Struct Hook 

pub struct Hook {
    pub name: String,
    pub return_type: String,
}

Definition of a Parser Hook

After generating the Abstract Syntax Tree (AST), we still need to convert it to the internal objects. This is done by the Parse Tree (PT) and Parser Hooks. The PT uses the body of the rules to prelimilarily convert the AST to a simpler form and the hooks can be used to inject custom validation logic and types to the PT. The goal of the hooks is that the PT will produce the final object ready to be used by the application. Therefore there is no need to do another round of traversing.

The hooks are extern and need to be imported, therefore 3 things need to be defined

• The module name as a string literal
• The function name
• The return type of the function (used to generate appropriate structs higher up in the PT)

The generated import statement depends on the target language:

• Rust: use {module}::{name};
• Python: from {module} import {name}
• TypeScript: import { {name} } from "{module}";

The hooks are implemented as extern functions. The exact implementation depends on the target language. The inputs are:

• The PT node that is being processed
• The context object, which contains semantic information, errors, and optionally a custom context

The hook will wrap the PT node with a custom object returned by the hook

Fields

name: String

Function name

return_type: String

Return type

Trait Implementations

impl Clone for Hook

fn clone(&self) -> Hook

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Hook

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.