Flex中，野牛和C：寻找一个非常基本的介绍 [英] Flex, Bison, and C: Looking for a very basic introduction
问题描述
我要寻找的flex和野牛与随行的Makefile，这使得利用内置的规则很短的工作示例。我已经试过了是凌乱的几个谷歌的结果，也不会建或正在C ++这是不能接受的。良好的网上资源和短采样code是AP preciated。
I am looking for a very short working example of flex and bison with an accompanying Makefile which makes use of the builtin rules. I've tried several google results that were messy, wouldn't build, or were in C++ which isn't acceptable. Good online resources and short sample code is appreciated.
其他
# Makefile example -- scanner and parser.
# Creates "myprogram" from "scan.l", "parse.y", and "myprogram.c"
#
LEX = flex
YACC = bison -y
YFLAGS = -d
objects = scan.o parse.o myprogram.o
myprogram: $(objects)
scan.o: scan.l parse.c
parse.o: parse.y
myprogram.o: myprogram.c
我想一个Makefile文件，看起来大约是这样附加的源文件而做一些简单随意
I would like a Makefile which looks approximately like this with attached source files which do something arbitrarily simple.
推荐答案
Flex项目本身自带一个体面的一套例子，包括使文件和野牛文件。
The flex project itself comes with a decent set of examples, including make files and bison files.
<一个href=\"http://flex.sourceforge.net/index.html#downloads\">http://flex.sourceforge.net/index.html#downloads
对于一个优秀的介绍到的话题，我建议lex和yacc第二版：
For an excellent intro to the topic, I suggest lex and yacc 2nd edition:
http://oreilly.com/catalog/9781565920002
最后，去这里一个快速入门：
Finally, go here for a quick primer:
<一个href=\"http://ds9a.nl/lex-yacc/cvs/lex-yacc-howto.html\">http://ds9a.nl/lex-yacc/cvs/lex-yacc-howto.html
编辑：
由于巴特提到，另一个来源是： http://oreilly.com/catalog/9780596155988/
As Bart mentioned, another source is: http://oreilly.com/catalog/9780596155988/
和下面是我使用启动Flex项目的框架文件。它采用GNU getopts的解析命令行选项和获取文件名。我并没有要求以便携性还是易用性！ ：）
And the following is the skeleton file I use to start a flex project. It uses gnu getopts for parsing command line options and getting the file name. I make no claims as to portability or ease of use! :)
/*
* This file is part of flex.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE.
*/
/**************************************************
start of definitions section
***************************************************/
%{
/* A template scanner file to build "scanner.c". */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <getopt.h>
/*#include "parser.h" */
//put your variables here
char FileName[256];
FILE *outfile;
char **myOut;
char inputName[256];
// flags for command line options
static int specificFile_flag = 0;
static int output_flag = 0;
static int help_flag = 0;
%}
%option 8bit outfile="scanner.c"
%option nounput nomain noyywrap
%option warn
%x header
%x fileType
%x final
%%
/************************************************
start of rules section
*************************************************/
/* these flex patterns will eat all input */
. { }
\n { }
%%
/****************************************************
start of code section
*****************************************************/
int main(int argc, char **argv);
int main (argc,argv)
int argc;
char **argv;
{
/****************************************************
The main method drives the program. It gets the filename from the
command line, and opens the initial files to write to. Then it calls the lexer.
After the lexer returns, the main method finishes out the report file,
closes all of the open files, and prints out to the command line to let the
user know it is finished.
****************************************************/
int c;
// the gnu getopt library is used to parse the command line for flags
// afterwards, the final option is assumed to be the input file
while (1) {
static struct option long_options[] = {
/* These options set a flag. */
{"specific-file", no_argument, &specificFile_flag, 1},
{"help", no_argument, &help_flag, 1},
/* These options don't set a flag. We distinguish them by their indices. */
{"debug", no_argument, 0, 'd'},
{"specificFile", no_argument, 0, 's'},
{"useStdOut", no_argument, 0, 'o'},
{0, 0, 0, 0}
};
/* getopt_long stores the option index here. */
int option_index = 0;
c = getopt_long (argc, argv, "dso",
long_options, &option_index);
/* Detect the end of the options. */
if (c == -1)
break;
switch (c) {
case 0:
/* If this option set a flag, do nothing else now. */
if (long_options[option_index].flag != 0)
break;
printf ("option %s", long_options[option_index].name);
if (optarg)
printf (" with arg %s", optarg);
printf ("\n");
break;
case 'd':
break;
case 's':
specificFile_flag = 1;
break;
case 'o':
output_flag = 1;
break;
case '?':
/* getopt_long already printed an error message. */
break;
default:
abort ();
}
}
if (help_flag == 1) {
printf("proper syntax is: addressGrabber.exe [OPTIONS]... INFILE OUTFILE\n");
printf("grabs address from prn files\n\n");
printf("Option list: \n");
printf("-s --specific-file changes INFILE from a prn list to a specific prn\n");
printf("-d turns on debug information\n");
printf("-o sets output to stdout\n");
printf("--help print help to screen\n");
printf("\n");
printf("list example: addressGrabber.exe list.csv\n");
printf("prn example: addressGrabber.exe -s 01110500.prn\n\n");
printf("If infile is left out, then stdin is used for input.\n");
printf("If outfile is a filename, then that file is used.\n");
printf("If there is no outfile, then infile-EDIT.tab is used.\n");
printf("There cannot be an outfile without an infile.\n");
return 0;
}
//get the filename off the command line and redirect it to input
//if there is no filename or it is a - then use stdin
if (optind < argc) {
FILE *file;
file = fopen(argv[optind], "rb");
if (!file) {
fprintf(stderr, "Flex could not open %s\n",argv[optind]);
exit(1);
}
yyin = file;
strcpy(inputName, argv[optind]);
}
else {
printf("no input file set, using stdin. Press ctrl-c to quit");
yyin = stdin;
strcpy(inputName, "\b\b\b\b\bagainst stdin");
}
//increment current place in argument list
optind++;
/********************************************
if no input name, then output set to stdout
if no output name then copy input name and add -EDIT.csv
if input name is '-' then output set to stdout
otherwise use output name
*********************************************/
if (optind > argc) {
yyout = stdout;
}
else if (output_flag == 1) {
yyout = stdout;
}
else if (optind < argc){
outfile = fopen(argv[optind], "wb");
if (!outfile) {
fprintf(stderr, "Flex could not open %s\n",FileName);
exit(1);
}
yyout = outfile;
}
else {
strncpy(FileName, argv[optind-1], strlen(argv[optind-1])-4);
FileName[strlen(argv[optind-1])-4] = '\0';
strcat(FileName, "-EDIT.tab");
outfile = fopen(FileName, "wb");
if (!outfile) {
fprintf(stderr, "Flex could not open %s\n",FileName);
exit(1);
}
yyout = outfile;
}
yylex();
if (output_flag == 0) {
fclose(yyout);
}
printf("Flex program finished running file %s\n", inputName);
return 0;
}
最后，由于不断有人检查了这一点，我也有在GitHub上的例子词法和语法分析器与makefile文件。
Finally, since people keep checking this out, I also have an example lexer and parser with makefile on github.
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