From 3fc11964254e0add22c0394556c26cc6ee0697c1 Mon Sep 17 00:00:00 2001
From: "benoit.thomas" <thoben@hotmail.fr>
Date: Fri, 16 Jul 2021 18:42:12 +0900
Subject: [PATCH] Add the "& rule"

---
 parse.leg | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/parse.leg b/parse.leg
index d836cc4..2ba6838 100644
--- a/parse.leg
+++ b/parse.leg
@@ -20,7 +20,7 @@ void fatal(char *fmt, ...)
     exit(1);
 }
 
-enum op { String, Query, Star, Plus, Or, And, Class, Dot, Exc, Id } ;
+enum op { String, Query, Star, Plus, Or, And, Class, Dot, Exc, Et, Id} ;
 
 
 typedef union Node Node;
@@ -41,6 +41,7 @@ struct And     { enum op type;  Node *children[2]; };
 struct Class   { enum op type;  char *stringValue; int len; };
 struct Dot     { enum op type; };
 struct Exc     { enum op type;  Node *children[1]; };
+struct Et      { enum op type;  Node *children[1]; };
 struct Id      { enum op type; Symbol *symbol; };
 
 union Node {
@@ -54,6 +55,7 @@ union Node {
     struct Class Class;
     struct Dot Dot;
     struct Exc Exc;
+    struct Et Et;
     struct Id Id;
 };
 
@@ -163,6 +165,13 @@ Node *mkExc(Node *n)
     return node;
 }
 
+Node *mkEt(Node *n)
+{
+    Node *node= new(Et);
+    node->Et.children[0]= n;
+    return node;
+}
+
 Node *_checktype(Node *object, enum op type)
 {
     if (object->type == type) return object;
@@ -211,6 +220,10 @@ void print(Node *node)
 	  printf("!");
 	  print(node->Exc.children[0]);
 	  return;
+      case Et:
+	  printf("&");
+	  print(node->Et.children[0]);
+	  return;
       case Id:
 	  printf("%s\n",get(node,Id,symbol)->name);
 	  return;
@@ -288,6 +301,7 @@ and		= p:prefix a:and		{ $$ = mkAnd(p, a) }
 		| p:prefix			{ $$ = p }
 
 prefix		= "!" - p : postfix      	{ $$ = mkExc(p) }
+        | "&" - p : postfix         { $$ = mkEt(p) }
 		| p: postfix            	{ $$ = p}
 
 postfix		= s:atom ( "?" -		{ s = mkQuery(s) }
@@ -374,6 +388,14 @@ int execute(Node *node, InputBuffer *in)
 	  setPosition(in, pos);
 	  return 0;
       }
+      case Et: {
+	  int pos= getPosition(in);
+	  if (!execute(get(node,Et,children[0]), in)) {
+	      return 0;
+	  }
+	  setPosition(in, pos);
+	  return 1;
+      }
       case Dot: {
 	  if (atEnd(in)) {
 	      return 0;