74 lines
1.1 KiB
C++
74 lines
1.1 KiB
C++
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#ifndef __value_h__
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#define __value_h__
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#include <string>
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#include <cstdint>
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// hold a string and number value.
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struct value {
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public:
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std::string string;
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int32_t number = 0;
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// empty token treated as 0.
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value() : status(valid)
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{}
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value(const value &) = default;
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value(value &&) = default;
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value(int32_t n) :
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string(std::to_string(n)),
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number(n),
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status(valid)
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{}
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value(const std::string &s) : string(s)
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{}
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value(std::string &&s) : string(std::move(s))
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{}
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value &operator=(const value&) = default;
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value &operator=(value &&) = default;
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int32_t to_number() {
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if (status == unknown)
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scan_number();
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if (status == valid) return number;
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expect_number();
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}
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int32_t to_number(int default_value) noexcept {
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if (status == unknown)
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scan_number();
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if (status == valid) return number;
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return default_value;
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}
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bool is_number() noexcept {
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if (status == unknown)
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scan_number();
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return status == valid;
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}
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private:
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[[noreturn]] void expect_number() const;
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void scan_number() noexcept;
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mutable enum {
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unknown,
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valid,
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invalid
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} status = unknown;
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};
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#endif
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