Enable strict mode on PHP files

Signed-off-by: Maurício Meneghini Fauth <mauriciofauth@gmail.com>

160 files changed, 177 insertions, 103 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 98af7b8..747fd20 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@
 ## [Unreleased]
 
 * Drop support for PHP 5.3, PHP 5.4, PHP 5.5, PHP 5.6, PHP 7.0 and HHVM
+* Enable strict mode on PHP files
 
 ## [4.3.1] - 2019-01-05
 
diff --git a/bin/highlight-query b/bin/highlight-query
index 577e4fb..a25a3e2 100755
--- a/bin/highlight-query
+++ b/bin/highlight-query
@@ -1,5 +1,6 @@
 #!/usr/bin/env php
 <?php
+declare(strict_types=1);
 
 $files = array(
     __DIR__ . "/../vendor/autoload.php",
diff --git a/bin/lint-query b/bin/lint-query
index 67e7114..8d7cd29 100755
--- a/bin/lint-query
+++ b/bin/lint-query
@@ -1,5 +1,6 @@
 #!/usr/bin/env php
 <?php
+declare(strict_types=1);
 
 $files = array(
     __DIR__ . "/../vendor/autoload.php",
@@ -27,4 +28,3 @@ if (!$found) {
 
 $cli = new PhpMyAdmin\SqlParser\Utils\CLI();
 exit($cli->runLint());
-
diff --git a/bin/tokenize-query b/bin/tokenize-query
index f32a4e0..97012c7 100755
--- a/bin/tokenize-query
+++ b/bin/tokenize-query
@@ -1,5 +1,6 @@
 #!/usr/bin/env php
 <?php
+declare(strict_types=1);
 
 $files = array(
     __DIR__ . "/../vendor/autoload.php",
diff --git a/src/Component.php b/src/Component.php
index d121e9b..520735b 100644
--- a/src/Component.php
+++ b/src/Component.php
@@ -1,5 +1,4 @@
 <?php
-
 /**
  * Defines a component that is later extended to parse specialized components or
  * keywords.
@@ -8,6 +7,7 @@
  * *Component parsers can be reused in multiple  situations and *Keyword parsers
  * count on the *Component classes to do their job.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser;
 
diff --git a/src/Components/AlterOperation.php b/src/Components/AlterOperation.php
index 25a62a5..35960ee 100644
--- a/src/Components/AlterOperation.php
+++ b/src/Components/AlterOperation.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Parses an alter operation.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Components;
 
diff --git a/src/Components/Array2d.php b/src/Components/Array2d.php
index ced529a..7c99952 100644
--- a/src/Components/Array2d.php
+++ b/src/Components/Array2d.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `VALUES` keyword parser.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Components;
 
diff --git a/src/Components/ArrayObj.php b/src/Components/ArrayObj.php
index f968d87..7748be9 100644
--- a/src/Components/ArrayObj.php
+++ b/src/Components/ArrayObj.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Parses an array.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Components;
 
diff --git a/src/Components/CaseExpression.php b/src/Components/CaseExpression.php
index d66ddc3..a79b52e 100644
--- a/src/Components/CaseExpression.php
+++ b/src/Components/CaseExpression.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Parses a reference to a CASE expression.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Components;
 
diff --git a/src/Components/Condition.php b/src/Components/Condition.php
index 83b80b2..c37ce19 100644
--- a/src/Components/Condition.php
+++ b/src/Components/Condition.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `WHERE` keyword parser.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Components;
 
@@ -87,7 +87,7 @@ class Condition extends Component
      */
     public function __construct($expr = null)
     {
-        $this->expr = trim($expr);
+        $this->expr = trim((string) $expr);
     }
 
     /**
diff --git a/src/Components/CreateDefinition.php b/src/Components/CreateDefinition.php
index ccf8497..3d3a3f4 100644
--- a/src/Components/CreateDefinition.php
+++ b/src/Components/CreateDefinition.php
@@ -1,10 +1,10 @@
 <?php
-
 /**
  * Parses the create definition of a column or a key.
  *
  * Used for parsing `CREATE TABLE` statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Components;
 
diff --git a/src/Components/DataType.php b/src/Components/DataType.php
index 47fffba..5be45c6 100644
--- a/src/Components/DataType.php
+++ b/src/Components/DataType.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Parses a data type.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Components;
 
@@ -127,7 +127,7 @@ class DataType extends Component
             }
 
             if ($state === 0) {
-                $ret->name = strtoupper($token->value);
+                $ret->name = strtoupper((string) $token->value);
                 if (($token->type !== Token::TYPE_KEYWORD) || (! ($token->flags & Token::FLAG_KEYWORD_DATA_TYPE))) {
                     $parser->error('Unrecognized data type.', $token);
                 }
diff --git a/src/Components/Expression.php b/src/Components/Expression.php
index 7383275..7a71c76 100644
--- a/src/Components/Expression.php
+++ b/src/Components/Expression.php
@@ -1,9 +1,9 @@
 <?php
-
 /**
  * Parses a reference to an expression (column, table or database name, function
  * call, mathematical expression, etc.).
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Components;
 
@@ -269,7 +269,7 @@ class Expression extends Component
                         continue;
                     }
                     $isExpr = true;
-                } elseif ($brackets === 0 && strlen($ret->expr) > 0 && ! $alias) {
+                } elseif ($brackets === 0 && strlen((string) $ret->expr) > 0 && ! $alias) {
                     /* End of expression */
                     break;
                 }
@@ -413,7 +413,7 @@ class Expression extends Component
         }
 
         // White-spaces might be added at the end.
-        $ret->expr = trim($ret->expr);
+        $ret->expr = trim((string) $ret->expr);
 
         if ($ret->expr === '') {
             return null;
diff --git a/src/Components/ExpressionArray.php b/src/Components/ExpressionArray.php
index 5d94681..2f44d7a 100644
--- a/src/Components/ExpressionArray.php
+++ b/src/Components/ExpressionArray.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Parses a list of expressions delimited by a comma.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Components;
 
diff --git a/src/Components/FunctionCall.php b/src/Components/FunctionCall.php
index 067987f..382ee8f 100644
--- a/src/Components/FunctionCall.php
+++ b/src/Components/FunctionCall.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Parses a function call.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Components;
 
diff --git a/src/Components/GroupKeyword.php b/src/Components/GroupKeyword.php
index 86de663..9aa583d 100644
--- a/src/Components/GroupKeyword.php
+++ b/src/Components/GroupKeyword.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `GROUP BY` keyword parser.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Components;
 
@@ -126,6 +126,6 @@ class GroupKeyword extends Component
             return implode(', ', $component);
         }
 
-        return trim($component->expr);
+        return trim((string) $component->expr);
     }
 }
diff --git a/src/Components/IndexHint.php b/src/Components/IndexHint.php
index 12edda7..a0cb0f1 100644
--- a/src/Components/IndexHint.php
+++ b/src/Components/IndexHint.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Parses an Index hint.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Components;
 
diff --git a/src/Components/IntoKeyword.php b/src/Components/IntoKeyword.php
index 524d94c..1941c22 100644
--- a/src/Components/IntoKeyword.php
+++ b/src/Components/IntoKeyword.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `INTO` keyword parser.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Components;
 
diff --git a/src/Components/JoinKeyword.php b/src/Components/JoinKeyword.php
index 6a13177..330c1f2 100644
--- a/src/Components/JoinKeyword.php
+++ b/src/Components/JoinKeyword.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `JOIN` keyword parser.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Components;
 
diff --git a/src/Components/Key.php b/src/Components/Key.php
index 3093f01..37e51a4 100644
--- a/src/Components/Key.php
+++ b/src/Components/Key.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Parses the definition of a key.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Components;
 
diff --git a/src/Components/Limit.php b/src/Components/Limit.php
index d02ce49..edb25fb 100644
--- a/src/Components/Limit.php
+++ b/src/Components/Limit.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `LIMIT` keyword parser.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Components;
 
diff --git a/src/Components/LockExpression.php b/src/Components/LockExpression.php
index 7cbfa72..8bf03ce 100644
--- a/src/Components/LockExpression.php
+++ b/src/Components/LockExpression.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Parses a reference to a LOCK expression.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Components;
 
diff --git a/src/Components/OptionsArray.php b/src/Components/OptionsArray.php
index 2b17cdd..f872b14 100644
--- a/src/Components/OptionsArray.php
+++ b/src/Components/OptionsArray.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Parses a list of options.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Components;
 
diff --git a/src/Components/OrderKeyword.php b/src/Components/OrderKeyword.php
index f6d60eb..820fdd1 100644
--- a/src/Components/OrderKeyword.php
+++ b/src/Components/OrderKeyword.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `ORDER BY` keyword parser.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Components;
 
diff --git a/src/Components/ParameterDefinition.php b/src/Components/ParameterDefinition.php
index f45d6ac..d4165ee 100644
--- a/src/Components/ParameterDefinition.php
+++ b/src/Components/ParameterDefinition.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * The definition of a parameter of a function or procedure.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Components;
 
diff --git a/src/Components/PartitionDefinition.php b/src/Components/PartitionDefinition.php
index 03f4aa6..58223ea 100644
--- a/src/Components/PartitionDefinition.php
+++ b/src/Components/PartitionDefinition.php
@@ -1,10 +1,10 @@
 <?php
-
 /**
  * Parses the create definition of a partition.
  *
  * Used for parsing `CREATE TABLE` statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Components;
 
diff --git a/src/Components/Reference.php b/src/Components/Reference.php
index 3f8e453..4077f77 100644
--- a/src/Components/Reference.php
+++ b/src/Components/Reference.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `REFERENCES` keyword parser.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Components;
 
diff --git a/src/Components/RenameOperation.php b/src/Components/RenameOperation.php
index 4bdb67e..d11a187 100644
--- a/src/Components/RenameOperation.php
+++ b/src/Components/RenameOperation.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `RENAME TABLE` keyword parser.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Components;
 
diff --git a/src/Components/SetOperation.php b/src/Components/SetOperation.php
index 68f2297..4c8ced3 100644
--- a/src/Components/SetOperation.php
+++ b/src/Components/SetOperation.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `SET` keyword parser.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Components;
 
diff --git a/src/Components/UnionKeyword.php b/src/Components/UnionKeyword.php
index 220f86e..dc06831 100644
--- a/src/Components/UnionKeyword.php
+++ b/src/Components/UnionKeyword.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `UNION` keyword builder.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Components;
 
diff --git a/src/Context.php b/src/Context.php
index 646f373..3f51dc7 100644
--- a/src/Context.php
+++ b/src/Context.php
@@ -1,11 +1,11 @@
 <?php
-
 /**
  * Defines a context class that is later extended to define other contexts.
  *
  * A context is a collection of keywords, operators and functions used for
  * parsing.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser;
 
diff --git a/src/Contexts/ContextMariaDb100000.php b/src/Contexts/ContextMariaDb100000.php
index a260083..cb0ac6e 100644
--- a/src/Contexts/ContextMariaDb100000.php
+++ b/src/Contexts/ContextMariaDb100000.php
@@ -1,5 +1,4 @@
 <?php
-
 /**
  * Context for MariaDB 10.0.
  *
@@ -7,6 +6,7 @@
  *
  * @see https://mariadb.com/kb/en/the-mariadb-library/reserved-words/
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Contexts;
 
diff --git a/src/Contexts/ContextMariaDb100100.php b/src/Contexts/ContextMariaDb100100.php
index 0208084..7a419ab 100644
--- a/src/Contexts/ContextMariaDb100100.php
+++ b/src/Contexts/ContextMariaDb100100.php
@@ -1,5 +1,4 @@
 <?php
-
 /**
  * Context for MariaDB 10.1.
  *
@@ -7,6 +6,7 @@
  *
  * @see https://mariadb.com/kb/en/the-mariadb-library/reserved-words/
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Contexts;
 
diff --git a/src/Contexts/ContextMariaDb100200.php b/src/Contexts/ContextMariaDb100200.php
index f2f7334..e0923ad 100644
--- a/src/Contexts/ContextMariaDb100200.php
+++ b/src/Contexts/ContextMariaDb100200.php
@@ -1,5 +1,4 @@
 <?php
-
 /**
  * Context for MariaDB 10.2.
  *
@@ -7,6 +6,7 @@
  *
  * @see https://mariadb.com/kb/en/the-mariadb-library/reserved-words/
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Contexts;
 
diff --git a/src/Contexts/ContextMariaDb100300.php b/src/Contexts/ContextMariaDb100300.php
index c2a3847..b162600 100644
--- a/src/Contexts/ContextMariaDb100300.php
+++ b/src/Contexts/ContextMariaDb100300.php
@@ -1,5 +1,4 @@
 <?php
-
 /**
  * Context for MariaDB 10.3.
  *
@@ -7,6 +6,7 @@
  *
  * @see https://mariadb.com/kb/en/the-mariadb-library/reserved-words/
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Contexts;
 
diff --git a/src/Contexts/ContextMySql50000.php b/src/Contexts/ContextMySql50000.php
index 649a731..5a8322b 100644
--- a/src/Contexts/ContextMySql50000.php
+++ b/src/Contexts/ContextMySql50000.php
@@ -1,5 +1,4 @@
 <?php
-
 /**
  * Context for MySQL 5.0.
  *
@@ -7,6 +6,7 @@
  *
  * @see https://dev.mysql.com/doc/refman/5.0/en/keywords.html
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Contexts;
 
diff --git a/src/Contexts/ContextMySql50100.php b/src/Contexts/ContextMySql50100.php
index 2531f2c..e4d353e 100644
--- a/src/Contexts/ContextMySql50100.php
+++ b/src/Contexts/ContextMySql50100.php
@@ -1,5 +1,4 @@
 <?php
-
 /**
  * Context for MySQL 5.1.
  *
@@ -7,6 +6,7 @@
  *
  * @see https://dev.mysql.com/doc/refman/5.1/en/keywords.html
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Contexts;
 
diff --git a/src/Contexts/ContextMySql50500.php b/src/Contexts/ContextMySql50500.php
index 9587116..2ef9b81 100644
--- a/src/Contexts/ContextMySql50500.php
+++ b/src/Contexts/ContextMySql50500.php
@@ -1,5 +1,4 @@
 <?php
-
 /**
  * Context for MySQL 5.5.
  *
@@ -7,6 +6,7 @@
  *
  * @see https://dev.mysql.com/doc/refman/5.5/en/keywords.html
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Contexts;
 
diff --git a/src/Contexts/ContextMySql50600.php b/src/Contexts/ContextMySql50600.php
index 0720957..5fa8786 100644
--- a/src/Contexts/ContextMySql50600.php
+++ b/src/Contexts/ContextMySql50600.php
@@ -1,5 +1,4 @@
 <?php
-
 /**
  * Context for MySQL 5.6.
  *
@@ -7,6 +6,7 @@
  *
  * @see https://dev.mysql.com/doc/refman/5.6/en/keywords.html
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Contexts;
 
diff --git a/src/Contexts/ContextMySql50700.php b/src/Contexts/ContextMySql50700.php
index b87affa..6f24dc1 100644
--- a/src/Contexts/ContextMySql50700.php
+++ b/src/Contexts/ContextMySql50700.php
@@ -1,5 +1,4 @@
 <?php
-
 /**
  * Context for MySQL 5.7.
  *
@@ -7,6 +6,7 @@
  *
  * @see https://dev.mysql.com/doc/refman/5.7/en/keywords.html
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Contexts;
 
diff --git a/src/Contexts/ContextMySql80000.php b/src/Contexts/ContextMySql80000.php
index 35ac008..df581f5 100644
--- a/src/Contexts/ContextMySql80000.php
+++ b/src/Contexts/ContextMySql80000.php
@@ -1,5 +1,4 @@
 <?php
-
 /**
  * Context for MySQL 8.0.
  *
@@ -7,6 +6,7 @@
  *
  * @see https://dev.mysql.com/doc/refman/8.0/en/keywords.html
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Contexts;
 
diff --git a/src/Core.php b/src/Core.php
index 5672b99..1965a2f 100644
--- a/src/Core.php
+++ b/src/Core.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Defines the core helper infrastructure of the library.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser;
 
diff --git a/src/Exceptions/LexerException.php b/src/Exceptions/LexerException.php
index 61e88c9..7dd85a4 100644
--- a/src/Exceptions/LexerException.php
+++ b/src/Exceptions/LexerException.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Exception thrown by the lexer.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Exceptions;
 
diff --git a/src/Exceptions/LoaderException.php b/src/Exceptions/LoaderException.php
index bfbd4c3..d809876 100644
--- a/src/Exceptions/LoaderException.php
+++ b/src/Exceptions/LoaderException.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Exception thrown by the lexer.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Exceptions;
 
diff --git a/src/Exceptions/ParserException.php b/src/Exceptions/ParserException.php
index eb13653..575eeb1 100644
--- a/src/Exceptions/ParserException.php
+++ b/src/Exceptions/ParserException.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Exception thrown by the parser.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Exceptions;
 
diff --git a/src/Lexer.php b/src/Lexer.php
index 13796cd..53545af 100644
--- a/src/Lexer.php
+++ b/src/Lexer.php
@@ -1,5 +1,4 @@
 <?php
-
 /**
  * Defines the lexer of the library.
  *
@@ -7,6 +6,7 @@
  *
  * Depends on context to extract lexemes.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser;
 
diff --git a/src/Parser.php b/src/Parser.php
index c0e755a..91524fd 100644
--- a/src/Parser.php
+++ b/src/Parser.php
@@ -1,10 +1,10 @@
 <?php
-
 /**
  * Defines the parser of the library.
  *
  * This is one of the most important components, along with the lexer.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser;
 
diff --git a/src/Statement.php b/src/Statement.php
index 281701c..41cf3e6 100644
--- a/src/Statement.php
+++ b/src/Statement.php
@@ -1,11 +1,11 @@
 <?php
-
 /**
  * The result of the parser is an array of statements are extensions of the
  * class defined here.
  *
  * A statement represents the result of parsing the lexemes.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser;
 
diff --git a/src/Statements/AlterStatement.php b/src/Statements/AlterStatement.php
index 3909c42..0620936 100644
--- a/src/Statements/AlterStatement.php
+++ b/src/Statements/AlterStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `ALTER` statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
diff --git a/src/Statements/AnalyzeStatement.php b/src/Statements/AnalyzeStatement.php
index 4166bdb..ebc7f70 100644
--- a/src/Statements/AnalyzeStatement.php
+++ b/src/Statements/AnalyzeStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `ANALYZE` statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
diff --git a/src/Statements/BackupStatement.php b/src/Statements/BackupStatement.php
index 0c8c314..574dc9a 100644
--- a/src/Statements/BackupStatement.php
+++ b/src/Statements/BackupStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `BACKUP` statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
diff --git a/src/Statements/CallStatement.php b/src/Statements/CallStatement.php
index 51f1011..8b02787 100644
--- a/src/Statements/CallStatement.php
+++ b/src/Statements/CallStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `CALL` statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
diff --git a/src/Statements/CheckStatement.php b/src/Statements/CheckStatement.php
index 690818c..789679f 100644
--- a/src/Statements/CheckStatement.php
+++ b/src/Statements/CheckStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `CHECK` statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
diff --git a/src/Statements/ChecksumStatement.php b/src/Statements/ChecksumStatement.php
index 3ddca9a..3214748 100644
--- a/src/Statements/ChecksumStatement.php
+++ b/src/Statements/ChecksumStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `CHECKSUM` statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
diff --git a/src/Statements/CreateStatement.php b/src/Statements/CreateStatement.php
index 61ffac2..ffa08bc 100644
--- a/src/Statements/CreateStatement.php
+++ b/src/Statements/CreateStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `CREATE` statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
diff --git a/src/Statements/DeleteStatement.php b/src/Statements/DeleteStatement.php
index 879fe2e..b55d5f4 100644
--- a/src/Statements/DeleteStatement.php
+++ b/src/Statements/DeleteStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `DELETE` statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
@@ -184,7 +184,7 @@ class DeleteStatement extends Statement
         if (! is_null($this->order) && count($this->order) > 0) {
             $ret .= ' ORDER BY ' . ExpressionArray::build($this->order);
         }
-        if (! is_null($this->limit) && strlen($this->limit) > 0) {
+        if (! is_null($this->limit) && strlen((string) $this->limit) > 0) {
             $ret .= ' LIMIT ' . Limit::build($this->limit);
         }
 
diff --git a/src/Statements/DropStatement.php b/src/Statements/DropStatement.php
index 1ec1c72..453bed1 100644
--- a/src/Statements/DropStatement.php
+++ b/src/Statements/DropStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `DROP` statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
diff --git a/src/Statements/ExplainStatement.php b/src/Statements/ExplainStatement.php
index 96a5828..65ea597 100644
--- a/src/Statements/ExplainStatement.php
+++ b/src/Statements/ExplainStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `EXPLAIN` statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
diff --git a/src/Statements/InsertStatement.php b/src/Statements/InsertStatement.php
index f2b6348..4230033 100644
--- a/src/Statements/InsertStatement.php
+++ b/src/Statements/InsertStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `INSERT` statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
@@ -117,7 +117,7 @@ class InsertStatement extends Statement
             $ret .= ' VALUES ' . Array2d::build($this->values);
         } elseif (! is_null($this->set) && count($this->set) > 0) {
             $ret .= ' SET ' . SetOperation::build($this->set);
-        } elseif (! is_null($this->select) && strlen($this->select) > 0) {
+        } elseif (! is_null($this->select) && strlen((string) $this->select) > 0) {
             $ret .= ' ' . $this->select->build();
         }
 
diff --git a/src/Statements/LoadStatement.php b/src/Statements/LoadStatement.php
index c9179aa..c5186cf 100644
--- a/src/Statements/LoadStatement.php
+++ b/src/Statements/LoadStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `LOAD` statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
@@ -194,7 +194,7 @@ class LoadStatement extends Statement
 
         $ret .= ' INTO TABLE ' . $this->table;
 
-        if ($this->partition !== null && strlen($this->partition) > 0) {
+        if ($this->partition !== null && strlen((string) $this->partition) > 0) {
             $ret .= ' PARTITION ' . ArrayObj::build($this->partition);
         }
 
@@ -206,7 +206,7 @@ class LoadStatement extends Statement
             $ret .= ' ' . $this->fields_keyword . ' ' . $this->fields_options;
         }
 
-        if ($this->lines_options !== null && strlen($this->lines_options) > 0) {
+        if ($this->lines_options !== null && strlen((string) $this->lines_options) > 0) {
             $ret .= ' LINES ' . $this->lines_options;
         }
 
diff --git a/src/Statements/LockStatement.php b/src/Statements/LockStatement.php
index 354d446..0166dca 100644
--- a/src/Statements/LockStatement.php
+++ b/src/Statements/LockStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `LOCK` statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
diff --git a/src/Statements/MaintenanceStatement.php b/src/Statements/MaintenanceStatement.php
index ac3b8c9..c59bb77 100644
--- a/src/Statements/MaintenanceStatement.php
+++ b/src/Statements/MaintenanceStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Maintenance statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
diff --git a/src/Statements/NotImplementedStatement.php b/src/Statements/NotImplementedStatement.php
index f5da4a1..254ca15 100644
--- a/src/Statements/NotImplementedStatement.php
+++ b/src/Statements/NotImplementedStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Not implemented (yet) statements.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
diff --git a/src/Statements/OptimizeStatement.php b/src/Statements/OptimizeStatement.php
index 19c95e5..cd9be0c 100644
--- a/src/Statements/OptimizeStatement.php
+++ b/src/Statements/OptimizeStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `OPTIMIZE` statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
diff --git a/src/Statements/PurgeStatement.php b/src/Statements/PurgeStatement.php
index 79a684f..4dc385e 100644
--- a/src/Statements/PurgeStatement.php
+++ b/src/Statements/PurgeStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `PURGE` statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
diff --git a/src/Statements/RenameStatement.php b/src/Statements/RenameStatement.php
index e1bcf0d..17662d3 100644
--- a/src/Statements/RenameStatement.php
+++ b/src/Statements/RenameStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `RENAME` statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
diff --git a/src/Statements/RepairStatement.php b/src/Statements/RepairStatement.php
index a9e058a..e17cdee 100644
--- a/src/Statements/RepairStatement.php
+++ b/src/Statements/RepairStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `REPAIR` statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
diff --git a/src/Statements/ReplaceStatement.php b/src/Statements/ReplaceStatement.php
index 72e6841..c5903c0 100644
--- a/src/Statements/ReplaceStatement.php
+++ b/src/Statements/ReplaceStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `REPLACE` statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
@@ -93,7 +93,7 @@ class ReplaceStatement extends Statement
             $ret .= ' VALUES ' . Array2d::build($this->values);
         } elseif (! is_null($this->set) && count($this->set) > 0) {
             $ret .= ' SET ' . SetOperation::build($this->set);
-        } elseif (! is_null($this->select) && strlen($this->select) > 0) {
+        } elseif (! is_null($this->select) && strlen((string) $this->select) > 0) {
             $ret .= ' ' . $this->select->build();
         }
 
diff --git a/src/Statements/RestoreStatement.php b/src/Statements/RestoreStatement.php
index 6a2b44f..6d2a72e 100644
--- a/src/Statements/RestoreStatement.php
+++ b/src/Statements/RestoreStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `RESTORE` statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
diff --git a/src/Statements/SelectStatement.php b/src/Statements/SelectStatement.php
index 1bff148..dab8db4 100644
--- a/src/Statements/SelectStatement.php
+++ b/src/Statements/SelectStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `SELECT` statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
diff --git a/src/Statements/SetStatement.php b/src/Statements/SetStatement.php
index 129cc14..cc1e487 100644
--- a/src/Statements/SetStatement.php
+++ b/src/Statements/SetStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `SET` statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
diff --git a/src/Statements/ShowStatement.php b/src/Statements/ShowStatement.php
index 4205310..d332968 100644
--- a/src/Statements/ShowStatement.php
+++ b/src/Statements/ShowStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `SHOW` statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
diff --git a/src/Statements/TransactionStatement.php b/src/Statements/TransactionStatement.php
index fae935a..7c07b5f 100644
--- a/src/Statements/TransactionStatement.php
+++ b/src/Statements/TransactionStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Transaction statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
diff --git a/src/Statements/TruncateStatement.php b/src/Statements/TruncateStatement.php
index c95dfd0..52f6347 100644
--- a/src/Statements/TruncateStatement.php
+++ b/src/Statements/TruncateStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `TRUNCATE` statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
diff --git a/src/Statements/UpdateStatement.php b/src/Statements/UpdateStatement.php
index 2dee189..8e6708f 100644
--- a/src/Statements/UpdateStatement.php
+++ b/src/Statements/UpdateStatement.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * `UPDATE` statement.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Statements;
 
diff --git a/src/Token.php b/src/Token.php
index 1965f8b..fe43e8b 100644
--- a/src/Token.php
+++ b/src/Token.php
@@ -1,10 +1,10 @@
 <?php
-
 /**
  * Defines a token along with a set of types and flags and utility functions.
  *
  * An array of tokens will result after parsing the query.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser;
 
diff --git a/src/TokensList.php b/src/TokensList.php
index 8d711f8..507d68b 100644
--- a/src/TokensList.php
+++ b/src/TokensList.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Defines an array of tokens and utility functions to iterate through it.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser;
 
diff --git a/src/Translator.php b/src/Translator.php
index 622bec9..a169632 100644
--- a/src/Translator.php
+++ b/src/Translator.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Defines the localization helper infrastructure of the library.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser;
 
diff --git a/src/UtfString.php b/src/UtfString.php
index 58905f3..9e6e55b 100644
--- a/src/UtfString.php
+++ b/src/UtfString.php
@@ -1,5 +1,4 @@
 <?php
-
 /**
  * Implementation for UTF-8 strings.
  *
@@ -10,6 +9,7 @@
  * Because the lexer relies on the subscript operator this class had to be
  * implemented.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser;
 
diff --git a/src/Utils/BufferedQuery.php b/src/Utils/BufferedQuery.php
index 5edf903..c2dd074 100644
--- a/src/Utils/BufferedQuery.php
+++ b/src/Utils/BufferedQuery.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Buffered query utilities.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Utils;
 
diff --git a/src/Utils/CLI.php b/src/Utils/CLI.php
index d2c27f2..31d09ce 100644
--- a/src/Utils/CLI.php
+++ b/src/Utils/CLI.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * CLI interface.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Utils;
 
diff --git a/src/Utils/Error.php b/src/Utils/Error.php
index af9706f..d0f82ed 100644
--- a/src/Utils/Error.php
+++ b/src/Utils/Error.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Error related utilities.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Utils;
 
@@ -86,7 +86,7 @@ class Error
                 ++$i,
                 $err[0],
                 $err[1],
-                htmlspecialchars($err[2]),
+                htmlspecialchars((string) $err[2]),
                 $err[3]
             );
         }
diff --git a/src/Utils/Formatter.php b/src/Utils/Formatter.php
index 2d2ca40..94d908c 100644
--- a/src/Utils/Formatter.php
+++ b/src/Utils/Formatter.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Utilities that are used for formatting queries.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Utils;
 
@@ -500,7 +500,7 @@ class Formatter
                             // No space after . (
                             || ($curr->type === Token::TYPE_OPERATOR && ($curr->value === '.' || $curr->value === ',' || $curr->value === '(' || $curr->value === ')'))
                             // No space before . , ( )
-                            || $curr->type === Token::TYPE_DELIMITER && mb_strlen($curr->value, 'UTF-8') < 2
+                            || $curr->type === Token::TYPE_DELIMITER && mb_strlen((string) $curr->value, 'UTF-8') < 2
                         )
                     ) {
                         $ret .= ' ';
@@ -706,7 +706,7 @@ class Formatter
             }
 
             // Keeping track of this group's length.
-            $length += mb_strlen($list->tokens[$idx]->value, 'UTF-8');
+            $length += mb_strlen((string) $list->tokens[$idx]->value, 'UTF-8');
         }
 
         return $length;
diff --git a/src/Utils/Misc.php b/src/Utils/Misc.php
index aa9e13a..9e3ae02 100644
--- a/src/Utils/Misc.php
+++ b/src/Utils/Misc.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Miscellaneous utilities.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Utils;
 
diff --git a/src/Utils/Query.php b/src/Utils/Query.php
index 1416629..662404b 100644
--- a/src/Utils/Query.php
+++ b/src/Utils/Query.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Statement utilities.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Utils;
 
diff --git a/src/Utils/Routine.php b/src/Utils/Routine.php
index 50f319a..9842ff1 100644
--- a/src/Utils/Routine.php
+++ b/src/Utils/Routine.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Routine utilities.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Utils;
 
diff --git a/src/Utils/Table.php b/src/Utils/Table.php
index 49e3f35..140ed2a 100644
--- a/src/Utils/Table.php
+++ b/src/Utils/Table.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Table utilities.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Utils;
 
diff --git a/src/Utils/Tokens.php b/src/Utils/Tokens.php
index cde1a79..b7f5935 100644
--- a/src/Utils/Tokens.php
+++ b/src/Utils/Tokens.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Token utilities.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Utils;
 
@@ -44,7 +44,7 @@ class Tokens
         }
 
         if (isset($pattern['value_str'])
-            && strcasecmp($pattern['value_str'], $token->value)
+            && strcasecmp($pattern['value_str'], (string) $token->value)
         ) {
             return false;
         }
diff --git a/tests/Builder/AlterStatementTest.php b/tests/Builder/AlterStatementTest.php
index 2372b6d..70236e4 100644
--- a/tests/Builder/AlterStatementTest.php
+++ b/tests/Builder/AlterStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Builder;
 
diff --git a/tests/Builder/CreateStatementTest.php b/tests/Builder/CreateStatementTest.php
index 6facd88..328d381 100644
--- a/tests/Builder/CreateStatementTest.php
+++ b/tests/Builder/CreateStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Builder;
 
diff --git a/tests/Builder/DeleteStatementTest.php b/tests/Builder/DeleteStatementTest.php
index 5aa037e..0327e03 100644
--- a/tests/Builder/DeleteStatementTest.php
+++ b/tests/Builder/DeleteStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Builder;
 
diff --git a/tests/Builder/ExplainStatement.php b/tests/Builder/ExplainStatement.php
index 44bb817..7b6215f 100644
--- a/tests/Builder/ExplainStatement.php
+++ b/tests/Builder/ExplainStatement.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Builder;
 
diff --git a/tests/Builder/InsertStatementTest.php b/tests/Builder/InsertStatementTest.php
index 50a04d4..a2b2ef8 100644
--- a/tests/Builder/InsertStatementTest.php
+++ b/tests/Builder/InsertStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Builder;
 
diff --git a/tests/Builder/LoadStatementTest.php b/tests/Builder/LoadStatementTest.php
index 4c4e9b1..051e13d 100644
--- a/tests/Builder/LoadStatementTest.php
+++ b/tests/Builder/LoadStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Builder;
 
diff --git a/tests/Builder/LockStatementTest.php b/tests/Builder/LockStatementTest.php
index b0b4d38..8593a87 100644
--- a/tests/Builder/LockStatementTest.php
+++ b/tests/Builder/LockStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Builder;
 
diff --git a/tests/Builder/PurgeStatementTest.php b/tests/Builder/PurgeStatementTest.php
index caa1652..aae52b5 100644
--- a/tests/Builder/PurgeStatementTest.php
+++ b/tests/Builder/PurgeStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Builder;
 
diff --git a/tests/Builder/RenameStatementTest.php b/tests/Builder/RenameStatementTest.php
index 97852ab..e803786 100644
--- a/tests/Builder/RenameStatementTest.php
+++ b/tests/Builder/RenameStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Builder;
 
diff --git a/tests/Builder/ReplaceStatementTest.php b/tests/Builder/ReplaceStatementTest.php
index f96bd43..2610ac0 100644
--- a/tests/Builder/ReplaceStatementTest.php
+++ b/tests/Builder/ReplaceStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Builder;
 
diff --git a/tests/Builder/SelectStatementTest.php b/tests/Builder/SelectStatementTest.php
index 614c561..eaf80c3 100644
--- a/tests/Builder/SelectStatementTest.php
+++ b/tests/Builder/SelectStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Builder;
 
diff --git a/tests/Builder/SetStatementTest.php b/tests/Builder/SetStatementTest.php
index 746e92f..406e369 100644
--- a/tests/Builder/SetStatementTest.php
+++ b/tests/Builder/SetStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Builder;
 
diff --git a/tests/Builder/StatementTest.php b/tests/Builder/StatementTest.php
index 42e9a57..da16602 100644
--- a/tests/Builder/StatementTest.php
+++ b/tests/Builder/StatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Builder;
 
diff --git a/tests/Builder/TransactionStatementTest.php b/tests/Builder/TransactionStatementTest.php
index b35d2ea..4bdfe70 100644
--- a/tests/Builder/TransactionStatementTest.php
+++ b/tests/Builder/TransactionStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Builder;
 
diff --git a/tests/Components/Array2dTest.php b/tests/Components/Array2dTest.php
index 2e2cf6b..3413f8a 100644
--- a/tests/Components/Array2dTest.php
+++ b/tests/Components/Array2dTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Components;
 
diff --git a/tests/Components/ArrayObjTest.php b/tests/Components/ArrayObjTest.php
index ccef92f..f32173c 100644
--- a/tests/Components/ArrayObjTest.php
+++ b/tests/Components/ArrayObjTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Components;
 
diff --git a/tests/Components/CaseExpressionTest.php b/tests/Components/CaseExpressionTest.php
index 52078ef..cb9290c 100644
--- a/tests/Components/CaseExpressionTest.php
+++ b/tests/Components/CaseExpressionTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Components;
 
diff --git a/tests/Components/ComponentTest.php b/tests/Components/ComponentTest.php
index 8686160..fec0f56 100644
--- a/tests/Components/ComponentTest.php
+++ b/tests/Components/ComponentTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Parser;
 
diff --git a/tests/Components/ConditionTest.php b/tests/Components/ConditionTest.php
index 27c6a4f..eb8cca1 100644
--- a/tests/Components/ConditionTest.php
+++ b/tests/Components/ConditionTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Components;
 
diff --git a/tests/Components/CreateDefinitionTest.php b/tests/Components/CreateDefinitionTest.php
index 3683e29..6b97cb1 100644
--- a/tests/Components/CreateDefinitionTest.php
+++ b/tests/Components/CreateDefinitionTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Components;
 
diff --git a/tests/Components/ExpressionArrayTest.php b/tests/Components/ExpressionArrayTest.php
index ede3954..597d0a3 100644
--- a/tests/Components/ExpressionArrayTest.php
+++ b/tests/Components/ExpressionArrayTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Components;
 
diff --git a/tests/Components/ExpressionTest.php b/tests/Components/ExpressionTest.php
index 943aa6a..ae7f0f6 100644
--- a/tests/Components/ExpressionTest.php
+++ b/tests/Components/ExpressionTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Components;
 
diff --git a/tests/Components/FunctionCallTest.php b/tests/Components/FunctionCallTest.php
index 20ac4c6..386b220 100644
--- a/tests/Components/FunctionCallTest.php
+++ b/tests/Components/FunctionCallTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Components;
 
diff --git a/tests/Components/GroupKeywordTest.php b/tests/Components/GroupKeywordTest.php
index aa88c60..41ff89a 100644
--- a/tests/Components/GroupKeywordTest.php
+++ b/tests/Components/GroupKeywordTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Components;
 
diff --git a/tests/Components/IntoKeywordTest.php b/tests/Components/IntoKeywordTest.php
index 2ebf5ee..896c363 100644
--- a/tests/Components/IntoKeywordTest.php
+++ b/tests/Components/IntoKeywordTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Components;
 
diff --git a/tests/Components/JoinKeywordTest.php b/tests/Components/JoinKeywordTest.php
index 9e8b85f..91fd4a6 100644
--- a/tests/Components/JoinKeywordTest.php
+++ b/tests/Components/JoinKeywordTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Components;
 
diff --git a/tests/Components/KeyTest.php b/tests/Components/KeyTest.php
index c27b9d8..aeb403d 100644
--- a/tests/Components/KeyTest.php
+++ b/tests/Components/KeyTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Components;
 
diff --git a/tests/Components/LimitTest.php b/tests/Components/LimitTest.php
index 8d336b2..f7bbbce 100644
--- a/tests/Components/LimitTest.php
+++ b/tests/Components/LimitTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Components;
 
diff --git a/tests/Components/LockExpressionTest.php b/tests/Components/LockExpressionTest.php
index 0f8e418..7f26c5e 100644
--- a/tests/Components/LockExpressionTest.php
+++ b/tests/Components/LockExpressionTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Components;
 
diff --git a/tests/Components/OptionsArrayTest.php b/tests/Components/OptionsArrayTest.php
index c5b6eb7..3904fdf 100644
--- a/tests/Components/OptionsArrayTest.php
+++ b/tests/Components/OptionsArrayTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Components;
 
diff --git a/tests/Components/OrderKeywordTest.php b/tests/Components/OrderKeywordTest.php
index ffacfd4..11468fb 100644
--- a/tests/Components/OrderKeywordTest.php
+++ b/tests/Components/OrderKeywordTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Components;
 
diff --git a/tests/Components/ParameterDefinitionTest.php b/tests/Components/ParameterDefinitionTest.php
index 683eb3a..38d28e0 100644
--- a/tests/Components/ParameterDefinitionTest.php
+++ b/tests/Components/ParameterDefinitionTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Components;
 
diff --git a/tests/Components/PartitionDefinitionTest.php b/tests/Components/PartitionDefinitionTest.php
index 7edc21e..93bc4d5 100644
--- a/tests/Components/PartitionDefinitionTest.php
+++ b/tests/Components/PartitionDefinitionTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Components;
 
diff --git a/tests/Components/ReferenceTest.php b/tests/Components/ReferenceTest.php
index 178776c..19768c7 100644
--- a/tests/Components/ReferenceTest.php
+++ b/tests/Components/ReferenceTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Components;
 
diff --git a/tests/Components/RenameOperationTest.php b/tests/Components/RenameOperationTest.php
index 919c4bd..6f38605 100644
--- a/tests/Components/RenameOperationTest.php
+++ b/tests/Components/RenameOperationTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Components;
 
diff --git a/tests/Lexer/ContextTest.php b/tests/Lexer/ContextTest.php
index d822cd3..47bd10a 100644
--- a/tests/Lexer/ContextTest.php
+++ b/tests/Lexer/ContextTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Lexer;
 
diff --git a/tests/Lexer/IsMethodsTest.php b/tests/Lexer/IsMethodsTest.php
index 56552c7..9095907 100644
--- a/tests/Lexer/IsMethodsTest.php
+++ b/tests/Lexer/IsMethodsTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Lexer;
 
diff --git a/tests/Lexer/LexerTest.php b/tests/Lexer/LexerTest.php
index 353e80a..f5276af 100644
--- a/tests/Lexer/LexerTest.php
+++ b/tests/Lexer/LexerTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Lexer;
 
diff --git a/tests/Lexer/TokenTest.php b/tests/Lexer/TokenTest.php
index 535f933..370824e 100644
--- a/tests/Lexer/TokenTest.php
+++ b/tests/Lexer/TokenTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Lexer;
 
diff --git a/tests/Lexer/TokensListTest.php b/tests/Lexer/TokensListTest.php
index 4bb844a..a03bfad 100644
--- a/tests/Lexer/TokensListTest.php
+++ b/tests/Lexer/TokensListTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Lexer;
 
diff --git a/tests/Misc/BugsTest.php b/tests/Misc/BugsTest.php
index 5dbb861..3065308 100644
--- a/tests/Misc/BugsTest.php
+++ b/tests/Misc/BugsTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Parser;
 
diff --git a/tests/Misc/ParameterTest.php b/tests/Misc/ParameterTest.php
index fa6b79c..a8b2f9b 100644
--- a/tests/Misc/ParameterTest.php
+++ b/tests/Misc/ParameterTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Misc;
 
diff --git a/tests/Misc/UtfStringTest.php b/tests/Misc/UtfStringTest.php
index afa3b0c..d2c4dbf 100644
--- a/tests/Misc/UtfStringTest.php
+++ b/tests/Misc/UtfStringTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Misc;
 
diff --git a/tests/Parser/AlterStatementTest.php b/tests/Parser/AlterStatementTest.php
index 4582a23..1680d4d 100644
--- a/tests/Parser/AlterStatementTest.php
+++ b/tests/Parser/AlterStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Parser;
 
diff --git a/tests/Parser/CallStatementTest.php b/tests/Parser/CallStatementTest.php
index 0bb34e1..671a9f9 100644
--- a/tests/Parser/CallStatementTest.php
+++ b/tests/Parser/CallStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Parser;
 
diff --git a/tests/Parser/CreateStatementTest.php b/tests/Parser/CreateStatementTest.php
index 1ac1ddc..56c3c72 100644
--- a/tests/Parser/CreateStatementTest.php
+++ b/tests/Parser/CreateStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Parser;
 
diff --git a/tests/Parser/DeleteStatementTest.php b/tests/Parser/DeleteStatementTest.php
index 348d666..ecfe9f4 100644
--- a/tests/Parser/DeleteStatementTest.php
+++ b/tests/Parser/DeleteStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Parser;
 
diff --git a/tests/Parser/ExplainStatement.php b/tests/Parser/ExplainStatement.php
index 804a0e4..2001bed 100644
--- a/tests/Parser/ExplainStatement.php
+++ b/tests/Parser/ExplainStatement.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Parser;
 
diff --git a/tests/Parser/InsertStatementTest.php b/tests/Parser/InsertStatementTest.php
index 396b6c4..a1b097c 100644
--- a/tests/Parser/InsertStatementTest.php
+++ b/tests/Parser/InsertStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Parser;
 
diff --git a/tests/Parser/LoadStatementTest.php b/tests/Parser/LoadStatementTest.php
index f18dcf6..41e947b 100644
--- a/tests/Parser/LoadStatementTest.php
+++ b/tests/Parser/LoadStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Parser;
 
diff --git a/tests/Parser/LockStatementTest.php b/tests/Parser/LockStatementTest.php
index 0f7a416..19b778e 100644
--- a/tests/Parser/LockStatementTest.php
+++ b/tests/Parser/LockStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Parser;
 
diff --git a/tests/Parser/ParserTest.php b/tests/Parser/ParserTest.php
index 16dcbf9..3f37072 100644
--- a/tests/Parser/ParserTest.php
+++ b/tests/Parser/ParserTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Parser;
 
diff --git a/tests/Parser/PurgeStatementTest.php b/tests/Parser/PurgeStatementTest.php
index 8716cb4..deca5c5 100644
--- a/tests/Parser/PurgeStatementTest.php
+++ b/tests/Parser/PurgeStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Parser;
 
diff --git a/tests/Parser/RenameStatementTest.php b/tests/Parser/RenameStatementTest.php
index 47db80e..84253bd 100644
--- a/tests/Parser/RenameStatementTest.php
+++ b/tests/Parser/RenameStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Parser;
 
diff --git a/tests/Parser/ReplaceStatementTest.php b/tests/Parser/ReplaceStatementTest.php
index 9745ada..ba304d8 100644
--- a/tests/Parser/ReplaceStatementTest.php
+++ b/tests/Parser/ReplaceStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Parser;
 
diff --git a/tests/Parser/RestoreStatementTest.php b/tests/Parser/RestoreStatementTest.php
index d8b73dc..1f2a308 100644
--- a/tests/Parser/RestoreStatementTest.php
+++ b/tests/Parser/RestoreStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Parser;
 
diff --git a/tests/Parser/SelectStatementTest.php b/tests/Parser/SelectStatementTest.php
index cc860f0..8c1af98 100644
--- a/tests/Parser/SelectStatementTest.php
+++ b/tests/Parser/SelectStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Parser;
 
diff --git a/tests/Parser/SetStatementTest.php b/tests/Parser/SetStatementTest.php
index b3ae9c2..7c767a5 100644
--- a/tests/Parser/SetStatementTest.php
+++ b/tests/Parser/SetStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Parser;
 
diff --git a/tests/Parser/TransactionStatementTest.php b/tests/Parser/TransactionStatementTest.php
index 6234f17..b72a21b 100644
--- a/tests/Parser/TransactionStatementTest.php
+++ b/tests/Parser/TransactionStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Parser;
 
diff --git a/tests/Parser/UpdateStatementTest.php b/tests/Parser/UpdateStatementTest.php
index 8a47f44..448be52 100644
--- a/tests/Parser/UpdateStatementTest.php
+++ b/tests/Parser/UpdateStatementTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Parser;
 
diff --git a/tests/TestCase.php b/tests/TestCase.php
index cb925e1..71febab 100644
--- a/tests/TestCase.php
+++ b/tests/TestCase.php
@@ -1,8 +1,8 @@
 <?php
-
 /**
  * Bootstrap for tests.
  */
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests;
 
diff --git a/tests/Utils/BufferedQueryTest.php b/tests/Utils/BufferedQueryTest.php
index f31dd78..bbf886f 100644
--- a/tests/Utils/BufferedQueryTest.php
+++ b/tests/Utils/BufferedQueryTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Utils;
 
diff --git a/tests/Utils/CLITest.php b/tests/Utils/CLITest.php
index ebcd35e..bacf5fb 100644
--- a/tests/Utils/CLITest.php
+++ b/tests/Utils/CLITest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Utils;
 
diff --git a/tests/Utils/ErrorTest.php b/tests/Utils/ErrorTest.php
index d7d1393..7e1326f 100644
--- a/tests/Utils/ErrorTest.php
+++ b/tests/Utils/ErrorTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Utils;
 
diff --git a/tests/Utils/FormatterTest.php b/tests/Utils/FormatterTest.php
index 152359e..7776a8e 100644
--- a/tests/Utils/FormatterTest.php
+++ b/tests/Utils/FormatterTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Utils;
 
diff --git a/tests/Utils/MiscTest.php b/tests/Utils/MiscTest.php
index 01a2926..dbd200e 100644
--- a/tests/Utils/MiscTest.php
+++ b/tests/Utils/MiscTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Utils;
 
diff --git a/tests/Utils/QueryTest.php b/tests/Utils/QueryTest.php
index 6991870..0d62915 100644
--- a/tests/Utils/QueryTest.php
+++ b/tests/Utils/QueryTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Utils;
 
diff --git a/tests/Utils/RoutineTest.php b/tests/Utils/RoutineTest.php
index 9a7c4ca..81a8325 100644
--- a/tests/Utils/RoutineTest.php
+++ b/tests/Utils/RoutineTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Utils;
 
diff --git a/tests/Utils/TableTest.php b/tests/Utils/TableTest.php
index fe68100..9d5d3b0 100644
--- a/tests/Utils/TableTest.php
+++ b/tests/Utils/TableTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Utils;
 
diff --git a/tests/Utils/TokensTest.php b/tests/Utils/TokensTest.php
index 533021c..200dfe6 100644
--- a/tests/Utils/TokensTest.php
+++ b/tests/Utils/TokensTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tests\Utils;
 
diff --git a/tools/ContextGenerator.php b/tools/ContextGenerator.php
index 5c6b747..ac24156 100644
--- a/tools/ContextGenerator.php
+++ b/tools/ContextGenerator.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tools;
 
@@ -56,7 +57,6 @@ class ContextGenerator
      */
     const TEMPLATE =
         '<?php' . "\n" .
-        '' . "\n" .
         '/**' . "\n" .
         ' * Context for %1$s.' . "\n" .
         ' *' . "\n" .
@@ -64,6 +64,7 @@ class ContextGenerator
         ' *' . "\n" .
         ' * @see %3$s' . "\n" .
         ' */' . "\n" .
+        'declare(strict_types=1);' . "\n" .
         '' . "\n" .
         'namespace PhpMyAdmin\\SqlParser\\Contexts;' . "\n" .
         '' . "\n" .
@@ -90,9 +91,9 @@ class ContextGenerator
         '     *' . "\n" .
         '     * @var array' . "\n" .
         '     */' . "\n" .
-        '    public static $KEYWORDS = array(' . "\n" .
+        '    public static $KEYWORDS = [' . "\n" .
         '%4$s' .
-        '    );' . "\n" .
+        '    ];' . "\n" .
         '}' . "\n";
 
     /**
diff --git a/tools/TestGenerator.php b/tools/TestGenerator.php
index 599387f..d52e708 100644
--- a/tools/TestGenerator.php
+++ b/tools/TestGenerator.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace PhpMyAdmin\SqlParser\Tools;