Implementation of Decoder which supports constructing objects using JavaScript.

The input stream provided to the Decoder is expected to contain a JavaScript object surrounded by '(' and ')'.

({
    name: "My Example",
    description: "This is an example of the format that should be provided to the Decoder"
});

And the class to decode this object to would be;

public class Example {
  private String name;
  private String description;

  public String getDescription() {
    return description;
  }

  public void setDescription(String description) {
    this.description = description;
  }

  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }
}

A function is available for use that will retrieve the value of a specified environment variable during decoding. It is used in the JavaScript by calling the getenv function, passing the name of the variable to retrieve.

({
    name: getenv("MY_STRING"),
    description: getenv("MY_DESCRIPTION")
});

If an environment variable specified is present at runtime, then its value will be used on the decoded object property. If the variable is not present the property will be set to the default value of the property type.

Within the object definition JavaScript operators may be used to control the values set for properties. This can be used to define fallback environment variables and default values.

({
    name: getenv("MY_STRING") || (getenv("GLOBAL_STRING") || "Default") + " Example",
    description: getenv("MY_DESCRIPTION") || "Default description"
});

In the above example;

• If the environment variable MY_STRING is set, the value of the decoded name property on the object will use that value. e.g. MY_STRING=My Name, name is set to "My Name".
• If MY_STRING is not set then the environment variable GLOBAL_STRING will be checked. If it has a value then the name property is set to that value concatenated with " Example". e.g. GLOBAL_STRING=Global, name is set to "Global Example".
• If Neither environment variable is set then the name property is set to "Default Example".