Struct ASTContext

pub struct ASTContext {
    pub arena: Bump,
}

A context for a GraphQL document which holds an arena allocator.

For the duration of parsing, storing, validating, traversing, and printing an AST its performant and convenient to allocate memory in one chunk for the AST’s operations. This context represents the lifetime of an AST and its derivatives.

An AST Context in other words represents the memory a query and the operations you perform on it take up. This is efficient since once you’re done with the query this entire allocated memory can be dropped all at once. Hence however, it’s inadvisable to reuse the AST Context across multiple incoming GraphQL requests.

Fields

arena: Bump

An arena allocator that holds the memory allocated for the AST Context’s lifetime

Implementations

impl ASTContext

pub fn new() -> Self

Create a new AST context with a preallocated arena.

pub fn alloc<T>(&self, item: T) -> &T

Put the value of item onto the arena and return a reference to it.

pub fn alloc_str(&self, str: &str) -> &str

Allocate an &str slice onto the arena and return a reference to it.

This is useful when the original slice has an undefined lifetime. This is typically unnecessary for static slices (&'static str) whose lifetimes are as long as the running program and don’t need to be allocated dynamically.

pub fn alloc_string(&self, str: String) -> &str

Puts a String onto the arena and returns a reference to it to tie the String’s lifetime to this AST context without reallocating or copying it.

Trait Implementations

impl Default for ASTContext

fn default() -> Self

Returns the “default value” for a type.