uCalc API Version: 2.1.3-preview.2 Released: 6/17/2026

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.

Pattern

Method

Product: 

Transformer Library

Class: 

Transformer

Defines a find-only search pattern that locates text without replacing it, populating the matches collection.

Syntax

Pattern(string)

Parameters

searchPattern
string
The uCalc pattern string that defines the text to find. It can contain literals, variables (e.g., `{name}`), and token category matchers (e.g., `{@Number}`).

Return

Rule

Rule containing the search pattern

Remarks

The Pattern method defines a rule for finding text within a Transformer without replacing it. It is the primary method for pure search-and-analysis operations where the goal is to locate text segments and inspect their properties, rather than modify the source string.

Implicit Replacement with {@Self}

Unlike its counterpart FromTo(), which requires an explicit replacement string, Pattern has an implicit replacement behavior. If a rule defined with Pattern is used in a Transform() operation, it automatically uses the special {@Self} keyword as its replacement. This means the matched text is simply replaced by itself, leaving the source string unchanged but still populating the Matches collection with the results of the find operation.

Pattern() vs. FromTo()

Choosing the right method depends on your goal:

MethodPurposeReplacement BehaviorPrimary Use Case
Pattern(p)Find OnlyImplicitly {@Self}. Re-inserts the matched text.Locating patterns, counting occurrences, and analyzing text without modification.
FromTo(p, r)Find and ReplaceExplicitly defined by the r parameter.Text transformation, data normalization, search-and-replace.

💡 Why uCalc? (Comparative Analysis)

For find-only operations, Pattern offers significant advantages over traditional regular expressions.

  • Token-Awareness: Regex is character-based and struggles with nested structures like func(a, (b+c)). uCalc's Pattern method operates on tokens, so it inherently understands these structures, preventing incorrect matches inside string literals or across mismatched brackets.
  • Concurrent Patterns: To search for multiple distinct patterns with regex, you must combine them into a large, unreadable alternation ((pattern1|pattern2|...)). With uCalc, you define each pattern with a separate, clear Pattern() call, and the engine executes them all concurrently in a single pass.

Examples

Returns Start and End positions of Transformer matches
				
					using uCalcSoftware;

var uc = new uCalc();
var t = uc.NewTransformer();
t.Text = "<br><h1>First</h1>Blah Blah<br>Testing<br><h2>Second</h2>";
//         ^             ^                       ^              ^
//     012345678901234567890123456789012345678901234567890123456789
//     0         10        20        30        40        50
// Carrets (^) point to Start and End locations of the matches

Console.WriteLine(t.Text);
Console.WriteLine("");

t.Pattern("<{tag}>{etc}</{tag}>");
t.Find();
var Matches = t.Matches;

Console.WriteLine(Matches[0].Text);
Console.WriteLine($"Start pos: {Matches[0].StartPosition}");
Console.WriteLine($"End pos: {Matches[0].EndPosition}");
Console.WriteLine($"Length: {Matches[0].Length}");
Console.WriteLine("");

Console.WriteLine(Matches[1].Text);
Console.WriteLine($"Start pos: {Matches[1].StartPosition}");
Console.WriteLine($"End pos: {Matches[1].EndPosition}");
Console.WriteLine($"Length: {Matches[1].Length}");
				
			
<br><h1>First</h1>Blah Blah<br>Testing<br><h2>Second</h2>

<h1>First</h1>
Start pos: 4
End pos: 18
Length: 14

<h2>Second</h2>
Start pos: 42
End pos: 57
Length: 15
				
					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

int main() {
   uCalc uc;
   auto t = uc.NewTransformer();
   t.Text("<br><h1>First</h1>Blah Blah<br>Testing<br><h2>Second</h2>");
   //         ^             ^                       ^              ^
   //     012345678901234567890123456789012345678901234567890123456789
   //     0         10        20        30        40        50
   // Carrets (^) point to Start and End locations of the matches

   cout << t.Text() << endl;
   cout << "" << endl;

   t.Pattern("<{tag}>{etc}</{tag}>");
   t.Find();
   auto Matches = t.Matches();

   cout << Matches[0].Text() << endl;
   cout << "Start pos: " << Matches[0].StartPosition() << endl;
   cout << "End pos: " << Matches[0].EndPosition() << endl;
   cout << "Length: " << Matches[0].Length() << endl;
   cout << "" << endl;

   cout << Matches[1].Text() << endl;
   cout << "Start pos: " << Matches[1].StartPosition() << endl;
   cout << "End pos: " << Matches[1].EndPosition() << endl;
   cout << "Length: " << Matches[1].Length() << endl;
}
				
			
<br><h1>First</h1>Blah Blah<br>Testing<br><h2>Second</h2>

<h1>First</h1>
Start pos: 4
End pos: 18
Length: 14

<h2>Second</h2>
Start pos: 42
End pos: 57
Length: 15
				
					Imports System
Imports uCalcSoftware
Public Module Program
   Public Sub Main()
      Dim uc As New uCalc()
      Dim t = uc.NewTransformer()
      t.Text = "<br><h1>First</h1>Blah Blah<br>Testing<br><h2>Second</h2>"
      '//         ^             ^                       ^              ^
      '//     012345678901234567890123456789012345678901234567890123456789
      '//     0         10        20        30        40        50
      '// Carrets (^) point to Start and End locations of the matches
      
      Console.WriteLine(t.Text)
      Console.WriteLine("")
      
      t.Pattern("<{tag}>{etc}</{tag}>")
      t.Find()
      Dim Matches = t.Matches
      
      Console.WriteLine(Matches(0).Text)
      Console.WriteLine($"Start pos: {Matches(0).StartPosition}")
      Console.WriteLine($"End pos: {Matches(0).EndPosition}")
      Console.WriteLine($"Length: {Matches(0).Length}")
      Console.WriteLine("")
      
      Console.WriteLine(Matches(1).Text)
      Console.WriteLine($"Start pos: {Matches(1).StartPosition}")
      Console.WriteLine($"End pos: {Matches(1).EndPosition}")
      Console.WriteLine($"Length: {Matches(1).Length}")
   End Sub
End Module
				
			
<br><h1>First</h1>Blah Blah<br>Testing<br><h2>Second</h2>

<h1>First</h1>
Start pos: 4
End pos: 18
Length: 14

<h2>Second</h2>
Start pos: 42
End pos: 57
Length: 15
Matches
				
					using uCalcSoftware;

var uc = new uCalc();
var t = uc.NewTransformer();
t.Text = "<h3>Title</h3><b>Bold statement</b><!--<h3>Title B</h3>--><b>Other text</b><p>My paragraph</p>";
//     0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456
//     0         10        20        30        40        50        60        70        80        90
//     ^             ^                                           ^                ^                  ^
// Carrets (^) represent starting and ending point of the matches

t.Pattern("<{tag}>{text}</{tag}>");
t.Pattern("<b>{text}</b>");
t.Pattern("<h3>{text}</h3>");
t.SkipOver("<!--{text}-->");
t.Find();

foreach(var match in t.Matches) {
   Console.WriteLine(match.Text);
   Console.WriteLine($"Start pos: {match.StartPosition}");
   Console.WriteLine($"End pos: {match.EndPosition}");
   Console.WriteLine($"Length: {match.Length}");
   Console.WriteLine("");
}
				
			
<h3>Title</h3>
Start pos: 0
End pos: 14
Length: 14

<b>Bold statement</b>
Start pos: 14
End pos: 35
Length: 21

<b>Other text</b>
Start pos: 58
End pos: 75
Length: 17

<p>My paragraph</p>
Start pos: 75
End pos: 94
Length: 19
				
					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

int main() {
   uCalc uc;
   auto t = uc.NewTransformer();
   t.Text("<h3>Title</h3><b>Bold statement</b><!--<h3>Title B</h3>--><b>Other text</b><p>My paragraph</p>");
   //     0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456
   //     0         10        20        30        40        50        60        70        80        90
   //     ^             ^                                           ^                ^                  ^
   // Carrets (^) represent starting and ending point of the matches

   t.Pattern("<{tag}>{text}</{tag}>");
   t.Pattern("<b>{text}</b>");
   t.Pattern("<h3>{text}</h3>");
   t.SkipOver("<!--{text}-->");
   t.Find();

   for(auto match : t.Matches()) {
      cout << match.Text() << endl;
      cout << "Start pos: " << match.StartPosition() << endl;
      cout << "End pos: " << match.EndPosition() << endl;
      cout << "Length: " << match.Length() << endl;
      cout << "" << endl;
   }
}
				
			
<h3>Title</h3>
Start pos: 0
End pos: 14
Length: 14

<b>Bold statement</b>
Start pos: 14
End pos: 35
Length: 21

<b>Other text</b>
Start pos: 58
End pos: 75
Length: 17

<p>My paragraph</p>
Start pos: 75
End pos: 94
Length: 19
				
					Imports System
Imports uCalcSoftware
Public Module Program
   Public Sub Main()
      Dim uc As New uCalc()
      Dim t = uc.NewTransformer()
      t.Text = "<h3>Title</h3><b>Bold statement</b><!--<h3>Title B</h3>--><b>Other text</b><p>My paragraph</p>"
      '//     0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456
      '//     0         10        20        30        40        50        60        70        80        90
      '//     ^             ^                                           ^                ^                  ^
      '// Carrets (^) represent starting and ending point of the matches
      
      t.Pattern("<{tag}>{text}</{tag}>")
      t.Pattern("<b>{text}</b>")
      t.Pattern("<h3>{text}</h3>")
      t.SkipOver("<!--{text}-->")
      t.Find()
      
      For Each match In t.Matches
         Console.WriteLine(match.Text)
         Console.WriteLine($"Start pos: {match.StartPosition}")
         Console.WriteLine($"End pos: {match.EndPosition}")
         Console.WriteLine($"Length: {match.Length}")
         Console.WriteLine("")
      Next
   End Sub
End Module
				
			
<h3>Title</h3>
Start pos: 0
End pos: 14
Length: 14

<b>Bold statement</b>
Start pos: 14
End pos: 35
Length: 21

<b>Other text</b>
Start pos: 58
End pos: 75
Length: 17

<p>My paragraph</p>
Start pos: 75
End pos: 94
Length: 19
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