• Skywalking-07: principle of oal — implementation of interpreter


    OALInterpreter implementation OALThe interpreter is based onAntlr4Yes, let’s first understandAntlr4 Antlr4Basic introduction Antlr4Use cases reference resourcesIntroduction to antlr4In this article, we implemented a simple case:ANTLR case: simple calculatorNext, let’s talk about this case. First, install itANTLR V4 (idea plug-in)Plug in, which will be used later when validating the syntax tree. staypom.xmlMedium configurationantlr4Dependencies and plug-ins for […]

  • NLP Essays (IV)


    NLP technology includes basic technology and Application Technology Since the 1970s, with the rapid development of the Internet, the corpus has become more and more abundant and the hardware has been updated and improved. The trend of natural language processing has changed from rationalism to empiricism, and the method based on statistics has gradually replaced […]

  • Uncover the “underlying logic” of your data processing and explain the calculation of formula engine (I)


    background In the information age, the most obvious thing we can feel is that a large number of intensive data burst, and people accumulate more and more data. These huge and miscellaneous data appear together. Many traditional data recording, querying and summarizing tools can not meet people’s needs. More effectively process these large amounts of […]

  • Easy to understand lexical scope


    What is lexical scope In short, it is the function scope determined at compile time example var value = 1; function bar() { var value = 2; function foo() { console.log(value); } foo(); } bar(); //2 The answer to the above code is 2. Because bar and foo are nested, their lexical scope is already […]

  • Posture of novice reading Nebula graph source code


    Absrtact: in this article, we will quickly learn Nepal graph through data flow to enable users to enter an ngql statement on the clientSHOW SPACESAs an example, how is the nebula graph called and run when using GDB to trace statement input. Launched on the Nepal graph blog: https://nebula-graph.com.cn/p… Reading guide For some small partners […]

  • Design and practice of self-developed SQL parser 30 times faster than open source


    Introduction: as a domain language, SQL was first used in relational database to facilitate the management of structured data; SQL is composed of many different types of languages, including data definition language, data control language and data operation language; Each database product has different declarations and implementations; Users can easily use SQL to operate data. […]

  • IOS startup Optimization — llvm compilation process & clang plug-in development


    1. LLVM 1.1 llvm overview LLVMIs the framework system of architecture compilerC++Written to optimize the performance of programs written in any programming languageCompile time、Link time、Run timeas well asIdle time。 Remain open to developers and compatible with existing scripts. At present, llvm has been adopted by Apple IOS development tool, Xilinx vivado, Facebook, Google and other […]

  • Understanding of JS closure


    Introduction to closure: Closures are functions that can read internal variables of other functions. Only the sub functions inside the function can read local variables. In essence, closure is a bridge between the inside and outside of the function. When a function can remember and access its lexical scope, a closure is generated, even if […]

  • JS series – scope


    1、 Scope A scope is a collection of accessible variables。 In JavaScript, objects and functions are also variables.In JavaScript, the scope is a collection of accessible variables, objects and functions. JavaScript function scope: the scope is modified within the function. Common scopes include: Global scope (window, global) Function scope Block level scope ({}) Lexical scope […]

  • Go inside chrome and learn how the V8 engine works


    As a front-end programmer, the first thing I do at work every day is to turn on the computer and turn it on involuntarilychromeBrowser, or touch the fish for a while or enter the working state immediately. Next, the browser window will accompany you through the day. Normally, it will be seven or eight o’clock, […]

  • [Apache Doris] Apache Doris metadata design and DDL operation source code reading


    Metadata design As shown in the figure above, Doris metadata mainly stores four types of data: User data information. Including database, table schema, fragment information, etc. Various operation information. Such as import job, clone job, schemachange job, etc. User and authority information Cluster and node information Metadata directory Metadata directory through Fe configuration item meta_ […]

  • JQuery source code series (IV) tokens lexical analysis


    WelcomeMy columnView a series of articles. In the compilation principle, lexical analysis is a very key link. The lexical analyzer reads the byte stream, and then divides it according to keywords, identifiers, punctuation, strings and so on to generate words. The matching idea of sizzle selector is very similar to this, which is internally called […]