Add preliminary user-defined type support
This commit is contained in:
Victor Zverovich
parent
5d48733596
commit
4faadff0a0
@ -1,172 +1,16 @@
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// Formatting library for C++ - scanning API proof of concept
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// Formatting library for C++ - scanning API test
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//
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// Copyright (c) 2012 - present, Victor Zverovich
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// Copyright (c) 2019 - present, Victor Zverovich
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// All rights reserved.
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//
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// For the license information refer to format.h.
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#include <array>
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#include <time.h>
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#include <climits>
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#include "fmt/format.h"
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#include "gmock.h"
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#include "gtest-extra.h"
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FMT_BEGIN_NAMESPACE
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namespace internal {
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enum class scan_type {
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none_type,
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int_type,
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uint_type,
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long_long_type,
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ulong_long_type,
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string_type,
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string_view_type
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};
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struct scan_arg {
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scan_type arg_type;
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union {
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int* int_value;
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unsigned* uint_value;
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long long* long_long_value;
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unsigned long long* ulong_long_value;
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std::string* string;
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fmt::string_view* string_view;
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// TODO: more types
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};
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scan_arg() : arg_type(scan_type::none_type) {}
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scan_arg(int& value) : arg_type(scan_type::int_type), int_value(&value) {}
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scan_arg(unsigned& value)
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: arg_type(scan_type::uint_type), uint_value(&value) {}
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scan_arg(long long& value)
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: arg_type(scan_type::long_long_type), long_long_value(&value) {}
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scan_arg(unsigned long long& value)
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: arg_type(scan_type::ulong_long_type), ulong_long_value(&value) {}
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scan_arg(std::string& value)
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: arg_type(scan_type::string_type), string(&value) {}
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scan_arg(fmt::string_view& value)
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: arg_type(scan_type::string_view_type), string_view(&value) {}
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};
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} // namespace internal
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struct scan_args {
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int size;
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const internal::scan_arg* data;
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template <size_t N>
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scan_args(const std::array<internal::scan_arg, N>& store)
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: size(N), data(store.data()) {
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static_assert(N < INT_MAX, "too many arguments");
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}
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};
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namespace internal {
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struct scan_handler : error_handler {
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private:
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const char* begin_;
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const char* end_;
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scan_args args_;
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int next_arg_id_;
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scan_arg arg_;
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template <typename T = unsigned> T read_uint() {
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T value = 0;
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while (begin_ != end_) {
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char c = *begin_++;
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if (c < '0' || c > '9') on_error("invalid input");
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// TODO: check overflow
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value = value * 10 + (c - '0');
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}
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return value;
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}
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template <typename T = int> T read_int() {
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T value = 0;
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bool negative = begin_ != end_ && *begin_ == '-';
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if (negative) ++begin_;
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value = read_uint<typename std::make_unsigned<T>::type>();
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if (negative) value = -value;
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return value;
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}
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public:
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scan_handler(string_view input, scan_args args)
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: begin_(input.data()),
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end_(begin_ + input.size()),
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args_(args),
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next_arg_id_(0) {}
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const char* pos() const { return begin_; }
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void on_text(const char* begin, const char* end) {
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auto size = end - begin;
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if (begin_ + size > end_ || !std::equal(begin, end, begin_))
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on_error("invalid input");
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begin_ += size;
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}
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void on_arg_id() {
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if (next_arg_id_ >= args_.size) on_error("argument index out of range");
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arg_ = args_.data[next_arg_id_++];
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}
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void on_arg_id(unsigned) { on_error("invalid format"); }
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void on_arg_id(string_view) { on_error("invalid format"); }
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void on_replacement_field(const char*) {
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switch (arg_.arg_type) {
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case scan_type::int_type:
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*arg_.int_value = read_int();
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break;
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case scan_type::uint_type:
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*arg_.uint_value = read_uint();
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break;
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case scan_type::long_long_type:
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*arg_.long_long_value = read_int<long long>();
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break;
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case scan_type::ulong_long_type:
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*arg_.ulong_long_value = read_uint<unsigned long long>();
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break;
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case scan_type::string_type:
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while (begin_ != end_ && *begin_ != ' ')
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arg_.string->push_back(*begin_++);
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break;
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case scan_type::string_view_type: {
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auto s = begin_;
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while (begin_ != end_ && *begin_ != ' ')
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++begin_;
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*arg_.string_view = fmt::string_view(s, begin_ - s);
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break;
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}
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default:
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assert(false);
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}
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}
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const char* on_format_specs(const char* begin, const char*) { return begin; }
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};
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} // namespace internal
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template <typename... Args>
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std::array<internal::scan_arg, sizeof...(Args)> make_scan_args(Args&... args) {
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return std::array<internal::scan_arg, sizeof...(Args)>{args...};
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}
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string_view::iterator vscan(string_view input, string_view format_str,
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scan_args args) {
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internal::scan_handler h(input, args);
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internal::parse_format_string<false>(format_str, h);
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return input.begin() + (h.pos() - &*input.begin());
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}
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template <typename... Args>
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string_view::iterator scan(string_view input, string_view format_str,
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Args&... args) {
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return vscan(input, format_str, make_scan_args(args...));
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}
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FMT_END_NAMESPACE
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#include "scan.h"
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TEST(ScanTest, ReadText) {
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fmt::string_view s = "foo";
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@ -219,6 +63,41 @@ TEST(ScanTest, ReadStringView) {
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EXPECT_EQ(s, "foo");
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}
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#ifndef _WIN32
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namespace fmt {
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template <> struct scanner<tm> {
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std::string format;
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scan_parse_context::iterator parse(scan_parse_context& ctx) {
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auto it = ctx.begin();
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if (it != ctx.end() && *it == ':') ++it;
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auto end = it;
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while (end != ctx.end() && *end != '}') ++end;
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format.reserve(internal::to_unsigned(end - it + 1));
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format.append(it, end);
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format.push_back('\0');
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return end;
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}
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template <class ScanContext>
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typename ScanContext::iterator scan(tm& t, ScanContext& ctx) {
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auto result = strptime(ctx.begin(), format.c_str(), &t);
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if (!result) throw format_error("failed to parse time");
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return result;
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}
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};
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} // namespace fmt
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TEST(ScanTest, ReadCustom) {
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const char* input = "Date: 1985-10-25";
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auto t = tm();
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fmt::scan(input, "Date: {0:%Y-%m-%d}", t);
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EXPECT_EQ(t.tm_year, 85);
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EXPECT_EQ(t.tm_mon, 9);
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EXPECT_EQ(t.tm_mday, 25);
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}
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#endif
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TEST(ScanTest, InvalidFormat) {
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EXPECT_THROW_MSG(fmt::scan("", "{}"), fmt::format_error,
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"argument index out of range");
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233
test/scan.h
Normal file
233
test/scan.h
Normal file
@ -0,0 +1,233 @@
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// Formatting library for C++ - scanning API proof of concept
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//
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// Copyright (c) 2019 - present, Victor Zverovich
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// All rights reserved.
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//
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// For the license information refer to format.h.
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#include <array>
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#include "fmt/format.h"
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FMT_BEGIN_NAMESPACE
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template <typename T, typename Char = char> struct scanner {
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// A deleted default constructor indicates a disabled scanner.
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scanner() = delete;
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};
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class scan_parse_context {
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private:
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string_view format_;
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public:
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using iterator = string_view::iterator;
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explicit FMT_CONSTEXPR scan_parse_context(string_view format)
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: format_(format) {}
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FMT_CONSTEXPR iterator begin() const { return format_.begin(); }
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FMT_CONSTEXPR iterator end() const { return format_.end(); }
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void advance_to(iterator it) {
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format_.remove_prefix(internal::to_unsigned(it - begin()));
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}
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};
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struct scan_context {
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private:
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string_view input_;
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public:
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using iterator = const char*;
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explicit scan_context(string_view input) : input_(input) {}
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iterator begin() const { return input_.data(); }
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iterator end() const { return begin() + input_.size(); }
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void advance_to(iterator it) {
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input_.remove_prefix(internal::to_unsigned(it - begin()));
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}
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};
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namespace internal {
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enum class scan_type {
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none_type,
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int_type,
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uint_type,
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long_long_type,
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ulong_long_type,
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string_type,
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string_view_type,
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custom_type
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};
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struct custom_scan_arg {
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void* value;
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void (*scan)(void* arg, scan_parse_context& parse_ctx, scan_context& ctx);
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};
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class scan_arg {
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public:
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scan_type type;
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union {
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int* int_value;
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unsigned* uint_value;
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long long* long_long_value;
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unsigned long long* ulong_long_value;
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std::string* string;
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fmt::string_view* string_view;
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custom_scan_arg custom;
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// TODO: more types
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};
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scan_arg() : type(scan_type::none_type) {}
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scan_arg(int& value) : type(scan_type::int_type), int_value(&value) {}
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scan_arg(unsigned& value) : type(scan_type::uint_type), uint_value(&value) {}
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scan_arg(long long& value)
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: type(scan_type::long_long_type), long_long_value(&value) {}
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scan_arg(unsigned long long& value)
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: type(scan_type::ulong_long_type), ulong_long_value(&value) {}
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scan_arg(std::string& value) : type(scan_type::string_type), string(&value) {}
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scan_arg(fmt::string_view& value)
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: type(scan_type::string_view_type), string_view(&value) {}
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template <typename T> scan_arg(T& value) : type(scan_type::custom_type) {
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custom.value = &value;
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custom.scan = scan_custom_arg<T>;
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}
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private:
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template <typename T>
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static void scan_custom_arg(void* arg, scan_parse_context& parse_ctx,
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scan_context& ctx) {
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scanner<T> s;
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parse_ctx.advance_to(s.parse(parse_ctx));
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ctx.advance_to(s.scan(*static_cast<T*>(arg), ctx));
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}
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};
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} // namespace internal
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struct scan_args {
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int size;
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const internal::scan_arg* data;
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template <size_t N>
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scan_args(const std::array<internal::scan_arg, N>& store)
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: size(N), data(store.data()) {
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static_assert(N < INT_MAX, "too many arguments");
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}
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};
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namespace internal {
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struct scan_handler : error_handler {
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private:
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scan_parse_context parse_ctx_;
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scan_context scan_ctx_;
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scan_args args_;
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int next_arg_id_;
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scan_arg arg_;
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template <typename T = unsigned> T read_uint() {
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T value = 0;
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auto it = scan_ctx_.begin(), end = scan_ctx_.end();
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while (it != end) {
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char c = *it++;
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if (c < '0' || c > '9') on_error("invalid input");
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// TODO: check overflow
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value = value * 10 + (c - '0');
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}
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scan_ctx_.advance_to(it);
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return value;
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}
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template <typename T = int> T read_int() {
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T value = 0;
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auto it = scan_ctx_.begin(), end = scan_ctx_.end();
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bool negative = it != end && *it == '-';
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if (negative) ++it;
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scan_ctx_.advance_to(it);
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value = read_uint<typename std::make_unsigned<T>::type>();
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if (negative) value = -value;
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return value;
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}
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public:
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scan_handler(string_view format, string_view input, scan_args args)
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: parse_ctx_(format), scan_ctx_(input), args_(args), next_arg_id_(0) {}
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const char* pos() const { return scan_ctx_.begin(); }
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void on_text(const char* begin, const char* end) {
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auto size = end - begin;
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auto it = scan_ctx_.begin();
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if (it + size > scan_ctx_.end() || !std::equal(begin, end, it))
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on_error("invalid input");
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scan_ctx_.advance_to(it + size);
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}
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void on_arg_id() { on_arg_id(next_arg_id_++); }
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void on_arg_id(unsigned id) {
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if (id >= args_.size) on_error("argument index out of range");
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arg_ = args_.data[id];
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}
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void on_arg_id(string_view) { on_error("invalid format"); }
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void on_replacement_field(const char*) {
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auto it = scan_ctx_.begin(), end = scan_ctx_.end();
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switch (arg_.type) {
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case scan_type::int_type:
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*arg_.int_value = read_int();
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break;
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case scan_type::uint_type:
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*arg_.uint_value = read_uint();
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break;
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case scan_type::long_long_type:
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*arg_.long_long_value = read_int<long long>();
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break;
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case scan_type::ulong_long_type:
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*arg_.ulong_long_value = read_uint<unsigned long long>();
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break;
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case scan_type::string_type:
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while (it != end && *it != ' ') arg_.string->push_back(*it++);
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scan_ctx_.advance_to(it);
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break;
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case scan_type::string_view_type: {
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auto s = it;
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while (it != end && *it != ' ') ++it;
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*arg_.string_view = fmt::string_view(s, it - s);
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scan_ctx_.advance_to(it);
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break;
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}
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default:
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assert(false);
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}
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}
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const char* on_format_specs(const char* begin, const char*) {
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if (arg_.type != scan_type::custom_type) return begin;
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parse_ctx_.advance_to(begin);
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arg_.custom.scan(arg_.custom.value, parse_ctx_, scan_ctx_);
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return parse_ctx_.begin();
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}
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};
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} // namespace internal
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template <typename... Args>
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std::array<internal::scan_arg, sizeof...(Args)> make_scan_args(Args&... args) {
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return std::array<internal::scan_arg, sizeof...(Args)>{args...};
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}
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string_view::iterator vscan(string_view input, string_view format_str,
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scan_args args) {
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internal::scan_handler h(format_str, input, args);
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internal::parse_format_string<false>(format_str, h);
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return input.begin() + (h.pos() - &*input.begin());
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}
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template <typename... Args>
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string_view::iterator scan(string_view input, string_view format_str,
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Args&... args) {
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return vscan(input, format_str, make_scan_args(args...));
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}
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FMT_END_NAMESPACE
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