Envuse Parser

Parser to Envuse files.

The standard library

Envuse definitions describe the rules for writing a file that defines a set of configurations for your project, typically in a file named .envuse.

To understand the format, it's necessary to understand some types of tokens:

• Keyword: This is an expression used to describe the name of variables or references. It's a set of characters that start with a letter of the alphabet (a-z or A-Z) or an underscore (_) and can then include numbers (0-9).
• Comment: This is an expression that describes anything. The content inside is ignored by the parsers.
• Other symbols: These will be described later because they will be used to describe the behavior.

How to write my first Envuse file

An envuse file expects two different expressions; the block comment is used to describe the next variable expression and the variable expression is used to describe the variable and type expected for your project.

Variable Expression

This expression is used to describe a variable name and expected type. It starts with a keyword to describe the name of your variable. The code samples below show a sample with a variable.

envuse ABC

The expression can also have a definition of type to transform later. This type describes how it might transform the values at runtime, for example when the values are loaded from the environment of the app.

"I say "might" because it depends on the engine used to run your app, as you can add more transformers."

The type is described just after the variable name and uses a colon symbol. The type is a keyword and is predefined for your app. Below you can see a variable with a type.

envuse ABC: String

Supported types:

• String: A literal value read.
• Number: Number of 32-bit (See more on wiki) ranging from −2,147,483,648 to 2,147,483,647.
• Boolean: Are values that can be true or false.

Nullable values

To define a variable as nullable, indicate it with a question mark (?) at the end of the type. You cannot use this symbol if the variable has a default value.

Nullable values are values that might not transform, as they may be undefined in the environment and not have a default value in the envuse file. Below you can see a nullable variable.

envuse ABC: String?

Default values

Sometimes we want to define a default value for the app if it's not defined in the environment. We can define a default value for any variable by following the variable type, or, if the type isn't defined, after the variable name. Below you can see two samples with default values.

envuse ABC = "FOO" DEF: Number = 3_000

LICENSE MIT

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