# Liquid Template Parser [![go badge][go-svg]][go-url] [![Golangci-lint badge][golangci-lint-svg]][golangci-lint-url] [![Go Report Card badge][go-report-card-svg]][go-report-card-url] [![Go Doc][godoc-svg]][godoc-url] [![MIT License][license-svg]][license-url] `liquid` is a pure Go implementation of [Shopify Liquid templates](https://shopify.github.io/liquid). It was developed for use in the [Gojekyll](https://github.com/osteele/gojekyll) port of the Jekyll static site generator. - [Liquid Template Parser](#liquid-template-parser) - [Installation](#installation) - [Usage](#usage) - [Command-Line tool](#command-line-tool) - [Documentation](#documentation) - [Status](#status) - [Drops](#drops) - [Value Types](#value-types) - [References](#references) - [Contributing](#contributing) - [Contributors](#contributors) - [Attribution](#attribution) - [Other Implementations](#other-implementations) - [Go](#go) - [Other Languages](#other-languages) - [License](#license) ## Installation `go get gopkg.in/osteele/liquid.v1` # latest snapshot `go get -u github.com/osteele/liquid` # development version ## Usage ```go engine := liquid.NewEngine() template := `

` bindings := map[string]interface{}{ "page": map[string]string{ "title": "Introduction", }, } out, err := engine.ParseAndRenderString(template, bindings) if err != nil { log.Fatalln(err) } fmt.Println(out) // Output:

Introduction

``` See the [API documentation][godoc-url] for additional examples. ### Command-Line tool `go install gopkg.in/osteele/liquid.v0/cmd/liquid` installs a command-line `liquid` executable. This is intended to make it easier to create test cases for bug reports. ```bash $ liquid --help usage: liquid [FILE] $ echo '{{ "Hello World" | downcase | split: " " | first | append: "!"}}' | liquid hello! ``` ## Documentation ### Status These features of Shopify Liquid aren't implemented: - Warn and lax [error modes](https://github.com/shopify/liquid#error-modes). - Non-strict filters. An undefined filter is currently an error. - Strict variables. An undefined variable is not an error. ### Drops Drops have a different design from the Shopify (Ruby) implementation. A Ruby drop sets `liquid_attributes` to a list of attributes that are exposed to Liquid. A Go drop implements `ToLiquid() interface{}`, that returns a proxy object. Conventionally, the proxy is a `map` or `struct` that defines the exposed properties. See for additional information. ### Value Types `Render` and friends take a `Bindings` parameter. This is a map of `string` to `interface{}`, that associates template variable names with Go values. Any Go value can be used as a variable value. These values have special meaning: - `false` and `nil` - These, and no other values, are recognized as false by `and`, `or`, `{% if %}`, `{% elsif %}`, and `{% case %}`. - Integers - (Only) integers can be used as array indices: `array[1]`; `array[n]`, where `array` has an array value and `n` has an integer value. - (Only) integers can be used as the endpoints of a range: `{% for item in (1..5) %}`, `{% for item in (start..end) %}` where `start` and `end` have integer values. - Integers and floats - Integers and floats are converted to their join type for comparison: `1 == 1.0` evaluates to `true`. Similarly, `int8(1)`, `int16(1)`, `uint8(1)` etc. are all `==`. - [There is currently no special treatment of complex numbers.] - Integers, floats, and strings - Integers, floats, and strings can be used in comparisons `<`, `>`, `<=`, `>=`. Integers and floats can be usefully compared with each other. Strings can be usefully compared with each other, but not with other values. Any other comparison, e.g. `1 < "one"`, `1 > "one"`, is always false. - Arrays (and slices) - An array can be indexed by integer value: `array[1]`; `array[n]` where `n` has an integer value. - Arrays have `first`, `last`, and `size` properties: `array.first == array[0]`, `array[array.size-1] == array.last` (where `array.size > 0`) - Maps - A map can be indexed by a string: `hash["key"]`; `hash[s]` where `s` has a string value - A map can be accessed using property syntax `hash.key` - Maps have a special `size` property, that returns the size of the map. - Drops - A value `value` of a type that implements the `Drop` interface acts as the value `value.ToLiquid()`. There is no guarantee about how many times `ToLiquid` will be called. [This is in contrast to Shopify Liquid, which both uses a different interface for drops, and makes stronger guarantees.] - Structs - A public field of a struct can be accessed by its name: `value.FieldName`, `value["fieldName"]`. - A field tagged e.g. `liquid:”name”` is accessed as `value.name` instead. - If the value of the field is a function that takes no arguments and returns either one or two arguments, accessing it invokes the function, and the value of the property is its first return value. - If the second return value is non-nil, accessing the field panics instead. - A function defined on a struct can be accessed by function name e.g. `value.Func`, `value["Func"]`. - The same rules apply as to accessing a func-valued public field. - Note that despite being array- and map-like, structs do not have a special `value.size` property. - `[]byte` - A value of type `[]byte` is rendered as the corresponding string, and presented as a string to filters that expect one. A `[]byte` is not (currently) equivalent to a `string` for all uses; for example, `a < b`, `a contains b`, `hash[b]` will not behave as expected where `a` or `b` is a `[]byte`. - `MapSlice` - An instance of `yaml.MapSlice` acts as a map. It implements `m.key`, `m[key]`, and `m.size`. ### References - [Shopify.github.io/liquid](https://shopify.github.io/liquid) - [Liquid for Designers](https://github.com/Shopify/liquid/wiki/Liquid-for-Designers) - [Liquid for Programmers](https://github.com/Shopify/liquid/wiki/Liquid-for-Programmers) - [Help.shopify.com](https://help.shopify.com/themes/liquid) goes into more detail, but includes features that aren't present in core Liquid as used by Jekyll. ## Contributing Bug reports, test cases, and code contributions are more than welcome. Please refer to the [contribution guidelines](./CONTRIBUTING.md). ### Contributors Thanks goes to these wonderful people ([emoji key](https://github.com/kentcdodds/all-contributors#emoji-key)):

_{Oliver Steele}
💻 📖 🤔 🚇 👀 ⚠️

_{James Littlejohn}
💻 📖 ⚠️

_nsf
💻 ⚠️

_{Tobias Salzmann}
💻

_{Ben Doerr}
💻

This project follows the [all-contributors](https://github.com/kentcdodds/all-contributors) specification. Contributions of any kind welcome! ### Attribution | Package | Author | Description | License | |-----------------------------------------------------|-----------------|----------------------|--------------------| | [Ragel](http://www.colm.net/open-source/ragel/) | Adrian Thurston | scanning expressions | MIT | | [gopkg.in/yaml.v2](https://github.com/go-yaml/yaml) | Canonical | MapSlice | Apache License 2.0 | Michael Hamrah's [Lexing with Ragel and Parsing with Yacc using Go](https://medium.com/@mhamrah/lexing-with-ragel-and-parsing-with-yacc-using-go-81e50475f88f) was essential to understanding `go yacc`. The [original Liquid engine](https://shopify.github.io/liquid), of course, for the design and documentation of the Liquid template language. Many of the tag and filter test cases are taken directly from the Liquid documentation. ## Other Implementations ### Go - [karlseguin/liquid](https://github.com/karlseguin/liquid) is a dormant implementation that inspired a lot of forks. - [acstech/liquid](https://github.com/acstech/liquid) is a more active fork of Karl Seguin's implementation. - [hownowstephen/go-liquid](https://github.com/hownowstephen/go-liquid) ### Other Languages See Shopify's [ports of Liquid to other environments](https://github.com/Shopify/liquid/wiki/Ports-of-Liquid-to-other-environments). ## License MIT License [coveralls-url]: https://coveralls.io/r/osteele/liquid?branch=master [coveralls-svg]: https://img.shields.io/coveralls/osteele/liquid.svg?branch=master [go-url]: https://github.com/osteele/liquid/actions?query=workflow%3A%22Build+Status%22 [go-svg]: https://github.com/osteele/liquid/actions/workflows/go.yml/badge.svg [golangci-lint-url]: https://github.com/osteele/liquid/actions?query=workflow%3Agolangci-lint [golangci-lint-svg]: https://github.com/osteele/liquid/actions/workflows/golangci-lint.yml/badge.svg [godoc-url]: https://godoc.org/github.com/osteele/liquid [godoc-svg]: https://godoc.org/github.com/osteele/liquid?status.svg [license-url]: https://github.com/osteele/liquid/blob/master/LICENSE [license-svg]: https://img.shields.io/badge/license-MIT-blue.svg [go-report-card-url]: https://goreportcard.com/report/github.com/osteele/liquid [go-report-card-svg]: https://goreportcard.com/badge/github.com/osteele/liquid

{{ page.title }}

Introduction