Function ExplainPropertyList

src/backend/commands/explain.c:5367–5431

* Explain a property, such as sort keys or targets, that takes the form of * a list of unlabeled items. "data" is a list of C strings. */

 * a list of unlabeled items.  "data" is a list of C strings.
 */
void
ExplainPropertyList(const char *qlabel, List *data, ExplainState *es)
{
	ListCell   *lc;
	bool		first = true;

	switch (es->format)
	{
		case EXPLAIN_FORMAT_TEXT:
			ExplainIndentText(es);
			appendStringInfo(es->str, "%s: ", qlabel);
			foreach(lc, data)
			{
				if (!first)
					appendStringInfoString(es->str, ", ");
				appendStringInfoString(es->str, (const char *) lfirst(lc));
				first = false;
			}
			appendStringInfoChar(es->str, '\n');
			break;

		case EXPLAIN_FORMAT_XML:
			ExplainXMLTag(qlabel, X_OPENING, es);
			foreach(lc, data)
			{
				char	   *str;

				appendStringInfoSpaces(es->str, es->indent * 2 + 2);
				appendStringInfoString(es->str, "<Item>");
				str = escape_xml((const char *) lfirst(lc));
				appendStringInfoString(es->str, str);
				pfree(str);
				appendStringInfoString(es->str, "</Item>\n");
			}
			ExplainXMLTag(qlabel, X_CLOSING, es);
			break;

		case EXPLAIN_FORMAT_JSON:
			ExplainJSONLineEnding(es);
			appendStringInfoSpaces(es->str, es->indent * 2);
			escape_json(es->str, qlabel);
			appendStringInfoString(es->str, ": [");
			foreach(lc, data)
			{
				if (!first)
					appendStringInfoString(es->str, ", ");
				escape_json(es->str, (const char *) lfirst(lc));
				first = false;
			}
			appendStringInfoChar(es->str, ']');
			break;

		case EXPLAIN_FORMAT_YAML:
			ExplainYAMLLineStarting(es);
			appendStringInfo(es->str, "%s: ", qlabel);
			foreach(lc, data)
			{
				appendStringInfoChar(es->str, '\n');