From 01c631af9587668a3359980f24a7eacc1102ed16 Mon Sep 17 00:00:00 2001
From: Victor Zverovich <victor.zverovich@gmail.com>
Date: Sun, 19 May 2019 07:02:41 -0700
Subject: [PATCH] Implement unsigned and long long parsing

---
 test/scan-test.cc | 147 +++++++++++++++++++++++++++++++++++++---------
 1 file changed, 118 insertions(+), 29 deletions(-)

diff --git a/test/scan-test.cc b/test/scan-test.cc
index 5d9fcce0..42417748 100644
--- a/test/scan-test.cc
+++ b/test/scan-test.cc
@@ -15,8 +15,22 @@
 FMT_BEGIN_NAMESPACE
 namespace internal {
 struct scan_arg {
-  int* value;
-  // TODO: more types
+  type arg_type;
+  union {
+    int* int_value;
+    unsigned* uint_value;
+    long long* long_long_value;
+    unsigned long long* ulong_long_value;
+    // TODO: more types
+  };
+
+  scan_arg() : arg_type(none_type) {}
+  scan_arg(int& value) : arg_type(int_type), int_value(&value) {}
+  scan_arg(unsigned& value) : arg_type(uint_type), uint_value(&value) {}
+  scan_arg(long long& value)
+      : arg_type(long_long_type), long_long_value(&value) {}
+  scan_arg(unsigned long long& value)
+      : arg_type(ulong_long_type), ulong_long_value(&value) {}
 };
 }  // namespace internal
 
@@ -32,62 +46,137 @@ struct scan_args {
 };
 
 namespace internal {
+
 struct scan_handler : error_handler {
-  const char* begin;
-  const char* end;
-  scan_args args;
-  int next_arg_id;
+ private:
+  const char* begin_;
+  const char* end_;
+  scan_args args_;
+  int next_arg_id_;
+  scan_arg arg_;
 
+  template <typename T = unsigned> T read_uint() {
+    T value = 0;
+    while (begin_ != end_) {
+      char c = *begin_++;
+      if (c < '0' || c > '9') on_error("invalid input");
+      // TODO: check overflow
+      value = value * 10 + (c - '0');
+    }
+    return value;
+  }
+
+  template <typename T = int> T read_int() {
+    T value = 0;
+    bool negative = begin_ != end_ && *begin_ == '-';
+    if (negative) ++begin_;
+    value = read_uint<typename std::make_unsigned<T>::type>();
+    if (negative) value = -value;
+    return value;
+  }
+
+ public:
   scan_handler(string_view input, scan_args args)
-      : begin(input.data()),
-        end(begin + input.size()),
-        args(args),
-        next_arg_id(0) {}
+      : begin_(input.data()),
+        end_(begin_ + input.size()),
+        args_(args),
+        next_arg_id_(0) {}
 
-  void on_text(const char*, const char*) { on_error("invalid format"); }
+  const char* pos() const { return begin_; }
+
+  void on_text(const char* begin, const char* end) {
+    auto size = end - begin;
+    if (begin_ + size > end_ || !std::equal(begin, end, begin_))
+      on_error("invalid input");
+    begin_ += size;
+  }
 
   void on_arg_id() {
-    if (next_arg_id >= args.size) on_error("argument index out of range");
+    if (next_arg_id_ >= args_.size) on_error("argument index out of range");
+    arg_ = args_.data[next_arg_id_++];
   }
   void on_arg_id(unsigned) { on_error("invalid format"); }
   void on_arg_id(string_view) { on_error("invalid format"); }
 
   void on_replacement_field(const char*) {
-    int value = 0;
-    while (begin != end) {
-      char c = *begin++;
-      if (c < '0' || c > '9') on_error("invalid input");
-      value = value * 10 + (c - '0');
+    switch (arg_.arg_type) {
+    case int_type:
+      *arg_.int_value = read_int();
+      break;
+    case uint_type:
+      *arg_.uint_value = read_uint();
+      break;
+    case long_long_type:
+      *arg_.long_long_value = read_int<long long>();
+      break;
+    case ulong_long_type:
+      *arg_.ulong_long_value = read_uint<unsigned long long>();
+      break;
+    default:
+      assert(false);
     }
-    *args.data[0].value = value;
   }
 
-  const char* on_format_specs(const char* begin, const char*) {
-    return begin;
-  }
+  const char* on_format_specs(const char* begin, const char*) { return begin; }
 };
 }  // namespace internal
 
-void vscan(string_view input, string_view format_str, scan_args args) {
-  internal::parse_format_string<false>(format_str,
-                                       internal::scan_handler(input, args));
-}
-
 template <typename... Args>
 std::array<internal::scan_arg, sizeof...(Args)> make_scan_args(Args&... args) {
-  return std::array<internal::scan_arg, sizeof...(Args)>{&args...};
+  return std::array<internal::scan_arg, sizeof...(Args)>{args...};
+}
+
+string_view::iterator vscan(string_view input, string_view format_str,
+                            scan_args args) {
+  internal::scan_handler h(input, args);
+  internal::parse_format_string<false>(format_str, h);
+  return input.begin() + (h.pos() - &*input.begin());
 }
 
 template <typename... Args>
-void scan(string_view input, string_view format_str, Args&... args) {
-  vscan(input, format_str, make_scan_args(args...));
+string_view::iterator scan(string_view input, string_view format_str,
+                           Args&... args) {
+  return vscan(input, format_str, make_scan_args(args...));
 }
 FMT_END_NAMESPACE
 
+TEST(ScanTest, ReadText) {
+  fmt::string_view s = "foo";
+  auto end = fmt::scan(s, "foo");
+  EXPECT_EQ(end, s.end());
+  EXPECT_THROW_MSG(fmt::scan("fob", "foo"), fmt::format_error, "invalid input");
+}
+
 TEST(ScanTest, ReadInt) {
   int n = 0;
   fmt::scan("42", "{}", n);
   EXPECT_EQ(n, 42);
+  fmt::scan("-42", "{}", n);
+  EXPECT_EQ(n, -42);
+}
+
+TEST(ScanTest, ReadLongLong) {
+  long long n = 0;
+  fmt::scan("42", "{}", n);
+  EXPECT_EQ(n, 42);
+  fmt::scan("-42", "{}", n);
+  EXPECT_EQ(n, -42);
+}
+
+TEST(ScanTest, ReadUInt) {
+  unsigned n = 0;
+  fmt::scan("42", "{}", n);
+  EXPECT_EQ(n, 42);
+  EXPECT_THROW_MSG(fmt::scan("-42", "{}", n), fmt::format_error,
+                   "invalid input");
+}
+
+TEST(ScanTest, ReadULongLong) {
+  unsigned long long n = 0;
+  fmt::scan("42", "{}", n);
+  EXPECT_EQ(n, 42);
+  EXPECT_THROW_MSG(fmt::scan("-42", "{}", n), fmt::format_error,
+                   "invalid input");
 }
 
 TEST(ScanTest, InvalidFormat) {