// virtual void SCI_METHOD Fold(Sci_PositionU startPos, i64 lengthDoc, int initStyle, IDocument *pAccess) = 0;
public static void Fold(IntPtr instance, UIntPtr start_pos, IntPtr length_doc, int init_style, IntPtr p_access)
{
/*
* is called with the exact range that needs folding.
* Previously, lexers were called with a range that started one line
* before the range that needs to be folded as this allowed fixing up
* the last line from the previous folding.
* The new approach allows the lexer to decide whether to backtrack
* or to handle this more efficiently.
*
* Lessons I have learned so far are
* - do not start with a base level of 0 to simplify the arithmetic int calculation
* - scintilla recommends to use 0x400 as a base level
* - when the value becomes smaller than the base value, set the base value
* - create an additional margin in which you set the levels of the respective lines,
* so it is easy to see when something breaks.
*/
int start = (int)start_pos;
int length = (int)length_doc;
IntPtr range_ptr = editor.GetRangePointer(start, length);
string content = Marshal.PtrToStringAnsi(range_ptr, length);
int cur_level = (int)SciMsg.SC_FOLDLEVELBASE;
int cur_line = editor.LineFromPosition(start);
if (cur_line > 0)
{
int prev_level = (int)editor.GetFoldLevel(cur_line - 1);
bool header_flag_set = (prev_level & (int)SciMsg.SC_FOLDLEVELHEADERFLAG) == (int)SciMsg.SC_FOLDLEVELHEADERFLAG;
if (header_flag_set)
{
cur_level = (prev_level & (int)SciMsg.SC_FOLDLEVELNUMBERMASK) + 1;
}
else
{
cur_level = (prev_level & (int)SciMsg.SC_FOLDLEVELNUMBERMASK);
}
}
int next_level = cur_level;
for (int i = 0; i < length; i++)
{
if (!SupportedProperties["fold"])
{
editor.SetFoldLevel(cur_line, (int)SciMsg.SC_FOLDLEVELBASE);
while (i < length)
{
// read rest of the line
if (content[i] == '\n')
{
break;
}
i++;
}
cur_line++;
continue;
}
string tag = "";
if (i + 2 < length)
{
tag = content.Substring(i, 3);
}
if (FoldOpeningTags.Contains(tag))
{
next_level++;
cur_level |= (int)SciMsg.SC_FOLDLEVELHEADERFLAG;
}
else if (FoldClosingTags.Contains(tag))
{
next_level--;
if (SupportedProperties["fold.compact"])
{
cur_level--;
}
cur_level &= (int)SciMsg.SC_FOLDLEVELNUMBERMASK;
}
else
{
cur_level &= (int)SciMsg.SC_FOLDLEVELNUMBERMASK;
}
while (i < length)
{
// read rest of the line
if (content[i] == '\n')
{
break;
}
i++;
}
// set fold level
if (cur_level < (int)SciMsg.SC_FOLDLEVELBASE)
{
cur_level = (int)SciMsg.SC_FOLDLEVELBASE;
}
editor.SetFoldLevel(cur_line, cur_level);
cur_line++;
cur_level = next_level;
}
}