Fast Parse
IParse
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Fast Parse | IParse | |
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4 | 5 | |
1,075 | 11 | |
0.7% | - | |
4.6 | 3.3 | |
11 days ago | 5 months ago | |
Scala | C++ | |
MIT License | GNU General Public License v3.0 only |
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Fast Parse
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How do I remove the forward reference error in my parser? (20 lines)
Perhaps use Li Haoyi's fastparse instead? https://github.com/com-lihaoyi/fastparse
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Parse slightly dirty, poorly escaped XML
You might want to adapt Li Haoyi’s XML parser for fastparse.
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-🎄- 2021 Day 18 Solutions -🎄-
Mostly a mess of pattern matching. I really need to make some generic tree utilities. Haven't been able to find a decent parser combinator that works in Scala 3 (I usually use fastparse which depends heavily on Scala 2 macros, and scala-parser-combinators works in Scala 3, but I've had a lot of trouble getting it to not be too greedy), so I used the state monad from cats to parse at the bottom of the file, which I think turned out fairly nice.
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Parser generators vs. handwritten parsers: surveying major languages in 2021
Agreed! I would say that parser combinators are the sweet spot and the right choice in most cases.
Scala has them as well, e.g.: https://com-lihaoyi.github.io/fastparse/
And the good thing is, you don't have to learn a completely new language/syntax, you can use the host language's syntax and you have full IDE support as well.
IParse
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I Wrote a String Type
Nice library with many features. But I do not always understand the focus on memory usage. I guess that the reason behind this is that less memory allocations, have a positive effect on execution times. In a parser, where you often have to compare identifiers, it is a good idea to put all strings for identifiers into a unique pointer with the help of a hash table.
In my interpreting parser [1] I use a hexa hash tree [2] for storing identifiers. It is not very memory efficient, but very fast. It turns every string (from the input buffer) into a unique pointer for that string pointing to a copy of the string. In this way comparing string (identifiers) is equivalent to comparing pointers.
The idea of the hexa hash tree is that is a tree where each node has sixteen child nodes. Which node is selected is based on a step wise evaluated hash function that first takes the lower four bytes of the string, and after reaching the end of the string, the higher four bytes of the string. The nodes often taken up more memory space than the strings themselves.
[1] https://github.com/FransFaase/IParse/
[2] https://github.com/FransFaase/IParse/blob/master/software/Id...
- Noulith: A new programming language currently used by the Advent of Code leader
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The Tools I Use to Write Books (2018)
I wrote a tool that can process a number of MarkDown files with fragments of C code and put all those fragments in the right order to produce a file that can be compiled. It is grammar based and works with manipulating Abstract Syntax Trees, so I guess, it could be adapted for different programming languages. See: https://github.com/FransFaase/IParse#markdownc
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C++ Compile Time Parser Generator
Interesting. I have not looked into the code, but I wonder whether it is a compiler, or just an interpreter, e.g. it converts the grammar into some internal representation that is executed by an interpreter or virtual machine. I started worked on an interpreting parser in C many years ago. And later also made Java, C++ and JavaScript version of it. For the JavaScript implementation, see: https://fransfaase.github.io/ParserWorkshop/Online_inter_par... For the C++ version, see: https://github.com/FransFaase/IParse
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Parser generators vs. handwritten parsers: surveying major languages in 2021
I implemented an unparse function in IParse, which is not a parser generator, but a parser that interprets a grammar. See for example https://github.com/FransFaase/IParse/blob/master/software/c_... where symbols starting with a back slash are a kind of white space terminals during the unparse. For example, \inc stands for incrementing the indentation where \dec decrements it. The \s is used to indicate that at given location a space should be included.
What are some alternatives?
Parboiled2 - A macro-based PEG parser generator for Scala 2.10+
Crate - CrateDB is a distributed and scalable SQL database for storing and analyzing massive amounts of data in near real-time, even with complex queries. It is PostgreSQL-compatible, and based on Lucene.
Scala Parser Combinators - simple combinator-based parsing for Scala. formerly part of the Scala standard library, now a separate community-maintained module
ruby - The Ruby Programming Language
atto - friendly little parsers
aoc - My Advent of Code solutions.
Scopt - command line options parsing for Scala
ctpg - Compile Time Parser Generator is a C++ single header library which takes a language description as a C++ code and turns it into a LR1 table parser with a deterministic finite automaton lexical analyzer, all in compile time.
Kaitai Struct - Kaitai Struct: declarative language to generate binary data parsers in C++ / C# / Go / Java / JavaScript / Lua / Nim / Perl / PHP / Python / Ruby
wefx - Basic WASM graphics package to draw to an HTML Canvas using C. In the style of the gfx library
decline - A composable command-line parser for Scala.
pp - PP - Generic preprocessor (with pandoc in mind) - macros, literate programming, diagrams, scripts...