IO Reader GENerator

Description

Iorgen is a multi languages code generator to parse a predefined input template. The user writes a YAML describing the input, and Iorgen will generate the code to read this input from stdin, in all supported languages.

The list of currently supported languages is: C, C++, C#, D, Go, Haskell, Java, Javascript, Lua, Ocaml, Pascal, Perl, PHP, Prolog, Python, Ruby, Rust, Scheme. A markdown description of the input in English and French can also be generated.

Installation

You can install iorgen in a virtual environment like this:

git clone git@github.com:prologin/iorgen.git
cd iorgen
python3 -m venv .venv
source .venv/bin/activate
pip3 install -e .

You can then run it with the iorgen command.

Testing the languages

You should be able to trust that Iorgen will generate valid files. But if you want to be sure that those files are valid, and want to generate the test suite for instance, you will have to install lots of compilers.

The complete dependencies for Archlinux are:

pacman -S --needed python-yaml fpc gambit-c gcc gdc ghc go jdk-openjdk lua \
    mono nodejs ocaml perl php ruby rust swi-prolog

For Debian based distros (tested on Debian 10, Ubuntu 18.04 and 20.04):

sudo apt install python3-yaml default-jdk-headless fp-compiler gambc gcc gdc \
    ghc golang lua5.3 mono-mcs nodejs ocaml-nox perl php-cli ruby rustc \
    swi-prolog-nox

Usage

Make sure python (version 3.6 and above) and python-yaml are installed on your computer and run python3 -m iorgen input.yaml. This will generate all languages parsers in a skeleton folder, and a subject-io-stub.md describing the input (in French by default).

Several options are available:

The --output_dir option specify the path and name of the directory holding the generated codes. The filenames will be the same as the input yaml, with the extensions replaced by the canonical extension of each language.
The --languages option can generate a subselections of languages.
The --markdown option specify the language (not programming language) in which the subject-io-stub.md will be written. The subject-io-stub.md is a file generated next to the output directory, and not inside.
The --validate option, changes completly Iorgen behavior. Instead of generating parsers reading some raw input, Iorgen will here directly read a file containing such a raw input, and check that it is valid, that is, that it matches the format described in the input YAML.
The --generate_random also changes the behavior. It will not generate a parser, but a valid possible raw input.
The --specify is to be used with --generate_random, it allows the user to specify the value, the min value or the max value of a variable for this output. NAME VALUE set the value. NAME_max VALUE (or NAME_min VALUE) set the maximum value (or the minimum).
```
$ iorgen -g -s N_max 10 integer 42 -- example.yaml
```
The perf_mode option is used with the --validate or --generate_random mode. This means that the raw input will be treated as in performance mode. The performance mode is a mode where the constraints are differents, usually the integers are bigger.
The --run option changes the behavior of Iorgen: generated parsers are written in a temporary folder, and Iorgen will compile those parsers and run them with the input given in arguments to the run option (a single path that can represent many input files thanks to a wildcard support). It will check that the parser is able to recreate exactly the input, and can be used as a proof that the generated parser is working. Using this option requires compilers of all tested languages to be installed (see this section to know more).

Input format

Types

Iorgen can use the following types:

Integer: the default integer type for the language
Char: can be either a byte, or a string depending of the language
String: a string with a given maximum size
List: an array, list, vector… of a given size, containing one of the Iorgen supported types
Struct: a C like struct, or a map which have strings as keys; each field can have any of Iorgen supported types (except the exact same struct)

Format

The input is described in YAML, and must have the following format:

A "function_name" field, containing the name of the generated function
A "subject" field, containing a string (can be several paragraphs) describing what the input is about (will no be used in generated code)
An "ouput" field, containing a string (can be several paragraphs) describing what the end user have to do with the parsed input
An "input" field, containing a list of variables. Each variable is a map with the following fields:
- A "type" field, containing a string (see the type syntax below)
- A "name" field, containing a string: the variable’s name
- A "comment" field, containing a string: a description of the variable
- An optional "min" field, if the variable is a integer, or a list (or list or list, or list of list of list, etc) of integers. This will be the minimal value possible for this variable. This is used in the markdown generator to show the constraints, and in some langages generators to check if the size of a list or a string is garantied to be not null. The "min" field can either be an integer, or a variable name.
- An optional "max" field (similar to the "min" one).
- An optional "min_perf" field: like the "min" one, but only used in the case of performance cases, often meaning that the variable will have a very big value.
- An optional "max_perf" field (similar to the "min_perf" one).
- An optional "choices" field, if the variable is a char or a integer, or a list (or list of list, etc) of chars or integers (for this definition a string is considered as a list of chars). "choices" is a list of values possible for this integer or char. If this list is not empty, then the "min" fields and similar fields will be ignored.
An optional "structs" field, if your input uses structs, a list of structs. Each struct is a map with the following fields:
- A "name" field, containing a string: the struct’s name
- A "comment" field, containing a string: a description of the struct
- A "fields" field, containing a list of the struct’s fields (same syntax as "input")

Syntax

Any "name" field (or "function_name") can hold any alphanumic character or spaces, but must start with a letter, and can not have trailing whitespaces. You do not have to worry about the name beeing a language’s keyword: it will automatically be modified if that is the case, usually by adding a trailing underscore.

A "comment" field can hold any character other than a newline. For now, strings that end comments in some languages, such as */ should be avoided. A protection against this will be added in a later version.

A "type" field must have one of the following format int, char, str(size), List[type](size), @structname. You must replace size, type and structname following this guidelines:

size can be either a number, or a variable name. If it is a variable name, it must be a toplevel one (i.e. in the "input" list), and must have been declared before use. One exception: you can use a struct with two fields: one integer, and a other a type whose size is the first field. For strings, the given size, in the maximum size the string will have, but it could be less.
type can be any valid type, even an other list
structname is the name of a struct, as declared in the "name" field of "structs"

Example

function_name: example
subject: This input is an example for Iorgen's README
structs:
    - name: a struct
      comment: A struct for the example
      fields:
          - type: int
            name: integer
            comment: an integer
            choices: [-4, 42, 1337]
          - type: char
            name: character
            comment: a char
            choices: [a, b, c]
input:
    - type: int
      name: N
      comment: a number, used as a size
      min: 1
      max: 10
      max_perf: 10000
    - type: List[@a struct](N)
      name: list
      comment: a list of structs
output: In a real life scenario, you will describe here what you want the end
    user to do with this generated code

If you want to generate the C code for parsing this kind of input, run python3 -m iorgen -l c example.yaml, and you will get the following skeleton/example.c:

#include <stdio.h>
#include <stdlib.h>

/// A struct for the example
struct a_struct {
    int integer; ///< an integer
    char character; ///< a char
};

/// \param n a number, used as a size
/// \param list a list of structs
void example(int n, struct a_struct* list) {
    /* TODO In a real life scenario, you will describe here what you want the
    end user to do with this generated code */
}

int main() {
    int n;
    scanf("%d", &n);
    struct a_struct* list = (struct a_struct*)malloc(n * sizeof(struct a_struct));
    for (int i = 0; i < n; ++i) {
        scanf("%d %c", &list[i].integer, &list[i].character);
    }
    example(n, list);

    return 0;
}

You can see every other thing that Iorgen can generate in the test samples; you can find parsers for lots of languages, and also a generated description of the input in YAML.

LeSeulArtichaut / iorgen