Startpunkten

Lab2/parser.y

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+/*
+ *  Laboration 2 i C och UNIX
+ *
+ *  Komplett shell
+ *  =========================================
+ *
+ *  Christian Ohlsson, di7chro@cse.kau.se
+ *  Stefan Sonesson, di7stes@cse.kau.se
+ *
+ *  Karlstads Universitet, 991209
+ *
+ *
+ *===========================================
+*/
+%{
+#include <stdio.h>
+#include "tree.h"
+	extern treePtr tree;
+%}
+
+%union {
+	int txt;
+	treePtr tPtr;
+};
+
+%token NL PIPE SEMI GREAT LESS AND DBLARR EXIT
+%token<txt> WORD OPT
+%type<tPtr> rad ccmd scmd cmd
+
+%start rad
+
+%%
+rad	: ccmd NL		{ tree=$1; return 0;}
+	| NL			{ return 1;}            	
+	;
+ccmd	: ccmd PIPE scmd	{ $$=(treePtr)makeNode(PIPE, $1, $3); }
+	| ccmd AND 		{ $$=(treePtr)makeNode(AND, $1, NULL); }
+	| ccmd SEMI scmd	{ $$=(treePtr)makeNode(SEMI, $1, $3); }
+	| ccmd SEMI 		{ $$=(treePtr)makeNode(SEMI, $1, NULL);}
+	| scmd			{ $$=$1;}
+	;
+scmd	: scmd GREAT WORD	{ $$=(treePtr)makeNode(GREAT, $1, makeLeaf($3));}
+	| scmd DBLARR WORD	{ $$=(treePtr)makeNode(DBLARR, $1, makeLeaf($3));}
+	| scmd LESS WORD	{ $$=(treePtr)makeNode(LESS, $1, makeLeaf($3));}
+	| cmd			{ $$=$1;}
+	| error			{ $$=NULL;}
+	;
+cmd	: cmd WORD		{ $$=$1;}
+	| WORD			{ $$=(treePtr)makeLeaf($1);}
+	;
+%%
+
+int yyerror() {
+	fprintf(stderr, "\nSyntax error\n");
+	tree=NULL;
+	return 0;
+}