From 90433f6ea3b2676f97991d89f14a9028bab6577b Mon Sep 17 00:00:00 2001
From: Mahmoud Al-Qudsi <mqudsi@neosmart.net>
Date: Tue, 8 Sep 2020 11:54:22 -0500
Subject: [PATCH] Minimize AST node vector reallocations

Closes #7201
---
 src/ast.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/ast.cpp b/src/ast.cpp
index 39fe5d2ff..c8749df0f 100644
--- a/src/ast.cpp
+++ b/src/ast.cpp
@@ -915,7 +915,11 @@ class ast_t::populator_t {
 
             // Now try parsing a node.
             if (auto node = this->try_parse<ContentsNode>()) {
-                contents.push_back(std::move(node));
+                // #7201: Minimize reallocations of contents vector
+                if (contents.empty()) {
+                    contents.reserve(64);
+                }
+                contents.emplace_back(std::move(node));
             } else if (exhaust_stream && peek_type() != parse_token_type_t::terminate) {
                 // We aren't allowed to stop. Produce an error and keep going.
                 consume_excess_token_generating_error();