add PEG macro flavor

src/Ast.php

@@ -130,12 +130,16 @@ function isEmpty() : bool {
         return !\count($this->ast) || null === $this->ast;
     }
 
-    function as(/*string|null*/ $label = null) : self {
-        if (null !== $label && null === $this->label) $this->label = $label;
+    function as(string $label = null) : self {
+        if (null !== $label) $this->label = $label;
 
         return $this;
     }
 
+    function label() {
+        return $this->label;
+    }
+
     function withParent(self $parent) : self {
         $this->parent = $parent;
 

src/Engine.php

@@ -105,7 +105,14 @@ function __construct() {
                 ->onCommit(function(Ast $macroAst) {
                     $scope = Map::fromEmpty();
                     $tags = Map::fromValues(array_map('strval', $macroAst->{'tags'}));
-                    $pattern = new Pattern($macroAst->{'declaration'}->line(), $macroAst->{'body pattern'}, $tags, $scope);
+
+                    if ($tags->contains('·grammar')) {
+                        $pattern = new GrammarPattern($macroAst->{'declaration'}->line(), $macroAst->{'body pattern'}, $tags, $scope);
+                    }
+                    else {
+                        $pattern = new Pattern($macroAst->{'declaration'}->line(), $macroAst->{'body pattern'}, $tags, $scope);
+                    }
+
                     $expansion = new Expansion($macroAst->{'body expansion'}, $tags, $scope);
                     $macro = new Macro($tags, $pattern, $expansion);
 

src/Expansion.php

@@ -6,14 +6,6 @@
 
 class Expansion extends MacroMember {
 
-    const
-        PRETTY_PRINT =
-                JSON_PRETTY_PRINT
-            |   JSON_BIGINT_AS_STRING
-            |   JSON_UNESCAPED_UNICODE
-            |   JSON_UNESCAPED_SLASHES
-    ;
-
     const
         E_BAD_EXPANSION = "Bad macro expansion identifier '%s' on line %d.",
         E_BAD_EXPANDER = "Bad macro expander '%s' on line %d.",