From 98b3775297afc10ea054ac3514d6977b263275d3 Mon Sep 17 00:00:00 2001
From: Victor Zverovich <victor.zverovich@gmail.com>
Date: Sun, 12 May 2019 10:03:10 -0700
Subject: [PATCH] Add support for exotic string_view iterators (#1156)

---
 include/fmt/format-inl.h |  2 +-
 include/fmt/format.h     | 14 ++++++++++----
 include/fmt/prepare.h    |  2 +-
 3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/include/fmt/format-inl.h b/include/fmt/format-inl.h
index 2a3d9c8c..29667beb 100644
--- a/include/fmt/format-inl.h
+++ b/include/fmt/format-inl.h
@@ -684,7 +684,7 @@ template <int GRISU_VERSION> struct grisu_shortest_handler {
 
 template <typename Double, FMT_ENABLE_IF_T(sizeof(Double) == sizeof(uint64_t))>
 FMT_API bool grisu_format(Double value, buffer<char>& buf, int precision,
-                           unsigned options, int& exp) {
+                          unsigned options, int& exp) {
   FMT_ASSERT(value >= 0, "value is negative");
   bool fixed = (options & grisu_options::fixed) != 0;
   if (value <= 0) {  // <= instead of == to silence a warning.
diff --git a/include/fmt/format.h b/include/fmt/format.h
index 977310b6..b082b456 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -2207,7 +2207,7 @@ class format_string_checker {
   FMT_CONSTEXPR void on_replacement_field(const Char*) {}
 
   FMT_CONSTEXPR const Char* on_format_specs(const Char* begin, const Char*) {
-    context_.advance_to(begin);
+    advance_to(context_, begin);
     return arg_id_ < NUM_ARGS ? parse_funcs_[arg_id_](context_) : begin;
   }
 
@@ -3215,6 +3215,12 @@ basic_format_context<Range, Char>::arg(basic_string_view<char_type> name) {
   return arg;
 }
 
+template <typename Char, typename ErrorHandler>
+FMT_CONSTEXPR void advance_to(basic_parse_context<Char, ErrorHandler>& ctx,
+                              const Char* p) {
+  ctx.advance_to(ctx.begin() + (p - &*ctx.begin()));
+}
+
 template <typename ArgFormatter, typename Char, typename Context>
 struct format_handler : internal::error_handler {
   typedef typename ArgFormatter::range range;
@@ -3242,7 +3248,7 @@ struct format_handler : internal::error_handler {
   void on_arg_id(basic_string_view<Char> id) { arg = context.arg(id); }
 
   void on_replacement_field(const Char* p) {
-    parse_context.advance_to(p);
+    advance_to(parse_context, p);
     internal::custom_formatter<Context> f(parse_context, context);
     if (!visit_format_arg(f, arg))
       context.advance_to(
@@ -3250,7 +3256,7 @@ struct format_handler : internal::error_handler {
   }
 
   const Char* on_format_specs(const Char* begin, const Char* end) {
-    parse_context.advance_to(begin);
+    advance_to(parse_context, begin);
     internal::custom_formatter<Context> f(parse_context, context);
     if (visit_format_arg(f, arg)) return parse_context.begin();
     basic_format_specs<Char> specs;
@@ -3261,7 +3267,7 @@ struct format_handler : internal::error_handler {
         arg.type());
     begin = parse_format_specs(begin, end, handler);
     if (begin == end || *begin != '}') on_error("missing '}' in format string");
-    parse_context.advance_to(begin);
+    advance_to(parse_context, begin);
     context.advance_to(
         visit_format_arg(ArgFormatter(context, &parse_context, &specs), arg));
     return begin;
diff --git a/include/fmt/prepare.h b/include/fmt/prepare.h
index bfa7d816..6435fb77 100644
--- a/include/fmt/prepare.h
+++ b/include/fmt/prepare.h
@@ -310,7 +310,7 @@ class prepared_format {
       const format_part_t& part) const {
     const auto view = to_string_view(format_);
     const auto specification_begin = view.data() + part.end_of_argument_id;
-    parse_ctx.advance_to(specification_begin);
+    advance_to(parse_ctx, specification_begin);
   }
 
   template <typename Range, typename Context, typename Id>