Author: greg.ercolano
Date: 2012-03-01 06:22:15 -0800 (Thu, 01 Mar 2012)
New Revision: 9260
Log:
Docs + cosmetics only.
> Added docs to utf8_input_filter() function
> Documented its variables
> Added comments to its code so it can be better understood in the future.
Modified:
branches/branch-1.3/src/Fl_Text_Buffer.cxx
Modified: branches/branch-1.3/src/Fl_Text_Buffer.cxx
===================================================================
--- branches/branch-1.3/src/Fl_Text_Buffer.cxx 2012-03-01 13:25:15 UTC (rev
9259)
+++ branches/branch-1.3/src/Fl_Text_Buffer.cxx 2012-03-01 14:22:15 UTC (rev
9260)
@@ -1586,43 +1586,63 @@
/*
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 @@
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;
}
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