Edge Parser

This repo is the parser to convert edge templates to a self invoked Javascript function. Later you can invoke this function by providing a context.

Example:

Input

Hello {{ username }}

Output

(function (template, ctx) {
  let out = ''
  out += 'Hello '
  out += `${ctx.escape(ctx.resolve('username'))}`
  return out
})(ctx)

Notice of use of ctx in the function body. Parser doesn't provide the implementation of ctx, the runtime of template engine should provide it.

Supported Expressions

The following expressions are supported by the parser.

Identifier

The identifier is wrapped inside ctx.resolve. The resolve method job is to resolve the value.

In following statement username is the identifier

Hello {{ username }}

Literal

A string literal

Hello {{ 'Guest' }}

ArrayExpression

The [1, 2, 3, 4] is an array expression.

Evens are {{
  [1, 2, 3, 4].filter((num) => num % 2 === 0)
}}

ObjectExpression

The { username: 'virk' } is an Object expression

{{ toJSON({ username: 'virk' })  }}

UnaryExpression

Following are examples of UnaryExpression.

{{ typeof(username) }}

{{ !!username }}

BinaryExpression

Here {{ 2 + 2 }} is the binary expression

{{ 2 + 2 }} = 4

LogicalExpression

Following is the example of LogicalExpression.

{{ username || admin.username }}

MemberExpression

{{ username.toUpperCase() }}

ConditionalExpression

{{ username ? username : 'Guest' }}

CallExpression

{{ upper(username) }}

SequenceExpression

Sequence is not supported in mustache blocks and instead used inside tags. For example:

Everything inside () is a sequence expression.

@component('button', text = 'Submit', type = 'Primary')

TemplateLiteral

{{ Hello `${username}` }}

ArrowFunctionExpression

{{
  users.map((user) => {
    return user.username
  })
}}

Context expectations

Context must have following methods to work with the core parser.

class Context {
  // Resolve value for a key
  resolve(key: string): any

  // make input HTML safe
  escape (input: string): string
}

Change log

The change log can be found in the CHANGELOG.md file.

Contributing

Everyone is welcome to contribute. Please go through the following guides, before getting started.

1. Contributing
2. Code of conduct

Authors & License

thetutlage and contributors.

MIT License, see the included MIT file.