From: Fletcher T. Penney <fletcher@fletcherpenney.net>
Date: Fri, 5 Apr 2019 14:42:37 +0000 (-0400)
Subject: FIXED: Improve efficiency when checking for existence of metadata
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=6906b474add0f8b400c9f68071e8731610340004;p=multimarkdown

FIXED: Improve efficiency when checking for existence of metadata
---

diff --git a/Sources/libMultiMarkdown/mmd.c b/Sources/libMultiMarkdown/mmd.c
index 7301404..64f2c3f 100644
--- a/Sources/libMultiMarkdown/mmd.c
+++ b/Sources/libMultiMarkdown/mmd.c
@@ -2329,11 +2329,21 @@ bool mmd_engine_has_metadata(mmd_engine * e, size_t * end) {
 	// Preserve existing parse tree (if any)
 	old_root = e->root;
 
-	// Tokenize the string (up until first empty line)
-	token * doc = mmd_tokenize_string(e, 0, e->dstr->currentStringLength, true);
+	token * doc;
+
+	if (old_root &&
+			(old_root->type == DOC_START_TOKEN) &&
+			(old_root->len == e->dstr->currentStringLength)
+	   ) {
+		// Already parsed
+		doc = old_root;
+	} else {
+		// Tokenize the string (up until first empty line)
+		doc = mmd_tokenize_string(e, 0, e->dstr->currentStringLength, true);
 
-	// Parse tokens into blocks
-	mmd_parse_token_chain(e, doc);
+		// Parse tokens into blocks
+		mmd_parse_token_chain(e, doc);
+	}
 
 	if (doc) {
 		if (doc->child && doc->child->type == BLOCK_META) {
@@ -2344,7 +2354,11 @@ bool mmd_engine_has_metadata(mmd_engine * e, size_t * end) {
 			}
 		}
 
-		token_tree_free(doc);
+		if (old_root != doc) {
+			token_tree_free(doc);
+
+			// TODO: Need to reset various stacks (e.g. header stack)...
+		}
 	}
 
 	// Restore previous parse tree