jio.console.JsConsole Maven / Gradle / Ivy

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package jio.console;

import jio.IO;
import jio.Lambda;
import jio.RetryPolicies;
import jsonvalues.JsNothing;
import jsonvalues.JsPath;
import jsonvalues.JsValue;
import jsonvalues.spec.JsParserException;
import jsonvalues.spec.JsSpec;

import java.util.Objects;

import static jio.console.Functions.indent;

/**
 * Represents a lambda that takes a JsPath and returns a JIO effect that executes an interactive program to compose the
 * associated JsValue to that path.
 * 
 * Use the static method {@link #of(JsSpec)} to create JsConsole programs from the spec the value introduced by the use
 * has to conform to.
 *
 * @param  type of the JsValue returned
 * @see JsObjConsole
 * @see JsTupleConsole
 */
public interface JsConsole extends Lambda {


  /**
   * Factory method to create console programs that ask for the user to type in a json value that conforms to the given
   * spec
   *
   * @param spec the spec the value has to conform to
   * @return JsConsole program
   */
  static JsConsole of(final JsSpec spec) {
    Objects.requireNonNull(spec);
    return path -> Programs.PRINT_LINE(String.format("%s%s -> ",
                                                     indent(path),
                                                     path
                                                    )
                                      )
                           .then(__ -> Programs.READ_LINE)
                           .then(s ->
                                 {
                                   try {
                                     if (s.isEmpty()) {
                                       return IO.succeed(JsNothing.NOTHING);
                                     }
                                     return IO.succeed(spec.parse(s));
                                   } catch (JsParserException e) {
                                     return IO.fail(e);
                                   }
                                 }
                                )
                           .peekFailure(exc -> System.out.println(indent(path) + "Error: " + exc.getMessage()))
                           .retry(RetryPolicies.limitRetries(3));
  }
}