57 lines
1.6 KiB
C
57 lines
1.6 KiB
C
/* Custom string builder, should be slightly faster than using Sv* macros directly. */
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typedef struct {
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SV *sv;
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char *cur;
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char *end;
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} fustr;
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static void fustr_init_(pTHX_ fustr *s, size_t prealloc) {
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s->sv = sv_2mortal(newSV(prealloc));
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SvPOK_only(s->sv);
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s->cur = SvPVX(s->sv);
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s->end = SvEND(s->sv);
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}
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static void fustr_grow(pTHX_ fustr *s, size_t add) {
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size_t off = s->cur - SvPVX(s->sv);
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size_t newlen = 64;
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add += off;
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/* Increment to next power of two; SvGROW's default strategy is slow */
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while (newlen < add) newlen <<= 1;
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char *buf = SvGROW(s->sv, newlen);
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s->cur = buf + off;
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s->end = buf + SvLEN(s->sv);
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}
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static inline void fustr_reserve_(pTHX_ fustr *s, size_t add) {
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if (UNLIKELY(s->end < s->cur + add)) fustr_grow(aTHX_ s, add);
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}
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static inline void fustr_write_(pTHX_ fustr *s, const char *str, size_t n) {
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fustr_reserve_(aTHX_ s, n);
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memcpy(s->cur, str, n);
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s->cur += n;
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}
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/* Adds n uninitialized bytes to the string and returns a buffer to write the data to */
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static inline char *fustr_write_buf_(pTHX_ fustr *s, size_t n) {
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fustr_reserve_(aTHX_ s, n);
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char *buf = s->cur;
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s->cur += n;
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return buf;
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}
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static SV *fustr_done_(pTHX_ fustr *s) {
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fustr_reserve_(aTHX_ s, 1);
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*s->cur = 0;
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SvCUR_set(s->sv, s->cur - SvPVX(s->sv));
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// TODO: SvPV_shrink_to_cur?
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return s->sv;
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}
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#define fustr_init(a,b) fustr_init_(aTHX_ a,b)
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#define fustr_reserve(a,b) fustr_reserve_(aTHX_ a,b)
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#define fustr_write(a,b,c) fustr_write_(aTHX_ a,b,c)
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#define fustr_write_buf(a,b) fustr_write_buf_(aTHX_ a,b)
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#define fustr_done(a) fustr_done_(aTHX_ a)
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