/* (c) https://github.com/MontiCore/monticore */
package de.monticore.regex;

/* Beta-version: This is intended to become a MontiCore stable grammar. */

import de.monticore.types.*;

/**
 * This grammar extends the normal type definitions to 
 * support regular expressions as typing constraints for Strings.
 * 
 * How to use this grammar:
 * For example a variable declared as `R"a*(b|c)" v` can only contain
 * Strings of the defined form. Appropriate context conditions of the
 * embedding language can check assignements, etc. 
 * Because containment in regular expressions is computable, e.g. 
 * when given variable `R"a+c" w` the assignement of `v=w` is always
 * correct, while `w=v` may lead to a runtime error
 * or even force an explicit coercion, such as `w= (R"a+c")v` with 
 * potential for runtime exceptions. This, however, depends on the
 * embedding language. 
 *
 * The regular expressions such forms a lattice of subtypes, with 
 * type `String` as the most common supertype (if this is enforced by the
 * context conditions).
 * 
 * The syntax for the regular expressions within "..." 
 * conforms to the specification at:
 * https://en.wikipedia.org/wiki/Regular_expression#Formal_language_theory
 *
 * This grammar is part of a hierarchy of types, namely 
 * * types.MCBasicTypes.mc4
 */

component grammar RegExType extends RegularExpressions, MCBasicTypes {

  /**
   * RegExType provides a syntax for using regular expression types.
   */
   RegExType implements MCType = RegExLiteral;
}