);
   }
 
   /// An expression that is true if `this` does not resolve to any of the values
   /// in [values].
   Expression<bool, BoolType> isNotIn(Iterable<D> values) {
-    return _InExpression(this, values, true);
+    return _InExpression(this, values.toList(), true);
   }
 
   /// Writes this expression into the [GenerationContext], assuming that there's
@@ -175,6 +177,18 @@ abstract class _InfixOperator<D, T extends SqlType<D>>
     context.writeWhitespace();
     writeInner(context, right);
   }
+
+  @override
+  int get hashCode =>
+      $mrjf($mrjc(left.hashCode, $mrjc(right.hashCode, operator.hashCode)));
+
+  @override
+  bool operator ==(other) {
+    return other is _InfixOperator &&
+        other.left == left &&
+        other.right == right &&
+        other.operator == operator;
+  }
 }
 
 class _BaseInfixOperator<D, T extends SqlType<D>> extends _InfixOperator<D, T> {
@@ -263,6 +277,14 @@ class _UnaryMinus<DT, ST extends SqlType<DT>> extends Expression<DT, ST> {
     context.buffer.write('-');
     inner.writeInto(context);
   }
+
+  @override
+  int get hashCode => inner.hashCode * 5;
+
+  @override
+  bool operator ==(other) {
+    return other is _UnaryMinus && other.inner == inner;
+  }
 }
 
 class _CastExpression<D1, D2, S1 extends SqlType<D1>, S2 extends SqlType<D2>>
@@ -281,6 +303,14 @@ class _CastExpression<D1, D2, S1 extends SqlType<D1>, S2 extends SqlType<D2>>
   void writeInto(GenerationContext context) {
     return inner.writeInto(context);
   }
+
+  @override
+  int get hashCode => inner.hashCode * 7;
+
+  @override
+  bool operator ==(other) {
+    return other is _CastExpression && other.inner == inner;
+  }
 }
 
 class _FunctionCallExpression<R, S extends SqlType<R>>
@@ -308,4 +338,15 @@ class _FunctionCallExpression<R, S extends SqlType<R>>
 
     context.buffer.write(')');
   }
+
+  @override
+  int get hashCode =>
+      $mrjf($mrjc(functionName.hashCode, _equality.hash(arguments)));
+
+  @override
+  bool operator ==(other) {
+    return other is _FunctionCallExpression &&
+        other.functionName == functionName &&
+        _equality.equals(other.arguments, arguments);
+  }
 }

moor/lib/src/runtime/query_builder/expressions/in.dart

@@ -23,7 +23,7 @@ Expression<bool, BoolType> isNotIn<X extends SqlType<T>, T>(
 class _InExpression<X extends SqlType<T>, T>
     extends Expression<bool, BoolType> {
   final Expression<T, X> _expression;
-  final Iterable<T> _values;
+  final List<T> _values;
   final bool _not;
 
   @override
@@ -57,4 +57,16 @@ class _InExpression<X extends SqlType<T>, T>
 
     context.buffer.write(')');
   }
+
+  @override
+  int get hashCode => $mrjf($mrjc(
+      _expression.hashCode, $mrjc(_equality.hash(_values), _not.hashCode)));
+
+  @override
+  bool operator ==(other) {
+    return other is _InExpression &&
+        other._expression == _expression &&
+        other._values == _values &&
+        other._not == _not;
+  }
 }

moor/lib/src/runtime/query_builder/expressions/null_check.dart

@@ -30,4 +30,14 @@ class _NullCheck extends Expression<bool, BoolType> {
     }
     context.buffer.write('NULL');
   }
+
+  @override
+  int get hashCode => $mrjf($mrjc(_inner.hashCode, _isNull.hashCode));
+
+  @override
+  bool operator ==(other) {
+    return other is _NullCheck &&
+        other._inner == _inner &&
+        other._isNull == _isNull;
+  }
 }

moor/lib/src/runtime/query_builder/expressions/text.dart

@@ -72,6 +72,16 @@ class _LikeOperator extends Expression<bool, BoolType> {
     context.buffer.write(' LIKE ');
     writeInner(context, regex);
   }
+
+  @override
+  int get hashCode => $mrjf($mrjc(target.hashCode, regex.hashCode));
+
+  @override
+  bool operator ==(other) {
+    return other is _LikeOperator &&
+        other.target == target &&
+        other.regex == regex;
+  }
 }
 
 /// Builtin collating functions from sqlite.
@@ -116,6 +126,16 @@ class _CollateOperator extends Expression<String, StringType> {
     context.buffer..write(' COLLATE ')..write(_operatorNames[collate]);
   }
 
+  @override
+  int get hashCode => $mrjf($mrjc(inner.hashCode, collate.hashCode));
+
+  @override
+  bool operator ==(other) {
+    return other is _CollateOperator &&
+        other.inner == inner &&
+        other.collate == collate;
+  }
+
   static const Map<Collate, String> _operatorNames = {
     Collate.binary: 'BINARY',
     Collate.noCase: 'NOCASE',

moor/lib/src/runtime/query_builder/expressions/variables.dart

@@ -6,6 +6,9 @@ class Variable<T, S extends SqlType<T>> extends Expression<T, S> {
   /// The Dart value that will be sent to the database
   final T value;
 
+  // note that we keep the identity hash/equals here because each variable would
+  // get its own index in sqlite and is thus different.
+
   @override
   final Precedence precedence = Precedence.primary;
 
@@ -82,4 +85,14 @@ class Constant<T, S extends SqlType<T>> extends Expression<T, S> {
     final type = context.typeSystem.forDartType<T>();
     context.buffer.write(type.mapToSqlConstant(value));
   }
+
+  @override
+  int get hashCode => value.hashCode;
+
+  @override
+  bool operator ==(other) {
+    return other.runtimeType == runtimeType &&
+        // ignore: test_types_in_equals
+        (other as Constant<T, S>).value == value;
+  }
 }

moor/lib/src/runtime/query_builder/query_builder.dart

@@ -1,6 +1,7 @@
 // Mega compilation unit that includes all Dart apis related to generating SQL
 // at runtime.
 
+import 'package:collection/collection.dart';
 import 'package:meta/meta.dart';
 // hidden because of https://github.com/dart-lang/sdk/issues/39262
 import 'package:moor/moor.dart'

moor/lib/src/runtime/query_builder/schema/columns.dart

@@ -101,6 +101,18 @@ abstract class GeneratedColumn<T, S extends SqlType<T>> extends Column<T, S> {
   bool get isRequired {
     return !$nullable && defaultValue == null;
   }
+
+  @override
+  int get hashCode => $mrjf($mrjc(tableName.hashCode, $name.hashCode));
+
+  @override
+  bool operator ==(other) {
+    if (other.runtimeType != runtimeType) return false;
+
+    // ignore: test_types_in_equals
+    final typedOther = other as GeneratedColumn;
+    return typedOther.tableName == tableName && typedOther.$name == $name;
+  }
 }
 
 /// Implementation for [TextColumn].

moor/lib/src/runtime/query_builder/schema/table_info.dart

@@ -15,7 +15,7 @@ mixin TableInfo<TableDsl extends Table, D extends DataClass> on Table {
   /// also contains auto-increment integers, which are primary key by default.
   Set<GeneratedColumn> get $primaryKey => null;
 
-  // ensure the primaryKey getter is consistent with $primarKey, which can
+  // ensure the primaryKey getter is consistent with $primaryKey, which can
   // contain additional columns.
   @override
   Set<Column> get primaryKey => $primaryKey;

moor/lib/src/runtime/query_builder/statements/select/custom_select.dart

@@ -73,6 +73,11 @@ class CustomSelectStatement with Selectable<QueryRow> {
 /// For custom select statements, represents a row in the result set.
 class QueryRow {
   /// The raw data in this row.
+  ///
+  /// Note that the values in this map aren't mapped to Dart yet. For instance,
+  /// a [DateTime] would be stored as an [int] in [data] because that's the way
+  /// it's stored in the database. To read a value, use any of the [read]
+  /// methods.
   final Map<String, dynamic> data;
   final QueryEngine _db;
 

moor/lib/src/runtime/query_builder/statements/select/select.dart

@@ -77,6 +77,7 @@ class SimpleSelectStatement<T extends Table, D extends DataClass>
     return statement;
   }
 
+  /// {@macro moor_select_addColumns}
   JoinedSelectStatement addColumns(List<Expression> expressions) {
     return join(const [])..addColumns(expressions);
   }
@@ -133,8 +134,10 @@ class TypedResult {
     return _parsedData[table] as D;
   }
 
-  /// Reads a single column from an [expr].
-  /// todo expand documentation
+  /// Reads a single column from an [expr]. The expression must have been added
+  /// as a column, for instance via [JoinedSelectStatement.addColumns].
+  ///
+  /// To access the underlying columns directly, use
   D read<D, T extends SqlType<D>>(Expression<D, T> expr) {
     if (_parsedExpressions != null) {
       return _parsedExpressions[expr] as D;

moor/lib/src/runtime/query_builder/statements/select/select_with_join.dart

@@ -109,14 +109,25 @@ class JoinedSelectStatement<FirstT extends Table, FirstD extends DataClass>
     orderByExpr = OrderBy(terms);
   }
 
+  /// {@template moor_select_addColumns}
   /// Adds a custom expression to the query.
   ///
   /// The database will evaluate the [Expression] for each row found for this
   /// query. The value of the expression can be extracted from the [TypedResult]
   /// by passing it to [TypedResult.read].
   ///
+  /// As an example, we could calculate the length of a column on the database:
+  /// ```dart
+  /// final contentLength = todos.content.length;
+  /// final results = await select(todos).addColumns([contentLength]).get();
+  ///
+  /// // we can now read the result of a column added to addColumns
+  /// final lengthOfFirst = results.first.read(contentLength);
+  /// ```
+  ///
   /// See also:
   ///  - The docs on expressions: https://moor.simonbinder.eu/docs/getting-started/expressions/
+  /// {@endtemplate}
   void addColumns(Iterable<Expression> expressions) {
     _selectedColumns.addAll(expressions);
   }

moor/test/data/utils/expect_equality.dart

@@ -0,0 +1,11 @@
+import 'package:test/test.dart';
+
+void expectEquals(dynamic a, dynamic expected) {
+  expect(a, equals(expected));
+  expect(a.hashCode, equals(expected.hashCode));
+}
+
+void expectNotEquals(dynamic a, dynamic expected) {
+  expect(a, isNot(equals(expected)));
+  expect(a.hashCode, isNot(equals(expected.hashCode)));
+}

moor/test/expressions/algebra_test.dart

@@ -1,6 +1,7 @@
 import 'package:moor/moor.dart';
 import 'package:test/test.dart';
 
+import '../data/utils/expect_equality.dart';
 import '../data/utils/expect_generated.dart';
 
 void main() {
@@ -16,6 +17,9 @@ void main() {
     (i1 - i2).expectGenerates('i1 - i2');
     (i1 - -i2).expectGenerates('i1 - -i2');
     (i1 / i2).expectGenerates('i1 / i2');
+
+    expectEquals(i1 + i2, i1 + i2);
+    expectNotEquals(i1 + i2, i2 + i1);
   });
 
   test('string concatenation', () {

moor/test/expressions/bools_test.dart

@@ -1,6 +1,7 @@
 import 'package:moor/moor.dart';
 import 'package:test/test.dart';
 
+import '../data/utils/expect_equality.dart';
 import '../data/utils/expect_generated.dart';
 
 // ignore_for_file: deprecated_member_use_from_same_package
@@ -13,11 +14,17 @@ void main() {
     (a | b).expectGenerates('a OR b');
     (a & b).expectGenerates('a AND b');
     a.not().expectGenerates('NOT a');
+
+    expectEquals(a & b, a & b);
+    expectNotEquals(a | b, b | a);
   });
 
   test('boolean expressions via top-level methods', () {
     or(a, b).expectGenerates('a OR b');
     and(a, b).expectGenerates('a AND b');
     not(a).expectGenerates('NOT a');
+
+    expectEquals(not(a), not(a));
+    expectNotEquals(not(a), not(b));
   });
 }

moor/test/expressions/comparable_test.dart

@@ -2,6 +2,7 @@ import 'package:moor/moor.dart';
 import 'package:test/test.dart';
 
 import '../data/tables/todos.dart';
+import '../data/utils/expect_equality.dart';
 
 void main() {
   final expression = GeneratedIntColumn('col', null, false);
@@ -31,6 +32,8 @@ void main() {
         fn(compare).writeInto(ctx);
 
         expect(ctx.sql, 'col $value compare');
+
+        expectEquals(fn(compare), fn(compare));
       });
     });
   });

moor/test/expressions/constant_test.dart

@@ -2,6 +2,7 @@ import 'package:moor/moor.dart';
 import 'package:test/test.dart';
 
 import '../data/tables/todos.dart';
+import '../data/utils/expect_equality.dart';
 
 void main() {
   group('string literals', () {
@@ -17,6 +18,16 @@ void main() {
       testStringMapping('\\\$"', "'\\\$\"'");
     });
   });
+
+  test('constant hash and equals', () {
+    // these shouldn't be identical, so no const constructor
+    final first = Constant('hi'); // ignore: prefer_const_constructors
+    final alsoFirst = Constant('hi'); // ignore: prefer_const_constructors
+    final second = const Constant(3);
+
+    expectEquals(first, alsoFirst);
+    expectNotEquals(first, second);
+  });
 }
 
 void testStringMapping(String dart, String expectedLiteral) {

moor/test/expressions/datetime_expression_test.dart

@@ -1,6 +1,8 @@
 import 'package:moor/moor.dart';
 import 'package:test/test.dart';
 
+import '../data/utils/expect_equality.dart';
+
 // ignore_for_file: deprecated_member_use_from_same_package
 
 typedef Expression<int, IntType> _Extractor(
@@ -26,6 +28,8 @@ void main() {
         key(column).writeInto(ctx);
 
         expect(ctx.sql, value);
+
+        expectEquals(key(column), key(column));
       });
     });
   });

moor/test/expressions/is_null_test.dart

@@ -3,6 +3,7 @@ import 'package:moor/moor.dart' as moor;
 import 'package:test/test.dart';
 
 import '../data/tables/todos.dart';
+import '../data/utils/expect_equality.dart';
 
 void main() {
   final innerExpression = GeneratedTextColumn('name', null, true);
@@ -23,5 +24,7 @@ void main() {
     expr.writeInto(context);
 
     expect(context.sql, 'name IS NOT NULL');
+
+    expectEquals(expr, moor.isNotNull(innerExpression));
   });
 }