// This is for UCSD CSE 141L, Spring 2006.  -Wei and JSampson
//
// documentation on flex found in:
//
// http://jflex.de
//

// This is a source file for Java flex.  Flex compiles this file
// into a text processing tool using the grammar specified below.  
// Run flex as to generate Sample_flex.java:
// > jflex sample_flex.flex
//
// The makefile adds an option to rename the generated output file.
// 
// The generated Sample_flex.java will provide an API to recognize 
// certain strings.  See further comments below

import java.util.*; 

%%
%{
// The following definitions specifies regular expressions.  Regular 
// expressions are patterns that may match a given string, indicating 
// some action is to be taken.  The action may communicate things like 
// what is it classified as, along with other information. 

// Everything between %{ and %} are directly passed to Sample_flex.java

    public String token;

    public String getToken() { return token; }

// The following five lines tells jflex to name the new class Sample_flex,
// keep track of line numbers, column count, 
// use C/C++ flex style yylex interface that returns an integer, andn
// assume unicode strings.
%}

%class Sample_flex
%line
%column
%byaccj
%unicode

ws=[ \t]+
token=[a-zA-Z][a-zA-Z0-9_\-]*
comment=\#[^\n]+

%% 

\n	        { /* This section contains several "rules" consisting of an
                   * a "pattern" and "action".  If an input string matches
                   * the pattern, then the action executes, often passing
                   * this information externally.  In this actions you can see that
                   * it return a macro defined NEWLINE (see Token_type.java). This is
                   * used in Jparser.java to count line numbers.
                   * The matched string is visible externally as yytext() method.
                   */
                  return Token_type.NEWLINE; }
{ws}            {}
{comment}       {}
{token}:	{ token = yytext().substring(0,yytext().length()-1); 
                  return Token_type.LABEL; }
{token}		    { token = yytext(); 
                  return Token_type.TOKEN; }