uCalc API Version: 2.1.3-preview.2 Released: 6/16/2026

Warning

uCalc API Preview Release Notice:The documentation describes the intended behavior of the API. The current preview build contains incomplete features, unoptimized performance, and is subject to breaking changes.

IsChildRule = [bool]

Property

Product: 

Transformer Library

Class: 

Rule

Determines if a rule belongs to a nested (local) transformer rather than the main (root) transformer.

Remarks

🌳 Understanding Rule Hierarchy

The IsChildRule property is a boolean flag that indicates whether a rule is part of a nested parsing context. It returns true if the rule was defined on a 'local' transformer—one obtained from another rule's LocalTransformer property. This is a key introspection tool for understanding the scope and hierarchy of your transformation logic.

  • Parent Rule (Root): A rule defined directly on a main Transformer object. For these rules, IsChildRule returns false.
  • Child Rule (Local): A rule defined on the Transformer object returned by another rule's @LocalTransformer() property. For these rules, IsChildRule returns true.

This property allows you to distinguish between top-level patterns and sub-patterns that only execute within the scope of a specific parent match. This is crucial for debugging complex, nested parsing logic or for writing generic functions that behave differently based on a rule's scope.

💡 Why uCalc? (Comparative Analysis)

  • vs. Regular Expressions: Standard regex engines have a 'flat' model; there is no concept of a rule hierarchy. Achieving nested parsing requires complex and often fragile recursive patterns or lookarounds. uCalc's LocalTransformer creates a true hierarchical parsing model, and IsChildRule is the built-in tool to inspect this structure. It provides a level of architectural clarity that is absent in traditional regex.

  • vs. Parser Generators (ANTLR, etc.): While parser generators define grammars with clear hierarchical rules (e.g., a statement contains an expression), this hierarchy is static and defined in a grammar file. uCalc's model is entirely dynamic and programmatic. You can build and query these parent-child relationships at runtime, and IsChildRule is the primary way to do so.

Examples

A succinct example demonstrating the basic distinction between a root rule and a child rule.
				
					using uCalcSoftware;

var uc = new uCalc();
var t = new uCalc.Transformer();
var rootRule = t.Pattern("root");
var localTransformer = rootRule.LocalTransformer;
var childRule = localTransformer.Pattern("child");

Console.WriteLine($"Is 'rootRule' a child? {rootRule.IsChildRule}");
Console.WriteLine($"Is 'childRule' a child? {childRule.IsChildRule}");
				
			
Is 'rootRule' a child? False
Is 'childRule' a child? True
				
					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

#define tf(IsTrue) ((IsTrue) ? "True" : "False")

int main() {
   uCalc uc;
   uCalc::Transformer t;
   auto rootRule = t.Pattern("root");
   auto localTransformer = rootRule.LocalTransformer();
   auto childRule = localTransformer.Pattern("child");

   cout << "Is 'rootRule' a child? " << tf(rootRule.IsChildRule()) << endl;
   cout << "Is 'childRule' a child? " << tf(childRule.IsChildRule()) << endl;
}
				
			
Is 'rootRule' a child? False
Is 'childRule' a child? True
				
					Imports System
Imports uCalcSoftware
Public Module Program
   Public Sub Main()
      Dim uc As New uCalc()
      Dim t As New uCalc.Transformer()
      Dim rootRule = t.Pattern("root")
      Dim localTransformer = rootRule.LocalTransformer
      Dim childRule = localTransformer.Pattern("child")
      
      Console.WriteLine($"Is 'rootRule' a child? {rootRule.IsChildRule}")
      Console.WriteLine($"Is 'childRule' a child? {childRule.IsChildRule}")
   End Sub
End Module
				
			
Is 'rootRule' a child? False
Is 'childRule' a child? True
Internal Test: Verifies that any rule not on the root transformer is considered a child, regardless of nesting depth.
				
					using uCalcSoftware;

var uc = new uCalc();
var t = new uCalc.Transformer();
var grandParentRule = t.Pattern("grandparent");

// Create a child
var parentTransformer = grandParentRule.LocalTransformer;
var parentRule = parentTransformer.Pattern("parent");

// Create a grandchild
var childTransformer = parentRule.LocalTransformer;
var childRule = childTransformer.Pattern("child");

Console.WriteLine($"Grandparent is child: {grandParentRule.IsChildRule}");
Console.WriteLine($"Parent is child: {parentRule.IsChildRule}");
Console.WriteLine($"Child (grandchild) is child: {childRule.IsChildRule}");
				
			
Grandparent is child: False
Parent is child: True
Child (grandchild) is child: True
				
					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

#define tf(IsTrue) ((IsTrue) ? "True" : "False")

int main() {
   uCalc uc;
   uCalc::Transformer t;
   auto grandParentRule = t.Pattern("grandparent");

   // Create a child
   auto parentTransformer = grandParentRule.LocalTransformer();
   auto parentRule = parentTransformer.Pattern("parent");

   // Create a grandchild
   auto childTransformer = parentRule.LocalTransformer();
   auto childRule = childTransformer.Pattern("child");

   cout << "Grandparent is child: " << tf(grandParentRule.IsChildRule()) << endl;
   cout << "Parent is child: " << tf(parentRule.IsChildRule()) << endl;
   cout << "Child (grandchild) is child: " << tf(childRule.IsChildRule()) << endl;
}
				
			
Grandparent is child: False
Parent is child: True
Child (grandchild) is child: True
				
					Imports System
Imports uCalcSoftware
Public Module Program
   Public Sub Main()
      Dim uc As New uCalc()
      Dim t As New uCalc.Transformer()
      Dim grandParentRule = t.Pattern("grandparent")
      
      '// Create a child
      Dim parentTransformer = grandParentRule.LocalTransformer
      Dim parentRule = parentTransformer.Pattern("parent")
      
      '// Create a grandchild
      Dim childTransformer = parentRule.LocalTransformer
      Dim childRule = childTransformer.Pattern("child")
      
      Console.WriteLine($"Grandparent is child: {grandParentRule.IsChildRule}")
      Console.WriteLine($"Parent is child: {parentRule.IsChildRule}")
      Console.WriteLine($"Child (grandchild) is child: {childRule.IsChildRule}")
   End Sub
End Module
				
			
Grandparent is child: False
Parent is child: True
Child (grandchild) is child: True
LocalTransformer, HasLocalTransformer, IsChildRule
				
					using uCalcSoftware;

var uc = new uCalc();
// Note the change in section/div/h2
var t = uc.NewTransformer();

var rule = t.Pattern("<section>{body}</section>").SetStatementSensitive(false);
var section = rule.LocalTransformer;
section.FromTo("<h2>{text}</h2>", "<h1>====> {@Eval: UCase(text)} <====</h1>");
section.SkipOver("&{entity};");
var ch = section.FromTo("<p>{text}</p>", "<p>SELECTED: {text}</p>");

Console.WriteLine($"Has a local transformer: {rule.HasLocalTransformer}");
Console.WriteLine($"rule is a child rule: {rule.IsChildRule}");
Console.WriteLine($"ch is a child rule: {ch.IsChildRule}");

var HtmlText =
"""

<div class="article" data-id="1">
  <h2>Article One</h2>
  <p>This is the first article.</p>
</div>

<div class="article" data-id="2">
  <h2>Article Two</h2>
  <p>This is the second article.</p>
</div>

<section>
  <div class="article" data-id="3">
    <h2>Article Three</h2>
    <p>This one is inside a &lt;section&gt;.</p>
  </div>
</section>

<div class="article" data-id="4">
  <h2>Article Four</h2>
  <p>This is the fourth article.</p>
</div>

""";

t.Text = HtmlText;
t.Transform();
Console.WriteLine(t.Text);


				
			
Has a local transformer: True
rule is a child rule: False
ch is a child rule: True

<div class="article" data-id="1">
  <h2>Article One</h2>
  <p>This is the first article.</p>
</div>

<div class="article" data-id="2">
  <h2>Article Two</h2>
  <p>This is the second article.</p>
</div>

<section>
  <div class="article" data-id="3">
    <h1>====> ARTICLE THREE <====</h1>
    <p>SELECTED: This one is inside a &lt;section&gt;.</p>
  </div>
</section>

<div class="article" data-id="4">
  <h2>Article Four</h2>
  <p>This is the fourth article.</p>
</div>
				
					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

#define tf(IsTrue) ((IsTrue) ? "True" : "False")

int main() {
   uCalc uc;
   // Note the change in section/div/h2
   auto t = uc.NewTransformer();

   auto rule = t.Pattern("<section>{body}</section>").SetStatementSensitive(false);
   auto section = rule.LocalTransformer();
   section.FromTo("<h2>{text}</h2>", "<h1>====> {@Eval: UCase(text)} <====</h1>");
   section.SkipOver("&{entity};");
   auto ch = section.FromTo("<p>{text}</p>", "<p>SELECTED: {text}</p>");

   cout << "Has a local transformer: " << tf(rule.HasLocalTransformer()) << endl;
   cout << "rule is a child rule: " << tf(rule.IsChildRule()) << endl;
   cout << "ch is a child rule: " << tf(ch.IsChildRule()) << endl;

   auto HtmlText =
   R"(
<div class="article" data-id="1">
  <h2>Article One</h2>
  <p>This is the first article.</p>
</div>

<div class="article" data-id="2">
  <h2>Article Two</h2>
  <p>This is the second article.</p>
</div>

<section>
  <div class="article" data-id="3">
    <h2>Article Three</h2>
    <p>This one is inside a &lt;section&gt;.</p>
  </div>
</section>

<div class="article" data-id="4">
  <h2>Article Four</h2>
  <p>This is the fourth article.</p>
</div>
)";

   t.Text(HtmlText);
   t.Transform();
   cout << t.Text() << endl;


}
				
			
Has a local transformer: True
rule is a child rule: False
ch is a child rule: True

<div class="article" data-id="1">
  <h2>Article One</h2>
  <p>This is the first article.</p>
</div>

<div class="article" data-id="2">
  <h2>Article Two</h2>
  <p>This is the second article.</p>
</div>

<section>
  <div class="article" data-id="3">
    <h1>====> ARTICLE THREE <====</h1>
    <p>SELECTED: This one is inside a &lt;section&gt;.</p>
  </div>
</section>

<div class="article" data-id="4">
  <h2>Article Four</h2>
  <p>This is the fourth article.</p>
</div>
				
					Imports System
Imports uCalcSoftware
Public Module Program
   Public Sub Main()
      Dim uc As New uCalc()
      '// Note the change in section/div/h2
      Dim t = uc.NewTransformer()
      
      Dim rule = t.Pattern("<section>{body}</section>").SetStatementSensitive(false)
      Dim section = rule.LocalTransformer
      section.FromTo("<h2>{text}</h2>", "<h1>====> {@Eval: UCase(text)} <====</h1>")
      section.SkipOver("&{entity};")
      Dim ch = section.FromTo("<p>{text}</p>", "<p>SELECTED: {text}</p>")
      
      Console.WriteLine($"Has a local transformer: {rule.HasLocalTransformer}")
      Console.WriteLine($"rule is a child rule: {rule.IsChildRule}")
      Console.WriteLine($"ch is a child rule: {ch.IsChildRule}")
      
      Dim HtmlText =
      "
<div class=""article"" data-id=""1"">
  <h2>Article One</h2>
  <p>This is the first article.</p>
</div>

<div class=""article"" data-id=""2"">
  <h2>Article Two</h2>
  <p>This is the second article.</p>
</div>

<section>
  <div class=""article"" data-id=""3"">
    <h2>Article Three</h2>
    <p>This one is inside a &lt;section&gt;.</p>
  </div>
</section>

<div class=""article"" data-id=""4"">
  <h2>Article Four</h2>
  <p>This is the fourth article.</p>
</div>
"
      
      t.Text = HtmlText
      t.Transform()
      Console.WriteLine(t.Text)
      
      
   End Sub
End Module
				
			
Has a local transformer: True
rule is a child rule: False
ch is a child rule: True

<div class="article" data-id="1">
  <h2>Article One</h2>
  <p>This is the first article.</p>
</div>

<div class="article" data-id="2">
  <h2>Article Two</h2>
  <p>This is the second article.</p>
</div>

<section>
  <div class="article" data-id="3">
    <h1>====> ARTICLE THREE <====</h1>
    <p>SELECTED: This one is inside a &lt;section&gt;.</p>
  </div>
</section>

<div class="article" data-id="4">
  <h2>Article Four</h2>
  <p>This is the fourth article.</p>
</div>
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