Installing a binding

Herb is a C library with bindings for Ruby, JavaScript, Java and Rust. Every binding wraps the same parser, so a template parses to the same tree whichever one you use.

Install

Ruby

bundle add herb

JavaScript

npm add @herb-tools/node

Java

git clone https://github.com/marcoroth/herb
cd herb/java
make templates
make jni
make java

Rust

cargo add herb

The Ruby gem and the npm packages ship precompiled. Java builds from source and produces a native library, libherb_jni.dylib on macOS and libherb_jni.so on Linux.

Load

Ruby

require "herb"

Herb.parse("<h1><%= title %></h1>")

JavaScript

import { Herb } from "@herb-tools/node"

await Herb.load()

Herb.parse("<h1><%= title %></h1>")

Java

import org.herb.Herb;
import org.herb.ParseResult;

ParseResult result = Herb.parse("<h1><%= title %></h1>");

Rust

use herb::parse;

let result = parse("<h1><%= title %></h1>").unwrap();

JavaScript is the one binding that has to be loaded before use. Herb.load() resolves once the native extension or the WebAssembly build is ready, and every call after that is synchronous.

Which package

Language	Package	Notes
Ruby	herb	Precompiled native extension
JavaScript, Node.js	@herb-tools/node	Native extension, reads files
JavaScript, browser	@herb-tools/browser	WebAssembly, no file access
Java	built from source	JNI, needs the native library on java.library.path
Rust	herb	FFI to the C library

The browser and Node packages expose the same API, so code that does not touch the filesystem moves between them unchanged. WebAssembly covers the browser build, and the per-language pages cover the rest of each setup, including unreleased commits from npm and the Java classpath.

Next

Parsing is where most work starts. Lexing gives you tokens instead of a tree, Extracting Ruby and HTML pulls one language out of a template, and Working with the tree walks what the parser returned.