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Get rid of ROLLBACK_ALL.
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This code is mess, consequences of its use for caller are very hard to
grasp correctly, and it also have strange corner cases.

The need to use it more or less always means there's something stinky in
the code calling it.
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@mity
mity committed Jan 17, 2024
1 parent 4728cd9 commit 76a3680
Showing 1 changed file with 19 additions and 45 deletions.
64 changes: 19 additions & 45 deletions src/md4c.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2647,26 +2647,20 @@ md_resolve_range(MD_CTX* ctx, MD_MARKCHAIN* chain, int opener_index, int closer_
}


#define MD_ROLLBACK_ALL 0
#define MD_ROLLBACK_CROSSING 1

/* In the range ctx->marks[opener_index] ... [closer_index], undo some or all
* resolvings accordingly to these rules:
/* Inside the range ctx->marks[opener_index] ... [closer_index], undo some
* previous resolving accordingly to these rules:
*
* (1) All openers BEFORE the range corresponding to any closer inside the
* range are un-resolved and they are re-added to their respective chains
* of unresolved openers. This ensures we can reuse the opener for closers
* AFTER the range.
*
* (2) If 'how' is MD_ROLLBACK_ALL, then ALL resolved marks inside the range
* are discarded.
*
* (3) If 'how' is MD_ROLLBACK_CROSSING, only closers with openers handled
* in (1) are discarded. I.e. pairs of openers and closers which are both
* inside the range are retained as well as any unpaired marks.
* (2) Closers with openers handled in (1) are discarded. I.e. pairs of openers
* and closers which are both inside the range are retained as well as any
* unpaired marks.
*/
static void
md_rollback(MD_CTX* ctx, int opener_index, int closer_index, int how)
md_rollback(MD_CTX* ctx, int opener_index, int closer_index)
{
int i;
int mark_index;
Expand All @@ -2685,12 +2679,11 @@ md_rollback(MD_CTX* ctx, int opener_index, int closer_index, int how)
}

/* Go backwards so that unresolved openers are re-added into their
* respective chains, in the right order. */
* respective chains in the right order. */
mark_index = closer_index - 1;
while(mark_index > opener_index) {
MD_MARK* mark = &ctx->marks[mark_index];
int mark_flags = mark->flags;
int discard_flag = (how == MD_ROLLBACK_ALL);

if(mark->flags & MD_MARK_CLOSER) {
int mark_opener_index = mark->prev;
Expand All @@ -2702,36 +2695,19 @@ md_rollback(MD_CTX* ctx, int opener_index, int closer_index, int how)

mark_opener->flags &= ~(MD_MARK_OPENER | MD_MARK_CLOSER | MD_MARK_RESOLVED);
chain = md_mark_chain(ctx, opener_index);
if(chain != NULL) {
if(chain != NULL)

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md_mark_chain_append(ctx, chain, mark_opener_index);
discard_flag = 1;
}
}
}

/* And reset our flags. */
if(discard_flag) {
/* Make zero-length closer a dummy mark as that's how it was born */
if((mark->flags & MD_MARK_CLOSER) && mark->beg == mark->end)
mark->ch = 'D';

mark->flags &= ~(MD_MARK_OPENER | MD_MARK_CLOSER | MD_MARK_RESOLVED);
}

/* Jump as far as we can over unresolved or non-interesting marks. */
switch(how) {
case MD_ROLLBACK_CROSSING:
if((mark_flags & MD_MARK_CLOSER) && mark->prev > opener_index) {
/* If we are closer with opener INSIDE the range, there may
* not be any other crosser inside the subrange. */
mark_index = mark->prev;
break;
}
MD_FALLTHROUGH();
default:
mark_index--;
break;
if((mark_flags & MD_MARK_CLOSER) && mark->prev > opener_index) {
/* If we are closer with opener INSIDE the range, there may
* not be any other crosser inside the subrange. */
mark_index = mark->prev;
break;
}
mark_index--;
}
}

Expand Down Expand Up @@ -3500,7 +3476,8 @@ md_resolve_links(MD_CTX* ctx, const MD_LINE* lines, int n_lines)

/* We don't allow destination to be longer than 100 characters.
* Lets scan to see whether there is '|'. (If not then the whole
* wiki-link has to be below the 100 characters.) */
* wiki-link has to be below the 100 characters.)
*/
delim_index = opener_index + 1;
while(delim_index < closer_index) {
MD_MARK* m = &ctx->marks[delim_index];
Expand Down Expand Up @@ -3536,13 +3513,10 @@ md_resolve_links(MD_CTX* ctx, const MD_LINE* lines, int n_lines)
if(is_link) {
if(delim != NULL) {
if(delim->end < closer->beg) {
md_rollback(ctx, opener_index, delim_index, MD_ROLLBACK_ALL);
md_rollback(ctx, delim_index, closer_index, MD_ROLLBACK_CROSSING);
delim->flags |= MD_MARK_RESOLVED;
opener->end = delim->beg;
} else {
/* The pipe is just before the closer: [[foo|]] */
md_rollback(ctx, opener_index, closer_index, MD_ROLLBACK_ALL);
closer->beg = delim->beg;
delim = NULL;
}
Expand Down Expand Up @@ -3815,7 +3789,7 @@ md_analyze_emph(MD_CTX* ctx, int mark_index)
md_split_emph_mark(ctx, mark_index, closer_size - opener_size);
}

md_rollback(ctx, opener_index, mark_index, MD_ROLLBACK_CROSSING);
md_rollback(ctx, opener_index, mark_index);
md_resolve_range(ctx, opener_chain, opener_index, mark_index);
return;
}
Expand All @@ -3839,7 +3813,7 @@ md_analyze_tilde(MD_CTX* ctx, int mark_index)
if((mark->flags & MD_MARK_POTENTIAL_CLOSER) && chain->tail >= 0) {
int opener_index = chain->tail;

md_rollback(ctx, opener_index, mark_index, MD_ROLLBACK_CROSSING);
md_rollback(ctx, opener_index, mark_index);
md_resolve_range(ctx, chain, opener_index, mark_index);
return;
}
Expand All @@ -3866,7 +3840,7 @@ md_analyze_dollar(MD_CTX* ctx, int mark_index)

if (open->end - open->beg == close->end - close->beg) {
/* We are the matching closer */
md_rollback(ctx, opener_index, mark_index, MD_ROLLBACK_ALL);
md_rollback(ctx, opener_index, mark_index);
md_resolve_range(ctx, &DOLLAR_OPENERS, opener_index, mark_index);
return;
}
Expand Down

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