From a7570e6141bb0674d7dd9732ad289f736f6e6638 Mon Sep 17 00:00:00 2001
From: Utz-Uwe Haus <lisp@uuhaus.de>
Date: Fri, 3 Oct 2008 23:48:51 +0200
Subject: [PATCH] Fix PEG grammar and add action support.

Add actions which are not part of the original PEG grammar.

Signed-off-by: Utz-Uwe Haus <lisp@uuhaus.de>
---
 opossum.peg | 34 +++++++++++++++++++++++++---------
 1 file changed, 25 insertions(+), 9 deletions(-)

diff --git a/opossum.peg b/opossum.peg
index d07760b..ce3ef23 100644
--- a/opossum.peg
+++ b/opossum.peg
@@ -21,7 +21,9 @@
 ##
 ## Commentary:
 ##
-## PEG syntax in PEG as in the original report
+## PEG syntax in PEG as in the report from 2004 (`Parsing Expression Grammars:
+## A Recognition-Based Syntactic Foundation'' by Bryan Ford)
+##
 #
 # Process this file with an existing PEG parser to bootstrap.
 # The output needs to be adjusted by replacing the package OPOSSUM
@@ -45,12 +47,13 @@ Definition <- Identifier LEFTARROW Expression {
 	`(,(opossum::make-name (first data)) #'(lambda () ,(third data))) ;'
 	} 
 #
-Expression <- Sequence (SLASH Sequence)* { (if (null (second data))
-					       (first data)
-					       (let ((tail (second (cadr data))))
-						  (if (equal (first tail) 'seq) 
-						      `(seq ,(first data) ,@(rest tail))
-						      `(seq ,(first data) ,tail)))) ;'
+Expression <- Sequence Action? (SLASH Sequence Action?)* {
+	 (if (null (second data))
+	       (first data)
+	       (let ((tail (second (cadr data))))
+		  (if (equal (first tail) 'seq) 
+		      `(seq ,(first data) ,@(rest tail))
+		      `(seq ,(first data) ,tail)))) ;'
 	 }
 #
 Sequence <- Prefix* { `(many ,(first data)) }
@@ -59,11 +62,12 @@ Prefix <-   (AND Suffix) {
 	 `(follow ,(second data)) 
 		} / (NOT Suffix) {
 	 `(negate ,(second data))
-	 }
+	 } / Suffix { (second data) }
 #
 Suffix <-   Primary QUESTION { `(optional ,(first data))
 	} / Primary STAR     { `(many ,(first data)) 
-	} / Primary PLUS     { `(many1 ,(first data)) }
+	} / Primary PLUS     { `(many1 ,(first data)) 
+	} / Primary          { (first data) }
 #
 Primary <- Identifier !LEFTARROW { (first data)
 	} / OPEN Expression CLOSE { (second data) 
@@ -71,6 +75,18 @@ Primary <- Identifier !LEFTARROW { (first data)
 	} / Class              { (first data) 
 	} / DOT                { `(match-any-char ,data) }
 #
+Action <- "{" (!"}" .)* "}" Spacing { 
+	(let* ((action-data (second data))
+	       (action-code (coerce
+			       (opossum::fix-escape-sequences
+				(mapcar #'second action-data))
+		       	     'string))
+	       (action-name (opossum::make-action-name)))
+	    (opossum::store-action opossum:*context*
+				   `(,action-name ,action-code))
+	    `(list ':action nil ',action-name))
+	}
+#
 # Lexical syntax
 Identifier <- [a-zA-Z_] [a-zA-Z0-9_]* Spacing { (concatenate 'string (first data) (second data)) } 
 #
-- 
2.11.4.GIT