diff --git a/grammar/phpyLang.php b/grammar/phpyLang.php
new file mode 100644
index 0000000..1a9808d
--- /dev/null
+++ b/grammar/phpyLang.php
@@ -0,0 +1,192 @@
+<?php
+
+///////////////////////////////
+/// Utility regex constants ///
+///////////////////////////////
+
+const LIB = '(?(DEFINE)
+    (?<singleQuotedString>\'[^\\\\\']*+(?:\\\\.[^\\\\\']*+)*+\')
+    (?<doubleQuotedString>"[^\\\\"]*+(?:\\\\.[^\\\\"]*+)*+")
+    (?<string>(?&singleQuotedString)|(?&doubleQuotedString))
+    (?<comment>/\*[^*]*+(?:\*(?!/)[^*]*+)*+\*/)
+    (?<code>\{[^\'"/{}]*+(?:(?:(?&string)|(?&comment)|(?&code)|/)[^\'"/{}]*+)*+})
+)';
+
+const PARAMS = '\[(?<params>[^[\]]*+(?:\[(?&params)\][^[\]]*+)*+)\]';
+const ARGS   = '\((?<args>[^()]*+(?:\((?&args)\)[^()]*+)*+)\)';
+
+///////////////////////////////
+/// Preprocessing functions ///
+///////////////////////////////
+
+function preprocessGrammar($code) {
+    $code = resolveNodes($code);
+    $code = resolveMacros($code);
+    $code = resolveStackAccess($code);
+
+    return $code;
+}
+
+function resolveNodes($code) {
+    return preg_replace_callback(
+        '~\b(?<name>[A-Z][a-zA-Z_\\\\]++)\s*' . PARAMS . '~',
+        function($matches) {
+            // recurse
+            $matches['params'] = resolveNodes($matches['params']);
+
+            $params = magicSplit(
+                '(?:' . PARAMS . '|' . ARGS . ')(*SKIP)(*FAIL)|,',
+                $matches['params']
+            );
+
+            $paramCode = '';
+            foreach ($params as $param) {
+                $paramCode .= $param . ', ';
+            }
+
+            return 'new ' . $matches['name'] . '(' . $paramCode . 'attributes())';
+        },
+        $code
+    );
+}
+
+function resolveMacros($code) {
+    return preg_replace_callback(
+        '~\b(?<!::|->)(?!array\()(?<name>[a-z][A-Za-z]++)' . ARGS . '~',
+        function($matches) {
+            // recurse
+            $matches['args'] = resolveMacros($matches['args']);
+
+            $name = $matches['name'];
+            $args = magicSplit(
+                '(?:' . PARAMS . '|' . ARGS . ')(*SKIP)(*FAIL)|,',
+                $matches['args']
+            );
+
+            if ('attributes' === $name) {
+                assertArgs(0, $args, $name);
+                return '$this->startAttributeStack[#1] + $this->endAttributes';
+            }
+
+            if ('stackAttributes' === $name) {
+                assertArgs(1, $args, $name);
+                return '$this->startAttributeStack[' . $args[0] . ']'
+                       . ' + $this->endAttributeStack[' . $args[0] . ']';
+            }
+
+            if ('init' === $name) {
+                return '$$ = array(' . implode(', ', $args) . ')';
+            }
+
+            if ('push' === $name) {
+                assertArgs(2, $args, $name);
+
+                return $args[0] . '[] = ' . $args[1] . '; $$ = ' . $args[0];
+            }
+
+            if ('pushNormalizing' === $name) {
+                assertArgs(2, $args, $name);
+
+                return 'if (is_array(' . $args[1] . ')) { $$ = array_merge(' . $args[0] . ', ' . $args[1] . '); }'
+                       . ' else { ' . $args[0] . '[] = ' . $args[1] . '; $$ = ' . $args[0] . '; }';
+            }
+
+            if ('toArray' == $name) {
+                assertArgs(1, $args, $name);
+
+                return 'is_array(' . $args[0] . ') ? ' . $args[0] . ' : array(' . $args[0] . ')';
+            }
+
+            if ('parseVar' === $name) {
+                assertArgs(1, $args, $name);
+
+                return 'substr(' . $args[0] . ', 1)';
+            }
+
+            if ('parseEncapsed' === $name) {
+                assertArgs(3, $args, $name);
+
+                return 'foreach (' . $args[0] . ' as $s) { if ($s instanceof Node\Scalar\EncapsedStringPart) {'
+                       . ' $s->value = Node\Scalar\String_::parseEscapeSequences($s->value, ' . $args[1] . ', ' . $args[2] . '); } }';
+            }
+
+            if ('makeNop' === $name) {
+                assertArgs(3, $args, $name);
+
+                return '$startAttributes = ' . $args[1] . ';'
+                       . ' if (isset($startAttributes[\'comments\']))'
+                       . ' { ' . $args[0] . ' = new Stmt\Nop($startAttributes + ' . $args[2] . '); }'
+                       . ' else { ' . $args[0] . ' = null; }';
+            }
+
+            if ('makeZeroLengthNop' == $name) {
+                assertArgs(2, $args, $name);
+
+                return '$startAttributes = ' . $args[1] . ';'
+                       . ' if (isset($startAttributes[\'comments\']))'
+                       . ' { ' . $args[0] . ' = new Stmt\Nop($this->createCommentNopAttributes($startAttributes[\'comments\'])); }'
+                       . ' else { ' . $args[0] . ' = null; }';
+            }
+
+            if ('strKind' === $name) {
+                assertArgs(1, $args, $name);
+
+                return '(' . $args[0] . '[0] === "\'" || (' . $args[0] . '[1] === "\'" && '
+                       . '(' . $args[0] . '[0] === \'b\' || ' . $args[0] . '[0] === \'B\')) '
+                       . '? Scalar\String_::KIND_SINGLE_QUOTED : Scalar\String_::KIND_DOUBLE_QUOTED)';
+            }
+
+            if ('prependLeadingComments' === $name) {
+                assertArgs(1, $args, $name);
+
+                return '$attrs = $this->startAttributeStack[#1]; $stmts = ' . $args[0] . '; '
+                       . 'if (!empty($attrs[\'comments\'])) {'
+                       . '$stmts[0]->setAttribute(\'comments\', '
+                       . 'array_merge($attrs[\'comments\'], $stmts[0]->getAttribute(\'comments\', []))); }';
+            }
+
+            return $matches[0];
+        },
+        $code
+    );
+}
+
+function assertArgs($num, $args, $name) {
+    if ($num != count($args)) {
+        die('Wrong argument count for ' . $name . '().');
+    }
+}
+
+function resolveStackAccess($code) {
+    $code = preg_replace('/\$\d+/', '$this->semStack[$0]', $code);
+    $code = preg_replace('/#(\d+)/', '$$1', $code);
+    return $code;
+}
+
+function removeTrailingWhitespace($code) {
+    $lines = explode("\n", $code);
+    $lines = array_map('rtrim', $lines);
+    return implode("\n", $lines);
+}
+
+//////////////////////////////
+/// Regex helper functions ///
+//////////////////////////////
+
+function regex($regex) {
+    return '~' . LIB . '(?:' . str_replace('~', '\~', $regex) . ')~';
+}
+
+function magicSplit($regex, $string) {
+    $pieces = preg_split(regex('(?:(?&string)|(?&comment)|(?&code))(*SKIP)(*FAIL)|' . $regex), $string);
+
+    foreach ($pieces as &$piece) {
+        $piece = trim($piece);
+    }
+
+    if ($pieces === ['']) {
+        return [];
+    }
+
+    return $pieces;
+}
diff --git a/grammar/rebuildParsers.php b/grammar/rebuildParsers.php
index 88a53f1..2d0c6b1 100644
--- a/grammar/rebuildParsers.php
+++ b/grammar/rebuildParsers.php
@@ -1,5 +1,7 @@
 <?php
 
+require __DIR__ . '/phpyLang.php';
+
 $grammarFileToName = [
     __DIR__ . '/php5.y' => 'Php5',
     __DIR__ . '/php7.y' => 'Php7',
@@ -23,21 +25,6 @@ $options = array_flip($argv);
 $optionDebug = isset($options['--debug']);
 $optionKeepTmpGrammar = isset($options['--keep-tmp-grammar']);
 
-///////////////////////////////
-/// Utility regex constants ///
-///////////////////////////////
-
-const LIB = '(?(DEFINE)
-    (?<singleQuotedString>\'[^\\\\\']*+(?:\\\\.[^\\\\\']*+)*+\')
-    (?<doubleQuotedString>"[^\\\\"]*+(?:\\\\.[^\\\\"]*+)*+")
-    (?<string>(?&singleQuotedString)|(?&doubleQuotedString))
-    (?<comment>/\*[^*]*+(?:\*(?!/)[^*]*+)*+\*/)
-    (?<code>\{[^\'"/{}]*+(?:(?:(?&string)|(?&comment)|(?&code)|/)[^\'"/{}]*+)*+})
-)';
-
-const PARAMS = '\[(?<params>[^[\]]*+(?:\[(?&params)\][^[\]]*+)*+)\]';
-const ARGS   = '\((?<args>[^()]*+(?:\((?&args)\)[^()]*+)*+)\)';
-
 ///////////////////
 /// Main script ///
 ///////////////////
@@ -49,10 +36,7 @@ foreach ($grammarFileToName as $grammarFile => $name) {
 
     $grammarCode = file_get_contents($grammarFile);
     $grammarCode = str_replace('%tokens', $tokens, $grammarCode);
-
-    $grammarCode = resolveNodes($grammarCode);
-    $grammarCode = resolveMacros($grammarCode);
-    $grammarCode = resolveStackAccess($grammarCode);
+    $grammarCode = preprocessGrammar($grammarCode);
 
     file_put_contents($tmpGrammarFile, $grammarCode);
 
@@ -77,151 +61,9 @@ foreach ($grammarFileToName as $grammarFile => $name) {
     }
 }
 
-///////////////////////////////
-/// Preprocessing functions ///
-///////////////////////////////
-
-function resolveNodes($code) {
-    return preg_replace_callback(
-        '~\b(?<name>[A-Z][a-zA-Z_\\\\]++)\s*' . PARAMS . '~',
-        function($matches) {
-            // recurse
-            $matches['params'] = resolveNodes($matches['params']);
-
-            $params = magicSplit(
-                '(?:' . PARAMS . '|' . ARGS . ')(*SKIP)(*FAIL)|,',
-                $matches['params']
-            );
-
-            $paramCode = '';
-            foreach ($params as $param) {
-                $paramCode .= $param . ', ';
-            }
-
-            return 'new ' . $matches['name'] . '(' . $paramCode . 'attributes())';
-        },
-        $code
-    );
-}
-
-function resolveMacros($code) {
-    return preg_replace_callback(
-        '~\b(?<!::|->)(?!array\()(?<name>[a-z][A-Za-z]++)' . ARGS . '~',
-        function($matches) {
-            // recurse
-            $matches['args'] = resolveMacros($matches['args']);
-
-            $name = $matches['name'];
-            $args = magicSplit(
-                '(?:' . PARAMS . '|' . ARGS . ')(*SKIP)(*FAIL)|,',
-                $matches['args']
-            );
-
-            if ('attributes' === $name) {
-                assertArgs(0, $args, $name);
-                return '$this->startAttributeStack[#1] + $this->endAttributes';
-            }
-
-            if ('stackAttributes' === $name) {
-                assertArgs(1, $args, $name);
-                return '$this->startAttributeStack[' . $args[0] . ']'
-                     . ' + $this->endAttributeStack[' . $args[0] . ']';
-            }
-
-            if ('init' === $name) {
-                return '$$ = array(' . implode(', ', $args) . ')';
-            }
-
-            if ('push' === $name) {
-                assertArgs(2, $args, $name);
-
-                return $args[0] . '[] = ' . $args[1] . '; $$ = ' . $args[0];
-            }
-
-            if ('pushNormalizing' === $name) {
-                assertArgs(2, $args, $name);
-
-                return 'if (is_array(' . $args[1] . ')) { $$ = array_merge(' . $args[0] . ', ' . $args[1] . '); }'
-                     . ' else { ' . $args[0] . '[] = ' . $args[1] . '; $$ = ' . $args[0] . '; }';
-            }
-
-            if ('toArray' == $name) {
-                assertArgs(1, $args, $name);
-
-                return 'is_array(' . $args[0] . ') ? ' . $args[0] . ' : array(' . $args[0] . ')';
-            }
-
-            if ('parseVar' === $name) {
-                assertArgs(1, $args, $name);
-
-                return 'substr(' . $args[0] . ', 1)';
-            }
-
-            if ('parseEncapsed' === $name) {
-                assertArgs(3, $args, $name);
-
-                return 'foreach (' . $args[0] . ' as $s) { if ($s instanceof Node\Scalar\EncapsedStringPart) {'
-                     . ' $s->value = Node\Scalar\String_::parseEscapeSequences($s->value, ' . $args[1] . ', ' . $args[2] . '); } }';
-            }
-
-            if ('makeNop' === $name) {
-                assertArgs(3, $args, $name);
-
-                return '$startAttributes = ' . $args[1] . ';'
-                . ' if (isset($startAttributes[\'comments\']))'
-                . ' { ' . $args[0] . ' = new Stmt\Nop($startAttributes + ' . $args[2] . '); }'
-                . ' else { ' . $args[0] . ' = null; }';
-            }
-
-            if ('makeZeroLengthNop' == $name) {
-                assertArgs(2, $args, $name);
-
-                return '$startAttributes = ' . $args[1] . ';'
-                    . ' if (isset($startAttributes[\'comments\']))'
-                    . ' { ' . $args[0] . ' = new Stmt\Nop($this->createCommentNopAttributes($startAttributes[\'comments\'])); }'
-                    . ' else { ' . $args[0] . ' = null; }';
-            }
-
-            if ('strKind' === $name) {
-                assertArgs(1, $args, $name);
-
-                return '(' . $args[0] . '[0] === "\'" || (' . $args[0] . '[1] === "\'" && '
-                     . '(' . $args[0] . '[0] === \'b\' || ' . $args[0] . '[0] === \'B\')) '
-                     . '? Scalar\String_::KIND_SINGLE_QUOTED : Scalar\String_::KIND_DOUBLE_QUOTED)';
-            }
-
-            if ('prependLeadingComments' === $name) {
-                assertArgs(1, $args, $name);
-
-                return '$attrs = $this->startAttributeStack[#1]; $stmts = ' . $args[0] . '; '
-                . 'if (!empty($attrs[\'comments\'])) {'
-                . '$stmts[0]->setAttribute(\'comments\', '
-                . 'array_merge($attrs[\'comments\'], $stmts[0]->getAttribute(\'comments\', []))); }';
-            }
-
-            return $matches[0];
-        },
-        $code
-    );
-}
-
-function assertArgs($num, $args, $name) {
-    if ($num != count($args)) {
-        die('Wrong argument count for ' . $name . '().');
-    }
-}
-
-function resolveStackAccess($code) {
-    $code = preg_replace('/\$\d+/', '$this->semStack[$0]', $code);
-    $code = preg_replace('/#(\d+)/', '$$1', $code);
-    return $code;
-}
-
-function removeTrailingWhitespace($code) {
-    $lines = explode("\n", $code);
-    $lines = array_map('rtrim', $lines);
-    return implode("\n", $lines);
-}
+////////////////////////////////
+/// Utility helper functions ///
+////////////////////////////////
 
 function ensureDirExists($dir) {
     if (!is_dir($dir)) {
@@ -237,25 +79,3 @@ function execCmd($cmd) {
     }
     return $output;
 }
-
-//////////////////////////////
-/// Regex helper functions ///
-//////////////////////////////
-
-function regex($regex) {
-    return '~' . LIB . '(?:' . str_replace('~', '\~', $regex) . ')~';
-}
-
-function magicSplit($regex, $string) {
-    $pieces = preg_split(regex('(?:(?&string)|(?&comment)|(?&code))(*SKIP)(*FAIL)|' . $regex), $string);
-
-    foreach ($pieces as &$piece) {
-        $piece = trim($piece);
-    }
-
-    if ($pieces === ['']) {
-        return [];
-    }
-
-    return $pieces;
-}