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I have in my hands a Java project that has a parser for some language.
And it works very nice to read and parse.
But I would like to know if using ANTLR I can also get the other way around, like given a the Java Object go to the string representation of this same object in the language that the parser was built for?
So if I had a CSV parser, I would like to go from the java Object to a CSV file(or string that represents the file).
Not sure if ANTLR is the way to do that.
How can any tool know what the CSV representation of a given object is? Not even the CSV parser knows this. It can only take a CSV input and see if that matches any predefined rule.
ANTLR certainly is not a tool for that. It is a parser generator that takes a grammar of a language and creates recognition classes (a lexer and a parser at the bare minimum) out of it. That's it and ANTLR very good at it.
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In OCaml, there is a construct called univ_map.t, which allows you to map from 'a Type_equal.Id.t values to 'as. Here is an example.
Is there a construct that would allow me to do something similar in Rust? I know in OCaml they are implemented with open variants, which I don't believe Rust has.
I'm not familiar with OCaml, but looking at the docs:
Univ_map: Universal/heterogeneous maps [...] useful for storing values of arbitrary type in a single map [...] built on top of Univ.
Univ: An extensible universal variant type. Every type id corresponds to one branch of the variant type.
The closest thing that Rust has that sounds like Univ is the Any trait, which is designed to represent any type (with exceptions). However, there is no standard type for storing a collection of Anys that is accessed by its TypeId. From looking how popular crates handle this, its usually a bespoke wrapper around HashMap<TypeId, Box<dyn Any>> or similar. I hope I've understood correctly.
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I wanted to embed an image to my binary and used the "include_bytes" macro. The GUI library I wanted to use only accepts [u32] for input and the said macro produces only [u8].
How do I convert a [u8] to a [u32]? I've seen some in the internet but the explanations are a bit too technical for me (I'm only self-taught). There were several options that I saw like bitwise and a method in "u32" from the standard library. Anyone can give an actual code on how to do it? Like study it from there in case I will need it for other files in the future. Thank you. I almost always just understand things via code coz I'm not aware of many technical terms, algos, etc.
using .map(Into::<u32>::into)
fn main() {
assert_eq!([0_u8, 1_u8].map(Into::<u32>::into), [0_u32, 1_u32]);
}
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When creating a webserver in golang, is there any specific reason why JSON data would be represented as a MAP over a STRUCT or vice versa? ..or is this decision based purely on user preference ?
I think this discussion could go either way but the advantages of using structs vs maps are that structs give you an idea of how the schema should look like whereas a map leaves the schema open-ended.
If you use structs, developers who look at the code will have a clear idea of what parameters you're expecting for the API or how the response of the API may look like without digging further into implementation detail. On the other hand if the requests or responses were maps, they would have to look at the implementation detail to see what keys and values are being assigned. Hope this helps!
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I'm given a task of converting a bunch of code written in Python 2 to Python 3,
and this task was given with emphasis on having UTF-8 (didn't quite comprehend the concept but anyway..)
I've automated the conversion using 2to3, but not sure if using 2to3 achieves the goal of having UTF-8, or if there's some other parts that I should manually work on.
What is it exactly, and is it done automatically by using 2to3?
Thank you in advance.
"I was just told the importance of converting it into Python 3 due to importance of UTF-8 so that the program can work with any other language"
Whoever told you that was misinformed.
2to3 does not do anything towards "having UTF-8" whatever that means. 2to3 is to move your code from Python 2 to Python 3. Python 3 does mean you have have Unicode variable names, but I would strongly recommend against that anyway. Bad Idea. Otherwise Python 2 supports Unicode and UTF-8 perfectly well.
It seems your actual goal is not UTF-8, but translating the program to other language, also known as internationalization, or "18n". That's a completely different issue, and has nothing to do with 2to3. Instead you need to manually change all your text strings to gettext tokens that will be translated when rendered. See http://docs.python.org/library/gettext.html
See also http://regebro.wordpress.com/2011/03/23/unconfusing-unicode-what-is-unicode/ for more information on Unicode.
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I'd like to write a code beautifier and i thought of using Ruby to do it. Could someone show me a place to get started? I've seen a lot of code beautifiers online but I've never come across any tutorials on how to write one. Is this a very challenging task for someone who's never undertaken any projects such as writing a compiler, parser, etc. before?
(Is there another langauge which would be more well suited for this kind of task, excluding C/C++?)
Python has an interesting feature - it exposes its own parser to scripts. There are examples that use the AST - abstract syntax tree - and do the pretty printing.
I'm not aware that Ruby exposes its own parser to its scripts in such a way, but there are parsers for Ruby written in Ruby here.
Well... I think the initial steps are what you'd do for any project.
Write a list of requirements.
Describe a user interface to your program, that you like and won't prevent you meeting those requirements.
Now you can write down more of a "code" design, and pick the language that would be easiest for you to meet that design.
Here's some requirements off the top of my head:
Supports code beautifying of these languages: Ruby, Python, Perl
Output code behaves identically to input
Output has consistent use of tabs/spaces
Output has consistent function naming convention
Output has consistent variable naming convention
Output has matching braces and indentation
Make as many as you want, it's your program. ;p I was kidding about the Perl, but I think every language you support is going to add a more work.