Rust nom

Its goal is to provide tools to build safe parsers without compromising rust nom speed or memory consumption. To that end, rust nom, it uses extensively Rust's strong typing and memory safety to produce fast and correct parsers, and provides functions, macros and traits to abstract most of the error prone plumbing.

This tutorial is a guide to parsing with nom. It covers the basics of parsing and how to use nom to parse a string into a data structure. We will cover a variety of different examples ranging from parsing simple CSS like syntax to a full blown Markdown parser. If you would like to get involved in an open source project and like Rust crates, we welcome your contributions to the r3bl-open-core repo. For more information on general Rust type system design functional approach rather than object oriented , please take a look at this paper by Will Crichton demonstrating Typed Design Patterns with Rust.

Rust nom

Nom , documented here is a parser library for Rust which is well worth the initial time investment. Likewise, for configuration files use dedicated parsers like ini or toml. But if the text is not regular, or some made-up format, then you need to scan that text without writing a lot of tedious string-processing code. The suggested go-to is often regex , but regexes can be frustratingly opaque when sufficiently involved. Nom provides a way to parse text which is just as powerful and can be built up by combining simpler parsers. If you ever had the itch to write your own programming language, Nom is a good place for you start on that hard road to obscurity. There are some excellent tutorials for learning Nom, but I want to start at the hello-world level to build some initial familiarity. The basic things you need to know - first, Nom is macros all the way down, and second, Nom prefers to work with byte slices, not strings. The first means that you have to be especially careful to get Nom expressions right, because the error messages are not going to be friendly. And the second means that Nom can be used for any data format, not just text. People have used Nom to decode binary protocols and file headers. It can also work with 'text' in encodings other than UTF

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Welcome to Nominomicon; a guide to using the Nom parser for great good. This guide will give you an introduction to the theory and practice of using Nom. By combining parsers with combinators, you can build complex parsers up from simpler ones. Introduction 1. The Nom Way 2. Tags and Character Classes 3. Alternatives and Composition 4.

This is a combination of the alt! You should use this only if you know you will not receive partial input for the rules you're trying to match this is almost always the case for parsing programming languages. The number of bits of the input to compare must be specified. A bit like std::try! Add an error if the child parser fails. Used to wrap common expressions and function as macros. Used to called methods then move self back into self. Prints a message if the parser fails. Prints a message and the input if the parser fails.

Rust nom

It conjures visions of obscure grammars fed into arcane tools to generate thousands of lines of unreadable code. Parser combinator libraries such as nom present a library of small functions that each do one thing, and then allow you to put them together to create a full parser. Some expressions, such as Bold , contain other expressions.

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Skip to content. Useful functions to calculate the offset between slices and show a hexdump of a slice. While nom was made for binary format at first, it soon grew to work just as well with text formats. Bytes By just wrapping the tag! Latest commit History 2, Commits. However, the resources listed below are very useful for learning nom. Rust version requirements MSRV. Report repository. The resulting code is small, and looks like the grammar you would have written with other parser approaches. There are a few guides with more details about how to write parsers , or the error management system. Some benchmarks are available on GitHub. You signed out in another tab or window. We want to ignore whitespace. Generalized workflow Build a Markdown parser Introduction This tutorial is a guide to parsing with nom.

Its goal is to provide tools to build safe parsers without compromising the speed or memory consumption. To that end, it uses extensively Rust's strong typing and memory safety to produce fast and correct parsers, and provides functions, macros and traits to abstract most of the error prone plumbing. Hexadecimal color parser:.

Parser combinators. Errors are a key part of it being able to apply a variety of different parsers to the same input. Introduction 1. Characters vs. And the second means that Nom can be used for any data format, not just text. Tags and Character Classes 3. We can do better. We can write a generic dump function that handles any return value that can be debug-printed. Notice that it was straightforward to combine an existing parser for greetings with a parser that picks up names, and then it was easy to make that name optional. This guide will give you an introduction to the theory and practice of using Nom. Again we map to string slice from the byte slice over all these matches. The match values are combined into a single value, using a binary operator. Notifications Fork Star 8. However, the resources listed below are very useful for learning nom. Threads, Networking and Sharing 8.