uCalc API Version: 5.7.0-preview.1 Released: 7/30/2026

Warning

uCalc API Preview Release Notice:This preview documentation describes the intended behavior of the API. It is not fully accurate or complete.The current preview build contains incomplete features, unoptimized performance, and is subject to breaking changes.Use of the preview version in your production code is not recommended.

Variables and Anchors

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Remarks

uCalc patterns are constructed using two fundamental building blocks: Anchors and Variables. While effective patterns often combine both to define structure and capture data, a valid pattern may consist of only anchors, only variables, or a mixture of both.

  • Anchors (Literals): Text that must appear in the source string.
    • Example: In the pattern Code: {val}, the text Code: serves as the anchor. A pattern like Error consists solely of an anchor.
    • Tokenization Note: Because uCalc is token-based, a sequence like Code: actually represents two distinct anchors: Code and :. Unless WhitespaceSensitive is explicitly enabled, Code: will match both Code: and Code : equally.
  • Variables (Captures): Named placeholders enclosed in curly braces {...}.
    • Example: In the pattern Code: {val}, the variable {val} captures the dynamic content immediately following the anchors.
    • Pure Variable Patterns: Patterns can be purely dynamic. For instance, {mytoken:1} captures exactly one token of any kind, while {groupA:2}{groupB:3} captures 2 tokens followed by 3 tokens.
    • Stop Condition: An unconstrained variable captures content until:
      1. The Next Anchor defined in the pattern is found.
      2. The End of the String is reached.
      3. A Statement Separator is encountered (e.g., a newline or semicolon).
      • Note: For the default list of statement separators, see the topic Matching by token category -> Introduction.
      • Customizing Separators: If you need newlines to be treated as whitespace rather than separators, you can modify the token definitions. (See the Whitespace topic for details on releasing tokens like _token_newline or redefining them).

Escaping Characters:Because { and } are reserved for variable definitions, if you need to match them as literal anchors, you must enclose them in single quotes.

  • Correct: func '{' {body} '}' (Matches func { ... })
  • Incorrect: func { {body} } (This does not generate a syntax error, but it fails to capture literal braces. Instead, it interprets the inner structure as a variable definition or nested expression, leading to unexpected matching behavior.)

Comparative Analysis: Why uCalc?

  • vs. Regex (Named Groups):
    • Simplicity: In Regex, defining a named capture and an anchor requires complex syntax escaping: Code:\s*(?<val>.*). In uCalc, it is simply Code: {val}.
    • Implicit Boundaries: Regex is greedy by default. uCalc variables are "smart-lazy"—they automatically stop at the next anchor or statement separator without requiring complex look-ahead assertions.
  • vs. String.Split (Native Code):
    • Structure: Using Split(':') relies on array indices (parts[1]). uCalc Variables preserve context and allow you to access data by Name (e.g., referencing {val} in replacements or callbacks) rather than fragile numeric indices.

Examples

Variables and anchors

ID: 193

See: Variables and Anchors 
				
					using uCalcSoftware;

var uc = new uCalc();
var t = uc.NewTransformer();
t.FromTo("is {etc} see", "({@Self})");
Console.WriteLine(t.Transform("This is a test to see how anchors/variables work"));
				
			
This (is a test to see) how anchors/variables work
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					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

int main() {
   uCalc uc;
   auto t = uc.NewTransformer();
   t.FromTo("is {etc} see", "({@Self})");
   cout << t.Transform("This is a test to see how anchors/variables work") << endl;
}
				
			
This (is a test to see) how anchors/variables work
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					Imports System
Imports uCalcSoftware
Public Module Program
   Public Sub Main()
      Dim uc As New uCalc()
      Dim t = uc.NewTransformer()
      t.FromTo("is {etc} see", "({@Self})")
      Console.WriteLine(t.Transform("This is a test to see how anchors/variables work"))
   End Sub
End Module
				
			
This (is a test to see) how anchors/variables work
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More on variables and anchors

ID: 194

See: Replacement, Variables and Anchors 
				
					using uCalcSoftware;

var uc = new uCalc();
var t = uc.NewTransformer();

// Variables are {etc} and {ch}
// Anchors are "This", either "a small" or "an easy", and "Test"

t.FromTo("This {etc} {ch: a small | an easy } Test", "<{etc}> ({ch}) experiment");
Console.WriteLine(t.Transform("This is such an easy test."));
				
			
<is such> (an easy) experiment.
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					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

int main() {
   uCalc uc;
   auto t = uc.NewTransformer();

   // Variables are {etc} and {ch}
   // Anchors are "This", either "a small" or "an easy", and "Test"

   t.FromTo("This {etc} {ch: a small | an easy } Test", "<{etc}> ({ch}) experiment");
   cout << t.Transform("This is such an easy test.") << endl;
}
				
			
<is such> (an easy) experiment.
Explore 600+ other examples
				
					Imports System
Imports uCalcSoftware
Public Module Program
   Public Sub Main()
      Dim uc As New uCalc()
      Dim t = uc.NewTransformer()
      
      '// Variables are {etc} and {ch}
      '// Anchors are "This", either "a small" or "an easy", and "Test"
      
      t.FromTo("This {etc} {ch: a small | an easy } Test", "<{etc}> ({ch}) experiment")
      Console.WriteLine(t.Transform("This is such an easy test."))
   End Sub
End Module
				
			
<is such> (an easy) experiment.
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Using the same pattern variable multiple times in a pattern

ID: 199

See: Syntax Definitions, Replacement, Variables and Anchors 
				
					using uCalcSoftware;

var uc = new uCalc();
var t = uc.NewTransformer();

// When a variable is used multiple times in a pattern,
// such as {tag} in this case, the matching text must be the same

t.FromTo("<{tag}> {words:2} {more} </{tag}>",
"tag={tag}, 2 words={words}, text={more}");

Console.WriteLine(t.Transform("<div>abc xyz more words<b>bold</b></div>").Text);
				
			
tag=div, 2 words=abc xyz, text=more words<b>bold</b>
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					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

int main() {
   uCalc uc;
   auto t = uc.NewTransformer();

   // When a variable is used multiple times in a pattern,
   // such as {tag} in this case, the matching text must be the same

   t.FromTo("<{tag}> {words:2} {more} </{tag}>",
   "tag={tag}, 2 words={words}, text={more}");

   cout << t.Transform("<div>abc xyz more words<b>bold</b></div>").Text() << endl;
}
				
			
tag=div, 2 words=abc xyz, text=more words<b>bold</b>
Explore 600+ other examples
				
					Imports System
Imports uCalcSoftware
Public Module Program
   Public Sub Main()
      Dim uc As New uCalc()
      Dim t = uc.NewTransformer()
      
      '// When a variable is used multiple times in a pattern,
      '// such as {tag} in this case, the matching text must be the same
      
      t.FromTo("<{tag}> {words:2} {more} </{tag}>",
      "tag={tag}, 2 words={words}, text={more}")
      
      Console.WriteLine(t.Transform("<div>abc xyz more words<b>bold</b></div>").Text)
   End Sub
End Module
				
			
tag=div, 2 words=abc xyz, text=more words<b>bold</b>
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Basic Key-Value extraction using a colon as an anchor.

ID: 230

See: Variables and Anchors 
				
					using uCalcSoftware;

var uc = new uCalc();
var t = uc.NewTransformer();
// "ID" and ":" are Anchors. "{id}" is the Variable.
t.FromTo("ID: {id}", "Found ID: {id}");
Console.WriteLine(t.Transform("ID: 12345").Text); 
				
			
Found ID: 12345
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					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

int main() {
   uCalc uc;
   auto t = uc.NewTransformer();
   // "ID" and ":" are Anchors. "{id}" is the Variable.
   t.FromTo("ID: {id}", "Found ID: {id}");
   cout << t.Transform("ID: 12345").Text() << endl;
}
				
			
Found ID: 12345
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					Imports System
Imports uCalcSoftware
Public Module Program
   Public Sub Main()
      Dim uc As New uCalc()
      Dim t = uc.NewTransformer()
      '// "ID" and ":" are Anchors. "{id}" is the Variable.
      t.FromTo("ID: {id}", "Found ID: {id}")
      Console.WriteLine(t.Transform("ID: 12345").Text)
   End Sub
End Module
				
			
Found ID: 12345
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Parsing a standard connection string. Note how the semicolon acts as both an anchor and a natural statement separator.

ID: 231

See: Variables and Anchors 
				
					using uCalcSoftware;

var uc = new uCalc();
var t = uc.NewTransformer();
// Anchors: "Server", "=", ";", "Database"
// Variables: {srv}, {db}
t.FromTo("Server={srv};Database={db};",
"Connecting to database '{db}' on server '{srv}'...");

var connStr = "Server = LocalHost; Database = MyData;";
Console.WriteLine(t.Transform(connStr).Text);
// Note: Spaces around '=' handled automatically by default tokenization.
				
			
Connecting to database 'MyData' on server 'LocalHost'...
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					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

int main() {
   uCalc uc;
   auto t = uc.NewTransformer();
   // Anchors: "Server", "=", ";", "Database"
   // Variables: {srv}, {db}
   t.FromTo("Server={srv};Database={db};",
   "Connecting to database '{db}' on server '{srv}'...");

   auto connStr = "Server = LocalHost; Database = MyData;";
   cout << t.Transform(connStr).Text() << endl;
   // Note: Spaces around '=' handled automatically by default tokenization.
}
				
			
Connecting to database 'MyData' on server 'LocalHost'...
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					Imports System
Imports uCalcSoftware
Public Module Program
   Public Sub Main()
      Dim uc As New uCalc()
      Dim t = uc.NewTransformer()
      '// Anchors: "Server", "=", ";", "Database"
      '// Variables: {srv}, {db}
      t.FromTo("Server={srv};Database={db};",
      "Connecting to database '{db}' on server '{srv}'...")
      
      Dim connStr = "Server = LocalHost; Database = MyData;"
      Console.WriteLine(t.Transform(connStr).Text)
      '// Note: Spaces around '=' handled automatically by default tokenization.
   End Sub
End Module
				
			
Connecting to database 'MyData' on server 'LocalHost'...
Explore 600+ other examples