Lua Requires Chilkat v11.1.0+

Unicode Escape and Unescape Text in StringBuilder

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

local chilkat = require("chilkat")

local sbOriginal = chilkat.StringBuilder.new()
local success = sbOriginal:load_file("qa_data/txt/utf16_emojis_accented_jap.txt", "utf-16")
if not success then
    print(sbOriginal.last_error_text)
    return
end

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

local sb = chilkat.StringBuilder.new()
sb:append_sb(sbOriginal)

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

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

sb:encode(encoding, charsetNotUsed)
print(sb:get_as_string())

-- 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:
sb:decode(encoding, charsetNotUsed)
print(sb:get_as_string())

-- -----------------------------------------------------------------------------------------
-- Do the same, but use uppercase letters (A-F) in the hex values.
encoding = "unicodeescape-upper"
sb:encode(encoding, charsetNotUsed)
print(sb:get_as_string())

-- 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:
sb:decode(encoding, charsetNotUsed)
print(sb:get_as_string())

-- -----------------------------------------------------------------------------------------
--  ECMAScript (JavaScript) �code point escape� syntax

encoding = "unicodeescape-curly"
sb:encode(encoding, charsetNotUsed)
print(sb:get_as_string())

-- 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:
sb:decode(encoding, charsetNotUsed)
print(sb:get_as_string())

-- -----------------------------------------------------------------------------------------
-- Do the same, but use uppercase letters (A-F) in the hex values.
encoding = "unicodeescape-curly-upper"
sb:encode(encoding, charsetNotUsed)
print(sb:get_as_string())

-- 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:
sb:decode(encoding, charsetNotUsed)
print(sb:get_as_string())

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

encoding = "unicodeescape-htmlhex"
sb:encode(encoding, charsetNotUsed)
print(sb:get_as_string())

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

-- Revert back to the unescaped chars:
sb:decode(encoding, charsetNotUsed)
print(sb:get_as_string())

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

encoding = "unicodeescape-htmldec"
sb:encode(encoding, charsetNotUsed)
print(sb:get_as_string())

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

-- Revert back to the unescaped chars:
sb:decode(encoding, charsetNotUsed)
print(sb:get_as_string())

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

encoding = "unicodeescape-plus"
sb:encode(encoding, charsetNotUsed)
print(sb:get_as_string())

-- 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"
-- ...
-- ...

sb:clear()
sb:append_sb(sbOriginal)

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

encoding = "unicodeescape-angle"
sb:encode(encoding, charsetNotUsed)
print(sb:get_as_string())

-- 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.

sb:clear()
sb:append_sb(sbOriginal)