CSC/ECE 517 Fall 2015/oss/M1503/IntegrateXMLParser

Rust

Rust is a general-purpose, compiled programming language developed by Mozilla Research. The syntax of Rust is somewhat similar to C and C++, with blocks of code delimited by curly brackets, and control flow and structure. Rust does not use automatic garbage collection mechanism similar to java. It accomplishes the goals of memory safe without using garbage collection and it supports concurrency and parallelism in building platforms.

Servo

Servo is web browser layout engine developed by Mozilla Research. It was developed in Rust. Servo handles parallel environments such as rendering, layout, image decoding as a separate tasks. Servo provides APIs, JavaScript support. Servo was not developed explicitly to create full web browser but to achieve maximum parallelism.

Project Description

Servo currently lacks a parser for XML documents, which prevents implementation of several APIs. The goal of the project is to integrate xml5ever parser into Servo.

Design

To integrate XML5ever, dependencies need to be added to for XML parsing similar to HTML5ever.A separate interface need to be created and webidl file along with necessary stubs to parse XML. An Adapter Design Pattern was applied to enhance parsing mechanism for XML5 in Servo.

Initial Implementation

To achieve project goal we have done following initial steps.

Complied servo and add xml5ever as a dependency to the script using cargo package manager. To do this we edited Cargo.toml located at components/script by adding xml5ever as a dependency.

Added xml.rs at components/script/parse with parse_xml() as a function. mod.rs also need to be modified in order to declare file.

Added ServoXMLParser interface with necessary stubs in servoxmlparser.rs located at components/script/dom. Also servoxmlparser need to be declared in mod.rs located at components/script/dom

Called parse_xml(); from domparser.rs located at components/script/dom this will help compile.

Challenges

Continuous build success

Sync with servo latest commits

Adding of necessary stubs

Subsequent steps for final project

Modify ScriptTask::load in script_task.rs to recognize the text/xml content type and call parse_xml instead of parse_html as appropriate, while passing the appropriate flag to the Document constructor

Implement a TreeSink for the XML parser that performs appropriate tree modifications for each action (see the implementation in parse/html.rs for an excellent model)

Implement support in xmlhttprequest.rs for XML document responses (see step 7 in https://xhr.spec.whatwg.org/#document-response)

Implement XMLDocument API by following the documentation and implementing the steps laid out in the specification for the load method

External Links

Documentation of servo - http://doc.servo.org/servo/index.html

HTML5ever - https://github.com/servo/html5ever/

XML5ever - https://github.com/Ygg01/xml5ever

Pull request - https://github.com/servo/servo/pull/8278

YouTube - https://youtu.be/i8dONOzYwlc