Default Processor

The cyan/default processor uses Eta templating with custom delimiters for variable substitution.

Overview

The default processor is the most commonly used processor. It:

Replaces variable placeholders with values
Supports nested variable access
Allows custom delimiters
Handles all text file types

Variable Syntax

Default Delimiters

The default syntax uses var__ prefix and __ suffix:

title="template.md"

var__name__
var__project.version__

Example

Template file:

title="template.md"

# var__name__

Welcome to var__name__!

Author: var__author__
Version: var__version__

With config:

{5-9} title="cyan.yaml"

processor:
  name: cyan/default
  files:
    - '**/*'
  config:
    vars:
      name: 'my-project'
      author: 'John Doe'
      version: '1.0.0'

Generated output:

title="output.md"

# my-project

Welcome to my-project!

Author: John Doe
Version: 1.0.0

Nested Variables

Access nested properties with dot notation:

{5-10} title="cyan.yaml"

processor:
  name: cyan/default
  files:
    - '**/*'
  config:
    vars:
      project:
        name: 'my-project'
        version: '1.0.0'

Template:

title="template.md"

Project: var__project.name__
Version: var__project.version__

Custom Delimiters

Change the delimiters for compatibility with other template syntaxes:

Using Angle Brackets

{5-8} title="cyan.yaml"

processor:
  name: cyan/default
  files:
    - '**/*'
  config:
    vars:
      name: 'my-project'
    parser:
      varSyntax:
        - ['<%', '%>']

Template:

title="template.md"

# <% name %>

Using Mustache Style

{5-8} title="cyan.yaml"

processor:
  name: cyan/default
  files:
    - '**/*'
  config:
    vars:
      name: 'my-project'
    parser:
      varSyntax:
        - ['{{', '}}']

Template:

title="template.md"

# {{ name }}

Using Double Braces

{5-8} title="cyan.yaml"

processor:
  name: cyan/default
  files:
    - '**/*'
  config:
    vars:
      name: 'my-project'
    parser:
      varSyntax:
        - ['${{', '}}']

Template:

title="template.md"

# ${{ name }}

Why var__ Syntax?

The var__name__ syntax is chosen to avoid conflicts:

Syntax	Potential Conflicts
`${name}`	JavaScript template literals
`{{name}}`	Handlebars, Mustache
`<%= name %>`	EJS
`{name}`	JSON, YAML
`var__name__`	Rarely used in any language

The var__ prefix is verbose but ensures templates work correctly even when generating code that uses other template syntaxes.

Eta Features

The default processor is built on Eta, which supports more than simple substitution:

Conditionals

title="template.md"

<% if (typescript) { %>
## TypeScript Configuration

This project uses TypeScript.
<% } %>

Note: This requires changing delimiters to avoid var__.

Loops

title="template.md"

## Features
<% features.forEach(function(feature) { %>
- <%= feature %>
<% }) %>

Advanced Eta features like conditionals and loops require custom delimiters and may need adjustments to work correctly with the default processor's configuration. For complex templating needs, consider creating a custom processor.

Processor Configuration

The default processor supports the following configuration options:

title="cyan.yaml"

processor:
  name: cyan/default
  files:
    - '**/*'
  config:
    # Variables to substitute
    vars:
      name: 'my-project'
      version: '1.0.0'

    # Parser configuration
    parser:
      # Custom tag pairs (default is ['var__', '__'])
      varSyntax:
        - ['var__', '__']

The cyan/default processor is a specific implementation provided as the reference processor. Other registries or organizations may provide their own default processors with different capabilities. Options like autoEscape, autoTrim, and filters are hardcoded in the processor implementation and cannot be configured by template authors.

When to Use Default vs Custom

Use Default When

Standard variable substitution is sufficient
Working with common file formats
No special processing needed

Use Custom When

Need different template engine (Handlebars, Mustache)
Complex code generation required
Special file transformations needed

See Processors vs Plugins for more guidance.

Tutorial: Adding Variables - Variable basics
Processors vs Plugins - When to use each
Use Custom Processor - Using custom processors

Default Processor

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