Dart Requires Chilkat v11.1.0+

Unicode Escape

Demonstrates options for unicode escaping non-us-ascii chars and emojis. Dart

import 'package:chilkat/chilkat.dart';

void main() {
  final sb = CkStringBuilder();
  try {
    sb.loadFile('qa_data/txt/utf16_emojis_accented_jap.txt', 'utf-16');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  final original = sb.getAsString();

  // The above file contains the following text, which includes some emoji's,
  // Japanese chars, and accented chars.

  // 🧠
  // 🔐
  // ✅
  // ⚠️
  // ❌
  // ✓
  // 中
  // é xyz à
  // abc 私 は ん ghi

  final crypt = CkCrypt2();

  // Charset is not used for unicode escaping.  Set it to "utf-8", but it means nothing.
  final charsetNotUsed = 'utf-8';

  // Indicate the desired format/style of Unicode escaping.
  // Choose JSON-style (JavaScript-style) Unicode escape sequences by using "unicodeescape"
  var encoding = 'unicodeescape';

  var escaped = crypt.encodeString(original, charsetNotUsed, encoding);
  print(escaped);

  // Output:
  // \ud83e\udde0
  // \ud83d\udd10
  // \u2705
  // \u26a0\ufe0f
  // \u274c
  // \u2713
  // \u4e2d
  // \u00e9 xyz \u00e0
  // abc \u79c1 \u306f \u3093 ghi

  // Revert back to the unescaped chars:
  var unescaped = crypt.decodeString(escaped, charsetNotUsed, encoding);
  print(unescaped);

  // -----------------------------------------------------------------------------------------
  // Do the same, but use uppercase letters (A-F) in the hex values.
  encoding = 'unicodeescape-upper';
  escaped = crypt.encodeString(original, charsetNotUsed, encoding);
  print(escaped);

  // Output:
  // \uD83E\uDDE0
  // \uD83D\uDD10
  // \u2705
  // \u26A0\uFE0F
  // \u274C
  // \u2713
  // \u4E2D
  // \u00E9 xyz \u00E0
  // abc \u79C1 \u306F \u3093 ghi

  // Revert back to the unescaped chars:
  unescaped = crypt.decodeString(escaped, charsetNotUsed, encoding);
  print(unescaped);

  // -----------------------------------------------------------------------------------------
  //  ECMAScript (JavaScript) “code point escape” syntax

  encoding = 'unicodeescape-curly';
  escaped = crypt.encodeString(original, charsetNotUsed, encoding);
  print(escaped);

  // Output:
  // \u{d83e}\u{dde0}
  // \u{d83d}\u{dd10}
  // \u{2705}
  // \u{26a0}\u{fe0f}
  // \u{274c}
  // \u{2713}
  // \u{4e2d}
  // \u{00e9} xyz \u{00e0}
  // abc \u{79c1} \u{306f} \u{3093} ghi

  // Revert back to the unescaped chars:
  unescaped = crypt.decodeString(escaped, charsetNotUsed, encoding);
  print(unescaped);

  // -----------------------------------------------------------------------------------------
  // Do the same, but use uppercase letters (A-F) in the hex values.
  encoding = 'unicodeescape-curly-upper';
  escaped = crypt.encodeString(original, charsetNotUsed, encoding);
  print(escaped);

  // Output:
  // \u{D83E}\u{DDE0}
  // \u{D83D}\u{DD10}
  // \u{2705}
  // \u{26A0}\u{FE0F}
  // \u{274C}
  // \u{2713}
  // \u{4E2D}
  // \u{00E9} xyz \u{00E0}
  // abc \u{79C1} \u{306F} \u{3093} ghi

  // Revert back to the unescaped chars:
  unescaped = crypt.decodeString(escaped, charsetNotUsed, encoding);
  print(unescaped);

  // -----------------------------------------------------------------------------------------
  // Unicode code point notation or U+ notation

  encoding = 'unicodeescape-plus';
  escaped = crypt.encodeString(original, charsetNotUsed, encoding);
  print(escaped);

  // Output:
  // u+1f9e0
  // u+1f510
  // u+2705
  // u+26a0u+fe0f
  // u+274c
  // u+2713
  // u+4e2d
  // u+00e9 xyz u+00e0
  // abc u+79c1 u+306f u+3093 ghi

  // Chilkat cannot unescape the Unicode code point notation or U+ notation.
  // For this style, Chilkat only goes in one direction, which is to escape.

  // To emit uppercase hex, specify unicodeescape-plus-upper
  encoding = 'unicodeescape-plus-upper';
  // ...
  // ...

  // -----------------------------------------------------------------------------------------
  // HTML hexadecimal character reference

  encoding = 'unicodeescape-htmlhex';
  escaped = crypt.encodeString(original, charsetNotUsed, encoding);
  print(escaped);

  // Output:
  // 🧠
  // 🔐
  // ✅
  // ⚠️
  // ❌
  // ✓
  // 中
  // é xyz à
  // abc 私 は ん ghi

  // Revert back to the unescaped chars:
  unescaped = crypt.decodeString(escaped, charsetNotUsed, encoding);
  print(unescaped);

  // -----------------------------------------------------------------------------------------
  // HTML decimal character reference

  encoding = 'unicodeescape-htmldec';
  escaped = crypt.encodeString(original, charsetNotUsed, encoding);
  print(escaped);

  // Output:
  // 🧠
  // 🔐
  // ✅
  // ⚠️
  // ❌
  // ✓
  // 中
  // é xyz à
  // abc 私 は ん ghi

  // Revert back to the unescaped chars:
  unescaped = crypt.decodeString(escaped, charsetNotUsed, encoding);
  print(unescaped);

  // -----------------------------------------------------------------------------------------
  // Hex in Angle Brackets

  encoding = 'unicodeescape-angle';
  escaped = crypt.encodeString(original, charsetNotUsed, encoding);
  print(escaped);

  // Output:
  // <1f9e0>
  // <1f510>
  // <2705>
  // <26a0><fe0f>
  // <274c>
  // <2713>
  // <4e2d>
  // <e9> xyz <e0>
  // abc <79c1> <306f> <3093> ghi

  // Chilkat cannot unescape the angle bracket notation.
  // For this style, Chilkat only goes in one direction, which is to escape.
}