Alchemistry mod custom.xml8/16/2023 ![]() BitBucket Code Repository - Most of the source code for all the various UESP sites and services is available here.Discord - A Discord server where editors and users can discuss TES/UESP-related things.- The UESP blog where we post a variety of Elder Scrolls and game-related articles.- The UESP forums where we discuss a variety of Elder Scrolls and site-related topics.We add a :skip tag for the opening of the first.While nasty, it's perfectly valid XML that risks the following: We either want one, or many, of each of these things. Usually, everything we ever need from the XML boils down to one of three things: There or if you just typed the path wrong). That just returns nil when it's not happy (leaving you to figure out if the data wasn't Opting to navigate a DOM in Elixir means we don't have a black box XPath implementation While a custom query engine may sound scary, it's an opportunity to improve. Less memory and a latency improvement of the same.įor 2, we can go with SimpleForm for now, but let's look at what we can do about 1. I have seen amazing improvements over xmerl doing just this an order of magnitude That (and I maintain that we can, nay, we can improve on it), we can significantly reduce The xmerl DOM we mentioned before is designed to enable XPath, but if we can live without We are in full control of the created DOM, which means we Great.but haven't we just run slap-bang into all of the DOM problems we mentionedĪbove? Well, almost. You a sense of what it does without getting bogged down in edge cases. This is not how VTD works exactly, but it will give Instead, in a VTD we build up all the information we need to query the original binary. We leave the original XML binary untouched in a VTD approach (unlike a DOM, where we manipulate the original XML binary). To access any given location (in constant time!) and extract values when needed. In Elixir, this could mean storing the start index and length of all the nodes and attrs To tokenize the XML document and store the locations of key bits of information A VTD is aĬompletely different way to think about parsing XML. That's a lot of megabytes! And as the output indicates, we can do much better. xmerl with querying 0.0809 - 12.68x slower + 11.39 s Memory usage statistics: Name Memory usage. Name ips average deviation median 99th %. It is to XML what SQL is to a database - a query language for accessing the data inside it.įor example, here is an XPath query to get the text from the XML snippet below: /Author/text()īenchmarking xmerl with querying. Queries are possible, and an XPath query engine is also built into Erlang. Structure for representing an XML document called xmerl. There are lots of mature tools in this area. Elixir doesn't have Objects, but we can still have a DOM. Thinking about and validating an XML document much easier.ĭOM stands for Document Object Model - but it really means a structured representation of XML in your given language. It's what browsers do with HTML, and it preserves the tree structure that can make ![]() There are three broad approaches we will talk about:īuilding a DOM from XML is probably the most common way to think about XML Three Approaches to XML Parsing with Elixir We'll provide an overview of some possibilities when parsing XML, including actual numbers from We will also specifically talk about XML documents where we know the expected shape of the XML ahead of time. Extracting values from that valid document.Ī valid document is not much use if we can't access the values in our.Verifying a document is valid (i.e., that it is actually XML).We will define parsing in this post as doing two things: You work in those industries, you will likely need to parse it. The entire airline industry and much of finance run on XML - so if Or improve it, or when deciding whether you should use it.Ĭhoice is already made for us. Thinking critically about XML as a format is great if you are in a position to change Let's get going! XML Parsing with Elixir - An IntroductionĪs much as we may want to criticize XML (and there is plenty toĬriticize), we have to put it in its historical context. How can we parse XML quickly and efficiently? What does state-of-the-art XML parsing look like? That brings us to the topic of today's post. So much hasĬhanged in that short time that it's easy to forget just how different the world was when In software, though, 26 years is like a lifetime - and in hardware, it's an eternity. It was first envisioned as a lingua franca (bridging language)įor data to be serialized and read into completely disparate systems (withĭifferent programming languages, operating systems, and even hardware). The XML data format has been around since 1996.
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