new file mode 100644
--- /dev/null
+++ b/parser/c_compiler/lexer.l
@@ -0,0 +1,151 @@
+%{
+	#include <prototypes.h>
+	#include "parser.h"
+	int column = 0;
+	int c;
+%}
+
+D						[0-9]
+L						[a-zA-Z_]
+H						[a-fA-F0-9]
+E						[Ee][+-]?{D}+
+FS						(f|F|l|L)
+IS						(u|U|l|L)*
+
+%%
+"/*"           			{ comment(); }
+"#include <"			{ c = input(); while ( c != '>') c = input();  }
+"#include \""			{ c = input(); while ( c != '\"') c = input(); }
+
+"auto"					{ count(); return(AUTO); }
+"break"					{ count(); return(BREAK); }
+"case"					{ count(); return(CASE); }
+"char"					{ count(); return(CHAR); }
+"const"					{ count(); return(CONST); }
+"continue"				{ count(); return(CONTINUE); }
+"default"				{ count(); return(DEFAULT); }
+"do"					{ count(); return(DO); }
+"double"				{ count(); return(DOUBLE); }
+"else"					{ count(); return(ELSE); }
+"enum"					{ count(); return(ENUM); }
+"extern"				{ count(); return(EXTERN); }
+"float"					{ count(); return(FLOAT); }
+"for"					{ count(); return(FOR); }
+"goto"					{ count(); return(GOTO); }
+"if"					{ count(); return(IF); }
+"int"					{ count(); return(INT); }
+"long"					{ count(); return(LONG); }
+"register"				{ count(); return(REGISTER); }
+"return"				{ count(); return(RETURN); }
+"short"					{ count(); return(SHORT); }
+"signed"					{ count(); return(SIGNED); }
+"sizeof"				{ count(); return(SIZEOF); }
+"static"				{ count(); return(STATIC); }
+"struct"				{ count(); return(STRUCT); }
+"switch"				{ count(); return(SWITCH); }
+"typedef"				{ count(); return(TYPEDEF); }
+"union"					{ count(); return(UNION); }
+"unsigned"				{ count(); return(UNSIGNED); }
+"void"					{ count(); return(VOID); }
+"volatile"				{ count(); return(VOLATILE); }
+"while"					{ count(); return(WHILE); }
+
+{L}({L}|{D})*			{ count(); return(check_type()); }
+0[xX]{H}+{IS}?			{ count(); return(CONSTANT); }
+0{D}+{IS}?				{ count(); return(CONSTANT); }
+{D}+{IS}?				{ count(); return(CONSTANT); }
+'(\\.|[^\\'])+'			{ count(); return(CONSTANT); }
+
+{D}+{E}{FS}?			{ count(); return(CONSTANT); }
+{D}*"."{D}+({E})?{FS}?	{ count(); return(CONSTANT); }
+{D}+"."{D}*({E})?{FS}?	{ count(); return(CONSTANT); }
+
+\"(\\.|[^\\"])*\"		{ count(); return(STRING_LITERAL); }
+
+">>="					{ count(); return(RIGHT_ASSIGN); }
+"<<="					{ count(); return(LEFT_ASSIGN); }
+"+="					{ count(); return(ADD_ASSIGN); }
+"-="					{ count(); return(SUB_ASSIGN); }
+"*="					{ count(); return(MUL_ASSIGN); }
+"/="					{ count(); return(DIV_ASSIGN); }
+"%="					{ count(); return(MOD_ASSIGN); }
+"&="					{ count(); return(AND_ASSIGN); }
+"^="					{ count(); return(XOR_ASSIGN); }
+"|="					{ count(); return(OR_ASSIGN); }
+">>"					{ count(); return(RIGHT_OP); }
+"<<"					{ count(); return(LEFT_OP); }
+"++"					{ count(); return(INC_OP); }
+"--"					{ count(); return(DEC_OP); }
+"->"					{ count(); return(PTR_OP); }
+"&&"					{ count(); return(AND_OP); }
+"||"					{ count(); return(OR_OP); }
+"<="					{ count(); return(LE_OP); }
+">="					{ count(); return(GE_OP); }
+"=="					{ count(); return(EQ_OP); }
+"!="					{ count(); return(NE_OP); }
+";"						{ count(); return(';'); }
+"{"						{ count(); return('{'); }
+"}"						{ count(); return('}'); }
+","						{ count(); return(','); }
+":"						{ count(); return(':'); }
+"="						{ count(); return('='); }
+"("						{ count(); return('('); }
+")"						{ count(); return(')'); }
+"["						{ count(); return('['); }
+"]"						{ count(); return(']'); }
+"."						{ count(); return('.'); }
+"&"						{ count(); return('&'); }
+"!"						{ count(); return('!'); }
+"~"						{ count(); return('~'); }
+"-"						{ count(); return('-'); }
+"+"						{ count(); return('+'); }
+"*"						{ count(); return('*'); }
+"/"						{ count(); return('/'); }
+"%"						{ count(); return('%'); }
+"<"						{ count(); return('<'); }
+">"						{ count(); return('>'); }
+"^"						{ count(); return('^'); }
+"|"						{ count(); return('|'); }
+"?"						{ count(); return('?'); }
+
+[ \t\v\n\f]				{ count(); }
+.						{ printf ("Unknown Token: %s\n", yytext); }
+%%
+
+int yywrap()
+{
+	/* stop after eof */
+	return 1;
+}
+
+int count()
+{
+	int i;
+
+	for (i = 0; yytext[i] != '\0'; i++)
+		if (yytext[i] == '\n')
+			column = 0;
+		else if (yytext[i] == '\t')
+			column += 4 - (column % 4);
+		else
+			column++;
+
+	return column;
+}
+
+int check_type()
+{
+	return IDENTIFIER;
+}
+
+void comment() 
+{
+	int c;
+
+	c = input(); 
+	do { 
+		while ( c != '*') 
+			c = input();
+		c=input();
+	} while(c != '/');
+}