Basic URI Parsing topic

Declaration

Basic URI Parsing

Description

The URIParser unit provides simple functions to parse and construct URIs. The main function is ParseURI which parses a URI string into a TURI record containing all the components.

The following example demonstrates basic URI parsing and reconstruction:

program BasicURIExample;

{$mode objfpc}{$h+}

uses
  URIParser, SysUtils;

procedure ParseAndDisplay(const URIString: string);
var
  URI: TURI;
begin
  WriteLn('Original URI: ', URIString);

  // Parse the URI
  URI := ParseURI(URIString);

  // Display all components
  WriteLn('  Protocol: ', URI.Protocol);
  WriteLn('  Username: ', URI.Username);
  WriteLn('  Password: ', URI.Password);
  WriteLn('  Host: ', URI.Host);
  WriteLn('  Port: ', URI.Port);
  WriteLn('  Path: ', URI.Path);
  WriteLn('  Document: ', URI.Document);
  WriteLn('  Params: ', URI.Params);
  WriteLn('  Bookmark: ', URI.Bookmark);
  WriteLn('  Has Authority: ', URI.HasAuthority);

  // Reconstruct the URI
  WriteLn('  Reconstructed: ', EncodeURI(URI));
  WriteLn;
end;

begin
  // Parse different types of URIs
  ParseAndDisplay('https://user:pass@www.example.com:8080/path/to/page.html?param1=value1&param2=value2#section1');
  ParseAndDisplay('ftp://files.example.org/pub/software/myfile.tar.gz');
  ParseAndDisplay('mailto:user@example.com');
  ParseAndDisplay('file:///home/user/document.txt');
  ParseAndDisplay('/relative/path/file.html');
end.

The following example shows how to work with relative URIs and file paths:

program URIUtilitiesExample;

{$mode objfpc}{$h+}

uses
  URIParser, SysUtils;

var
  BaseURI, RelativeURI, AbsoluteURI: string;
  Filename: string;
  URI: string;

begin
  WriteLn('=== Relative URI Resolution ===');
  BaseURI := 'https://www.example.com/docs/manual/';
  RelativeURI := '../images/logo.png';

  if ResolveRelativeURI(BaseURI, RelativeURI, AbsoluteURI) then
  begin
    WriteLn('Base URI: ', BaseURI);
    WriteLn('Relative URI: ', RelativeURI);
    WriteLn('Absolute URI: ', AbsoluteURI);
  end
  else
    WriteLn('Failed to resolve relative URI');

  WriteLn;
  WriteLn('=== File/URI Conversion ===');

  // Convert filename to URI
  Filename := '/home/user/documents/readme.txt';
  URI := FilenameToURI(Filename);
  WriteLn('Filename: ', Filename);
  WriteLn('File URI: ', URI);

  // Convert URI back to filename
  if URIToFilename(URI, Filename) then
  begin
    WriteLn('Converted back to filename: ', Filename);
  end
  else
    WriteLn('Failed to convert URI to filename');

  WriteLn;
  WriteLn('=== URI Type Checking ===');

  // Check if URIs are absolute
  URI := 'https://www.example.com/page.html';
  WriteLn('URI: ', URI, ' - Is absolute: ', IsAbsoluteURI(URI));

  URI := '/relative/path.html';
  WriteLn('URI: ', URI, ' - Is absolute: ', IsAbsoluteURI(URI));

  URI := 'mailto:test@example.com';
  WriteLn('URI: ', URI, ' - Is absolute: ', IsAbsoluteURI(URI));
end.

The following example demonstrates URI parsing with default values:

program DefaultsURIExample;

{$mode objfpc}{$h+}

uses
  URIParser, SysUtils;

procedure ParseWithDefaults(const URIString: string; const DefaultProtocol: string; DefaultPort: Word);
var
  URI: TURI;
begin
  WriteLn('Parsing: ', URIString);
  WriteLn('Default protocol: ', DefaultProtocol);
  WriteLn('Default port: ', DefaultPort);

  // Parse with default protocol and port
  URI := ParseURI(URIString, DefaultProtocol, DefaultPort);

  WriteLn('Results:');
  WriteLn('  Protocol: ', URI.Protocol);
  WriteLn('  Host: ', URI.Host);
  WriteLn('  Port: ', URI.Port);
  WriteLn('  Path: ', URI.Path);
  WriteLn('  Document: ', URI.Document);
  WriteLn('  Full URI: ', EncodeURI(URI));
  WriteLn;
end;

begin
  // Parse URIs with missing protocol/port using defaults
  ParseWithDefaults('www.example.com/index.html', 'http', 80);
  ParseWithDefaults('ftp.example.org/pub/files/', 'ftp', 21);
  ParseWithDefaults('mail.example.com:993/inbox', 'imaps', 993);

  // Parse complete URIs (defaults are ignored)
  ParseWithDefaults('https://secure.example.com:443/login', 'http', 80);
end.

Key functions in the URIParser unit:

• ParseURI - Parses a URI string into components
• EncodeURI - Reconstructs a URI string from components
• ResolveRelativeURI - Resolves relative URIs against a base URI
• URIToFilename - Converts file URIs to local filenames
• FilenameToURI - Converts local filenames to file URIs
• IsAbsoluteURI - Checks if a URI is absolute (has a protocol)

See also

• ParseURI
• EncodeURI
• TURI
• ResolveRelativeURI