encodings/shift_jis_text.rb

tests/_examples/encodings/shift_jis_text.rb in the metorex repository.

# Shift_JIS spells the Japanese scripts with pairs of bytes, and the
# half-width katakana with single bytes of its own. `encode` rewrites the
# bytes rather than re-tagging them, so the text reads back the same.
written = "日本語"
held = written.encode Encoding::SHIFT_JIS
p held.encoding
p held.bytes
p held.length
p held.bytesize
p held.valid_encoding?
p held.encode(Encoding::UTF_8) == written

# The half-width katakana take one byte each.
narrow = "｢ｦ｣".encode Encoding::SHIFT_JIS
p narrow.bytes
p narrow.length
p narrow.valid_encoding?

# A run of bytes read through the encoding it was written in.
raw = [0x93, 0xfa].pack "C*"
p raw.force_encoding("Shift_JIS").encode(Encoding::UTF_8)

# Windows-31J spells the same characters.
p "あ".encode(Encoding::Windows_31J).bytes

# A byte that opens no character leaves the run unreadable.
broken = [0x93].pack "C*"
p broken.force_encoding("Shift_JIS").valid_encoding?

Output:

#<Encoding:Shift_JIS>
[147, 250, 150, 123, 140, 234]
3
6
true
true
[162, 166, 163]
3
true
"日"
[130, 160]
false