From 5daed4cc72bc252e7278a53f7ab9bc2890b5f009 Mon Sep 17 00:00:00 2001
From: Jake Hillion <jakehillion@meta.com>
Date: Thu, 12 Oct 2023 17:29:38 -0700
Subject: [PATCH] tbv2: add a repeat instruction

---
 include/oi/exporters/inst.h | 12 +++++++++++-
 oi/IntrospectionResult.cpp  |  6 ++++++
 types/seq_type.toml         |  3 +--
 3 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/include/oi/exporters/inst.h b/include/oi/exporters/inst.h
index db8856f..8397cd6 100644
--- a/include/oi/exporters/inst.h
+++ b/include/oi/exporters/inst.h
@@ -32,8 +32,10 @@ namespace oi::exporters::inst {
 
 struct PopTypePath;
 struct Field;
+struct Repeat;
 
-using Inst = std::variant<PopTypePath, std::reference_wrapper<const Field>>;
+using Inst =
+    std::variant<PopTypePath, Repeat, std::reference_wrapper<const Field>>;
 using Processor = void (*)(result::Element&,
                            std::function<void(Inst)>,
                            ParsedData);
@@ -41,6 +43,14 @@ using ProcessorInst = std::pair<types::dy::Dynamic, Processor>;
 
 struct PopTypePath {};
 
+struct Repeat {
+  constexpr Repeat(size_t n_, const Field& field_) : n(n_), field(field_) {
+  }
+
+  size_t n;
+  std::reference_wrapper<const Field> field;
+};
+
 struct Field {
   template <size_t N0, size_t N1, size_t N2>
   constexpr Field(size_t static_size_,
diff --git a/oi/IntrospectionResult.cpp b/oi/IntrospectionResult.cpp
index e44d740..bc6cf22 100644
--- a/oi/IntrospectionResult.cpp
+++ b/oi/IntrospectionResult.cpp
@@ -44,6 +44,12 @@ IntrospectionResult::const_iterator::operator++() {
           type_path_.pop_back();
           dynamic_type_path_.pop_back();
           return operator++();
+        } else if constexpr (std::is_same_v<U, exporters::inst::Repeat>) {
+          if (r.n-- != 0) {
+            stack_.emplace(r);
+            stack_.emplace(r.field);
+          }
+          return operator++();
         } else {
           // reference wrapper
           auto ty = r.get();
diff --git a/types/seq_type.toml b/types/seq_type.toml
index 495fa7c..1da8fd6 100644
--- a/types/seq_type.toml
+++ b/types/seq_type.toml
@@ -101,6 +101,5 @@ auto list = std::get<ParsedData::List>(d.val);
 el.container_stats->length = list.length;
 el.exclusive_size += (el.container_stats->capacity - el.container_stats->length) * sizeof(T0);
 
-for (size_t i = 0; i < list.length; i++)
-  stack_ins(childField);
+stack_ins(inst::Repeat{ list.length, childField });
 """