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.

{@String}

Product: 

Class: 

Remarks

Description: A category matcher that identifies any token defined as a string literal, supporting single, double, and triple quotes, as well as interpolated strings.

The {@String} directive is the primary tool for matching text literals in a uCalc::Transformer. It handles the structural complexity of delimiters and escaping automatically.

Supported Formats

  • Quotes: Matches 'Single', "Double", or """Triple""" quoted blocks.
  • Interpolation: Matches $"{expression}" patterns. Note that for pattern matching, the content within the braces { } is captured based on balanced syntax; it does not require the internal identifiers to be defined unless the expression is being evaluated.

Comparison with Specific Matchers

While {@String} captures any string literal, you can use more specific variants if your logic requires it:

  • {@dqs}: Matches only double-quoted strings.
  • {@sqs}: Matches only single-quoted strings.
  • {@String}: Matches any string.

Inverse Matching with !

The universal inversion operator ! can be applied to this category:

  • {@String}: Matches any string literal.
  • {!String}: Matches any token that is not a string (e.g., numbers, identifiers, or operators).

Advanced Capture: Suffix Indexing

When capturing a string with a named variable (e.g., {@String:txt}), the captured value includes the surrounding quotes. uCalc provides a powerful shortcut to access only the inner content:

  • {txt(0)}: Returns the full string with quotes (e.g., "Hello").
  • {txt(1)}: Returns the "inner" content without quotes (e.g., Hello). {txt} defaults to {txt(1)}

This is particularly useful when converting code to data formats (like XML or JSON) where delimiters must be stripped or changed.

  • Why uCalc? Matching strings with regex is notoriously difficult due to escaping and greedy matching. {@String} leverages the lexer's pre-defined knowledge of where a string starts and ends, ensuring perfect accuracy even with nested quotes or escape characters.

Examples

Matching by token type
				
					using uCalcSoftware;

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

t.FromTo("{@String:txt}", "<<InnerQuote={txt}><TxtWithQuotes={txt(0)}>>");
t.FromTo("{@Number:MyNum}", "<NumericValue={MyNum}>");
t.FromTo("{@Bracket:MyBrack}", "<Brack={MyBrack}>");
t.FromTo("{@CloseBracket:CloseBr}", "<CloseBrack={CloseBr}>");
t.FromTo("{@StatementSeparator:Sep}", "<Separator={Sep}>");
t.FromTo("{@Alphanumeric:alpha}", "<Alpha={alpha}>");
t.FromTo("{@Whitespace:ws}", "<whitespace count={@Eval: Length(ws)}>");
t.FromTo("{@Reducible:r}", "<Reducible={r}>");
t.FromTo("{@Newline}", "<New line{@Newline}>");

var s = """
This is   55.2*6 "Hello world";
'Single quote'(parenth)
""";

Console.WriteLine(t.Filter(s).Matches.Text);
				
			
<Alpha=This>
<whitespace count=1>
<Alpha=is>
<whitespace count=3>
<NumericValue=55.2>
<Reducible=*>
<NumericValue=6>
<whitespace count=1>
<<InnerQuote=Hello world><TxtWithQuotes="Hello world">>
<Separator=;>
<New line
>
<<InnerQuote=Single quote><TxtWithQuotes='Single quote'>>
<Brack=(>
<Alpha=parenth>
<CloseBrack=)>
				
					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

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

   t.FromTo("{@String:txt}", "<<InnerQuote={txt}><TxtWithQuotes={txt(0)}>>");
   t.FromTo("{@Number:MyNum}", "<NumericValue={MyNum}>");
   t.FromTo("{@Bracket:MyBrack}", "<Brack={MyBrack}>");
   t.FromTo("{@CloseBracket:CloseBr}", "<CloseBrack={CloseBr}>");
   t.FromTo("{@StatementSeparator:Sep}", "<Separator={Sep}>");
   t.FromTo("{@Alphanumeric:alpha}", "<Alpha={alpha}>");
   t.FromTo("{@Whitespace:ws}", "<whitespace count={@Eval: Length(ws)}>");
   t.FromTo("{@Reducible:r}", "<Reducible={r}>");
   t.FromTo("{@Newline}", "<New line{@Newline}>");

   auto s = R"(This is   55.2*6 "Hello world";
'Single quote'(parenth))";

   cout << t.Filter(s).Matches().Text() << endl;
}
				
			
<Alpha=This>
<whitespace count=1>
<Alpha=is>
<whitespace count=3>
<NumericValue=55.2>
<Reducible=*>
<NumericValue=6>
<whitespace count=1>
<<InnerQuote=Hello world><TxtWithQuotes="Hello world">>
<Separator=;>
<New line
>
<<InnerQuote=Single quote><TxtWithQuotes='Single quote'>>
<Brack=(>
<Alpha=parenth>
<CloseBrack=)>
				
					Imports System
Imports uCalcSoftware
Public Module Program
   Public Sub Main()
      Dim uc As New uCalc()
      Dim t = uc.NewTransformer()
      
      t.FromTo("{@String:txt}", "<<InnerQuote={txt}><TxtWithQuotes={txt(0)}>>")
      t.FromTo("{@Number:MyNum}", "<NumericValue={MyNum}>")
      t.FromTo("{@Bracket:MyBrack}", "<Brack={MyBrack}>")
      t.FromTo("{@CloseBracket:CloseBr}", "<CloseBrack={CloseBr}>")
      t.FromTo("{@StatementSeparator:Sep}", "<Separator={Sep}>")
      t.FromTo("{@Alphanumeric:alpha}", "<Alpha={alpha}>")
      t.FromTo("{@Whitespace:ws}", "<whitespace count={@Eval: Length(ws)}>")
      t.FromTo("{@Reducible:r}", "<Reducible={r}>")
      t.FromTo("{@Newline}", "<New line{@Newline}>")
      
      Dim s = "This is   55.2*6 ""Hello world"";
'Single quote'(parenth)"
      
      Console.WriteLine(t.Filter(s).Matches.Text)
   End Sub
End Module
				
			
<Alpha=This>
<whitespace count=1>
<Alpha=is>
<whitespace count=3>
<NumericValue=55.2>
<Reducible=*>
<NumericValue=6>
<whitespace count=1>
<<InnerQuote=Hello world><TxtWithQuotes="Hello world">>
<Separator=;>
<New line
>
<<InnerQuote=Single quote><TxtWithQuotes='Single quote'>>
<Brack=(>
<Alpha=parenth>
<CloseBrack=)>
Demonstrating the difference between the `(0)` and `(1)` index.
				
					using uCalcSoftware;

var uc = new uCalc();
var t = new uCalc.Transformer();
// Capture the string and show both versions in the replacement
t.FromTo("{@String:txt}", "With: {txt(0)}, Without: {txt(1)}, Default: {txt}");

Console.WriteLine(t.Transform("'uCalc'"));
				
			
With: 'uCalc', Without: uCalc, Default: uCalc
				
					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

int main() {
   uCalc uc;
   uCalc::Transformer t;
   // Capture the string and show both versions in the replacement
   t.FromTo("{@String:txt}", "With: {txt(0)}, Without: {txt(1)}, Default: {txt}");

   cout << t.Transform("'uCalc'") << endl;
}
				
			
With: 'uCalc', Without: uCalc, Default: uCalc
				
					Imports System
Imports uCalcSoftware
Public Module Program
   Public Sub Main()
      Dim uc As New uCalc()
      Dim t As New uCalc.Transformer()
      '// Capture the string and show both versions in the replacement
      t.FromTo("{@String:txt}", "With: {txt(0)}, Without: {txt(1)}, Default: {txt}")
      
      Console.WriteLine(t.Transform("'uCalc'"))
   End Sub
End Module
				
			
With: 'uCalc', Without: uCalc, Default: uCalc
Converting quoted strings into XML-style elements by stripping the original quotes.
				
					using uCalcSoftware;

var uc = new uCalc();
var t = new uCalc.Transformer();
// Use {s(1)} to get just the text inside the quotes
t.FromTo("msg = {@String:s}", "<message>{s(1)}</message>");

string input = """
msg = "Welcome to uCalc!"
""";
Console.WriteLine(t.Transform(input));
				
			
<message>Welcome to uCalc!</message>
				
					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

int main() {
   uCalc uc;
   uCalc::Transformer t;
   // Use {s(1)} to get just the text inside the quotes
   t.FromTo("msg = {@String:s}", "<message>{s(1)}</message>");

   string input = R"(msg = "Welcome to uCalc!")";
   cout << t.Transform(input) << endl;
}
				
			
<message>Welcome to uCalc!</message>
				
					Imports System
Imports uCalcSoftware
Public Module Program
   Public Sub Main()
      Dim uc As New uCalc()
      Dim t As New uCalc.Transformer()
      '// Use {s(1)} to get just the text inside the quotes
      t.FromTo("msg = {@String:s}", "<message>{s(1)}</message>")
      
      Dim input As String = "msg = ""Welcome to uCalc!"""
      Console.WriteLine(t.Transform(input))
   End Sub
End Module
				
			
<message>Welcome to uCalc!</message>
(Real World: Sensitive Data Redaction) Masking the content of all string literals in a log or script, while preserving the non-string code structure.
				
					using uCalcSoftware;

var uc = new uCalc();
var t = new uCalc.Transformer();
// Replace every string literal with a placeholder
t.FromTo("{@String}", """
"[REDACTED]"
""");

string log = """
UserLogin(id: 101, pass: 'secret123', name: "Admin")
""";
Console.WriteLine(t.Transform(log));
				
			
UserLogin(id: 101, pass: "[REDACTED]", name: "[REDACTED]")
				
					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

int main() {
   uCalc uc;
   uCalc::Transformer t;
   // Replace every string literal with a placeholder
   t.FromTo("{@String}", R"("[REDACTED]")");

   string log = R"(UserLogin(id: 101, pass: 'secret123', name: "Admin"))";
   cout << t.Transform(log) << endl;
}
				
			
UserLogin(id: 101, pass: "[REDACTED]", name: "[REDACTED]")
				
					Imports System
Imports uCalcSoftware
Public Module Program
   Public Sub Main()
      Dim uc As New uCalc()
      Dim t As New uCalc.Transformer()
      '// Replace every string literal with a placeholder
      t.FromTo("{@String}", """[REDACTED]""")
      
      Dim log As String = "UserLogin(id: 101, pass: 'secret123', name: ""Admin"")"
      Console.WriteLine(t.Transform(log))
   End Sub
End Module
				
			
UserLogin(id: 101, pass: "[REDACTED]", name: "[REDACTED]")
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