src/tint/utils/strconv/parse_num.cc

// Copyright 2023 The Dawn & Tint Authors
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#include "src/tint/utils/strconv/parse_num.h"

#include <charconv>

#include "absl/strings/charconv.h"
#include "src/utils/compiler.h"

namespace tint::strconv {

namespace {

// The unsafe buffer warnings here are intrinsic to how the underlying API being called operates, so
// cannot be easily avoided.
template <typename T>
Result<T, ParseNumberError> Parse(std::string_view number) {
    T val = 0;
    if constexpr (std::is_floating_point_v<T>) {
        // SAFETY: `number` is a valid string_view, so `number.data()` and `number.data() +
        // number.size()` are valid pointers within bounds.
        auto result = DAWN_UNSAFE_BUFFERS(
            absl::from_chars(number.data(), number.data() + number.size(), val));
        if (result.ec == std::errc::result_out_of_range) {
            return ParseNumberError::kResultOutOfRange;
        }
        // SAFETY: `number` is a valid string_view, so `number.data() + number.size()` is
        // bounds-safe.
        if (result.ec != std::errc() ||
            result.ptr != DAWN_UNSAFE_BUFFERS(number.data() + number.size())) {
            return ParseNumberError::kUnparsable;
        }
    } else {
        // SAFETY: `number` is a valid string_view, so `number.data()` and `number.data() +
        // number.size()` are valid pointers within bounds.
        auto result =
            DAWN_UNSAFE_BUFFERS(std::from_chars(number.data(), number.data() + number.size(), val));
        if (result.ec == std::errc::result_out_of_range) {
            return ParseNumberError::kResultOutOfRange;
        }
        // SAFETY: `number` is a valid string_view, so `number.data() + number.size()` is
        // bounds-safe.
        if (result.ec != std::errc() ||
            result.ptr != DAWN_UNSAFE_BUFFERS(number.data() + number.size())) {
            return ParseNumberError::kUnparsable;
        }
    }
    return val;
}

}  // namespace

Result<float, ParseNumberError> ParseFloat(std::string_view str) {
    return Parse<float>(str);
}

Result<double, ParseNumberError> ParseDouble(std::string_view str) {
    return Parse<double>(str);
}

Result<int, ParseNumberError> ParseInt(std::string_view str) {
    return Parse<int>(str);
}

Result<unsigned int, ParseNumberError> ParseUint(std::string_view str) {
    return Parse<unsigned int>(str);
}

Result<int64_t, ParseNumberError> ParseInt64(std::string_view str) {
    return Parse<int64_t>(str);
}

Result<uint64_t, ParseNumberError> ParseUint64(std::string_view str) {
    return Parse<uint64_t>(str);
}

Result<int32_t, ParseNumberError> ParseInt32(std::string_view str) {
    return Parse<int32_t>(str);
}

Result<uint32_t, ParseNumberError> ParseUint32(std::string_view str) {
    return Parse<uint32_t>(str);
}

Result<int16_t, ParseNumberError> ParseInt16(std::string_view str) {
    return Parse<int16_t>(str);
}

Result<uint16_t, ParseNumberError> ParseUint16(std::string_view str) {
    return Parse<uint16_t>(str);
}

Result<int8_t, ParseNumberError> ParseInt8(std::string_view str) {
    return Parse<int8_t>(str);
}

Result<uint8_t, ParseNumberError> ParseUint8(std::string_view str) {
    return Parse<uint8_t>(str);
}

}  // namespace tint::strconv