Crate libgraphql_parser 

libgraphql-parser provides a lossless, error-tolerant, and highly-optimized GraphQL tokenizer and GraphQL parser. Capable of parsing schema documents, executable documents, and mixed schema + executable documents.

By default, libgraphql-parser targets the September 2025 GraphQL Spec.

Usage

Parse valid documents

use libgraphql_parser::ast;

// Parse any GraphQL document
let parse_result = libgraphql_parser::parse(r#"
  type User { firstName: String, lastName: String }
  type Query { me: User }

  query GetUserFullName {
    me {
      firstName,
      lastName,
    }
  }
"#);

// Count and print the number of top-level definitions parsed out of the
// GraphQL document.
let ast: &ast::Document<'_> = parse_result.ast();
println!("Parsed {} GraphQL definitions.", ast.definitions.len());

Parse documents with errors

// Parse GraphQL documents with errors
let parse_result = libgraphql_parser::parse(r#"
  type User { firstName String }
  type Query { me: User }
"#);

// Access an "error recovered" version of the AST -- best-effort parsing.
let (recovered_ast, parse_errors, _) = parse_result.recovered().unwrap();
// Print nicely-formatted output for all parse errors
eprintln!(
  "Found {} errors while parsing:\n{}",
  parse_errors.len(),
  parse_result.formatted_errors(),
);

println!(
  "Found {} definitions after best-effort parse error recovery.",
  recovered_ast.definitions.len(),
);

This crate provides a unified token-based parser infrastructure with support for multiple token sources (string input, proc-macro input, etc.).

Modules

ast

AST types for representing parsed GraphQL documents.

compat

smallvec

token

This module provides the core token types used by GraphQL lexers and the parser.

Structs

ByteSpan

A compact source span representing a half-open byte range [start, end).

GraphQLErrorNote

An error note providing additional context about an error.

GraphQLParseError

A parse error with location information and contextual notes.

GraphQLParser

A recursive descent parser for GraphQL documents.

GraphQLParserConfig

Configuration for GraphQLParser controlling parser behavior.

GraphQLTokenStream

Streaming lexer that produces GraphQLTokens given some GraphQLTokenSource with a bounded lookahead buffer.

SourceMap

Provides utilities for mapping ByteSpans to SourceSpans, byte offsets to SourcePositions, and extracting content from the original source text.

SourcePosition

Source position information for parsing, with dual column tracking.

SourceSpan

Represents a span of source text from start to end position.

Enums

GraphQLErrorNoteKind

The kind of an error note (determines how the note is rendered).

GraphQLParseErrorKind

Categorizes parse errors for programmatic handling.

GraphQLStringParsingError

Error returned when parsing a GraphQL string value fails.

ParseResult

The result of a parsing operation.

ReservedNameContext

Contexts where certain names are reserved in GraphQL.

ValueParsingError

Errors that occur when parsing literal values.

Functions

parse

Parses a mixed document (both schema and executable definitions) from a string.

parse_executable

Parses an executable document (operations and fragments) from a string.

parse_schema

Parses a schema document from a string.