Hyperbee.Templating 1.0.0

Hyperbee.Templating

A simple templating engine supporting value replacements, code expressions, token nesting, in-line definitions, and if else conditions.

Syntax

The templating engine supports a simple syntax.

Token Values

Token values are either simple substitutions or expression results:

• {{token}}
• {{context => context.token}}
• {{context => context.token.ToUpper()}}

Token Conditions

Token conditions are either simple truthy tokens or expression results:

• {{if token}} _truthy_content_ {{/if}}
• {{if !token}} _falsy_content_ {{/if}}
• {{if token}} _true_content_ {{else}} _false_content_ {{/if}}
• {{if context => context.token == "test"}} _true_content_ {{/if}}
• {{if context => context.token == "test"}} _true_content_ {{else}} _false_content_ {{/if}}

Methods

The templating engine supports two kinds of method evaluations; strongly typed CLR class methods through the Roslyn compiler, and dynamic methods in the form of Func expressions that are runtime bound to the expression argument context.

\\ example of CLR String.ToUpper

var parser = new TemplateParser
{
    Tokens =
    {
        ["name"] = "me"
    }
};

var result = parser.Render( $"hello {{x => x.name.ToUpper()}}." );

\\ example of a Func expression MyUpper

var parser = new TemplateParser
{
    Methods =
    {
        ["MyUpper"] = args => ((string)args[0]).ToUpper()
    },
    Tokens =
    {
        ["name"] = "me"
    }
};

var result = parser.Render( $"hello {{x => x.MyUpper( x.name )}}." );

Token Nesting

Token values can contain tokens.

\\ example of token nesting

var parser = new TemplateParser
{
    Tokens =
    {
        ["fullname"] = "{{first}} {{last}}",
        ["first"] = "Hari",
        ["last"] = "Seldon"
    }
};

var result = parser.Render( $"hello {{fullname}}." );

Inline Token Definitions

You can define tokens, inline, within a template. Inline tokens must be defined before they are referenced.

{{identity:"me"}}
hello {{identity}}.

{{identity:{{x=> "me"}} }}
hello {{identity}}.

TODO

It would be useful to support simple enumerations.

{{each regex}}
    {{@value}} {{@index}}
{{/each}}

{{each x => IEnumeration<string>}}
    {{ x => x().value + x().index }}
{{/each}}