Neutral Web Template System

Neutral is a web application template system, designed to work with any programming language (language-agnostic) via IPC and natively as library/crate in Rust.

(*) Currently, the IPC is not implemented and can be used natively in Rust in any framework.

Safe

Neutral is developed in Rust, one of the most secure programming languages. It does not have access to the application's data; it cannot do so because it is designed this way. It implements security mechanisms like "allow," which prevent arbitrary files from being loaded into templates.

Which is not

It is not a programming language, but a markup language, it does not modify data, only its representation.

It is NOT possible:

• Logical operator: varname == varname
• Mathematical operators: varname + varname
• Assignment operators: varname = 1

Features

It allows you to create templates compatible with any system and any programming language.

• Safe
• Language-agnostic
• Modular
• Parameterizable
• Parse files
• Embed files
• Localization
• Loops: for and each
• Snippets
• Nesting, grouping and wrapping
• Redirections: HTTP y JavaScript
• Exit with error: 403, 404, 503, ...
• Comments

Localization

Neutral provides powerful and easy-to-use translation utilities... define the translation in a JSON:

"locale": {
    "current": "en",
    "trans": {
        "en": {
            "Hello": "Hello",
            "ref:greeting-nts": "Hello"
        },
        "es": {
            "Hello": "Hola",
            "ref:greeting-nts": "Hola"
        },
        "de": {
            "Hello": "Hallo",
            "ref:greeting-nts": "Hallo"
        },
        "fr": {
            "Hello": "Bonjour",
            "ref:greeting-nts": "Bonjour"
        },
        "el": {
            "Hello": "Γεια σας",
            "ref:greeting-nts": "Γεια σας"
        }
    }
}

Now you can use:

{:trans; Hello :}

Actually you can always use "trans" because if there is no translation it returns the text.

Bif layout (Build-in function)

    .-- open bif
    |    .-- bif name
    |    |   .-- name separator
    |    |   |    .-- params
    |    |   |    |    .-- params/code separatos
    |    |   |    |    |    .-- code
    |    |   |    |    |    |   .-- close bif
    |    |   |    |    |    |   |
    v    v   v    v    v    v   v
    -- ----- - ------- -- ----- --
    {:snippet; varname >>  ...  :}
    ------------------------------
            ^  ----------------
            |         ^
            |         |
            |         `-- source
            `-- Build-in function

Bif example:

{:filled; varname >>
    Hello!
:}

Neutral is based on Bifs with block structure, we call the set of nested Bifs of the same level a block:

              .-- {:coalesce;
              |       {:code;
              |           {:code; ... :}
              |           {:code; ... :}
    Block --> |           {:code; ... :}
              |       :}
              |       {:code;
              |           {:code; ... :}
              |       :}
              `-- :}

                  {:coalesce;
              .------ {:code;
              |           {:code; ... :}
    Block --> |           {:code; ... :}
              |           {:code; ... :}
              `------ :}
              .------ {:code;
    Block --> |           {:code; ... :}
              `------ :}
                  :}

Short circuit at block level, if varname is not defined, the following ">>" is not evaluated:

{:defined; varname >>
    {:code;
        {:code;
            ...
        :}
    :}
:}

By design all Bifs can be nested and there can be a Bif anywhere in another Bif except in the name.

Data

The data is defined in a JSON:

"data": {
    "true": true,
    "false": false,
    "hello": "hello",
    "zero": "0",
    "one": "1",
    "spaces": "  ",
    "empty": "",
    "null": null,
    "emptyarr": [],
    "array": {
        "true": true,
        "false": false,
        "hello": "hello",
        "zero": "0",
        "one": "1",
        "spaces": "  ",
        "empty": "",
        "null": null
    }
}

And they are displayed with the bif {:; ... :} (var)

Simple variable:

{:;hello:}

Arrays with the "->" operator

{:;array->hello:}

Snippets

Snippet is a tool that can be used in a similar way to a function, it defines a snippet:

{:snippet; name >>
    Any content here, including other snippet.
:}

From then on you can invoke it like this:

{:snippet; name :}

Template example

{:locale; locale.json :}
{:include; theme-snippets.ntpl :}
<!DOCTYPE html>
<html lang="{:lang;:}">
    <head>
        <title>{:trans; Site title :}</title>
        <meta charset="utf-8">
        <meta name="viewport" content="width=device-width, initial-scale=1">
        {:snippet; current-theme:head :}
        <link rel="stylesheet" href="bootstrap.min.css">
    </head>
    <body class="{:;body-class:}">
        {:snippet; current-theme:body_begin  :}
        {:snippet; current-theme:body-content :}
        {:snippet; current-theme:body-footer  :}
        <script src="jquery.min.js"></script>
    </body>
</html>

Native use (Rust)

You need two things, a template file and a json schema:

let schema = json!({
    "config": {
        "comments": "remove"
    },
    "inherit": {
        "locale": {
            "current": "en",
            "trans": {
                "en": {
                    "Hello nts": "Hello",
                    "ref:greeting-nts": "Hello"
                },
                "es": {
                    "Hello nts": "Hola",
                    "ref:greeting-nts": "Hola"
                },
                "de": {
                    "Hello nts": "Hallo",
                    "ref:greeting-nts": "Hallo"
                },
                "fr": {
                    "Hello nts": "Bonjour",
                    "ref:greeting-nts": "Bonjour"
                },
                "el": {
                    "Hello nts": "Γεια σας",
                    "ref:greeting-nts": "Γεια σας"
                }
            }
        }
    },
    "data": {
        "web-site-name": "MySite",
        "varname": "value",
        "true": true,
        "false": false,
        "hello": "hello",
        "zero": "0",
        "one": "1",
        "spaces": "  ",
        "empty": "",
        "null": null,
        "emptyarr": [],
        "array": {
            "true": true,
            "false": false,
            "hello": "hello",
            "zero": "0",
            "one": "1",
            "spaces": "  ",
            "empty": "",
            "null": null
        }
    }
});

Template file.ntpl:

{:;web-site-name:}

In Rust:

let template = Template::from_file_value("file.ntpl", schema).unwrap();
let content = template.render();

// e.g.: 200
let status_code = template.get_status_code();

// e.g.: OK
let status_text = template.get_status_text();

// empty if no error
let status_param = template.get_status_param();

// act accordingly at this point according to your framework

Rust examples

• actix-web
• axum
• rocket
• examples