hogql-parser 1.3.18

HogQL parser for internal PostHog use

HogQL Parser

ANTLR4-based parser for HogQL and Hog, available as both a Python C++ extension and a WebAssembly module for JavaScript/TypeScript.

Packages

Package	Runtime	Registry
hogql_parser	CPython (native C++ extension)	PyPI
@posthog/hogql-parser	Any JS environment (WebAssembly)	npm

Both packages share the same C++ parser core and ANTLR4 grammar, so they produce identical ASTs.

npm package (@posthog/hogql-parser)

Installation

npm install @posthog/hogql-parser

Usage

import createHogQLParser from '@posthog/hogql-parser'

const parser = await createHogQLParser()

// Parse a HogQL expression
const exprAST = JSON.parse(parser.parseExpr('1 + 2'))

// Parse a SELECT statement
const selectAST = JSON.parse(parser.parseSelect('SELECT event FROM events WHERE timestamp > now()'))

// Parse a Hog program
const programAST = JSON.parse(parser.parseProgram('let x := 42; return x;'))

All parse functions return JSON strings. On failure they return a JSON error object instead of throwing:

const result = JSON.parse(parser.parseExpr('!!!'))
if ('error' in result) {
  console.error(result.type, result.message) // e.g. "SyntaxError ..."
}

API

Method	Description
parseExpr(input, isInternal?)	Parse a HogQL expression
parseSelect(input, isInternal?)	Parse a SELECT statement
parseOrderExpr(input, isInternal?)	Parse an ORDER BY expression
parseProgram(input, isInternal?)	Parse a Hog program
parseFullTemplateString(input, isInternal?)	Parse a template string (f'...')
parseStringLiteralText(input)	Unquote a string literal

Setting isInternal to true omits position information from the AST.

Python package (hogql_parser)

Installation

pip install hogql_parser

The Python package is a native C++ extension and requires a platform with prebuilt wheels (macOS and Linux, x86_64 and arm64).

Local development

pip install ./common/hogql_parser

Building from source

Python

pip install ./common/hogql_parser

WebAssembly

Requires the Emscripten toolchain and Ninja.

cd common/hogql_parser
npm run build

This compiles the parser to WASM and places the output in dist/.