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Questions tagged [parsing]

Analyzing (un)structured data to convert it into a structured, normalized format.

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1 vote
0 answers
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Compound container for storing output from a parser

Consider a hierarchical structure like this directory [ [item_0;item_1;...;item_n] [item_0;item_1;inner_directory[...];item_m] other_directory [...] ] ...
user877329's user avatar
1 vote
1 answer
273 views

Grammar: start: (a b)? a c; Input: a d. Which error correct at position 2? 1. expected "b", "c". OR expected "c"

I am writing a parser (a parser generator for PEGs) and am trying to figure out how to report errors. Grammar: rule: (a b)? a c ; Input: a d Question: Which error message correct at position 2 ...
mezoni's user avatar
  • 113
4 votes
1 answer
498 views

Sentence Tree vs. Words List

I was recently tasked with building a Name Entity Recognizer as part of a project. The objective was to parse a given sentence and come up with all the possible combinations of the entities. One ...
Rohit Jose's user avatar
0 votes
1 answer
95 views

Should a structure be refactored into smaller structures?

In one of the projects (in C), I have the code that looks like this (the names are obfuscated specially for question to not give out details of the probject): typedef struct Module_s { /* These ...
Michael Pankov's user avatar
10 votes
1 answer
1k views

Does a GPL Bison grammar infect my application?

I am thinking about using a GPL Bison grammar for my own compiler. Will the grammar "infect" my parser such that it needs to be open source? The grammar - in terms of - the input of bison is GPL.
Stasik's user avatar
  • 201
4 votes
1 answer
2k views

Object oriented parser model review

First time I make use of Code Review. At the moment I'm creating an Android application and the company I'm developing it for, has a specific file format that can be used to give text based data ...
Rolf ツ's user avatar
  • 185
30 votes
1 answer
2k views

The Inglish parser (for The Hobbit 1982)

Was fascinated to read about the text adventure game The Hobbit which featured an incredibly robust parser called "Inglish": ...Inglish allowed one to type advanced sentences such as "ask Gandalf ...
Jordan Reiter's user avatar
1 vote
1 answer
621 views

Haskell: Best tools to validate textual input?

In Haskell, there are a few different options to "parsing text". I know of Alex & Happy, Parsec and Attoparsec. Probably some others. I'd like to put together a library where the user can input ...
Ana's user avatar
  • 119
2 votes
1 answer
306 views

content fingerprint algorithm

I have a database containing just simple URLs. It is as simple as it sounds for now and URL can link to a website or a document(i.e. anything parseable to text). Now I have a simple code which ...
lukas.pukenis's user avatar
3 votes
3 answers
10k views

An ideal way to decode JSON documents in C?

Assuming I have an API to consume that uses JSON as a data transmission method, what is an ideal way to decode the JSON returned by each API resource? For example, in Java I'd create a class for each ...
Abdulaziz's user avatar
  • 131
2 votes
0 answers
344 views

Implementing semantic actions in table driven predictive parsing

When doing table driven predictive parsing on an LL(1) grammar, (as explained in good detail here for example), how can we augment the algorithm to allow processing of semantic actions while doing the ...
Basel Shishani's user avatar
6 votes
2 answers
492 views

Should I commit my generated parser to source control?

I'm using a parser generator to build a compiler. Should I commit the source files produced by the parser generator? I want to commit them to avoid a dependency on the parser generator during the ...
Jared Beck's user avatar
2 votes
4 answers
459 views

The right place to embed a parser : Server or the Client?

I'm writing a database management software. It has a client-server architecture where the server has the piece of code to store and retrieve. The client has to get the input from the user, connects to ...
Lakshmi Narayanan's user avatar
1 vote
2 answers
314 views

How would my custom language be categorized?

I'm developing my own scripting language to solve some unique challenges for a project. The language takes source code and converts the contents into tokens, and then a command factory is used to ...
Reactgular's user avatar
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6 votes
3 answers
3k views

What is the proper way to distinguish between keywords and identifiers?

I'm aware that most modern languages use reserved words to prevent things like keywords from being used as identifiers. Reserved words aside, let's assume a language that allows keywords to be used ...
jhewlett's user avatar
  • 2,284
6 votes
1 answer
6k views

Any ASN.1 parsers written completely in managed code & safe from buffer overflows

ASN.1 is a data format used on HTTPS certificates, and various other critical pieces of infrastructure. I need to analyze some potentially hostile ASN.1 data, and want to ensure my code is safe from ...
makerofthings7's user avatar
3 votes
2 answers
4k views

Learning YACC nowadays, does it make sense? [closed]

I have a huge project that is using YACC and I would need to fix a bug in it. I might ask someone else who wrote that to fix it but I'm interested in how compilers work. Does it make sense to learn ...
Makane Elhay's user avatar
1 vote
1 answer
1k views

PHP Simplest XML tokenizer for string processing?

I need to do some text processing tasks with short XML fragments. The section "details" shows an example... My solution is to use a tokenizer based on regular expresions, but it is not ...
Peter Krauss's user avatar
2 votes
1 answer
3k views

Why nginx's http parser doesnt use regular expressions?

I see the http parser written by Igor Sysoev for nginx does not use regular expressions https://github.com/joyent/http-parser What could be the main reason for such design decision? I guess I could ...
botchedDevil's user avatar
14 votes
2 answers
2k views

What does scannerless parsing have to do with the "Dangling Else Problem"?

I do not understand this sentence from the Wikipedia article on the Dangling Else problem: [The Dangling Else problem] is a problem that often comes up in compiler construction, especially ...
user avatar
9 votes
3 answers
1k views

What the correct algorithm to invert italics in a mixed text?

The question motivations was depicted in the section below. There are many ways to make text italic, so, perhaps, there are more than one good "swap italics algorithm". The problem reveals some ...
Peter Krauss's user avatar
40 votes
7 answers
4k views

Why was strict parsing not chosen for HTML?

I have often wondered why strict parsing was not chosen when creating HTML. For most of the Internet history, browsers have accepted any kind of markup and tried their best to parse it. The process ...
Shubham's user avatar
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6 votes
1 answer
1k views

Chosing a parser for a code beautifier

I'm in the planning stage of making a code beautifier (similar to AStyle or Uncrustify) - originally I was going to just contribute to one of those projects, but reviewing their source led me to the ...
Matt Kline's user avatar
1 vote
4 answers
1k views

Is it possible to create a single tokenizer to parse this?

This extends off this other Q&A thread, but is going into details that are out of scope from the original question. I am generating a parser that is to parse a context-sensitive grammar which can ...
Adrian's user avatar
  • 157
-3 votes
2 answers
338 views

What is the name of a grammar which can change its tokenizer in mid parse?

I was creating a language and discovered that my language tokenizer would have to change depending where in the parse it is. I.e. abc[1] would be parsed as 4 tokens (abc, [, 1, ]), where as { abc[1] }...
Adrian's user avatar
  • 157
10 votes
4 answers
2k views

Writing a Compiler Compiler - Insight on Use and Features

This is part of a series of questions which focuses on the sister project to the Abstraction Project, which aims to abstract the concepts used in language design in the form of a framework. The ...
2 votes
1 answer
641 views

Should I use a formal grammar for my interpreted scripting language

I have a scripting engine I just published as an open source project. It's been sitting on my harddrive waiting for about a year. My engine of course isn't complete in any way, but it does work for ...
Earlz's user avatar
  • 22.9k
2 votes
1 answer
1k views

How to choose a proper parser generator for PHP

Some programmers avoid regexes in some situations (see this popular @nickf comment), perhaps using a parsing framework such as Lex/Yacc. Others prefer to stay within PHP, perhaps using regular ...
Peter Krauss's user avatar
26 votes
3 answers
25k views

Implementing the Visitor Pattern for an Abstract Syntax Tree

I'm in the process of creating my own programming language, which I do for learning purposes. I already wrote the lexer and a recursive descent parser for a subset of my language (I currently support ...
marco-fiset's user avatar
  • 8,771
4 votes
3 answers
829 views

How are line/column position data dealt with in parser combinator libraries?

I'm building a parser using a parser combinator library. I need to keep track of where AST nodes started and ended in the textual input -- line and column numbers. How is this problem approached and/...
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14 votes
3 answers
32k views

Generic file parser design in Java using the Strategy pattern

I am working on a product in which the responsibility of one of the modules is to parse XML files and dump the required content in a database. Even though the present requirement is only to parse XML ...
CKing's user avatar
  • 1,012
1 vote
2 answers
176 views

Creating a text input simplifaction tool

I have been working on a project for several months now to write a web-based tool that will help me at work. I work at a call center and the CRM software that is used is wretched, we basically have to ...
Mrow's user avatar
  • 19
3 votes
1 answer
1k views

Practical reference for learning about graph reduction

Are there any practical references (with actual examples) for getting started implementing a small, lazy functional programming language with graph reduction? A reference that included the lexing and ...
user avatar
8 votes
4 answers
2k views

Using a "dead man's switch" to manage time-sensitive code

In our software environment, we often run a/b tests, as is probably good practice. However, our environment is set up such that, in very short order, the code starts to become very crufty with dead ...
dclowd9901's user avatar
3 votes
1 answer
307 views

Showing a grammar is ambiguous

I have the following question taken from a compilers course exam: Show that the following grammar is ambiguous. S = XcY X = a Y = b | Z Z = bW W = d | ϵ I drew the following tree: Am I correct in ...
TomSelleck's user avatar
0 votes
2 answers
726 views

How to extract operators from the grammar productions for conflict resolution in LALR parser?

Is there some standardized or widely accepted algorithm for picking up operators in shift/reduce conflicts in LALR parser? The question is naive, my problem is not with implementing my solution, but ...
greenoldman's user avatar
  • 1,526
3 votes
1 answer
2k views

REST efficiency on count and sum methods

For example, if I have a Customer Transactions Table and I create a REST for it. The fields are: date, description, and total_amount. I am trying to figure out which one is much more efficient when ...
Franz Noel's user avatar
9 votes
2 answers
7k views

Language parsing to find important words

I'm looking for some input and theory on how to approach a lexical topic. Let's say I have a collection of strings, which may just be one sentence or potentially multiple sentences. I'd like to ...
Matt Huggins's user avatar
8 votes
3 answers
3k views

What is a real-world use case of using a Chomsky Type-I (context-sensitive) grammar

I have been having some fun lately exploring the development of language parsers in the context of how they fit into the Chomsky Hierarchy. What is a good real-world (ie not theoretical) example of a ...
Evan Plaice's user avatar
  • 5,765
1 vote
2 answers
183 views

Extracting useful information from free text

We filter and analyse seats for events. Apparently writing a domain query language for the floor people isn't an option. I'm using C# 4.0 & .NET 4.0, and have relatively free reign to use ...
Bryan Boettcher's user avatar
5 votes
1 answer
3k views

How to add precedence to LALR parser like in YACC?

Please note, I am asking about writing LALR parser, not writing rules for LALR parser. What I need is... ...to mimic YACC precedence definitions. I don't know how it is implemented, and below I ...
greenoldman's user avatar
  • 1,526
0 votes
1 answer
387 views

How lookaheads are propagated in "channel" method of building LALR parser?

The method is described in Dragon Book, however I read about it in ""Parsing Techniques" by D.Grune and C.J.H.Jacobs". I start from my understanding of building channels for NFA: channels are built ...
greenoldman's user avatar
  • 1,526
1 vote
1 answer
651 views

How to read reduce/shift conflicts in LR(1) DFA?

I am reading an explanation (awesome "Parsing Techniques" by D.Grune and C.J.H.Jacobs; p.293 in the 2nd edition) and I moved forward from my last question: How to get lookahead symbol when ...
greenoldman's user avatar
  • 1,526
3 votes
2 answers
8k views

How to get lookahead symbol when constructing LR(1) NFA for parser?

I am reading an explanation (awesome "Parsing Techniques" by D.Grune and C.J.H.Jacobs; p.292 in the 2nd edition) about how to construct an LR(1) parser, and I am at the stage of building the initial ...
greenoldman's user avatar
  • 1,526
7 votes
1 answer
6k views

Extracting color profile information from JPEG files

I'm trying to look up info about reading JPEG's color profile info and to my surprise there's very little open specific how-to information on that regard, but rather lots of general explanation on ...
Igor K.'s user avatar
  • 173
9 votes
4 answers
425 views

How should I implement a command processing application?

I want to make a simple, proof-of-concept application (REPL) that takes a number and then processes commands on that number. Example: I start with 1. Then I write "add 2", it gives me 3. Then I ...
Nini Michaels's user avatar
13 votes
5 answers
548 views

How can I best manage making open source code releases from my company's confidential research code?

My company (let's call them Acme Technology) has a library of approximately one thousand source files that originally came from its Acme Labs research group, incubated in a development group for a ...
DeveloperDon's user avatar
  • 4,978
5 votes
2 answers
1k views

Scripting custom drawing in Delphi application with IF/THEN/ELSE statements?

I'm building a Delphi application which displays a blueprint of a building, including doors, windows, wiring, lighting, outlets, switches, etc. I have implemented a very lightweight script of my own ...
Jerry Dodge's user avatar
3 votes
1 answer
238 views

What does it mean that StAX parsers aren't complete or correct?

I've been browsing the net and found theses two slides on site of XOM (XML object model): slide1 slide2 Where they refer to SAX(push) and StAX(pull) parsers. So I'm wondering, what does it mean that ...
Daniel Fath's user avatar
19 votes
4 answers
2k views

Generic rule parser for RPG board game rules - how to do it?

I want to build a generic rule parser for pen and paper style RPG systems. A rule can involve usually 1 to N entities 1 to N roles of a dice and calculating values based on multiple attributes of an ...
floriank's user avatar
  • 471