Suggest CREATE TABLE statements in moor files

sqlparser/lib/src/engine/autocomplete/engine.dart

@@ -33,6 +33,10 @@ class AutoCompleteEngine {
   ///
   /// This api will change in the future.
   ComputedSuggestions suggestCompletions(int offset) {
+    if (_hints.isEmpty) {
+      return ComputedSuggestions(-1, -1, []);
+    }
+
     final hint = foundHints[_lastHintBefore(offset)];
 
     final suggestions = hint.description.suggest(CalculationRequest()).toList();
@@ -68,7 +72,7 @@ class Hint {
   /// appears at the beginning of the file.
   final Token before;
 
-  int get offset => before.span.end.offset;
+  int get offset => before?.span?.end?.offset ?? 0;
 
   final HintDescription description;
 

sqlparser/lib/src/engine/sql_engine.dart

@@ -60,7 +60,7 @@ class SqlEngine {
 
     final autoComplete = AutoCompleteEngine();
     final tokens = tokenize(content);
-    final parser = Parser(tokens, useMoor: true);
+    final parser = Parser(tokens, useMoor: true, autoComplete: autoComplete);
 
     final moorFile = parser.moorFile();
 

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

@@ -54,7 +54,8 @@ abstract class ParserBase {
   ParserBase(this.tokens, this.enableMoorExtensions, this.autoComplete);
 
   void _suggestHint(HintDescription description) {
-    autoComplete?.addHint(Hint(_previous, description));
+    final tokenBefore = _current == 0 ? null : _previous;
+    autoComplete?.addHint(Hint(tokenBefore, description));
   }
 
   bool get _isAtEnd => _peek.type == TokenType.eof;
@@ -226,7 +227,13 @@ class Parser extends ParserBase
       _error('Expected the file to end here.');
     }
 
-    return MoorFile(foundComponents)..setSpan(first, _previous);
+    final file = MoorFile(foundComponents);
+    if (foundComponents.isNotEmpty) {
+      file.setSpan(first, _previous);
+    } else {
+      file.setSpan(first, first); // empty file
+    }
+    return file;
   }
 
   ImportStatement _import() {

sqlparser/test/engine/autocomplete/static_test.dart

@@ -0,0 +1,43 @@
+import 'package:sqlparser/sqlparser.dart';
+import 'package:sqlparser/src/engine/autocomplete/engine.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('suggests a CREATE TABLE statements for an empty file', () {
+    final engine = SqlEngine(useMoorExtensions: true);
+    final parseResult = engine.parseMoorFile('');
+
+    final suggestions = parseResult.autoCompleteEngine.suggestCompletions(0);
+
+    expect(suggestions.anchor, 0);
+    expect(suggestions.suggestions, contains(hasCode('CREATE TABLE')));
+  });
+
+  test('suggests completions for started expressions', () {
+    final engine = SqlEngine(useMoorExtensions: true);
+    final parseResult = engine.parseMoorFile('creat');
+
+    final suggestions = parseResult.autoCompleteEngine.suggestCompletions(0);
+
+    expect(suggestions.anchor, 0);
+    expect(suggestions.suggestions, contains(hasCode('CREATE TABLE')));
+  });
+}
+
+dynamic hasCode(code) => SuggestionWithCode(code);
+
+class SuggestionWithCode extends Matcher {
+  final Matcher codeMatcher;
+
+  SuggestionWithCode(dynamic code) : codeMatcher = wrapMatcher(code);
+
+  @override
+  Description describe(Description description) {
+    return description.add('suggests ').addDescriptionOf(codeMatcher);
+  }
+
+  @override
+  bool matches(item, Map matchState) {
+    return item is Suggestion && codeMatcher.matches(item.code, matchState);
+  }
+}