From c486f0006b36a2488516124e0ae46fa838a7f35f Mon Sep 17 00:00:00 2001
From: Utz-Uwe Haus <lisp@uuhaus.de>
Date: Thu, 2 Oct 2008 10:43:58 +0200
Subject: [PATCH] Flesh out examples.

Signed-off-by: Utz-Uwe Haus <lisp@uuhaus.de>
---
 example.lisp |  3 ++-
 example.peg  | 26 ++++++++++++++++++++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/example.lisp b/example.lisp
index 59a62da..6305bd8 100644
--- a/example.lisp
+++ b/example.lisp
@@ -34,13 +34,14 @@
 
 ;; load the opossum package
 (asdf:operate 'asdf:load-op :opossum)
+;; => NIL
 
 ;; Create a parser for the grammar defined in example.peg, in a fresh package
 (setq *p* (opossum:make-string-parser "example.peg"))
 ;; => ...
 
 ;; use the parser to parse a string
-(setq *t* (funcall *p* "14+7*(1+1)^2"))
+(setq *t* (funcall *p* "14+7*(1+1)*2"))
 ;; => ...
 
 ;; and try out the code generated by the grammar
diff --git a/example.peg b/example.peg
index 38db164..9d7476d 100644
--- a/example.peg
+++ b/example.peg
@@ -1,3 +1,29 @@
 # Sample PEG file to demonstrate CL-Opossum use -*- mode:peg -*-
 # $Id$
 #
+# Every successfully matched rule makes a list named DATA available to the action code
+
+
+Expr <- Sum { data }
+
+Sum <- Product (('+' / '-') Product)*  { 
+	`(+ ,(first data) 
+	    ,(reduce #'(lambda (op/p tail)
+			(if (char= #\+ (car op/p))
+			    `(+ ,(second op/p) ,old)
+	 		    `(- ,(second op/p) ,old))))
+	      (cdr data) :from-end T :initial-value 0))
+	}
+
+Product <- Value (('*' / '/') Value)* {
+	`(* ,(first data) 
+	    ,(reduce #'(lambda (op/p tail)
+			(if (char= #\* (car op/p))
+			    `(* ,(second op/p) ,old)
+	 		    `(/ ,(second op/p) ,old))))
+	      (cdr data) :from-end T :initial-value 1))
+	}
+
+Value <- [1-9] [0-9]+   { (reduce  #'(lambda (x y) (+ y (* x 10))) data :initial-value 0) }
+	/ '(' Expr ')'  { (second data) }
+
-- 
2.11.4.GIT