# Leonetienne/Hazelnupp: Hazelnupp

Hazelnupp

is a simple, easy to use command line parameter parser.
Hazelnupp does not support windows-, or bsd-style arguments. Only linux-style.

What is the linux-style? This:

# Using a long parameter
$ a.out --long-parameter 1234
# Using an abbreviated parameter
$ a.out -lp 1234

# Note

These examples reference exceptions. These are not enabled by default. The default behaviour for user-fault exceptions is to produce output to `stderr` and kill the process.
To enable exceptions, call this method:

CmdArgsInterface args;
args.SetCrashOnFail(false);

# Index

1. Importing into a project
2. What's the concept?
3. Minimal working example
4. Abbreviations
5. Constraints
6. Automatic parameter documentation
7. Descriptive error messages
8. More examples?
9. What is not supported?
10. Further notes
11. Contributing
12. LICENSE

# Importing into a project

> How do i actually import this into my existing project?

Super easily! Just grab the latest files (2) from /INCLUDE and put them into your project! You may have to add the .cpp to your compile list, but most IDEs should do this automatically.

# What's the concept?

The concept is that each parameter must be one of five types. These are:

- Void
- Int
- Float
- String
- List (non-recursive)

Here are examples on how to create them

# Void
$ a.out --foo
# Int
$ a.out --foo 5
# Float
$ a.out --foo 5.5
# String
$ a.out --foo peter
# List (any type above works, except void)
$ a.out --foo peter jake jeff billy
# List, mixed types
$ a.out --foo 1 2 3 4 peter willy billy bob 3

These parameters can then be accessed via a simple lookup!

# Minimal working example

So what's the simplest way to use Hazelnupp to work with command-line parameters? See:

#include "Hazelnupp.h"
using namespace Hazelnp;
int main(int argc, char** argv)
{
CmdArgsInterface args(argc, argv);
if (args.HasParam("--force"))
// do forced
else
// be gentle
return 0;
}

Looks super easy! But what about actual values?

#include "Hazelnupp.h"
using namespace Hazelnp;
int main(int argc, char** argv)
{
CmdArgsInterface args(argc, argv);
// Either check via HasParam(), or do a try-catch
try
{
int myInt = args["--my-int"].GetInt32();
double myFlt = args["--my-float"].GetFloat32();
std::string myStr = args["--my-string"].GetString();
}
catch (HazelnuppInvalidKeyException&)
{
return -1;
}
return 0;
}

What about lists?

#include "Hazelnupp.h"
using namespace Hazelnp;
int main(int argc, char** argv)
{
CmdArgsInterface args(argc, argv);
const auto& myList = args["--my-list"].GetList(); // std::vector<Value*>
for (const auto* it : myList)
{
// Should probably check for type-correctness with it->GetDataType()
std::cout << it->GetString() << std::endl;
}
return 0;
}

# Abbreviations

Abbreviations are a very important part of command line arguments. Like, typing `-f` instead of `--force`. Here's how to use them in Hazelnupp:

#include "Hazelnupp.h"
using namespace Hazelnp;
int main(int argc, char** argv)
{
CmdArgsInterface args;
// Register abbreviations
args.RegisterAbbreviation("-f", "--force");
// Parse
args.Parse(argc, argv);
if (args.HasParam("--force")) // This key will be present, even if the user passed '-f'
// do forced
else
// be gentle
return 0;
}

# Constraints

> That's all cool and stuff, but this looks like a LOT of error-checking and not elegant at all! How would i actually use this?

For exactly this reason, there are constraints. With this, you can control what the data looks like! Constraints serve two main purposes:

## Requiring data

With `ParamConstraint::Require()` you can declare that a paramater must either always be present, or provide a default value.

- If a parameter is not present, but has a default value, it will be automatically created.
- If a parameter is not present, and has no default value, an exception will be thrown.

Minimal working example:

#include "Hazelnupp.h"
using namespace Hazelnp;
int main(int argc, char** argv)
{
CmdArgsInterface args;
// Register constraints
args.RegisterConstraint("--this-is-required", ParamConstraint::Require()); // This missing throws an exception
args.RegisterConstraint("--also-required-but-defaulted", ParamConstraint::Require({"122"})); // This will default to 122
// Parse
args.Parse(argc, argv);
return 0;
}

## Type safety

With type safety you can always be certain that you are working with the correct type!
By creating a type-constraint you force Hazelnupp to use a certain type.
If a supplied type does not match, but is convertible, it will be converted.
If it is not convertible, an exception will be thrown.

These conversions are:

- int -> [float, string, list, void]
- float ->[int, string, list, void]
- string -> [list, void]
- list -> [void]
- void -> [list, string]

The conversions `*->list` just create a list with a single entry (except for `void->list` which produces an empty list).
The `*->void` conversions just drop their value.
`void->string` just produces an empty string.

Minimal working example:

#include "Hazelnupp.h"
using namespace Hazelnp;
int main(int argc, char** argv)
{
CmdArgsInterface args;
// Register constraints
args.RegisterConstraint("--this-must-be-int", ParamConstraint::TypeSafety(DATA_TYPE::INT));
// Parse
args.Parse(argc, argv);
return 0;
}

If `--this-must-be-int` would be passed as a float, it would be converted to int. If it was passed, for example, as a string, it would throw an exception.

Note that you can also combine these two constraint-types by populating the struct yourself:

ParamConstraint pc;
pc.constrainType = true;
pc.requiredType = DATA_TYPE::STRING;
pc.defaultValue = {}; // no default value
pc.required = true;
args.RegisterConstraint("--my-key", pc);

What doesn't work is inserting multiple constraints for one key. It will just discard the older one. But that's okay because one can describe all possible constraints for a single key in one struct.

# Automatic parameter documentation

Hazelnupp does automatically create a parameter documentation, accessible via `--help`.
If you want to use `--help` yourself, just turn it off.

CmdArgsInterface args;
args.SetCatchHelp(false);

What does this automatically generated documentation look like?

$ a.out --help
This is the testing application for Hazelnupp.
==== AVAILABLE PARAMETERS ====
--help This will display the parameter documentation.
--names LIST default=['peter' 'hannes'] The names to target
--force -f Just forces it.
--width -w FLOAT The width of something...
--fruit STRING [[REQUIRED]] The fruit to use
--height -h

This documentation is automatically fed by any information provided on parameters.
You have to set the brief descriptions yourself though.

CmdArgsInterface args;
args.RegisterDescription("--force", "Just forces it.");

Additionally you can provide a brief description of your application to be added right above the parameter list.

CmdArgsInterface args;
args.SetBriefDescription("This is the testing application for Hazelnupp.");

If you want to display this information somewhere else, you can always access it as a string via `args.GenerateDocumentation()`.

# Descriptive error messages

Given that you did not disable crash-on-error, Hazelnupps default behaviour on user error is to terminate the process with a descriptive error message to stderr.

Here's how they look like:

Type mismatch:

$ a.out --width "about 3 meters"
<< --help page gets printed here aswell >>
Parameter error: Cannot convert parameter --width to type FLOAT. You supplied type: VOID.
--width => The width of something...

Missing required parameter:

$ a.out"
<< --help page gets printed here aswell >>
Parameter error: Missing required parameter --width.
--width => The width of something...

This assumes that you've set a description for, in this example, `--width`. If a description is not set, the last line will simply be omitted.

# More examples?

Check out the tests! They may help you out!
Also make sure to check out the doxygen docs!

# What is not supported?

Chaining abbreviated parameters, like this:

# This is not supported. It would think -ltr is one parameter.
$ a.out -ltr
# Instead do this
$ a.out -l -t -r

Using parameters multiple times

# This is not supported.
# Let's say -i is short for --input
$ a.out -i hello.txt -i shoe.txt -i somsang.txt
# Instead do this
$ a.out -i hello.txt shoe.txt somsang.txt

# Further notes

This is still in alpha! There is no guarantee at all that this actually works.
Whilst i did my best to make sure it does, i bet there are still a few flaws i've overlooked.
Please know that i am not obliged to work on fixes. I do have other stuff to do. This does not mean that i won't, but i'm not sure when.
Feel free to submit a PR if you think you improved it in any way :)

# Contributing

If you want to contribute, feel free to fork the repository, and submit a pull request.
Bugfixes and tests are almost certain to be accepted, features should be agreed upon and come with tests.
Just create an issue with the tag `feature request`. Don't forget to update the UML (`Hazelnupp.vpp`)! The (free) modelling software used is Visual Paradigm.

Any code added must match the existing style!

- Objects begin with a lowercase initial
- Classifiers and Functions/Methods begin with an uppercase initial
- Classifiers are camel-case
- Classifiers get documented via `/** */` for doxygen. See existing classifiers
- Members (methods and objects) get documented via `//!` for doxygen. See existing definitions
- `{` always gets a new line
- Enumerations (and their values) and macros are all-upper case snake-case
- No `using namespace std`
- Do `using namespace Hazelnp` in cpp files. Don't do `Hazelnp::` if possible
- Files outside the project (like STL) have to be included with `#include <>`. Not `""`

# LICENSE

Copyright (c) 2021, Leon Etienne
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
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.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Hazelnp
Definition: CmdArgsInterface.h:7
Hazelnp::CmdArgsInterface
The main class to interface with.
Definition: CmdArgsInterface.h:11
Hazelnp::CmdArgsInterface::SetCatchHelp
void SetCatchHelp(bool catchHelp)
Sets whether the CmdArgsInterface should automatically catch the –help parameter, print the parameter...
Definition: CmdArgsInterface.cpp:334
Hazelnp::HazelnuppInvalidKeyException
Gets thrown when an non-existent key gets dereferenced.
Definition: HazelnuppException.h:29
Hazelnp::CmdArgsInterface::RegisterConstraint
void RegisterConstraint(const std::string &key, const ParamConstraint &constraint)
Will register a constraint for a parameter.
Definition: CmdArgsInterface.cpp:598
Hazelnp::CmdArgsInterface::RegisterAbbreviation
void RegisterAbbreviation(const std::string &abbrev, const std::string &target)
Will register an abbreviation (like -f for –force)
Definition: CmdArgsInterface.cpp:567
Hazelnp::CmdArgsInterface::HasParam
bool HasParam(const std::string &key) const
Will check wether a parameter exists given a key, or not.
Definition: CmdArgsInterface.cpp:165
Hazelnp::CmdArgsInterface::Parse
void Parse(const int argc, const char *const *argv)
Will parse command line arguments.
Definition: CmdArgsInterface.cpp:36
Hazelnp::ParamConstraint::TypeSafety
static ParamConstraint TypeSafety(DATA_TYPE requiredType, bool constrainType=true)
Constructs a type-safety constraint.
Definition: ParamConstraint.h:26
Hazelnp::DATA_TYPE::INT
@ INT
Hazelnp::ParamConstraint::Require
static ParamConstraint Require(const std::vector< std::string > &defaultValue={}, bool required=true)
Constructs a require constraint.
Definition: ParamConstraint.h:16