ast

@xml-tools/ast

Utilities for building and traversing an XML Abstract Syntax Tree ([AST][ast]).

There are two things which distinguish this AST from most others ASTs:

1. This AST can represent a partially valid XML, in practice this means virtually all properties on the AST are optional and may have undefined values.
2. This AST contains additional syntactic information to enable additional linting & formatting flows, for example:
   • the original position and value of an attribute's value (including the quotes).
   • The original positions and values of an XMLElement's open/close names.

The input for constructing the AST is a CST which is created by the @xml-tools/parser package.

The AST structure is used as part of the input for the @xml-tools/content-assist APIs.

Installation

With npm:

• npm install @xml-tools/ast

With Yarn

• yarn add @xml-tools/ast

Usage

Please see the TypeScript Definitions for full API details.

A simple usage example:

const { parse } = require("xml-tools/parser");
const { buildAst, accept } = require("xml-tools/ast");

const xmlText = `<note>
                     <to>Bill</to>
                     <from>Tim</from>
                 </note>
`;

const { cst, tokenVector } = parse(xmlText);
const xmlDocAst = buildAst(cst, tokenVector);
console.log(xmlDocAst.rootElement.name); // -> note

// A Visitor allows us to invoke actions on the XML ASTNodes without worrying about
// The XML AST structure / traversal method.
const printVisitor = {
  // Will be invoked once for each Element node in the AST.
  visitXMLElement: function (node) {
    console.log(node.name);
  },

  // An XML AST Visitor may have other methods as well, see the api.d.ts file/
};

// Invoking the Visitor
accept(xmlDocAst, printVisitor); // -> note, Bill, Tim

Support

Please open issues on github.

Contributing

See CONTRIBUTING.md.