diff options
| -rw-r--r-- | lexilla/test/TestDocument.cxx | 28 |
1 files changed, 26 insertions, 2 deletions
diff --git a/lexilla/test/TestDocument.cxx b/lexilla/test/TestDocument.cxx index 780265305..7356768c8 100644 --- a/lexilla/test/TestDocument.cxx +++ b/lexilla/test/TestDocument.cxx @@ -52,6 +52,10 @@ namespace { } } + inline constexpr bool UTF8IsTrailByte(unsigned char ch) noexcept { + return (ch >= 0x80) && (ch < 0xc0); + } + } void TestDocument::Set(std::string_view sv) { @@ -187,10 +191,30 @@ Sci_Position SCI_METHOD TestDocument::LineEnd(Sci_Position line) const { } Sci_Position SCI_METHOD TestDocument::GetRelativePosition(Sci_Position positionStart, Sci_Position characterOffset) const { - // TODO: negative characterOffset + Sci_Position pos = positionStart; + if (characterOffset < 0) { + while (characterOffset < 0) { + if (pos <= 0) { + return 0; + } + unsigned char previousByte = text.at(pos - 1); + if (previousByte < 0x80) { + pos--; + characterOffset++; + } else { + while ((pos > 1) && UTF8IsTrailByte(previousByte)) { + pos--; + previousByte = text.at(pos - 1); + } + pos--; + // text[pos] is now a character start + characterOffset++; + } + } + return pos; + } assert(characterOffset >= 0); // TODO: invalid UTF-8 - Sci_Position pos = positionStart; while (characterOffset > 0) { Sci_Position width = 0; GetCharacterAndWidth(pos, &width); |