Regular Expressions in Modelica

model RegularExpressions
  import Modelica.Utilities.Strings;
  import Modelica.Utilities.System;

  function main
    input String[] args;
  algorithm
    // Modelica doesn't have built-in support for regular expressions
    // We'll simulate some regex operations using string functions

    // This tests whether a pattern matches a string
    System.print(String(Strings.find("peach", "p.*ch") > 0));

    // Find the first match for the pattern
    System.print(Strings.substring("peach punch", Strings.find("peach punch", "p.*ch"), Strings.len("peach")));

    // Find the start and end indexes for the match
    System.print("idx: " + String({Strings.find("peach punch", "p.*ch"), Strings.find("peach punch", "p.*ch") + Strings.len("peach") - 1}));

    // Replace subsets of strings with other values
    System.print(Strings.replace("a peach", "peach", "<fruit>"));

    // Transform matched text (to uppercase in this case)
    System.print(Strings.toUpperCase(Strings.substring("a peach", Strings.find("a peach", "peach"), Strings.len("peach"))));
  end main;

equation
  main({});
end RegularExpressions;

This example demonstrates how to perform some basic regular expression-like operations in Modelica. It’s important to note that Modelica doesn’t have built-in support for regular expressions, so we’re using string manipulation functions to simulate similar behavior.

Here’s what each part of the code does:

1. We use Strings.find() to check if a pattern exists in a string, simulating a simple regex match.

2. We use Strings.substring() along with Strings.find() to extract the first match of a pattern.

3. We use Strings.find() to get the start index of a match, and calculate the end index based on the length of the match.

4. We use Strings.replace() to substitute a part of the string with another value.

5. We use Strings.toUpperCase() along with Strings.substring() and Strings.find() to transform matched text to uppercase.

To run this Modelica code, you would typically use a Modelica-compatible simulation environment. The output would depend on the specific environment, but it would print the results of each operation.

Note that this is a basic simulation of regex operations. For more complex pattern matching and text processing, you might need to implement additional functions or use external libraries if available in your Modelica environment.