AST

The Abstract Syntax Tree (AST) is the data structure produced by the Parser. It captures the complete structure of a BrainRot program as a tree of typed nodes. The Interpreter then walks this tree to execute the program.

AST Overview

BrainRot's AST is defined in parser/ast.go and has 20+ node types. Every node implements either the Expression or Statement interface.

ast.go (excerpt)

// Every AST node implements one of two interfaces:

type Expression interface {
    expressionNode()
    TokenLiteral() string
}

type Statement interface {
    statementNode()
    TokenLiteral() string
}

// Example node — VarStatement
type VarStatement struct {
    Token token.Token  // the trust_me_bro token
    Name  *Identifier
    Value Expression
}

Node Types

Node	Type	Description
`Program`	Root	Top-level container
`VarStatement`	Statement	`trust_me_bro x = ...`
`AssignStatement`	Statement	`x = ...` / `x += ...`
`PrintStatement`	Statement	`say_my_name(...)`
`IfStatement`	Statement	if / else-if / else branches
`WhileStatement`	Statement	`on_repeat` loop
`ForStatement`	Statement	`run_it_back` loop
`FuncDecl`	Statement	Function definition
`ReturnStatement`	Statement	`take_this`
`BreakStatement`	Statement	`mission_abort`
`ContinueStatement`	Statement	`skip_this_one`
`IntegerLiteral`	Expression	`42`
`FloatLiteral`	Expression	`3.14`
`StringLiteral`	Expression	`"hello"`
`BooleanLiteral`	Expression	`fr_fr` / `cap`
`NilLiteral`	Expression	`ghosted`
`ArrayLiteral`	Expression	`[1, 2, 3]`
`Identifier`	Expression	Variable reference
`InfixExpression`	Expression	Binary operator
`PrefixExpression`	Expression	Unary `!` / `-`
`CallExpression`	Expression	Function call
`IndexExpression`	Expression	Array index `arr[i]`

Viewing the AST

Use the ast command to print the full tree for any source file:

terminal

# Given this source:
# trust_me_bro x = 42
# say_my_name(x + 1)

# brainrot ast example.brt outputs:
Program
├── VarStatement
│   ├── Name: Identifier("x")
│   └── Value: IntegerLiteral(42)
└── PrintStatement
    └── InfixExpression(+)
        ├── Left: Identifier("x")
        └── Right: IntegerLiteral(1)

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