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JavaScript

// Process front matter and pass to cb
'use strict';
module.exports = function front_matter_plugin(md, cb) {
var min_markers = 3,
marker_str = '-',
marker_char = marker_str.charCodeAt(0),
marker_len = marker_str.length;
function frontMatter(state, startLine, endLine, silent) {
var pos,
nextLine,
marker_count,
token,
old_parent,
old_line_max,
start_content,
auto_closed = false,
start = state.bMarks[startLine] + state.tShift[startLine],
max = state.eMarks[startLine];
// Check out the first character of the first line quickly,
// this should filter out non-front matter
if (startLine !== 0 || marker_char !== state.src.charCodeAt(0)) {
return false;
}
// Check out the rest of the marker string
// while pos <= 3
for (pos = start + 1; pos <= max; pos++) {
if (marker_str[(pos - start) % marker_len] !== state.src[pos]) {
start_content = pos + 1;
break;
}
}
marker_count = Math.floor((pos - start) / marker_len);
if (marker_count < min_markers) {
return false;
}
pos -= (pos - start) % marker_len;
// Since start is found, we can report success here in validation mode
if (silent) {
return true;
}
// Search for the end of the block
nextLine = startLine;
for (;;) {
nextLine++;
if (nextLine >= endLine) {
// unclosed block should be autoclosed by end of document.
// also block seems to be autoclosed by end of parent
break;
}
if (state.src.slice(start, max) === '...') {
break;
}
start = state.bMarks[nextLine] + state.tShift[nextLine];
max = state.eMarks[nextLine];
if (start < max && state.sCount[nextLine] < state.blkIndent) {
// non-empty line with negative indent should stop the list:
// - ```
// test
break;
}
if (marker_char !== state.src.charCodeAt(start)) {
continue;
}
if (state.sCount[nextLine] - state.blkIndent >= 4) {
// closing fence should be indented less than 4 spaces
continue;
}
for (pos = start + 1; pos <= max; pos++) {
if (marker_str[(pos - start) % marker_len] !== state.src[pos]) {
break;
}
}
// closing code fence must be at least as long as the opening one
if (Math.floor((pos - start) / marker_len) < marker_count) {
continue;
}
// make sure tail has spaces only
pos -= (pos - start) % marker_len;
pos = state.skipSpaces(pos);
if (pos < max) {
continue;
}
// found!
auto_closed = true;
break;
}
old_parent = state.parentType;
old_line_max = state.lineMax;
state.parentType = 'container';
// this will prevent lazy continuations from ever going past our end marker
state.lineMax = nextLine;
token = state.push('front_matter', null, 0);
token.hidden = true;
token.markup = state.src.slice(startLine, pos);
token.block = true;
token.map = [ startLine, nextLine + (auto_closed ? 1 : 0) ];
token.meta = state.src.slice(start_content, start - 1);
state.parentType = old_parent;
state.lineMax = old_line_max;
state.line = nextLine + (auto_closed ? 1 : 0);
cb(token.meta);
return true;
}
md.block.ruler.before(
'table',
'front_matter',
frontMatter,
{
alt: [
'paragraph',
'reference',
'blockquote',
'list'
]
}
);
};