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#include "impl.h"
struct bufio·Reader
{
io·Reader r;
Buffer buf;
};
bufio·Reader*
bufio·newreader(io·Reader r)
{
bufio·Reader* br = newbuffer(offsetof(bufio·Reader, buf), 0);
br->r = r;
br->buf.pos = br->buf.end;
return br;
}
error
bufio·freereader(bufio·Reader* r)
{
free(r);
return 0;
}
static int
refill(bufio·Reader* r)
{
if (r->buf.eof) return BUF·err;
int nr = r->r.read(r->r.impl, r->buf.base, r->buf.size);
if (nr <= 0) {
r->buf.eof = 1;
goto end;
}
r->buf.off += nr;
r->buf.pos = r->buf.base;
if (nr < r->buf.size) {
int d = (r->buf.size - nr);
r->buf.eof = 1;
memmove(r->buf.pos + d, r->buf.pos, nr);
memmove(r->buf.pos + d - BUF·ungets, r->buf.b, BUF·ungets);
r->buf.pos += d;
}
end:
return nr;
}
// Read will attempt to read n bytes from the buffer, starting at the offet
// offset. Returns the actual number of bytes read from the stream. Input buf
// can not alias b
int
bufio·read(bufio·Reader* r, byte* buf, int count)
{
if (count == 0 || buf == nil || r->buf.off == BUF·eof) return BUF·err;
int remain = count;
byte* rdr = buf;
int n, nr;
while (remain) {
int bdiff = r->buf.end - r->buf.pos;
n = (bdiff > remain) ? remain : bdiff;
if (!n) {
if (r->buf.eof | (refill(r) <= 0)) break;
}
memmove(rdr, r->buf.pos, n);
rdr += n;
r->buf.pos += n;
remain -= n;
}
return count - remain;
}
int
bufio·readln(bufio·Reader* r, byte* buf, int count, error* err)
{
byte *it, *end, *cnt;
int nb;
Search:
nb = 0;
cnt = r->buf.pos + count;
end = MIN(r->buf.end, cnt);
for (it = r->buf.pos; it != end && *it != EOF; ++it, nb++) {
if (*it == '\n') {
*err = 0;
goto End;
}
}
if (it == r->buf.end) {
memmove(buf, r->buf.pos, nb);
r->buf.pos = r->buf.end;
if (refill(r) <= 0) {
*err = 1;
return nb;
}
Assert(nb < count);
count -= nb;
buf += nb;
goto Search;
}
if (it == cnt) {
Assert(nb == count);
*err = 2;
}
Assert(*it == EOF || *err == 2);
End:
memmove(buf, r->buf.pos, nb);
r->buf.pos = it;
return nb;
}
// advanceBuffer moves the buffer ahead by n without reading.
void
bufio·discard(bufio·Reader* r, int count)
{
if (count > BUF·max)
panicf("can't discard %d bytes", count);
byte stack[BUF·max];
bufio·read(r, stack, count);
}
// ReadByte reads a single byte from the buffered stream.
byte
bufio·get(bufio·Reader* r)
{
getbyte:
if (r->buf.pos < r->buf.end) { return *r->buf.pos++; }
memmove(r->buf.b, r->buf.end - BUF·ungets, BUF·ungets);
if (refill(r) <= 0) { return EOF; }
goto getbyte;
}
error
bufio·unget(bufio·Reader* r)
{
if (r->buf.pos == r->buf.b) { return BUF·err; }
r->buf.pos--;
return 0;
}
byte
bufio·peek(bufio·Reader* r)
{
if (r->buf.pos != r->buf.end) return *r->buf.pos;
byte* old = r->buf.pos;
byte c = bufio·get(r);
if (r->buf.pos != old && (bufio·unget(r) == BUF·err)) {
panicf("buffer failure, can't move backwards");
}
return c;
}
// peekBytes has the same behavior as read, but doesn't advance the buffer.
int
bufio·peekfor(bufio·Reader* r, byte* buf, int count)
{
if (count == 0 || buf == nil) return 0;
int delta = r->buf.end - r->buf.pos;
if (delta > count) {
memcpy(buf, r->buf.pos, count);
return count;
}
byte c, *it;
for (it = buf; it != buf + count; ++it) {
c = bufio·get(r);
*it = c;
if (c == EOF) break;
}
int diff = it - buf;
for (int n = 0; n < diff; n++) {
bufio·unget(r);
}
return diff;
}
void
bufio·clear(bufio·Reader* r)
{
memset(r->buf.b, 0, r->buf.size);
}
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