Refactor sql scoping, make aliased tables explicit

.gitignore

@@ -8,4 +8,5 @@ pubspec.lock
 .dart_tool/
 
 benchmark_results.json
-.flutter-plugins-dependencies
+.flutter-plugins-dependencies
+flutter_export_environment.sh

extras/integration_tests/flutter_db/pubspec.lock

@@ -187,7 +187,7 @@ packages:
       path: "../../../moor_flutter"
       relative: true
     source: path
-    version: "2.0.0"
+    version: "2.1.0"
   multi_server_socket:
     dependency: transitive
     description:

sqlparser/lib/src/analysis/schema/references.dart

@@ -7,17 +7,18 @@ mixin ReferenceOwner {
 }
 
 /// Mixin for classes which can be referenced by a [ReferenceOwner].
-mixin Referencable {}
-
-/// A referencable which is still visible in child scopes. This doesn't apply to
-/// many things, basically only tables.
-///
-/// For instance: "SELECT *, 1 AS d, (SELECT id FROM demo WHERE id = out.id)
-/// FROM demo AS out;"
-/// is a valid sql query when the demo table has an id column. However,
-/// "SELECT *, 1 AS d, (SELECT id FROM demo WHERE id = d) FROM demo AS out;" is
-/// not, the "d" referencable is not visible for the child select statement.
-mixin VisibleToChildren on Referencable {}
+mixin Referencable {
+  /// Whether this referencable is still visible in child scopes. This doesn't
+  /// apply to many things, basically only to tables.
+  ///
+  /// For instance: "SELECT *, 1 AS d, (SELECT id FROM demo WHERE id = out.id)
+  /// FROM demo AS out;"
+  /// is a valid sql query when the demo table has an id column. However,
+  /// "SELECT *, 1 AS d, (SELECT id FROM demo WHERE id = d) FROM demo AS out;"
+  /// is not, the "d" referencable is not visible for the child select
+  /// statement.
+  bool get visibleToChildren => false;
+}
 
 /// Class which keeps track of references for tables, columns and functions in a
 /// query.
@@ -86,7 +87,7 @@ class ReferenceScope {
       if (scope._references.containsKey(upper)) {
         final candidates = scope._references[upper];
         final resolved = candidates.whereType<T>().where((x) {
-          return x is VisibleToChildren || !isAtParent;
+          return x.visibleToChildren || !isAtParent;
         });
         if (resolved.isNotEmpty) {
           return resolved.first;
@@ -102,7 +103,7 @@ class ReferenceScope {
   }
 
   /// Returns everything that is in scope and a subtype of [T].
-  List<T> allOf<T>() {
+  List<T> allOf<T extends Referencable>() {
     var scope = this;
     var isInCurrentScope = true;
     final collected = <T>[];
@@ -112,7 +113,8 @@ class ReferenceScope {
           scope._references.values.expand((list) => list).whereType<T>();
 
       if (!isInCurrentScope) {
-        foundValues = foundValues.whereType<VisibleToChildren>().cast();
+        foundValues =
+            foundValues.where((element) => element.visibleToChildren).cast();
       }
 
       collected.addAll(foundValues);

sqlparser/lib/src/analysis/schema/table.dart

@@ -18,6 +18,9 @@ abstract class ResultSet implements ResolvesToResultSet {
   @override
   ResultSet get resultSet => this;
 
+  @override
+  bool get visibleToChildren => false;
+
   Column findColumn(String name) {
     return resolvedColumns.firstWhere((c) => c.name == name,
         orElse: () => null);
@@ -34,9 +37,7 @@ class CustomResultSet with ResultSet {
 
 /// A database table. The information stored here will be used to resolve
 /// references and for type inference.
-class Table
-    with ResultSet, VisibleToChildren, HasMetaMixin
-    implements HumanReadable {
+class Table with ResultSet, HasMetaMixin implements HumanReadable {
   /// The name of this table, as it appears in sql statements. This should be
   /// the raw name, not an escaped version.
   ///
@@ -66,6 +67,9 @@ class Table
   /// The ast node that created this table
   final TableInducingStatement definition;
 
+  @override
+  bool get visibleToChildren => true;
+
   TableColumn _rowIdColumn;
 
   /// Constructs a table from the known [name] and [resolvedColumns].
@@ -102,3 +106,31 @@ class Table
     return name;
   }
 }
+
+class TableAlias implements ResultSet, HumanReadable {
+  final ResultSet delegate;
+  final String alias;
+
+  TableAlias(this.delegate, this.alias);
+
+  @override
+  List<Column> get resolvedColumns => delegate.resolvedColumns;
+
+  @override
+  Column findColumn(String name) => delegate.findColumn(name);
+
+  @override
+  ResultSet get resultSet => this;
+
+  @override
+  bool get visibleToChildren => delegate.visibleToChildren;
+
+  @override
+  String humanReadableDescription() {
+    final delegateDescription = delegate is HumanReadable
+        ? (delegate as HumanReadable).humanReadableDescription()
+        : delegate.toString();
+
+    return '$alias (alias to $delegateDescription)';
+  }
+}

sqlparser/lib/src/analysis/steps/column_resolver.dart

@@ -73,12 +73,12 @@ class ColumnResolver extends RecursiveVisitor<void, void> {
   @override
   void visitDoUpdate(DoUpdate e, void arg) {
     final surroundingInsert = e.parents.whereType<InsertStatement>().first;
-    final table = surroundingInsert.resolvedTable;
+    final table = surroundingInsert.table.resultSet;
 
     if (table != null) {
       // add "excluded" table qualifier that referring to the row that would
       // have been inserted had the uniqueness constraint not been violated.
-      e.scope.register('excluded', table);
+      e.scope.register('excluded', TableAlias(table, 'excluded'));
     }
 
     visitChildren(e, arg);
@@ -94,7 +94,6 @@ class ColumnResolver extends RecursiveVisitor<void, void> {
   @override
   void visitInsertStatement(InsertStatement e, void arg) {
     final table = _resolveTableReference(e.table);
-    e.resolvedTable = table;
     visitChildren(e, arg);
     e.scope.availableColumns = table.resolvedColumns;
     visitChildren(e, arg);
@@ -118,10 +117,10 @@ class ColumnResolver extends RecursiveVisitor<void, void> {
 
     final scope = e.scope;
     if (e.target.introducesNew) {
-      scope.register('new', table);
+      scope.register('new', TableAlias(table, 'new'));
     }
     if (e.target.introducesOld) {
-      scope.register('old', table);
+      scope.register('old', TableAlias(table, 'old'));
     }
 
     visitChildren(e, arg);
@@ -251,7 +250,13 @@ class ColumnResolver extends RecursiveVisitor<void, void> {
   ResultSet _resolveTableReference(TableReference r) {
     final scope = r.scope;
     final resolvedTable = scope.resolve<ResultSet>(r.tableName, orElse: () {
-      final available = scope.allOf<Table>().map((t) => t.name);
+      final available = scope.allOf<ResultSet>().map((t) {
+        if (t is HumanReadable) {
+          return (t as HumanReadable).humanReadableDescription();
+        }
+
+        return t.toString();
+      });
 
       context.reportError(UnresolvedReferenceError(
         type: AnalysisErrorType.referencedUnknownTable,

sqlparser/lib/src/ast/clauses/with.dart

@@ -22,7 +22,7 @@ class WithClause extends AstNode {
   bool contentEquals(WithClause other) => other.recursive == recursive;
 }
 
-class CommonTableExpression extends AstNode with ResultSet, VisibleToChildren {
+class CommonTableExpression extends AstNode with ResultSet {
   final String cteTableName;
 
   /// If this common table expression has explicit column names, e.g. with
@@ -78,4 +78,7 @@ class CommonTableExpression extends AstNode with ResultSet, VisibleToChildren {
 
     return _cachedColumns;
   }
+
+  @override
+  bool get visibleToChildren => true;
 }

sqlparser/lib/src/ast/common/queryables.dart

@@ -43,7 +43,7 @@ abstract class TableOrSubquery extends Queryable {}
 /// set.
 class TableReference extends TableOrSubquery
     with ReferenceOwner
-    implements Renamable, ResolvesToResultSet, VisibleToChildren {
+    implements Renamable, ResolvesToResultSet {
   final String tableName;
   Token tableNameToken;
 
@@ -64,6 +64,9 @@ class TableReference extends TableOrSubquery
   ResultSet get resultSet {
     return resolved as ResultSet;
   }
+
+  @override
+  bool get visibleToChildren => true;
 }
 
 /// A nested select statement that appears after a FROM clause. This is
@@ -189,6 +192,9 @@ class TableValuedFunction extends Queryable
   @override
   Iterable<AstNode> get childNodes => [parameters];
 
+  @override
+  bool get visibleToChildren => false;
+
   @override
   bool contentEquals(TableValuedFunction other) {
     return other.name == name;

sqlparser/lib/src/ast/statements/insert.dart

@@ -17,8 +17,6 @@ class InsertStatement extends CrudStatement {
   final InsertSource source;
   final UpsertClause upsert;
 
-  ResultSet /*?*/ resolvedTable;
-
   List<Column> get resolvedTargetColumns {
     if (targetColumns.isNotEmpty) {
       return targetColumns.map((c) => c.resolvedColumn).toList();

sqlparser/lib/src/ast/statements/select.dart

@@ -122,6 +122,9 @@ class ExpressionResultColumn extends ResultColumn
 
   ExpressionResultColumn({@required this.expression, this.as});
 
+  @override
+  bool get visibleToChildren => false;
+
   @override
   Iterable<AstNode> get childNodes => [expression];
 

sqlparser/lib/src/engine/module/module.dart

@@ -65,7 +65,7 @@ abstract class TableValuedFunctionHandler {
 
 /// An sqlite module, which can be used in a `CREATE VIRTUAL TABLE` statement
 /// to find providers.
-abstract class Module implements Referencable, VisibleToChildren {
+abstract class Module implements Referencable {
   /// The name of this module, which is referenced by the `USING` clause in a
   /// `CREATE VIRTUAL TABLE` statement.
   final String name;
@@ -76,4 +76,7 @@ abstract class Module implements Referencable, VisibleToChildren {
   /// refers to this module. The module is responsible for setting
   /// [Table.definition].
   Table parseTable(CreateVirtualTableStatement stmt);
+
+  @override
+  bool get visibleToChildren => true;
 }