473,624 Members | 2,273 Online
Bytes | Software Development & Data Engineering Community
+ Post

Home Posts Topics Members FAQ

Lex / Yacc problem

Hi, mates:

I'm trying to write a grammar to read files with the following structure,
for example:
text
...
more text

'text' ='another text',

...

'more text' = 'some more text',

text
...

Text can contain any kind of characters and symbols: a-z, 0-9, ?, *, ], (, {...

When applying this file to the parser, I only want things in the right
side of the "=>" to be in the output.

I paste here some parts of my grammar:

lex)

[\n] { return 0; }
' { return SYMBOL; }
= { return ARROW; }
, { return COMMA; }
" "+ { return SPACE; }
.+ { yylval = strdup(yytext); return TEXT; }

yacc)

line: SYMBOL TEXT SYMBOL SPACE ARROW SPACE SYMBOL TEXT SYMBOL COMMA
{ printf("%s\n", $8); }
;
With YYSTYPE defined as "char *"

My code compiles perfectly but when I run it I get a lot of syntax errors,
and nothing is in the output.

I'd be very pleased if somebody gives my some advice in how to build a
correct grammar for my purpose.
Best regards

--

Xose Lois
Jan 10 '08 #1
2 1737
In article <pa************ *************** *@yahoo.com>,
Xose Lois Castro <gt************ *****@yahoo.com wrote:

[Subject line: "Lex/Yacc problem"]
>My code compiles perfectly but when I run it I get a lot of syntax errors,
and nothing is in the output.

I'd be very pleased if somebody gives my some advice in how to build a
correct grammar for my purpose.
Code generators like lex and yacc are not defined by the C language and
are therefore beyond the scope of comp.lang.c.

comp.compilers might be a better place to ask.
dave

--
Dave Vandervies dj3vande at eskimo dot com
Yes, P.J. Plauger is more or less a regular.
Less, I think. More of a sporadic than a regular.
--Keith Thompson and Richard Heathfield in comp.lang.c
Jan 10 '08 #2
Xose Lois Castro wrote, On 10/01/08 22:25:
Hi, mates:
As far as I am aware you are not my mate.

<snip>
I paste here some parts of my grammar:

lex)
<snip>
yacc)

<snip>

I see no C, only lex and yacc neither of which are C. I suggest you find
a group or mailing list where they are topical. It might be worth
checking out comp.compilers, but check there FAQ and at least a weeks
worth of posts before posting there. Alternatively comp.programmin g,
comp.unix.progr ammer or comp.lang.misc might be worth a try.
--
Flash Gordon
Jan 11 '08 #3

This thread has been closed and replies have been disabled. Please start a new discussion.

Similar topics

4
6336
by: Profetas | last post by:
Hi. I was wondering how can I access the yacc functions? because when use a normal yacc function such as qstring { yylval.string = strdup(yytext+1); if(yylval.string !='"') warning("Undeterminated Character strig",(char *)0); else
10
409
by: Antoon Pardon | last post by:
I have the following little piece of code: class Cfg:pass #config = Cfg() def assign(): setattr(config, 'Start' , ) def foo(): config = Cfg()
1
4273
by: deepusrp | last post by:
Helo everyone, i am doing a project on some graphic tool using qt as the front end. i am using lex and yacc as parser. now i am facing a problem since yacc generates only c code as i want to bring c++ features. so my request is " is there any way that we can create parser in qt itself or is there any method by which i can make a c++ (yacc) Parser... "
13
5012
by: Berk Birand | last post by:
Hi, I am working on a school project where we use lex/yacc to write a compiler for a fictional (Java-like) language. I have handled all the details about the yacc and lex files, but I still have a question regarding the dynamic memory allocation for strings. When the lex file encounters a variable name, I want it to pass this to yacc through yylval, and then retrieve it to add to a syntax tree. For this purpose, I wrote the following...
2
7506
by: max.giacometti | last post by:
Hi everybody! I am using lex and yacc to write a vhdl to systemc converter. Lex simply reads the input file and yacc implements grammar and translation. I'd like to be able to make yacc able to command lex to stop reading the current file and starting reading another file, when the inclusion syntax is reached.
2
1951
by: Mohitz | last post by:
Hi Guys, I am facing a peculiar problem with my yacc script. Following is the snippet of the yacc script that i am using. I am using lex as the lexical analyzer. Sample Input :
1
1913
by: neena.usenet | last post by:
I have a gui that reads in a file using C++/yacc. If the file has a parsing error, yacc throws the error to my program and I report it. The problem is at that point, I would like to try to open a different file, one that has no syntax errors. When I try to open this second file, yacc throws me another error which I believe is leftover from parsing the first file. How do I clear the yacc "error stack"?
0
1159
by: Laszlo Nagy | last post by:
This is a fragment from my yacc file: import ply.yacc as yacc from lex import tokens from ast import * def p_msd(p): r"""msd : SCHEMA WORD LBRACE defs RBRACE """ p = MSDSchema(p)
2
3114
by: betterking | last post by:
I want to write a tiny sql parser with lex and yacc. At first I just write sql.l sql.y with simple CREATE TABLE funciton. sql.l %{ #include "y.tab.h" //<> #include <stdlib.h> #include <string.h> void yyerror(char *);
0
8233
marktang
by: marktang | last post by:
ONU (Optical Network Unit) is one of the key components for providing high-speed Internet services. Its primary function is to act as an endpoint device located at the user's premises. However, people are often confused as to whether an ONU can Work As a Router. In this blog post, we’ll explore What is ONU, What Is Router, ONU & Router’s main usage, and What is the difference between ONU and Router. Let’s take a closer look ! Part I. Meaning of...
0
8170
by: Hystou | last post by:
Most computers default to English, but sometimes we require a different language, especially when relocating. Forgot to request a specific language before your computer shipped? No problem! You can effortlessly switch the default language on Windows 10 without reinstalling. I'll walk you through it. First, let's disable language synchronization. With a Microsoft account, language settings sync across devices. To prevent any complications,...
0
8675
Oralloy
by: Oralloy | last post by:
Hello folks, I am unable to find appropriate documentation on the type promotion of bit-fields when using the generalised comparison operator "<=>". The problem is that using the GNU compilers, it seems that the internal comparison operator "<=>" tries to promote arguments from unsigned to signed. This is as boiled down as I can make it. Here is my compilation command: g++-12 -std=c++20 -Wnarrowing bit_field.cpp Here is the code in...
0
8619
jinu1996
by: jinu1996 | last post by:
In today's digital age, having a compelling online presence is paramount for businesses aiming to thrive in a competitive landscape. At the heart of this digital strategy lies an intricately woven tapestry of website design and digital marketing. It's not merely about having a website; it's about crafting an immersive digital experience that captivates audiences and drives business growth. The Art of Business Website Design Your website is...
0
8474
tracyyun
by: tracyyun | last post by:
Dear forum friends, With the development of smart home technology, a variety of wireless communication protocols have appeared on the market, such as Zigbee, Z-Wave, Wi-Fi, Bluetooth, etc. Each protocol has its own unique characteristics and advantages, but as a user who is planning to build a smart home system, I am a bit confused by the choice of these technologies. I'm particularly interested in Zigbee because I've heard it does some...
0
7158
agi2029
by: agi2029 | last post by:
Let's talk about the concept of autonomous AI software engineers and no-code agents. These AIs are designed to manage the entire lifecycle of a software development project—planning, coding, testing, and deployment—without human intervention. Imagine an AI that can take a project description, break it down, write the code, debug it, and then launch it, all on its own.... Now, this would greatly impact the work of software developers. The idea...
1
6108
isladogs
by: isladogs | last post by:
The next Access Europe User Group meeting will be on Wednesday 1 May 2024 starting at 18:00 UK time (6PM UTC+1) and finishing by 19:30 (7.30PM). In this session, we are pleased to welcome a new presenter, Adolph Dupré who will be discussing some powerful techniques for using class modules. He will explain when you may want to use classes instead of User Defined Types (UDT). For example, to manage the data in unbound forms. Adolph will...
0
4173
by: adsilva | last post by:
A Windows Forms form does not have the event Unload, like VB6. What one acts like?
1
1784
muto222
by: muto222 | last post by:
How can i add a mobile payment intergratation into php mysql website.

By using Bytes.com and it's services, you agree to our Privacy Policy and Terms of Use.

To disable or enable advertisements and analytics tracking please visit the manage ads & tracking page.