A practical, real-world parser that handles multiple key-value pairs and URL-encoded characters using a custom callback.

ID: 1399

See: Project: Building a Custom Query String Parser 
				
					using uCalcSoftware;

var uc = new uCalc();

static void URLDecode(uCalc.Callback cb) {
   // In a real application, this would be a full URL decoding implementation.
   // For this example, we'll just handle spaces (%20) and plus signs (+).
   uCalc.String s = cb.ArgStr(1);
   s.Replace("%20", " ").Replace("+", " ");
   cb.ReturnStr(s.Text);
}


// 1. Define the custom URLDecode function in the uCalc engine
uc.DefineFunction("URLDecode(s As String) As String", URLDecode);

// 2. Create the transformer and configure its tokenizer
using (var t = new uCalc.Transformer(uc)) {
   // Treat '&' as a statement separator to process each pair individually
   t.Tokens.Add("&", TokenType.StatementSep);

   // 3. Define the rule to capture key-value pairs and decode the value
   t.FromTo("{@Alphanumeric:key}={value}", "- {key}: '{@Eval: URLDecode(value)}'");

   // 4. Process a real-world query string
   var queryString = "name=John%20Doe&role=user+admin&id=123";

   // Use Filter() to get a clean, newline-separated list of the results
   Console.WriteLine(t.Transform(queryString).Matches);
}
				
			
- name: 'John Doe'
- role: 'user admin'
- id: '123'
Explore 600+ other examples
				
					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

void ucalc_call URLDecode(uCalcBase::Callback cb) {
   // In a real application, this would be a full URL decoding implementation.
   // For this example, we'll just handle spaces (%20) and plus signs (+).
   uCalc::String s = cb.ArgStr(1);
   s.Replace("%20", " ").Replace("+", " ");
   cb.ReturnStr(s.Text());
}

int main() {
   uCalc uc;
   // 1. Define the custom URLDecode function in the uCalc engine
   uc.DefineFunction("URLDecode(s As String) As String", URLDecode);

   // 2. Create the transformer and configure its tokenizer
   {
      uCalc::Transformer t(uc);
      t.Owned(); // Causes t to be released when it goes out of scope
      // Treat '&' as a statement separator to process each pair individually
      t.Tokens().Add("&", TokenType::StatementSep);

      // 3. Define the rule to capture key-value pairs and decode the value
      t.FromTo("{@Alphanumeric:key}={value}", "- {key}: '{@Eval: URLDecode(value)}'");

      // 4. Process a real-world query string
      auto queryString = "name=John%20Doe&role=user+admin&id=123";

      // Use Filter() to get a clean, newline-separated list of the results
      cout << t.Transform(queryString).Matches() << endl;
   }
}
				
			
- name: 'John Doe'
- role: 'user admin'
- id: '123'
Explore 600+ other examples
				
					Imports System
Imports uCalcSoftware
Public Module Program
   
   Public Sub URLDecode(ByVal cb As uCalc.Callback)
      '// In a real application, this would be a full URL decoding implementation.
      '// For this example, we'll just handle spaces (%20) and plus signs (+).
      Dim s As uCalc.String = cb.ArgStr(1)
      s.Replace("%20", " ").Replace("+", " ")
      cb.ReturnStr(s.Text)
   End Sub
   
   Public Sub Main()
      Dim uc As New uCalc()
      '// 1. Define the custom URLDecode function in the uCalc engine
      uc.DefineFunction("URLDecode(s As String) As String", AddressOf URLDecode)
      
      '// 2. Create the transformer and configure its tokenizer
      Using t As New uCalc.Transformer(uc)
         '// Treat '&' as a statement separator to process each pair individually
         t.Tokens.Add("&", TokenType.StatementSep)
         
         '// 3. Define the rule to capture key-value pairs and decode the value
         t.FromTo("{@Alphanumeric:key}={value}", "- {key}: '{@Eval: URLDecode(value)}'")
         
         '// 4. Process a real-world query string
         Dim queryString = "name=John%20Doe&role=user+admin&id=123"
         
         '// Use Filter() to get a clean, newline-separated list of the results
         Console.WriteLine(t.Transform(queryString).Matches)
      End Using
   End Sub
End Module
				
			
- name: 'John Doe'
- role: 'user admin'
- id: '123'
Explore 600+ other examples