Liquid on Truffle

ATTENTION: this is still in development and far from being feature-complete. Pull requests are very welcome though!

A parser and interpreter for the Liquid language implemented as a GraalVM Truffle language.

Its main goal is to be a fast, JVM-based Liquid implementation, based on a hand-rolled lexer and recursive descent parser, which then generates an AST based on the Truffle Framework (from GraalVM).

In order to be as simple as possible, we only aim to be compatible with Shopify Liquid, not other alternatives such as Jekyll.

Functionality supported now:

• Text segments
• {{ variable }}
• Filter pipelines like {{ name | upcase }} or {{ a | append: b }}

To be done:

• Ifs: {% if variable %}...{% endif %} with truthy evaluation per Liquid basics
• Case
• Loops
• Comments
• Variables: assign, capture, increment, decrement
• Ensuring multi-line works correctly
• Reporting parsing / runtime issues with correct line / column numbers
• Annotating AST nodes and related classes with Truffle annotations
• Generating Liquid pre-compiled binaries
• Support for all original Liquid filter functions
• Support for custom filter functions
• Test suite checking full compatibility with Shopify Liquid

Build & Run

cd liquid-truffle
./gradlew run --args='--template "Hello, world!"'

Below does not work (yet!):

cd liquid-truffle
./gradlew run --args='--template "Hello, {{ name | upcase }}!" --vars "{\"name\":\"world\"}"'

Or render a file:

./gradlew run --args='--file sample.liquid --vars "{\"greet\":true,\"name\":\"world\"}"'

Attribution

• Liquid language reference: shopify.github.io/liquid