diff --git a/parse.leg b/parse.leg
index 2334526..d836cc4 100644
--- a/parse.leg
+++ b/parse.leg
@@ -3,8 +3,23 @@
 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
+#include <stdarg.h>
+#include <sys/stat.h>
+
 #include "inputBuffer.c"
 ;
+
+void fatal(char *fmt, ...)
+{
+    va_list ap;
+    va_start(ap, fmt);
+    fprintf(stderr, "\nError: ");
+    vfprintf(stderr, fmt, ap);
+    fprintf(stderr, "\n");
+    va_end(ap);
+    exit(1);
+}
+
 enum op { String, Query, Star, Plus, Or, And, Class, Dot, Exc, Id } ;
 
 
@@ -82,7 +97,7 @@ Node *mkString(char *s)
 }
 
 Node *mkId(Symbol *s){
-  
+
     Node *node= new(Id);
     node->Id.symbol=s;
     return node;
@@ -107,7 +122,7 @@ Node *mkOr(Node *node1, Node *node2)
 
 Node *mkAnd(Node *node1, Node *node2)
 {
-    Node *node= new(And);    
+    Node *node= new(And);
     node->And.children[0]= node1;
     node->And.children[1]= node2;
     return node;
@@ -162,43 +177,43 @@ void print(Node *node)
 {
     switch (node->type) {
       case String:
-        printf("\"%s\"", node->String.string);
-        return;
+	  printf("\"%s\"", node->String.string);
+	  return;
       case Query:
-        print(node->Query.children[0]);
-        printf("?");
-        return;
+	  print(node->Query.children[0]);
+	  printf("?");
+	  return;
       case Star:
-        print(node->Query.children[0]);
-        printf("*");
-        return;
+	  print(node->Query.children[0]);
+	  printf("*");
+	  return;
       case Plus:
-        print(node->Query.children[0]);
-        return;
+	  print(node->Query.children[0]);
+	  return;
       case Or:
-        print(node->Or.children[0]);
-        printf("Or");      
-        print(node->Or.children[1]);
-        return;
+	  print(node->Or.children[0]);
+	  printf("Or");
+	  print(node->Or.children[1]);
+	  return;
       case And:
-        print(node->And.children[0]);
-        printf("And");
-        print(node->And.children[1]);
-        return;
+	  print(node->And.children[0]);
+	  printf("And");
+	  print(node->And.children[1]);
+	  return;
       case Class:
-        printf("Class");
-        printf("\"%s\"", node->Class.stringValue);
-        return;
+	  printf("Class");
+	  printf("\"%s\"", node->Class.stringValue);
+	  return;
       case Dot:
-        printf("Dot");
-        return;
+	  printf("Dot");
+	  return;
       case Exc:
-        printf("!");
-        print(node->Exc.children[0]);
-        return;   
+	  printf("!");
+	  print(node->Exc.children[0]);
+	  return;
       case Id:
-        printf("%s\n",get(node,Id,symbol)->name);
-        return;
+	  printf("%s\n",get(node,Id,symbol)->name);
+	  return;
     }
     abort();
 }
@@ -218,7 +233,7 @@ else { \
     *buff=currentChar(inputBuffer); \
     advance(inputBuffer,1); \
     result=1; \
-}} 
+}}
 
 
 
@@ -226,11 +241,11 @@ else { \
 
 Symbol *intern(char *name){
     int left=0,right=symbolTable.length-1;
-    
-    while(left<=right){
+
+    while (left<=right) {
         int middle=(left+right)/2;
         int comp=strcmp(name,symbolTable.elements[middle]->name);
-        
+
         if(comp<0){
             right=middle-1;
         }
@@ -241,7 +256,7 @@ Symbol *intern(char *name){
             return symbolTable.elements[middle];
         }
     }
-    
+
     symbolTable.elements= realloc(symbolTable.elements,sizeof(symbolTable.elements[0]) * (symbolTable.length+1));
     memmove(symbolTable.elements+left+1,symbolTable.elements+left,(symbolTable.length-left)*sizeof(symbolTable.elements[0]));
     symbolTable.length++;
@@ -249,130 +264,127 @@ Symbol *intern(char *name){
 
 }
 
-void setRule(char *name, Node *rule){
+void setRule(char *name, Node *rule)
+{
+    printf("Setting rule %s to ", name);
+    println(rule);
     intern(name)->rule=rule;
 }
 
 #define YYSTYPE Node *
-YYSTYPE yylval = 0;
 
 %}
 
-start = declaration+
-
-declaration = i:id '=' - e:expression { setRule(get(i, Id, symbol)->name, e) }
+start		= - declaration+
 
-expression = or
+declaration	= i:id '=' - e:expression 	{ setRule(get(i, Id, symbol)->name, e) }
 
-or	= a:and - "|" - o:or	{$$ = mkOr(o, a) }
-	| a:and			{ $$ = a }
+expression	= or
 
-and	= p:prefix a:and	{ $$ = mkAnd(p, a); }
-	| p:prefix		{ $$ = p }
+or		= a:and "|" - o:or		{ $$ = mkOr(o, a) }
+		| a:and				{ $$ = a }
 
-prefix = "!"- p : postfix    {$$ = mkExc(p)}
-    | p: postfix             {$$ = p}
+and		= p:prefix a:and		{ $$ = mkAnd(p, a) }
+		| p:prefix			{ $$ = p }
 
-postfix	= s:atom ( "?" -	{ s = mkQuery(s) }
-	  	 | "*" -	{ s = mkStar(s) }
-		 | "+" -	{ s = mkPlus(s) }
-		 )?		{ $$ = s}
+prefix		= "!" - p : postfix      	{ $$ = mkExc(p) }
+		| p: postfix            	{ $$ = p}
 
-atom    = string | class | dot | rule
+postfix		= s:atom ( "?" -		{ s = mkQuery(s) }
+			 | "*" -		{ s = mkStar(s) }
+			 | "+" -		{ s = mkPlus(s) }
+			 )?			{ $$ = s }
 
-rule = i:id !'='        { $$ = mkId(intern(yytext)) }
+atom		= string | class | dot | rule
 
-id = < [a-zA-z_][a-zA-z_0-9]* > - { $$ = mkId(intern(yytext)) }
+rule		= i:id !'='        		{ $$ = mkId(intern(yytext)) }
 
-string	= '"' < [^"]* > '"'     { $$ = mkString(yytext) } -
+id		= < [a-zA-z_][a-zA-z_0-9]* > - 	{ $$ = mkId(intern(yytext)) }
 
-class	= '['-<(!']'string)*> ']'  { $$=mkClass(yytext) } -
+string		= '"' < [^\"]* > '"' -     	{ $$ = mkString(yytext) }
 
-dot = -'.'-               {$$=mkDot()} -
+class		= '['-<(!']'string)*> ']' - 	{ $$=mkClass(yytext) }
 
+dot		= '.' -               		{ $$=mkDot() }
 
--	= space*
+-		= space*
 
-space	= [ \t] | '\n' '\r'* | '\r' '\n'*
+space		= [ \t] | '\n' '\r'* | '\r' '\n'*
 
 %%
 
-
-
-
-
 int execute(Node *node, InputBuffer *in)
 {
     switch (node->type) {
       case String: {
-      if (strncmp(currentText(in), get(node,String,string), get(node,String,len))) {
-        return 0;
-      }
-      advance(in, get(node,String,len));
-      return 1;
+	  if (strncmp(currentText(in), get(node,String,string), get(node,String,len))) {
+	      return 0;
+	  }
+	  advance(in, get(node,String,len));
+	  return 1;
       }
       case And: {
-      int pos= getPosition(in);
-      if (!execute(get(node,And,children[0]), in)) //si il y a eu une erreur
-      {
-          return 0;
-      } //si ça s'est bien passé
-      if (!execute(get(node,And,children[1]), in)) {
-          setPosition(in, pos);
-          return 0;
-      }
-      return 1;
+	  int pos= getPosition(in);
+	  if (!execute(get(node,And,children[0]), in)) //si il y a eu une erreur
+	  {
+	      return 0;
+	  } //si ça s'est bien passé
+	  if (!execute(get(node,And,children[1]), in)) {
+	      setPosition(in, pos);
+	      return 0;
+	  }
+	  return 1;
       }
       case Or: {
-      if (execute(get(node,Or,children[0]), in)) {
-          return 1;
-      }
-      return execute(get(node,Or,children[1]), in);
+	  if (execute(get(node,Or,children[0]), in)) {
+	      return 1;
+	  }
+	  return execute(get(node,Or,children[1]), in);
       }
       case Star: {
-      while (execute(get(node,Star,children[0]), in));
-      return 1;
+	  while (execute(get(node,Star,children[0]), in));
+	  return 1;
       }
       case Plus: {
-      if (!execute(get(node,Plus,children[0]), in)) {
-        return 0;
-      }
-      while (execute(get(node,Plus,children[0]), in));
-      return 1;
+	  if (!execute(get(node,Plus,children[0]), in)) {
+	      return 0;
+	  }
+	  while (execute(get(node,Plus,children[0]), in));
+	  return 1;
       }
       case Class: {
-      if (!currentChar(in)) {
-        return 0;
-      }
-      if (strchr(get(node,Class,stringValue), currentChar(in))) {
-        advance(in, 1);
-        return 1;
-      }
-      return 0;
+	  if (!currentChar(in)) {
+	      return 0;
+	  }
+	  if (strchr(get(node,Class,stringValue), currentChar(in))) {
+	      advance(in, 1);
+	      return 1;
+	  }
+	  return 0;
       }
       case Query: {
-      execute(get(node,Query,children[0]), in);
-      return 1;
+	  execute(get(node,Query,children[0]), in);
+	  return 1;
       }
       case Exc: {
-      int pos= getPosition(in);
-      if (!execute(get(node,Exc,children[0]), in)) {
-        return 1;
-      }
-      setPosition(in, pos);
-      return 0;
+	  int pos= getPosition(in);
+	  if (!execute(get(node,Exc,children[0]), in)) {
+	      return 1;
+	  }
+	  setPosition(in, pos);
+	  return 0;
       }
       case Dot: {
-      if (atEnd(in)) {
-        return 0;
-      }
-      advance(in, 1);
-      return 1;
+	  if (atEnd(in)) {
+	      return 0;
+	  }
+	  advance(in, 1);
+	  return 1;
       }
       case Id: {
-        Symbol *symbol= get(node, Id, symbol);
-        if (0 == symbol->rule) { printf("undefined rule: %s\n", symbol->name); }
-        return execute(symbol->rule, in);
+	  Symbol *symbol= get(node, Id, symbol);
+	  if (0 == symbol->rule) { printf("undefined rule: %s\n", symbol->name); }
+	  return execute(symbol->rule, in);
       }
     }
     printf("this cannot happen\n");
@@ -381,33 +393,69 @@ int execute(Node *node, InputBuffer *in)
 
 int main(int argc, char **argv)
 {
-    if(argc<2) return 0;
-
-    inputBuffer = mkInputBuffer(argv[1]);
+    switch (argc) {
+      case 2: {
+	  inputBuffer = mkInputBuffer(argv[1]);
+	  break;
+      }
+      case 3: {
+	  if (!strcmp("-f", argv[1])) {
+	      FILE *fp= fopen(argv[2], "r");
+	      if (!fp) {
+		  perror(argv[2]);
+		  exit(1);
+	      }
+	      struct stat sb;
+	      if (fstat(fileno(fp), &sb)) {
+		  perror(argv[2]);
+		  exit(1);
+	      }
+	      char *text= malloc(sb.st_size);
+	      if (!text) {
+		  fatal("out of memory");
+		  exit(1);
+	      }
+	      if (fread(text, sb.st_size, 1, fp) < 1) {
+		  perror(argv[2]);
+		  exit(1);
+	      }
+	      fclose(fp);
+	      inputBuffer = mkInputBuffer(text);
+	      break;
+	  }
+	  fatal("unrecognised option: %s", argv[1]);
+      }
+      default: {
+	  fatal("usage: %s parsing-expression | -f filename", argv[0]);
+	  exit(1);
+      }
+    }
 
     if (!yyparse()) {
         printf("Error\n");
         return 1;
     }
-    println(yylval);
-    char *line=0;
-    size_t line_max=0;
+
+    char   *line=0;
+    size_t  line_max=0;
     ssize_t line_len=0;
-    Symbol *start= intern("start");
-    if (!start->rule) perror("no start rule");
-    while((line_len=getline(&line,&line_max,stdin))>=0){
-        if(line_len>0 && line[line_len-1]=='\n'){
+    Node   *startRule= intern("start")->rule;
+    if (!startRule) {
+	fatal("no start rule");
+	return 1;
+    }
+    while ((line_len=getline(&line,&line_max,stdin))>=0) {
+        if (line_len>0 && line[line_len-1]=='\n') {
             line[line_len-1]=0;
         }
         initInputBuffer(inputBuffer,line);
-        if (!execute(yylval, inputBuffer) || !atEnd(inputBuffer)){
+        if (!execute(startRule, inputBuffer) || !atEnd(inputBuffer)) {
             printf("no match, current position : %i\n", getPosition(inputBuffer));
-        } 
-        else{
+        }
+        else {
             printf("match, current position : %i\n", getPosition(inputBuffer));
-        }// 0 => no match, 1 => match
+        } // 0 => no match, 1 => match
     }
-    
 
     return 0;