From 6a6c376a64c14d820298671481ceaf5dcaaac4a6 Mon Sep 17 00:00:00 2001
From: P. J. McDermott <pj@pehjota.net>
Date: Fri, 19 Feb 2016 18:28:09 -0500
Subject: Recognize reserved words

---
diff --git a/parsing/lexer.sh b/parsing/lexer.sh
index bf6ad7d..f92534a 100644
--- a/parsing/lexer.sh
+++ b/parsing/lexer.sh
@@ -456,13 +456,34 @@ accept()
 {
 	local t="${1}"
 
-	if [ "x${tok%%${US}*}" = "x${t}" ]; then
-		dbg "accept $t"
-		tokens="${tokens}${tok}${RS}"
-		next
-		return 0
-	fi
-	return 1
+	case "${t}" in
+		T_IF|T_THEN|T_ELSE|T_ELIF|T_FI|\
+		T_DO|T_DONE|T_CASE|T_ESAC|T_WHILE|T_UNTIL|\
+		T_FOR|T_LBRACE|T_RBRACE|T_BANG|T_IN)
+			# Reserved words are recognized as literal T_WORDs.
+			if ! [ "x${tok%%${US}*}" = T_WORD ]; then
+				return 1
+			fi
+			# T_WORD data unit must match reserved word exactly.
+			if ! [ "x${tok#T_WORD${US}}" = "x$(tokname "${t}")" ]
+			then
+				return 1
+			fi
+			# If the token matches the reserved word, replace it
+			# with the reserved word token.
+			tok="${t}"
+			;;
+		*)
+			if ! [ "x${tok%%${US}*}" = "x${t}" ]; then
+				return 1
+			fi
+			;;
+	esac
+
+	dbg "accept $t"
+	tokens="${tokens}${tok}${RS}"
+	next
+	return 0
 }
 
 expect()
--
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