Mustachio

Mustachio is a Mustache template engine implementation in Scala. It has been built and tested against the official mustache/spec, supporting all core Mustache features (but not the optional modules).

Features

The library fully supports the core Mustache specification features:

• Interpolation - Basic variable replacement with HTML escaping ({{name}}) and unescaped interpolation ({{{name}}} or {{&name}})
• Sections - Conditional and iterative sections ({{#section}}) with support for:
  • Boolean values
  • Lists/Arrays
  • Objects/Lambdas
  • Nested contexts
• Inverted Sections - Negative conditions ({{^section}})
• Partials - Template inclusion ({{>partial}}) with proper indentation support
• Comments - Comment blocks ({{!comment}}) with standalone comment removal
• Delimiters - Custom delimiter changes ({{=<% %>=}})

Usage

Basic usage example:

import dev.wishingtree.branch.mustachio.{Mustachio, Stache}

// Create context
val context = Stache.obj(
  "name" -> Stache.str("John"),
  "items" -> Stache.Arr(List(
    Stache.obj("item" -> Stache.str("one")),
    Stache.obj("item" -> Stache.str("two"))
  ))
)

// Define template
val template = """
Hello {{name}}!
{{#items}}
- {{item}}
{{/items}}
"""

// Render
val result = Mustachio.render(template, context)

Working with Partials

Partials can be provided as an optional parameter:

val partials = Stache.obj(
  "header" -> Stache.str("{{title}}")
)

Mustachio.render(template, context, Some(partials))

JSON Integration

The library provides convenient JSON integration through the Stache.fromJson method using the Friday JSON library:

import dev.wishingtree.branch.friday.Json

val jsonContext = Json.obj(
  "name" -> Json.str("John"),
  "age" -> Json.num(30)
)

val context = Stache.fromJson(jsonContext)

Specification Compliance

The implementation is tested against the official Mustache specification tests for:

• Interpolation
• Sections
• Inverted Sections
• Comments
• Partials
• Delimiter Changes

Unsupported Features

The following optional Mustache features are not currently supported:

• Dynamic partial names
• Template inheritance
• Lambda functions (advanced)

Implementation Notes

• HTML escaping is performed on all interpolated values by default unless using triple mustaches {{{var}}} or ampersand {{&var}}
• Whitespace handling follows the Mustache spec for standalone tags
• Partial indentation is preserved according to spec
• Numbers are formatted as integers when possible