Text Templates in Modelica

Our first example demonstrates how to create and use text templates in Modelica. While Modelica doesn’t have a built-in templating system like some other languages, we can create a simple string manipulation function to achieve similar results.

model TextTemplates
  function replace
    input String template;
    input String placeholder;
    input String value;
    output String result;
  algorithm
    result := Modelica.Utilities.Strings.replace(template, placeholder, value);
  end replace;

  function executeTemplate
    input String template;
    input String value;
    output String result;
  algorithm
    result := replace(template, "{{.}}", value);
  end executeTemplate;

equation
  // We can create a new template as a string
  // Templates are static text with placeholders enclosed in {{...}}
  String t1 = "Value is {{.}}";

  // By "executing" the template we generate its text with
  // specific values for its placeholders
  Modelica.Utilities.Streams.print(executeTemplate(t1, "some text"));
  Modelica.Utilities.Streams.print(executeTemplate(t1, String(5)));

  // For structured data, we can create more complex templates
  String t2 = "Name: {{Name}}";

  // Here we use a record to represent structured data
  record Person
    String Name;
  end Person;

  Person jane = Person(Name="Jane Doe");
  Modelica.Utilities.Streams.print(replace(t2, "{{Name}}", jane.Name));

  // Modelica doesn't have built-in maps, so we'll use a record again
  record NameMap
    String Name;
  end NameMap;

  NameMap mickey = NameMap(Name="Mickey Mouse");
  Modelica.Utilities.Streams.print(replace(t2, "{{Name}}", mickey.Name));

  // Conditional execution can be implemented using if-else statements
  // in Modelica functions, but it's not as straightforward as in some
  // other languages with more advanced templating systems

  // For iteration, we can use Modelica arrays
  String[] languages = {"Modelica", "C++", "Python", "Java"};
  String t4 = "Range: ";
  for i in 1:size(languages, 1) loop
    t4 := t4 + languages[i] + " ";
  end for;
  Modelica.Utilities.Streams.print(t4);

end TextTemplates;

In this Modelica example, we’ve created simple functions to mimic the behavior of text templates. The replace function is used to substitute placeholders in the template with actual values. The executeTemplate function is a simplified version that replaces {{.}} with a given value.

We demonstrate how to use these functions with different types of data, including strings, numbers, and structured data (using Modelica records).

Note that Modelica doesn’t have built-in support for advanced templating features like conditional execution within templates or iteration. These would typically be handled using standard Modelica control structures (if-else statements, for loops) outside of the template strings.

The example shows how to work with single values, structured data (similar to structs or maps in other languages), and arrays. While not as flexible as some dedicated templating systems, this approach allows for basic template-like functionality in Modelica.

To run this model, you would typically use a Modelica simulation environment. The output would be similar to the original example, printing the results of each template execution.

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Text Templates in Modelica