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Fix list tightness
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- Set the end position precisely
- Check list tightness by comparing line numbers
- Remove `LAST_LINE_BLANK` flag

See also commonmark/commonmark.js#269 .

Classification of end positions:

- The end of the current line:
  - Thematic breaks
  - ATX headings
  - Setext headings
  - Fenced code blocks closed explicitly
  - HTML blocks (`pre`, comments, and others)

- The end of the previous line:
  - Fenced code blocks closed by the end of the parent or EOF
  - HTML blocks (`div` and others)
  - HTML blocks closed by the end of the parent or EOF
  - Paragraphs
  - Block quotes
  - Empty list items

- The end position of the last child:
  - Non-empty list items
  - Lists

- The end position of the last non-blank line:
  - Indented code blocks

The first two cases are handed by `finalize` and `closed_explicitly` flag.

Non empty list items and lists are handled in `switch` statements in `finalize`.

Indented code blocks are handled by setting the end position every time
non-blank line is added to the block.
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@taku0
taku0 committed Aug 17, 2023
1 parent fb9375b commit 34997d4
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Showing 2 changed files with 65 additions and 75 deletions.
139 changes: 65 additions & 74 deletions src/blocks.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -32,21 +32,10 @@

#define peek_at(i, n) (i)->data[n]

static bool S_last_line_blank(const cmark_node *node) {
return (node->flags & CMARK_NODE__LAST_LINE_BLANK) != 0;
}

static CMARK_INLINE cmark_node_type S_type(const cmark_node *node) {
return (cmark_node_type)node->type;
}

static void S_set_last_line_blank(cmark_node *node, bool is_blank) {
if (is_blank)
node->flags |= CMARK_NODE__LAST_LINE_BLANK;
else
node->flags &= ~CMARK_NODE__LAST_LINE_BLANK;
}

static CMARK_INLINE bool S_is_line_end_char(char c) {
return (c == '\n' || c == '\r');
}
Expand Down Expand Up @@ -124,8 +113,6 @@ void cmark_parser_free(cmark_parser *parser) {
mem->free(parser);
}

static cmark_node *finalize(cmark_parser *parser, cmark_node *b);

// Returns true if line has only space characters, else false.
static bool is_blank_raw(const unsigned char *ptr, const bufsize_t size,
bufsize_t offset) {
Expand Down Expand Up @@ -209,26 +196,25 @@ static void remove_trailing_blank_lines(cmark_strbuf *ln) {
return;
}

// Scan forward until line end to keep trailing spaces of the last line.
for (; i < ln->size; ++i) {
c = ln->ptr[i];

if (!S_is_line_end_char(c))
continue;

cmark_strbuf_truncate(ln, i);
if (c == '\r' && i + 1 < ln->size && ln->ptr[i + 1] == '\n') {
i++;
}

cmark_strbuf_truncate(ln, i + 1);
break;
}
}

// Check to see if a node ends with a blank line, descending
// if needed into lists and sublists.
static bool S_ends_with_blank_line(cmark_node *node) {
if ((S_type(node) == CMARK_NODE_LIST ||
S_type(node) == CMARK_NODE_ITEM) && node->last_child) {
return(S_ends_with_blank_line(node->last_child));
} else {
return (S_last_line_blank(node));
}
// Check to see if a node ends with a blank line.
static CMARK_INLINE bool S_ends_with_blank_line(cmark_node *node) {
return node->next && node->end_line != node->next->start_line - 1;
}

// returns true if content remains after link defs are resolved.
Expand Down Expand Up @@ -331,7 +317,15 @@ static void resolve_all_reference_link_definitions(cmark_parser *parser) {
}
}

static cmark_node *finalize(cmark_parser *parser, cmark_node *b) {
// `closed_explicitly` states that the node is closed by explicit markers, or
// the node cannot span more than one line:
//
// - Close tag of HTML blocks
// - Closing code fence
// - ATX headings
// - Thematic breaks
static cmark_node *finalize(cmark_parser *parser, cmark_node *b,
bool closed_explicitly) {
bufsize_t pos;
cmark_node *item;
cmark_node *subitem;
Expand All @@ -342,22 +336,22 @@ static cmark_node *finalize(cmark_parser *parser, cmark_node *b) {
CMARK_NODE__OPEN); // shouldn't call finalize on closed blocks
b->flags &= ~CMARK_NODE__OPEN;

if (parser->curline.size == 0) {
// end of input - line number has not been incremented
b->end_line = parser->line_number;
b->end_column = parser->last_line_length;
} else if (S_type(b) == CMARK_NODE_DOCUMENT ||
(S_type(b) == CMARK_NODE_CODE_BLOCK && b->as.code.fenced) ||
(S_type(b) == CMARK_NODE_HEADING && b->as.heading.setext)) {
b->end_line = parser->line_number;
b->end_column = parser->curline.size;
if (b->end_column && parser->curline.ptr[b->end_column - 1] == '\n')
b->end_column -= 1;
if (b->end_column && parser->curline.ptr[b->end_column - 1] == '\r')
b->end_column -= 1;
} else {
b->end_line = parser->line_number - 1;
b->end_column = parser->last_line_length;
if (S_type(b) != CMARK_NODE_CODE_BLOCK || b->as.code.fenced) {
if (parser->curline.size == 0) {
// end of input - line number has not been incremented
b->end_line = parser->line_number;
b->end_column = parser->last_line_length;
} else if (closed_explicitly) {
b->end_line = parser->line_number;
b->end_column = parser->curline.size;
if (b->end_column && parser->curline.ptr[b->end_column - 1] == '\n')
b->end_column -= 1;
if (b->end_column && parser->curline.ptr[b->end_column - 1] == '\r')
b->end_column -= 1;
} else {
b->end_line = parser->line_number - 1;
b->end_column = parser->last_line_length;
}
}

cmark_strbuf *node_content = &parser->content;
Expand All @@ -371,7 +365,6 @@ static cmark_node *finalize(cmark_parser *parser, cmark_node *b) {
case CMARK_NODE_CODE_BLOCK:
if (!b->as.code.fenced) { // indented code
remove_trailing_blank_lines(node_content);
cmark_strbuf_putc(node_content, '\n');
} else {
// first line of contents becomes info
for (pos = 0; pos < node_content->size; ++pos) {
Expand Down Expand Up @@ -412,16 +405,15 @@ static cmark_node *finalize(cmark_parser *parser, cmark_node *b) {

while (item) {
// check for non-final non-empty list item ending with blank line:
if (S_last_line_blank(item) && item->next) {
if (item->next && S_ends_with_blank_line(item)) {
b->as.list.tight = false;
break;
}
// recurse into children of list item, to see if there are
// spaces between them:
subitem = item->first_child;
while (subitem) {
if ((item->next || subitem->next) &&
S_ends_with_blank_line(subitem)) {
if (subitem->next && S_ends_with_blank_line(subitem)) {
b->as.list.tight = false;
break;
}
Expand All @@ -432,9 +424,21 @@ static cmark_node *finalize(cmark_parser *parser, cmark_node *b) {
}
item = item->next;
}
b->end_line = b->last_child->end_line;
b->end_column = b->last_child->end_column;

break;

case CMARK_NODE_ITEM:
if (b->last_child) {
b->end_line = b->last_child->end_line;
b->end_column = b->last_child->end_column;
}
// If the item is empty, it is closed when the next line is processed and
// the end position is set by the normal path. Note that if the first line
// and second line of a item are blank, it is closed.
break;

case CMARK_NODE_DOCUMENT:
resolve_all_reference_link_definitions(parser);
break;
Expand All @@ -454,7 +458,7 @@ static cmark_node *add_child(cmark_parser *parser, cmark_node *parent,
// if 'parent' isn't the kind of node that can accept this child,
// then back up til we hit a node that can.
while (!can_contain(S_type(parent), block_type)) {
parent = finalize(parser, parent);
parent = finalize(parser, parent, false);
}

cmark_node *child =
Expand Down Expand Up @@ -594,10 +598,10 @@ static int lists_match(cmark_list *list_data, cmark_list *item_data) {

static cmark_node *finalize_document(cmark_parser *parser) {
while (parser->current != parser->root) {
parser->current = finalize(parser, parser->current);
parser->current = finalize(parser, parser->current, false);
}

finalize(parser, parser->root);
finalize(parser, parser->root, false);

// Limit total size of extra content created from reference links to
// document size to avoid superlinear growth. Always allow 100KB.
Expand Down Expand Up @@ -917,7 +921,7 @@ static bool parse_code_block_prefix(cmark_parser *parser, cmark_chunk *input,
// the end of a line, we can stop processing it:
*should_continue = false;
S_advance_offset(parser, input, matched, false);
parser->current = finalize(parser, container);
parser->current = finalize(parser, container, true);
} else {
// skip opt. spaces of fence parser->offset
int i = container->as.code.fence_offset;
Expand Down Expand Up @@ -1121,6 +1125,7 @@ static void open_new_blocks(cmark_parser *parser, cmark_node **container,
// it's only now that we know the line is not part of a setext heading:
*container = add_child(parser, *container, CMARK_NODE_THEMATIC_BREAK,
parser->first_nonspace + 1);
*container = finalize(parser, *container, true);
S_advance_offset(parser, input, input->len - 1 - parser->offset, false);
} else if ((!indented || cont_type == CMARK_NODE_LIST) &&
parser->indent < 4 &&
Expand Down Expand Up @@ -1207,35 +1212,11 @@ static void open_new_blocks(cmark_parser *parser, cmark_node **container,
static void add_text_to_container(cmark_parser *parser, cmark_node *container,
cmark_node *last_matched_container,
cmark_chunk *input) {
cmark_node *tmp;
// what remains at parser->offset is a text line. add the text to the
// appropriate container.

S_find_first_nonspace(parser, input);

if (parser->blank && container->last_child)
S_set_last_line_blank(container->last_child, true);

// block quote lines are never blank as they start with >
// and we don't count blanks in fenced code for purposes of tight/loose
// lists or breaking out of lists. we also don't set last_line_blank
// on an empty list item.
const cmark_node_type ctype = S_type(container);
const bool last_line_blank =
(parser->blank && ctype != CMARK_NODE_BLOCK_QUOTE &&
ctype != CMARK_NODE_HEADING && ctype != CMARK_NODE_THEMATIC_BREAK &&
!(ctype == CMARK_NODE_CODE_BLOCK && container->as.code.fenced) &&
!(ctype == CMARK_NODE_ITEM && container->first_child == NULL &&
container->start_line == parser->line_number));

S_set_last_line_blank(container, last_line_blank);

tmp = container;
while (tmp->parent) {
S_set_last_line_blank(tmp->parent, false);
tmp = tmp->parent;
}

// If the last line processed belonged to a paragraph node,
// and we didn't match all of the line prefixes for the open containers,
// and we didn't start any new containers,
Expand All @@ -1249,7 +1230,7 @@ static void add_text_to_container(cmark_parser *parser, cmark_node *container,
} else { // not a lazy continuation
// Finalize any blocks that were not matched and set cur to container:
while (parser->current != last_matched_container) {
parser->current = finalize(parser, parser->current);
parser->current = finalize(parser, parser->current, false);
assert(parser->current != NULL);
}

Expand Down Expand Up @@ -1291,7 +1272,7 @@ static void add_text_to_container(cmark_parser *parser, cmark_node *container,
}

if (matches_end_condition) {
container = finalize(parser, container);
container = finalize(parser, container, true);
assert(parser->current != NULL);
}
} else if (parser->blank) {
Expand Down Expand Up @@ -1324,6 +1305,7 @@ static void S_process_line(cmark_parser *parser, const unsigned char *buffer,
bool all_matched = true;
cmark_node *container;
cmark_chunk input;
bool need_set_end_position = false;

if (parser->options & CMARK_OPT_VALIDATE_UTF8)
cmark_utf8proc_check(&parser->curline, buffer, bytes);
Expand Down Expand Up @@ -1361,6 +1343,10 @@ static void S_process_line(cmark_parser *parser, const unsigned char *buffer,

add_text_to_container(parser, container, last_matched_container, &input);

need_set_end_position = S_type(container) == CMARK_NODE_CODE_BLOCK &&
!container->as.code.fenced &&
!parser->blank;

finished:
parser->last_line_length = input.len;
if (parser->last_line_length &&
Expand All @@ -1370,6 +1356,11 @@ static void S_process_line(cmark_parser *parser, const unsigned char *buffer,
input.data[parser->last_line_length - 1] == '\r')
parser->last_line_length -= 1;

if (need_set_end_position) {
container->end_line = parser->line_number;
container->end_column = parser->last_line_length;
}

cmark_strbuf_clear(&parser->curline);
}

Expand Down
1 change: 0 additions & 1 deletion src/node.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -48,7 +48,6 @@ typedef struct {

enum cmark_node__internal_flags {
CMARK_NODE__OPEN = (1 << 0),
CMARK_NODE__LAST_LINE_BLANK = (1 << 1),
};

struct cmark_node {
Expand Down

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