HOLY SHIFT! Linda Zheng Roadmap You are here My Shift - - PowerPoint PPT Presentation

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HOLY SHIFT! Linda Zheng Roadmap You are here My Shift - - PowerPoint PPT Presentation

Sep 21, 2022 336 likes •633 views

HOLY SHIFT! Linda Zheng Roadmap You are here My Shift Introduction Shift AST Experience Overview with Shift What is the Shift Project? Abstract Syntax Tree (AST) Binary Expression Identifier Identifier PLUS a + b a b

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HOLY SHIFT!

Linda Zheng

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Roadmap

Introduction Shift Overview Shift AST My Experience with Shift

You are here

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What is the Shift Project?

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Abstract Syntax Tree (AST)

Binary Expression Identifier PLUS “a” Identifier “b”

a + b

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Shift Parser

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  • ~100 nodes
  • Full support for ES6 features
  • Complies with ECMAScript Standard

The Shift AST

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  • So much JS code…
  • So much math...
  • Uh oh...
  • Replace all “+” with “*”

Example Use Case

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Text Find-and-Replace Problems

// ToDo: replace “+” with “*” // ToDo: replace “*” with “*”

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Text Find-and-Replace Problems

for (i = 0; i < 10; i++) { … } for (i = 0; i < 10; i**) { … }

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Text Find-and-Replace Problems

var pattern = /a+/ var pattern = /a*/

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Solution with Shift AST

Binary Expression Identifier Expression PLUS “a” Identifier Expression “b” MUL

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Next Step: Code Generator

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  • Transformations
  • Analysis

Where Shift AST Shines

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Roadmap (again)

Introduction Shift Overview Shift AST My Experience with Shift

You are here

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Contributions to Shift

  • Generate Shift AST nodes
  • Parser
  • Reducer (single state)
  • Code Generator
  • Fuzzer
  • AST Validator
  • Serializer / Deserializer
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Node Statement

Expression

“orphans”

➢ LiteralNumeric ➢ Array ➢ StaticMember ➢ Binary ➢ LiteralString ➢ This ➢ … ➢ If ➢ ForIn ➢ Break ➢ TryCatchFinally ➢ Return ➢ Block ➢ … ➢ BindingIdentifier ➢ FunctionBody ➢ ClassDeclaration ➢ Super ➢ Script ➢ Module ➢ …

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Function Declaration Function Expression Class Expression Class Declaration Function Expression Super Class Expression Super

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“{“ ObjectBinding “({x, y}=0)” (Orphans Family) ObjectExpression “({x, y})” (Expression Family) Either <Expression, Binding> Has “=” Return Expression Return Binding No “=” Transform Destructuring

ParseObject

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“[“ ArrayBinding “[x, y]=0” (Orphans Family) ArrayExpression “[x, y]” (Expression Family) Either <Expression, Binding> Has “=” Return Expression Return Binding No “=” Transform Destructuring

ParseArray

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Roadmap (final)

Introduction Shift Overview Shift AST My Experience with Shift

You are here!!!

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Check out these Links!

Shift Website http://shift-ast.org/ Shape Github Repo https://github.com/shapesecurity