diff options
Diffstat (limited to 'diff.c')
| -rw-r--r-- | diff.c | 279 |
1 files changed, 277 insertions, 2 deletions
@@ -608,6 +608,52 @@ struct emit_callback { struct strbuf *header; }; +/* + * State for the line-range callback wrappers that sit between + * xdi_diff_outf() and fn_out_consume(). xdiff produces a normal, + * unfiltered diff; the wrappers intercept each hunk header and line, + * track post-image position, and forward only lines that fall within + * the requested ranges. Contiguous in-range lines are collected into + * range hunks and flushed with a synthetic @@ header so that + * fn_out_consume() sees well-formed unified-diff fragments. + * + * Removal lines ('-') cannot be classified by post-image position, so + * they are buffered in pending_rm until the next '+' or ' ' line + * reveals whether they precede an in-range line (flush into range hunk) or + * an out-of-range line (discard). + */ +struct line_range_callback { + xdiff_emit_line_fn orig_line_fn; + void *orig_cb_data; + const struct range_set *ranges; /* 0-based [start, end) */ + unsigned int cur_range; /* index into the range_set */ + + /* Post/pre-image line counters (1-based, set from hunk headers) */ + long lno_post; + long lno_pre; + + /* + * Function name from most recent xdiff hunk header; + * size matches struct func_line.buf in xdiff/xemit.c. + */ + char func[80]; + long funclen; + + /* Range hunk being accumulated for the current range */ + struct strbuf rhunk; + long rhunk_old_begin, rhunk_old_count; + long rhunk_new_begin, rhunk_new_count; + int rhunk_active; + int rhunk_has_changes; /* any '+' or '-' lines? */ + + /* Removal lines not yet known to be in-range */ + struct strbuf pending_rm; + int pending_rm_count; + long pending_rm_pre_begin; /* pre-image line of first pending */ + + int ret; /* latched error from orig_line_fn */ +}; + static int count_lines(const char *data, int size) { int count, ch, completely_empty = 1, nl_just_seen = 0; @@ -2493,6 +2539,188 @@ static int quick_consume(void *priv, char *line UNUSED, unsigned long len UNUSED return 1; } +static void discard_pending_rm(struct line_range_callback *s) +{ + strbuf_reset(&s->pending_rm); + s->pending_rm_count = 0; +} + +static void flush_rhunk(struct line_range_callback *s) +{ + struct strbuf hdr = STRBUF_INIT; + const char *p, *end; + + if (!s->rhunk_active || s->ret) + return; + + /* Drain any pending removal lines into the range hunk */ + if (s->pending_rm_count) { + strbuf_addbuf(&s->rhunk, &s->pending_rm); + s->rhunk_old_count += s->pending_rm_count; + s->rhunk_has_changes = 1; + discard_pending_rm(s); + } + + /* + * Suppress context-only hunks: they contain no actual changes + * and would just be noise. This can happen when the inflated + * ctxlen causes xdiff to emit context covering a range that + * has no changes in this commit. + */ + if (!s->rhunk_has_changes) { + s->rhunk_active = 0; + strbuf_reset(&s->rhunk); + return; + } + + strbuf_addf(&hdr, "@@ -%ld,%ld +%ld,%ld @@", + s->rhunk_old_begin, s->rhunk_old_count, + s->rhunk_new_begin, s->rhunk_new_count); + if (s->funclen > 0) { + strbuf_addch(&hdr, ' '); + strbuf_add(&hdr, s->func, s->funclen); + } + strbuf_addch(&hdr, '\n'); + + s->ret = s->orig_line_fn(s->orig_cb_data, hdr.buf, hdr.len); + strbuf_release(&hdr); + + /* + * Replay buffered lines one at a time through fn_out_consume. + * The cast discards const because xdiff_emit_line_fn takes + * char *, though fn_out_consume does not modify the buffer. + */ + p = s->rhunk.buf; + end = p + s->rhunk.len; + while (!s->ret && p < end) { + const char *eol = memchr(p, '\n', end - p); + unsigned long line_len = eol ? (unsigned long)(eol - p + 1) + : (unsigned long)(end - p); + s->ret = s->orig_line_fn(s->orig_cb_data, (char *)p, line_len); + p += line_len; + } + + s->rhunk_active = 0; + strbuf_reset(&s->rhunk); +} + +static void line_range_hunk_fn(void *data, + long old_begin, long old_nr UNUSED, + long new_begin, long new_nr UNUSED, + const char *func, long funclen) +{ + struct line_range_callback *s = data; + + /* + * When count > 0, begin is 1-based. When count == 0, begin is + * adjusted down by 1 by xdl_emit_hunk_hdr(), but no lines of + * that type will arrive, so the value is unused. + * + * Any pending removal lines from the previous xdiff hunk are + * intentionally left in pending_rm: the line callback will + * flush or discard them when the next content line reveals + * whether the removals precede in-range content. + */ + s->lno_post = new_begin; + s->lno_pre = old_begin; + + if (funclen > 0) { + if (funclen > (long)sizeof(s->func)) + funclen = sizeof(s->func); + memcpy(s->func, func, funclen); + } + s->funclen = funclen; +} + +static int line_range_line_fn(void *priv, char *line, unsigned long len) +{ + struct line_range_callback *s = priv; + const struct range *cur; + long lno_0, cur_pre; + + if (s->ret) + return s->ret; + + if (line[0] == '-') { + if (!s->pending_rm_count) + s->pending_rm_pre_begin = s->lno_pre; + s->lno_pre++; + strbuf_add(&s->pending_rm, line, len); + s->pending_rm_count++; + return s->ret; + } + + if (line[0] == '\\') { + if (s->pending_rm_count) + strbuf_add(&s->pending_rm, line, len); + else if (s->rhunk_active) + strbuf_add(&s->rhunk, line, len); + /* otherwise outside tracked range; drop silently */ + return s->ret; + } + + if (line[0] != '+' && line[0] != ' ') + BUG("unexpected diff line type '%c'", line[0]); + + lno_0 = s->lno_post - 1; + cur_pre = s->lno_pre; /* save before advancing for context lines */ + s->lno_post++; + if (line[0] == ' ') + s->lno_pre++; + + /* Advance past ranges we've passed */ + while (s->cur_range < s->ranges->nr && + lno_0 >= s->ranges->ranges[s->cur_range].end) { + if (s->rhunk_active) + flush_rhunk(s); + discard_pending_rm(s); + s->cur_range++; + } + + /* Past all ranges */ + if (s->cur_range >= s->ranges->nr) { + discard_pending_rm(s); + return s->ret; + } + + cur = &s->ranges->ranges[s->cur_range]; + + /* Before current range */ + if (lno_0 < cur->start) { + discard_pending_rm(s); + return s->ret; + } + + /* In range so start a new range hunk if needed */ + if (!s->rhunk_active) { + s->rhunk_active = 1; + s->rhunk_has_changes = 0; + s->rhunk_new_begin = lno_0 + 1; + s->rhunk_old_begin = s->pending_rm_count + ? s->pending_rm_pre_begin : cur_pre; + s->rhunk_old_count = 0; + s->rhunk_new_count = 0; + strbuf_reset(&s->rhunk); + } + + /* Flush pending removals into range hunk */ + if (s->pending_rm_count) { + strbuf_addbuf(&s->rhunk, &s->pending_rm); + s->rhunk_old_count += s->pending_rm_count; + s->rhunk_has_changes = 1; + discard_pending_rm(s); + } + + strbuf_add(&s->rhunk, line, len); + s->rhunk_new_count++; + if (line[0] == '+') + s->rhunk_has_changes = 1; + else + s->rhunk_old_count++; + + return s->ret; +} + static void pprint_rename(struct strbuf *name, const char *a, const char *b) { const char *old_name = a; @@ -3592,7 +3820,8 @@ static void builtin_diff(const char *name_a, const char *xfrm_msg, int must_show_header, struct diff_options *o, - int complete_rewrite) + int complete_rewrite, + const struct range_set *line_ranges) { mmfile_t mf1, mf2; const char *lbl[2]; @@ -3833,6 +4062,52 @@ static void builtin_diff(const char *name_a, */ xdi_diff_outf(&mf1, &mf2, NULL, quick_consume, &ecbdata, &xpp, &xecfg); + } else if (line_ranges) { + struct line_range_callback lr_state; + unsigned int i; + long max_span = 0; + + memset(&lr_state, 0, sizeof(lr_state)); + lr_state.orig_line_fn = fn_out_consume; + lr_state.orig_cb_data = &ecbdata; + lr_state.ranges = line_ranges; + strbuf_init(&lr_state.rhunk, 0); + strbuf_init(&lr_state.pending_rm, 0); + + /* + * Inflate ctxlen so that all changes within + * any single range are merged into one xdiff + * hunk and the inter-change context is emitted. + * The callback clips back to range boundaries. + * + * The optimal ctxlen depends on where changes + * fall within the range, which is only known + * after xdiff runs; the max range span is the + * upper bound that guarantees correctness in a + * single pass. + */ + for (i = 0; i < line_ranges->nr; i++) { + long span = line_ranges->ranges[i].end - + line_ranges->ranges[i].start; + if (span > max_span) + max_span = span; + } + if (max_span > xecfg.ctxlen) + xecfg.ctxlen = max_span; + + if (xdi_diff_outf(&mf1, &mf2, + line_range_hunk_fn, + line_range_line_fn, + &lr_state, &xpp, &xecfg)) + die("unable to generate diff for %s", + one->path); + + flush_rhunk(&lr_state); + if (lr_state.ret) + die("unable to generate diff for %s", + one->path); + strbuf_release(&lr_state.rhunk); + strbuf_release(&lr_state.pending_rm); } else if (xdi_diff_outf(&mf1, &mf2, NULL, fn_out_consume, &ecbdata, &xpp, &xecfg)) die("unable to generate diff for %s", one->path); @@ -4674,7 +4949,7 @@ static void run_diff_cmd(const struct external_diff *pgm, builtin_diff(name, other ? other : name, one, two, xfrm_msg, must_show_header, - o, complete_rewrite); + o, complete_rewrite, p->line_ranges); if (p->status == DIFF_STATUS_COPIED || p->status == DIFF_STATUS_RENAMED) o->found_changes = 1; |