parboiled2 | A macro-based PEG parser generator for Scala

by sirthias Scala Version: v2.5.0 License: Non-SPDX

X-Ray Key Features Code Snippets Community Discussions(3)Vulnerabilities Install Support

kandi X-RAY | parboiled2 Summary

parboiled2 is a Scala library. parboiled2 has no bugs, it has no vulnerabilities and it has low support. However parboiled2 has a Non-SPDX License. You can download it from GitHub.

A macro-based PEG parser generator for Scala 2.10+

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Support

parboiled2 has a low active ecosystem.

It has 710 star(s) with 86 fork(s). There are 27 watchers for this library.

It had no major release in the last 6 months.

There are 33 open issues and 117 have been closed. On average issues are closed in 164 days. There are no pull requests.

It has a neutral sentiment in the developer community.

The latest version of parboiled2 is v2.5.0

Quality

parboiled2 has no bugs reported.

Security

parboiled2 has no vulnerabilities reported, and its dependent libraries have no vulnerabilities reported.

License

parboiled2 has a Non-SPDX License.

Non-SPDX licenses can be open source with a non SPDX compliant license, or non open source licenses, and you need to review them closely before use.

Reuse

parboiled2 releases are not available. You will need to build from source code and install.

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parboiled2 Key Features

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parboiled2 Examples and Code Snippets

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Community Discussions

Trending Discussions on parboiled2

Specifying covariant/contravariant behavior with C++ templates

Parboiled2: How to process dependent fields?

In parboiled2, how should I report an error in a parser action?

QUESTION

Specifying covariant/contravariant behavior with C++ templates

Asked 2018-May-19 at 17:54

I'm looking at parboiled2 in Scala and it's got an interesting way of encoding parser behavior in the type system using covariant/contravariant subtypes:

https://github.com/sirthias/parboiled2#rule-types-and-the-value-stack

I'm curious if something similar can be accomplished in C++ with template meta-programming.

I suspect the covariant behavior could be emulated with inheritance, but what about contravariant?

...

ANSWER

Answered 2018-May-19 at 17:54

In C++, like in other OO languages, subtypes are generally represented by inheritance.

However, we cannot model covariance and contravariance relationships through inheritance, because there is no way to list the base classes of a class (without any of the various reflection proposals, which have not made their way into the language yet).

The easiest way to allow this kind of behavior is to allow covariant and contravariant templated classes to convert based on the relationship of the related types.

Covariance

If Derived is-a Base, then Covariant "should-be-a" Covariant.

Normally, the solution would be to make Covariant inherit from Covariant, but we currently have no way of finding Base given only Derived. However, we can enable the conversion by writing a constructor for Covariant taking any Covariant:

Source https://stackoverflow.com/questions/50427648

QUESTION

Parboiled2: How to process dependent fields?

Asked 2018-Feb-21 at 19:05

I'm trying to parse a file format, using the excellent parboiled2 library, in which the presence of some fields is dependent upon the value of one or more fields already processed.

For example, say I have two fields, the first of which is a flag indicating whether the second is present. That is, if the first field is true, then the second field (which is an integer value, in this example) is present and must be processed - but if it's false, then the second field isn't present at all. Note that this second field isn't optional - it either must be processed (if the first field is true) or must not be processed (if the first field is false).

So, if a third field (which we'll assume is always present) is a quoted string, both of the following lines are valid:

...

ANSWER

Answered 2018-Feb-21 at 03:15

I would do something like this:

Source https://stackoverflow.com/questions/48897117

QUESTION

In parboiled2, how should I report an error in a parser action?

Asked 2017-Apr-20 at 18:24

What's the best way to report an error in a parser action in parboiled2 (I'm using v 2.1.4)?

For example, say I want to read an integer value and report an error if its not within the expected range? I tried calling fail, but that doesn't appear to be valid within a parser action. Also, I can't tell how I should provide the stack value to the test rule. Do I simply throw a ParseError exception?

To be a little more specific, consider the following rule:

...

ANSWER

Answered 2017-Apr-20 at 18:19

You can use test for that. The trick is that actions can also return a Rule.

Source https://stackoverflow.com/questions/43525576

Community Discussions, Code Snippets contain sources that include Stack Exchange Network

Vulnerabilities

No vulnerabilities reported

Install parboiled2

You can download it from GitHub.

Support

For any new features, suggestions and bugs create an issue on GitHub. If you have any questions check and ask questions on community page Stack Overflow .

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