Abstract Syntax Tree

Abstract Syntax Tree

AST stands for Abstract Syntax Tree.

It is the structured representation of NXL code.

The AST contains concepts such as:

Program
Statement
Expression
LiteralValue

Program

A program contains statements:

Program {
    statements: Vec<Statement>
}

For:

let x = 10
let y = 20

the structure is:

Program
├── VariableDeclaration
└── VariableDeclaration

Statements

Current statement concepts include:

VariableDeclaration
Expression
Block
If
Function
Return

Expressions

Current expression concepts include:

Literal
Identifier
Binary
Unary
Assignment
Call

Example

Source:

let result = a + b * 2

AST:

VariableDeclaration
│
├── name: result
│
└── initializer
       │
       ▼
     Binary(+)
      /         a    Binary(*)
          /               b        2

This tree is what the interpreter eventually walks.