Provide better error messages at unknown tables

sqlparser/lib/src/analysis/analysis.dart

@@ -1,6 +1,7 @@
 import 'dart:math';
 
 import 'package:meta/meta.dart';
+import 'package:source_span/source_span.dart';
 import 'package:sqlparser/sqlparser.dart';
 import 'package:sqlparser/src/reader/tokenizer/token.dart';
 

sqlparser/lib/src/analysis/error.dart

@@ -7,20 +7,49 @@ class AnalysisError {
 
   AnalysisError({@required this.type, this.message, this.relevantNode});
 
-  @override
-  String toString() {
+  /// The relevant portion of the source code that caused this error. Some AST
+  /// nodes don't have a span, in that case this error is going to be null.
+  SourceSpan get span {
     final first = relevantNode?.first?.span;
     final last = relevantNode?.last?.span;
 
     if (first != null && last != null) {
-      final span = first.expand(last);
-      return span.message(message ?? type.toString(), color: true);
+      return first.expand(last);
+    }
+    return null;
+  }
+
+  @override
+  String toString() {
+    final msgSpan = span;
+    if (msgSpan != null) {
+      return msgSpan.message(message ?? type.toString(), color: true);
     } else {
       return 'Error: $type: $message at $relevantNode';
     }
   }
 }
 
+class UnresolvedReferenceError extends AnalysisError {
+  /// The attempted reference that couldn't be resolved
+  final String reference;
+
+  /// A list of alternative references that would be available for [reference].
+  final Iterable<String> available;
+
+  UnresolvedReferenceError(
+      {@required AnalysisErrorType type,
+      this.reference,
+      this.available,
+      AstNode relevantNode})
+      : super(type: type, relevantNode: relevantNode);
+
+  @override
+  String get message {
+    return 'Could not find $reference. Available are: ${available.join(', ')}';
+  }
+}
+
 enum AnalysisErrorType {
   referencedUnknownTable,
   referencedUnknownColumn,

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

@@ -13,7 +13,7 @@ mixin Referencable {}
 /// 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 as an id column. However,
+/// 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 {}
@@ -79,12 +79,20 @@ class ReferenceScope {
   /// Returns everything that is in scope and a subtype of [T].
   List<T> allOf<T>() {
     var scope = this;
+    var isInCurrentScope = true;
     final collected = <T>[];
 
     while (scope != null) {
-      collected.addAll(
-          scope._references.values.expand((list) => list).whereType<T>());
+      var foundValues =
+          scope._references.values.expand((list) => list).whereType<T>();
+
+      if (!isInCurrentScope) {
+        foundValues = foundValues.whereType<VisibleToChildren>().cast();
+      }
+
+      collected.addAll(foundValues);
       scope = scope.parent;
+      isInCurrentScope = false;
     }
     return collected;
   }

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

@@ -115,10 +115,13 @@ class ColumnResolver extends RecursiveVisitor<void> {
   Table _resolveTableReference(TableReference r) {
     final scope = r.scope;
     final resolvedTable = scope.resolve<Table>(r.tableName, orElse: () {
-      context.reportError(AnalysisError(
+      final available = scope.allOf<Table>().map((t) => t.name);
+
+      context.reportError(UnresolvedReferenceError(
         type: AnalysisErrorType.referencedUnknownTable,
         relevantNode: r,
-        message: 'The table ${r.tableName} could not be found',
+        reference: r.tableName,
+        available: available,
       ));
     });
     return r.resolved = resolvedTable;

sqlparser/lib/src/ast/expressions/reference.dart

@@ -23,4 +23,13 @@ class Reference extends Expression with ReferenceOwner {
   bool contentEquals(Reference other) {
     return other.tableName == tableName && other.columnName == columnName;
   }
+
+  @override
+  String toString() {
+    if (tableName != null) {
+      return '$tableName.$columnName';
+    } else {
+      return columnName;
+    }
+  }
 }

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

@@ -130,9 +130,11 @@ mixin CrudParser on ParserBase {
     if (_matchOne(TokenType.identifier)) {
       // ignore the schema name, it's not supported. Besides that, we're on the
       // first branch in the diagram here
-      final tableName = (_previous as IdentifierToken).identifier;
+      final firstToken = _previous as IdentifierToken;
+      final tableName = firstToken.identifier;
       final alias = _as();
-      return TableReference(tableName, alias?.identifier);
+      return TableReference(tableName, alias?.identifier)
+        ..setSpan(firstToken, _previous);
     }
     return null;
   }