Changeset: 064ab92cd39d for MonetDB
URL: https://dev.monetdb.org/hg/MonetDB/rev/064ab92cd39d
Modified Files:
common/stream/text_stream.c
Branch: default
Log Message:
More efficient implementation of text_pump_in()
diffs (105 lines):
diff --git a/common/stream/text_stream.c b/common/stream/text_stream.c
--- a/common/stream/text_stream.c
+++ b/common/stream/text_stream.c
@@ -89,42 +89,69 @@ take_byte(inner_state_t *ist)
static pump_result
text_pump_in(inner_state_t *ist, pump_action action)
{
- bool crlf_pending = ist->crlf_pending;
+ assert(ist->dst_win.count > 0);
+ assert(ist->src_win.count > 0 || action == PUMP_FINISH);
- while (ist->src_win.count > 0 && ist->dst_win.count > 0) {
- char c = take_byte(ist);
- switch (c) {
- case '\r':
- if (crlf_pending) {
- // put the previous one, which is
clearly not followed by an \n
- put_byte(ist, '\r');
- }
- crlf_pending = true;
- continue;
- case '\n':
- put_byte(ist, c);
- crlf_pending = false;
- continue;
- default:
- if (crlf_pending) {
- put_byte(ist, '\r');
- crlf_pending = false;
- // if dst_win.count was 1, there is no
room for another put_byte().
- if (ist->dst_win.count > 0) {
- put_byte(ist, c);
- } else {
- // no room anymore for char c,
put it back!
- ist->src_win.start--;
- ist->src_win.count++;
- }
- } else {
- put_byte(ist, c);
- }
- continue;
+ if (ist->crlf_pending) {
+ if (ist->src_win.count > 0) {
+ if (ist->src_win.start[0] != '\n') {
+ // CR not followed by a LF, emit it
+ put_byte(ist, '\r');
+ }
+ } else {
+ assert(action == PUMP_FINISH);
+ // CR followed by end of file, not LF, so emit it
+ put_byte(ist, '\r');
}
+ // in any case, the CR is no longer pending
+ ist->crlf_pending = false;
}
- ist->crlf_pending = crlf_pending;
+ while (1) {
+ size_t span = ist->src_win.count < ist->dst_win.count
+ ? ist->src_win.count
+ : ist->dst_win.count;
+ if (span == 0)
+ break;
+
+ if (ist->src_win.start[0] == '\r') {
+ // Looking at a CR. We'll handle just that, then make
another round of the while loop
+ if (ist->src_win.count == 1) {
+ // Don't know what will follow, move it to the
flag.
+ // Then stop, as all available input has been
consumed
+ take_byte(ist);
+ ist->crlf_pending = true;
+ break;
+ }
+ assert(ist->src_win.count > 1); // We can safely look
ahead
+ if (ist->src_win.start[1] == '\n') {
+ // Drop the CR, move the LF
+ take_byte(ist);
+ put_byte(ist, take_byte(ist));
+ } else {
+ // Move the CR
+ put_byte(ist, take_byte(ist));
+ }
+ // progress has been made, consider the situation anew
+ continue;
+ } else {
+ // The remaining input data does not start with a CR.
+ // Move all non-CR data to the output buffer
+ char *cr = memchr(ist->src_win.start, '\r', span);
+ if (cr != NULL) {
+ span = cr - ist->src_win.start;
+ }
+ assert(span > 0);
+ memcpy(ist->dst_win.start, ist->src_win.start, span);
+ ist->src_win.start += span;
+ ist->src_win.count -= span;
+ ist->dst_win.start += span;
+ ist->dst_win.count -= span;
+ continue;
+ }
+ // Unreachable, all branches above explicitly break or continue
+ assert(0 && "UNREACHABLE");
+ }
if (action == PUMP_FINISH) {
if (ist->src_win.count > 0)
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