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Docs + cosmetics only.

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> Added docs to utf8_input_filter() function
    > Documented its variables
    > Added comments to its code so it can be better understood in the future.



git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@9260 ea41ed52-d2ee-0310-a9c1-e6b18d33e121
This commit is contained in:
Greg Ercolano
2012-03-01 14:22:15 +00:00
parent 4e934c01be
commit 4ce583c0f8
1 changed files with 39 additions and 19 deletions
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src/Fl_Text_Buffer.cxx
+39 -19
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@@ -1586,43 +1586,63 @@ static int general_input_filter(char *buffer, int buflen,
/*
filter that produces, from an input stream fed by reading from fp,
a UTF-8-encoded output stream written in buffer.
Returns #bytes read into 'buffer'.
Input can be UTF-8. If it is not, it is decoded with CP1252.
Output is UTF-8.
*input_was_changed is set to true if the input was not strict UTF-8 so output
*input_was_changed returns true if input was not strict UTF-8, so output
differs from input.
*/
static int utf8_input_filter(char *buffer, int buflen, char *line, int sline, char* &endline,
FILE *fp, int *input_was_changed)
static int utf8_input_filter(char *buffer, // result buffer we fill with utf8 encoded text
int buflen, // max size of buffer from caller
char *line, // file line buffer caller wants us to use
int sline, // max size of line buffer
char* &endline, // keeps track of leftovers in line[] buffer between calls
FILE *fp, // open file we're reading data from
int *input_was_changed) // returned flag: 'true' if buffer[] different from file due to utf8 encoding
{
// p - work pointer to line[]
// q - work pointer to buffer[]
// l - length of utf8 sequence being worked on
// lp - fl_utf8decode() length of utf8 sequence being worked on
// lq - fl_utf8encode() length of utf8 sequence being worked on
// r - bytes read from last fread()
// u - utf8 decoded sequence as a single multibyte unsigned integer
char *p, *q, multibyte[5];
int l, lp, lq, r;
unsigned u;
p = line;
q = buffer;
while (q < buffer + buflen) {
if (p >= endline) {
r = fread(line, 1, sline, fp);
if (p >= endline) { // walked off end of input file's line buffer?
r = fread(line, 1, sline, fp); // read another block of sline bytes from file
endline = line + r;
if (r == 0) return q - buffer;
if (r == 0) return q - buffer; // EOF? return bytes read into buffer[]
p = line;
}
l = fl_utf8len1(*p);
if (p + l > endline) {
memmove(line, p, endline - p);
// Predict length of utf8 sequence
// See if utf8 seq we're working on would extend off end of line buffer,
// and if so, adjust + load more data so that it doesn't.
//
l = fl_utf8len1(*p); // anticipate length of utf8 sequence
if (p + l > endline) { // would walk off end of line buffer?
memmove(line, p, endline - p); // re-jigger line buffer to get some room
endline -= (p - line);
r = fread(endline, 1, sline - (endline - line), fp);
r = fread(endline, 1, sline - (endline - line), fp); // re-fill line buffer
endline += r;
p = line;
if (endline - line < l) break;
if (endline - line < l) break; // sequence *still* extends past end? stop loop
}
while ( l > 0) {
u = fl_utf8decode(p, p+l, &lp);
lq = fl_utf8encode(u, multibyte);
u = fl_utf8decode(p, p+l, &lp); // get single utf8 encoded char as a Unicode value
lq = fl_utf8encode(u, multibyte); // re-encode Unicode value to utf8 in multibyte[]
if (lp != l || lq != l) *input_was_changed = true;
if (q + lq > buffer + buflen) {
memmove(line, p, endline - p);
endline -= (p - line);
return q - buffer;
if (q + lq > buffer + buflen) { // encoding would walk off end of buffer[]?
memmove(line, p, endline - p); // re-jigger line[] buffer for next call
endline -= (p - line); // adjust end of line[] buffer for next call
return q - buffer; // return what's decoded so far, caller will enlarge buffer
}
memcpy(q, multibyte, lq);
q += lq;
@@ -1672,13 +1692,13 @@ const char *Fl_Text_Buffer::file_encoding_warning_message =
buffer[l] = 0;
insert(pos, buffer);
pos += l;
}
}
int e = ferror(fp) ? 2 : 0;
fclose(fp);
delete[]buffer;
if ( (!e) && input_file_was_transcoded && transcoding_warning_action) {
transcoding_warning_action(this);
}
}
return e;
}