mirror of
https://github.com/nlohmann/json.git
synced 2024-12-12 12:09:08 +08:00
1278 lines
40 KiB
C++
1278 lines
40 KiB
C++
#pragma once
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#include <clocale> // localeconv
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#include <cstddef> // size_t
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#include <cstdlib> // strtof, strtod, strtold, strtoll, strtoull
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#include <initializer_list> // initializer_list
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#include <ios> // hex, uppercase
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#include <iomanip> // setw, setfill
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#include <sstream> // stringstream
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#include <string> // char_traits, string
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#include <vector> // vector
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#include <nlohmann/detail/macro_scope.hpp>
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#include <nlohmann/detail/input/input_adapters.hpp>
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namespace nlohmann
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{
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namespace detail
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{
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///////////
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// lexer //
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///////////
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/*!
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@brief lexical analysis
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This class organizes the lexical analysis during JSON deserialization.
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*/
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template<typename BasicJsonType>
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class lexer
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{
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using number_integer_t = typename BasicJsonType::number_integer_t;
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using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
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using number_float_t = typename BasicJsonType::number_float_t;
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public:
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/// token types for the parser
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enum class token_type
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{
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uninitialized, ///< indicating the scanner is uninitialized
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literal_true, ///< the `true` literal
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literal_false, ///< the `false` literal
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literal_null, ///< the `null` literal
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value_string, ///< a string -- use get_string() for actual value
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value_unsigned, ///< an unsigned integer -- use get_number_unsigned() for actual value
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value_integer, ///< a signed integer -- use get_number_integer() for actual value
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value_float, ///< an floating point number -- use get_number_float() for actual value
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begin_array, ///< the character for array begin `[`
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begin_object, ///< the character for object begin `{`
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end_array, ///< the character for array end `]`
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end_object, ///< the character for object end `}`
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name_separator, ///< the name separator `:`
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value_separator, ///< the value separator `,`
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parse_error, ///< indicating a parse error
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end_of_input, ///< indicating the end of the input buffer
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literal_or_value ///< a literal or the begin of a value (only for diagnostics)
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};
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/// return name of values of type token_type (only used for errors)
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static const char* token_type_name(const token_type t) noexcept
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{
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switch (t)
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{
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case token_type::uninitialized:
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return "<uninitialized>";
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case token_type::literal_true:
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return "true literal";
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case token_type::literal_false:
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return "false literal";
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case token_type::literal_null:
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return "null literal";
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case token_type::value_string:
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return "string literal";
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case lexer::token_type::value_unsigned:
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case lexer::token_type::value_integer:
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case lexer::token_type::value_float:
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return "number literal";
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case token_type::begin_array:
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return "'['";
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case token_type::begin_object:
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return "'{'";
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case token_type::end_array:
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return "']'";
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case token_type::end_object:
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return "'}'";
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case token_type::name_separator:
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return "':'";
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case token_type::value_separator:
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return "','";
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case token_type::parse_error:
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return "<parse error>";
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case token_type::end_of_input:
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return "end of input";
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case token_type::literal_or_value:
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return "'[', '{', or a literal";
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default: // catch non-enum values
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return "unknown token"; // LCOV_EXCL_LINE
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}
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}
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explicit lexer(detail::input_adapter_t adapter)
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: ia(std::move(adapter)), decimal_point_char(get_decimal_point()) {}
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// delete because of pointer members
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lexer(const lexer&) = delete;
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lexer& operator=(lexer&) = delete;
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private:
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/////////////////////
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// locales
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/////////////////////
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/// return the locale-dependent decimal point
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static char get_decimal_point() noexcept
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{
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const auto loc = localeconv();
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assert(loc != nullptr);
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return (loc->decimal_point == nullptr) ? '.' : *(loc->decimal_point);
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}
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/////////////////////
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// scan functions
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/////////////////////
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/*!
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@brief get codepoint from 4 hex characters following `\u`
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For input "\u c1 c2 c3 c4" the codepoint is:
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(c1 * 0x1000) + (c2 * 0x0100) + (c3 * 0x0010) + c4
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= (c1 << 12) + (c2 << 8) + (c3 << 4) + (c4 << 0)
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Furthermore, the possible characters '0'..'9', 'A'..'F', and 'a'..'f'
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must be converted to the integers 0x0..0x9, 0xA..0xF, 0xA..0xF, resp. The
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conversion is done by subtracting the offset (0x30, 0x37, and 0x57)
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between the ASCII value of the character and the desired integer value.
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@return codepoint (0x0000..0xFFFF) or -1 in case of an error (e.g. EOF or
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non-hex character)
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*/
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int get_codepoint()
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{
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// this function only makes sense after reading `\u`
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assert(current == 'u');
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int codepoint = 0;
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const auto factors = { 12, 8, 4, 0 };
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for (const auto factor : factors)
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{
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get();
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if (current >= '0' and current <= '9')
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{
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codepoint += ((current - 0x30) << factor);
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}
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else if (current >= 'A' and current <= 'F')
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{
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codepoint += ((current - 0x37) << factor);
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}
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else if (current >= 'a' and current <= 'f')
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{
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codepoint += ((current - 0x57) << factor);
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}
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else
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{
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return -1;
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}
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}
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assert(0x0000 <= codepoint and codepoint <= 0xFFFF);
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return codepoint;
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}
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/*!
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@brief check if the next byte(s) are inside a given range
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Adds the current byte and, for each passed range, reads a new byte and
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checks if it is inside the range. If a violation was detected, set up an
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error message and return false. Otherwise, return true.
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@param[in] ranges list of integers; interpreted as list of pairs of
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inclusive lower and upper bound, respectively
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@pre The passed list @a ranges must have 2, 4, or 6 elements; that is,
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1, 2, or 3 pairs. This precondition is enforced by an assertion.
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@return true if and only if no range violation was detected
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*/
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bool next_byte_in_range(std::initializer_list<int> ranges)
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{
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assert(ranges.size() == 2 or ranges.size() == 4 or ranges.size() == 6);
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add(current);
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for (auto range = ranges.begin(); range != ranges.end(); ++range)
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{
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get();
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if (JSON_LIKELY(*range <= current and current <= *(++range)))
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{
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add(current);
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}
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else
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{
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error_message = "invalid string: ill-formed UTF-8 byte";
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return false;
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}
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}
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return true;
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}
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/*!
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@brief scan a string literal
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This function scans a string according to Sect. 7 of RFC 7159. While
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scanning, bytes are escaped and copied into buffer token_buffer. Then the
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function returns successfully, token_buffer is *not* null-terminated (as it
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may contain \0 bytes), and token_buffer.size() is the number of bytes in the
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string.
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@return token_type::value_string if string could be successfully scanned,
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token_type::parse_error otherwise
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@note In case of errors, variable error_message contains a textual
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description.
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*/
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token_type scan_string()
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{
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// reset token_buffer (ignore opening quote)
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reset();
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// we entered the function by reading an open quote
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assert(current == '\"');
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while (true)
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{
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// get next character
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switch (get())
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{
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// end of file while parsing string
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case std::char_traits<char>::eof():
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{
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error_message = "invalid string: missing closing quote";
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return token_type::parse_error;
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}
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// closing quote
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case '\"':
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{
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return token_type::value_string;
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}
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// escapes
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case '\\':
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{
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switch (get())
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{
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// quotation mark
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case '\"':
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add('\"');
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break;
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// reverse solidus
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case '\\':
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add('\\');
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break;
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// solidus
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case '/':
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add('/');
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break;
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// backspace
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case 'b':
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add('\b');
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break;
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// form feed
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case 'f':
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add('\f');
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break;
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// line feed
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case 'n':
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add('\n');
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break;
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// carriage return
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case 'r':
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add('\r');
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break;
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// tab
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case 't':
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add('\t');
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break;
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// unicode escapes
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case 'u':
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{
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const int codepoint1 = get_codepoint();
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int codepoint = codepoint1; // start with codepoint1
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if (JSON_UNLIKELY(codepoint1 == -1))
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{
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error_message = "invalid string: '\\u' must be followed by 4 hex digits";
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return token_type::parse_error;
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}
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// check if code point is a high surrogate
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if (0xD800 <= codepoint1 and codepoint1 <= 0xDBFF)
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{
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// expect next \uxxxx entry
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if (JSON_LIKELY(get() == '\\' and get() == 'u'))
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{
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const int codepoint2 = get_codepoint();
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if (JSON_UNLIKELY(codepoint2 == -1))
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{
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error_message = "invalid string: '\\u' must be followed by 4 hex digits";
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return token_type::parse_error;
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}
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// check if codepoint2 is a low surrogate
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if (JSON_LIKELY(0xDC00 <= codepoint2 and codepoint2 <= 0xDFFF))
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{
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// overwrite codepoint
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codepoint =
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// high surrogate occupies the most significant 22 bits
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(codepoint1 << 10)
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// low surrogate occupies the least significant 15 bits
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+ codepoint2
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// there is still the 0xD800, 0xDC00 and 0x10000 noise
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// in the result so we have to subtract with:
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// (0xD800 << 10) + DC00 - 0x10000 = 0x35FDC00
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- 0x35FDC00;
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}
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else
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{
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error_message = "invalid string: surrogate U+DC00..U+DFFF must be followed by U+DC00..U+DFFF";
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return token_type::parse_error;
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}
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}
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else
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{
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error_message = "invalid string: surrogate U+DC00..U+DFFF must be followed by U+DC00..U+DFFF";
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return token_type::parse_error;
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}
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}
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else
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{
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if (JSON_UNLIKELY(0xDC00 <= codepoint1 and codepoint1 <= 0xDFFF))
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{
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error_message = "invalid string: surrogate U+DC00..U+DFFF must follow U+D800..U+DBFF";
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return token_type::parse_error;
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}
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}
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// result of the above calculation yields a proper codepoint
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assert(0x00 <= codepoint and codepoint <= 0x10FFFF);
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// translate codepoint into bytes
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if (codepoint < 0x80)
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{
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// 1-byte characters: 0xxxxxxx (ASCII)
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add(codepoint);
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}
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else if (codepoint <= 0x7FF)
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{
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// 2-byte characters: 110xxxxx 10xxxxxx
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add(0xC0 | (codepoint >> 6));
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add(0x80 | (codepoint & 0x3F));
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}
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else if (codepoint <= 0xFFFF)
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{
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// 3-byte characters: 1110xxxx 10xxxxxx 10xxxxxx
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add(0xE0 | (codepoint >> 12));
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add(0x80 | ((codepoint >> 6) & 0x3F));
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add(0x80 | (codepoint & 0x3F));
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}
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else
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{
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// 4-byte characters: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
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add(0xF0 | (codepoint >> 18));
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add(0x80 | ((codepoint >> 12) & 0x3F));
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add(0x80 | ((codepoint >> 6) & 0x3F));
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add(0x80 | (codepoint & 0x3F));
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}
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break;
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}
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// other characters after escape
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default:
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error_message = "invalid string: forbidden character after backslash";
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return token_type::parse_error;
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}
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break;
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}
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// invalid control characters
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case 0x00:
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case 0x01:
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case 0x02:
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case 0x03:
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case 0x04:
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case 0x05:
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case 0x06:
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case 0x07:
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case 0x08:
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case 0x09:
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case 0x0A:
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case 0x0B:
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case 0x0C:
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case 0x0D:
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case 0x0E:
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case 0x0F:
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case 0x10:
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case 0x11:
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case 0x12:
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case 0x13:
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case 0x14:
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case 0x15:
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case 0x16:
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case 0x17:
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case 0x18:
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case 0x19:
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case 0x1A:
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case 0x1B:
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case 0x1C:
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case 0x1D:
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case 0x1E:
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case 0x1F:
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{
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error_message = "invalid string: control character must be escaped";
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return token_type::parse_error;
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}
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// U+0020..U+007F (except U+0022 (quote) and U+005C (backspace))
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case 0x20:
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case 0x21:
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case 0x23:
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case 0x24:
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case 0x25:
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case 0x26:
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case 0x27:
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case 0x28:
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case 0x29:
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case 0x2A:
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case 0x2B:
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case 0x2C:
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case 0x2D:
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case 0x2E:
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case 0x2F:
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case 0x30:
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case 0x31:
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case 0x32:
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case 0x33:
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case 0x34:
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case 0x35:
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case 0x36:
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case 0x37:
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case 0x38:
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case 0x39:
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case 0x3A:
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case 0x3B:
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case 0x3C:
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case 0x3D:
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case 0x3E:
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case 0x3F:
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case 0x40:
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case 0x41:
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case 0x42:
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case 0x43:
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case 0x44:
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case 0x45:
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case 0x46:
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case 0x47:
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case 0x48:
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case 0x49:
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case 0x4A:
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case 0x4B:
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case 0x4C:
|
|
case 0x4D:
|
|
case 0x4E:
|
|
case 0x4F:
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|
case 0x50:
|
|
case 0x51:
|
|
case 0x52:
|
|
case 0x53:
|
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case 0x54:
|
|
case 0x55:
|
|
case 0x56:
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case 0x57:
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case 0x58:
|
|
case 0x59:
|
|
case 0x5A:
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|
case 0x5B:
|
|
case 0x5D:
|
|
case 0x5E:
|
|
case 0x5F:
|
|
case 0x60:
|
|
case 0x61:
|
|
case 0x62:
|
|
case 0x63:
|
|
case 0x64:
|
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case 0x65:
|
|
case 0x66:
|
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case 0x67:
|
|
case 0x68:
|
|
case 0x69:
|
|
case 0x6A:
|
|
case 0x6B:
|
|
case 0x6C:
|
|
case 0x6D:
|
|
case 0x6E:
|
|
case 0x6F:
|
|
case 0x70:
|
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case 0x71:
|
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case 0x72:
|
|
case 0x73:
|
|
case 0x74:
|
|
case 0x75:
|
|
case 0x76:
|
|
case 0x77:
|
|
case 0x78:
|
|
case 0x79:
|
|
case 0x7A:
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|
case 0x7B:
|
|
case 0x7C:
|
|
case 0x7D:
|
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case 0x7E:
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case 0x7F:
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{
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add(current);
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break;
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}
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// U+0080..U+07FF: bytes C2..DF 80..BF
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case 0xC2:
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case 0xC3:
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case 0xC4:
|
|
case 0xC5:
|
|
case 0xC6:
|
|
case 0xC7:
|
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case 0xC8:
|
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case 0xC9:
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|
case 0xCA:
|
|
case 0xCB:
|
|
case 0xCC:
|
|
case 0xCD:
|
|
case 0xCE:
|
|
case 0xCF:
|
|
case 0xD0:
|
|
case 0xD1:
|
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case 0xD2:
|
|
case 0xD3:
|
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case 0xD4:
|
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case 0xD5:
|
|
case 0xD6:
|
|
case 0xD7:
|
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case 0xD8:
|
|
case 0xD9:
|
|
case 0xDA:
|
|
case 0xDB:
|
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case 0xDC:
|
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case 0xDD:
|
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case 0xDE:
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case 0xDF:
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{
|
|
if (JSON_UNLIKELY(not next_byte_in_range({0x80, 0xBF})))
|
|
{
|
|
return token_type::parse_error;
|
|
}
|
|
break;
|
|
}
|
|
|
|
// U+0800..U+0FFF: bytes E0 A0..BF 80..BF
|
|
case 0xE0:
|
|
{
|
|
if (JSON_UNLIKELY(not (next_byte_in_range({0xA0, 0xBF, 0x80, 0xBF}))))
|
|
{
|
|
return token_type::parse_error;
|
|
}
|
|
break;
|
|
}
|
|
|
|
// U+1000..U+CFFF: bytes E1..EC 80..BF 80..BF
|
|
// U+E000..U+FFFF: bytes EE..EF 80..BF 80..BF
|
|
case 0xE1:
|
|
case 0xE2:
|
|
case 0xE3:
|
|
case 0xE4:
|
|
case 0xE5:
|
|
case 0xE6:
|
|
case 0xE7:
|
|
case 0xE8:
|
|
case 0xE9:
|
|
case 0xEA:
|
|
case 0xEB:
|
|
case 0xEC:
|
|
case 0xEE:
|
|
case 0xEF:
|
|
{
|
|
if (JSON_UNLIKELY(not (next_byte_in_range({0x80, 0xBF, 0x80, 0xBF}))))
|
|
{
|
|
return token_type::parse_error;
|
|
}
|
|
break;
|
|
}
|
|
|
|
// U+D000..U+D7FF: bytes ED 80..9F 80..BF
|
|
case 0xED:
|
|
{
|
|
if (JSON_UNLIKELY(not (next_byte_in_range({0x80, 0x9F, 0x80, 0xBF}))))
|
|
{
|
|
return token_type::parse_error;
|
|
}
|
|
break;
|
|
}
|
|
|
|
// U+10000..U+3FFFF F0 90..BF 80..BF 80..BF
|
|
case 0xF0:
|
|
{
|
|
if (JSON_UNLIKELY(not (next_byte_in_range({0x90, 0xBF, 0x80, 0xBF, 0x80, 0xBF}))))
|
|
{
|
|
return token_type::parse_error;
|
|
}
|
|
break;
|
|
}
|
|
|
|
// U+40000..U+FFFFF F1..F3 80..BF 80..BF 80..BF
|
|
case 0xF1:
|
|
case 0xF2:
|
|
case 0xF3:
|
|
{
|
|
if (JSON_UNLIKELY(not (next_byte_in_range({0x80, 0xBF, 0x80, 0xBF, 0x80, 0xBF}))))
|
|
{
|
|
return token_type::parse_error;
|
|
}
|
|
break;
|
|
}
|
|
|
|
// U+100000..U+10FFFF F4 80..8F 80..BF 80..BF
|
|
case 0xF4:
|
|
{
|
|
if (JSON_UNLIKELY(not (next_byte_in_range({0x80, 0x8F, 0x80, 0xBF, 0x80, 0xBF}))))
|
|
{
|
|
return token_type::parse_error;
|
|
}
|
|
break;
|
|
}
|
|
|
|
// remaining bytes (80..C1 and F5..FF) are ill-formed
|
|
default:
|
|
{
|
|
error_message = "invalid string: ill-formed UTF-8 byte";
|
|
return token_type::parse_error;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
static void strtof(float& f, const char* str, char** endptr) noexcept
|
|
{
|
|
f = std::strtof(str, endptr);
|
|
}
|
|
|
|
static void strtof(double& f, const char* str, char** endptr) noexcept
|
|
{
|
|
f = std::strtod(str, endptr);
|
|
}
|
|
|
|
static void strtof(long double& f, const char* str, char** endptr) noexcept
|
|
{
|
|
f = std::strtold(str, endptr);
|
|
}
|
|
|
|
/*!
|
|
@brief scan a number literal
|
|
|
|
This function scans a string according to Sect. 6 of RFC 7159.
|
|
|
|
The function is realized with a deterministic finite state machine derived
|
|
from the grammar described in RFC 7159. Starting in state "init", the
|
|
input is read and used to determined the next state. Only state "done"
|
|
accepts the number. State "error" is a trap state to model errors. In the
|
|
table below, "anything" means any character but the ones listed before.
|
|
|
|
state | 0 | 1-9 | e E | + | - | . | anything
|
|
---------|----------|----------|----------|---------|---------|----------|-----------
|
|
init | zero | any1 | [error] | [error] | minus | [error] | [error]
|
|
minus | zero | any1 | [error] | [error] | [error] | [error] | [error]
|
|
zero | done | done | exponent | done | done | decimal1 | done
|
|
any1 | any1 | any1 | exponent | done | done | decimal1 | done
|
|
decimal1 | decimal2 | [error] | [error] | [error] | [error] | [error] | [error]
|
|
decimal2 | decimal2 | decimal2 | exponent | done | done | done | done
|
|
exponent | any2 | any2 | [error] | sign | sign | [error] | [error]
|
|
sign | any2 | any2 | [error] | [error] | [error] | [error] | [error]
|
|
any2 | any2 | any2 | done | done | done | done | done
|
|
|
|
The state machine is realized with one label per state (prefixed with
|
|
"scan_number_") and `goto` statements between them. The state machine
|
|
contains cycles, but any cycle can be left when EOF is read. Therefore,
|
|
the function is guaranteed to terminate.
|
|
|
|
During scanning, the read bytes are stored in token_buffer. This string is
|
|
then converted to a signed integer, an unsigned integer, or a
|
|
floating-point number.
|
|
|
|
@return token_type::value_unsigned, token_type::value_integer, or
|
|
token_type::value_float if number could be successfully scanned,
|
|
token_type::parse_error otherwise
|
|
|
|
@note The scanner is independent of the current locale. Internally, the
|
|
locale's decimal point is used instead of `.` to work with the
|
|
locale-dependent converters.
|
|
*/
|
|
token_type scan_number()
|
|
{
|
|
// reset token_buffer to store the number's bytes
|
|
reset();
|
|
|
|
// the type of the parsed number; initially set to unsigned; will be
|
|
// changed if minus sign, decimal point or exponent is read
|
|
token_type number_type = token_type::value_unsigned;
|
|
|
|
// state (init): we just found out we need to scan a number
|
|
switch (current)
|
|
{
|
|
case '-':
|
|
{
|
|
add(current);
|
|
goto scan_number_minus;
|
|
}
|
|
|
|
case '0':
|
|
{
|
|
add(current);
|
|
goto scan_number_zero;
|
|
}
|
|
|
|
case '1':
|
|
case '2':
|
|
case '3':
|
|
case '4':
|
|
case '5':
|
|
case '6':
|
|
case '7':
|
|
case '8':
|
|
case '9':
|
|
{
|
|
add(current);
|
|
goto scan_number_any1;
|
|
}
|
|
|
|
default:
|
|
{
|
|
// all other characters are rejected outside scan_number()
|
|
assert(false); // LCOV_EXCL_LINE
|
|
}
|
|
}
|
|
|
|
scan_number_minus:
|
|
// state: we just parsed a leading minus sign
|
|
number_type = token_type::value_integer;
|
|
switch (get())
|
|
{
|
|
case '0':
|
|
{
|
|
add(current);
|
|
goto scan_number_zero;
|
|
}
|
|
|
|
case '1':
|
|
case '2':
|
|
case '3':
|
|
case '4':
|
|
case '5':
|
|
case '6':
|
|
case '7':
|
|
case '8':
|
|
case '9':
|
|
{
|
|
add(current);
|
|
goto scan_number_any1;
|
|
}
|
|
|
|
default:
|
|
{
|
|
error_message = "invalid number; expected digit after '-'";
|
|
return token_type::parse_error;
|
|
}
|
|
}
|
|
|
|
scan_number_zero:
|
|
// state: we just parse a zero (maybe with a leading minus sign)
|
|
switch (get())
|
|
{
|
|
case '.':
|
|
{
|
|
add(decimal_point_char);
|
|
goto scan_number_decimal1;
|
|
}
|
|
|
|
case 'e':
|
|
case 'E':
|
|
{
|
|
add(current);
|
|
goto scan_number_exponent;
|
|
}
|
|
|
|
default:
|
|
goto scan_number_done;
|
|
}
|
|
|
|
scan_number_any1:
|
|
// state: we just parsed a number 0-9 (maybe with a leading minus sign)
|
|
switch (get())
|
|
{
|
|
case '0':
|
|
case '1':
|
|
case '2':
|
|
case '3':
|
|
case '4':
|
|
case '5':
|
|
case '6':
|
|
case '7':
|
|
case '8':
|
|
case '9':
|
|
{
|
|
add(current);
|
|
goto scan_number_any1;
|
|
}
|
|
|
|
case '.':
|
|
{
|
|
add(decimal_point_char);
|
|
goto scan_number_decimal1;
|
|
}
|
|
|
|
case 'e':
|
|
case 'E':
|
|
{
|
|
add(current);
|
|
goto scan_number_exponent;
|
|
}
|
|
|
|
default:
|
|
goto scan_number_done;
|
|
}
|
|
|
|
scan_number_decimal1:
|
|
// state: we just parsed a decimal point
|
|
number_type = token_type::value_float;
|
|
switch (get())
|
|
{
|
|
case '0':
|
|
case '1':
|
|
case '2':
|
|
case '3':
|
|
case '4':
|
|
case '5':
|
|
case '6':
|
|
case '7':
|
|
case '8':
|
|
case '9':
|
|
{
|
|
add(current);
|
|
goto scan_number_decimal2;
|
|
}
|
|
|
|
default:
|
|
{
|
|
error_message = "invalid number; expected digit after '.'";
|
|
return token_type::parse_error;
|
|
}
|
|
}
|
|
|
|
scan_number_decimal2:
|
|
// we just parsed at least one number after a decimal point
|
|
switch (get())
|
|
{
|
|
case '0':
|
|
case '1':
|
|
case '2':
|
|
case '3':
|
|
case '4':
|
|
case '5':
|
|
case '6':
|
|
case '7':
|
|
case '8':
|
|
case '9':
|
|
{
|
|
add(current);
|
|
goto scan_number_decimal2;
|
|
}
|
|
|
|
case 'e':
|
|
case 'E':
|
|
{
|
|
add(current);
|
|
goto scan_number_exponent;
|
|
}
|
|
|
|
default:
|
|
goto scan_number_done;
|
|
}
|
|
|
|
scan_number_exponent:
|
|
// we just parsed an exponent
|
|
number_type = token_type::value_float;
|
|
switch (get())
|
|
{
|
|
case '+':
|
|
case '-':
|
|
{
|
|
add(current);
|
|
goto scan_number_sign;
|
|
}
|
|
|
|
case '0':
|
|
case '1':
|
|
case '2':
|
|
case '3':
|
|
case '4':
|
|
case '5':
|
|
case '6':
|
|
case '7':
|
|
case '8':
|
|
case '9':
|
|
{
|
|
add(current);
|
|
goto scan_number_any2;
|
|
}
|
|
|
|
default:
|
|
{
|
|
error_message =
|
|
"invalid number; expected '+', '-', or digit after exponent";
|
|
return token_type::parse_error;
|
|
}
|
|
}
|
|
|
|
scan_number_sign:
|
|
// we just parsed an exponent sign
|
|
switch (get())
|
|
{
|
|
case '0':
|
|
case '1':
|
|
case '2':
|
|
case '3':
|
|
case '4':
|
|
case '5':
|
|
case '6':
|
|
case '7':
|
|
case '8':
|
|
case '9':
|
|
{
|
|
add(current);
|
|
goto scan_number_any2;
|
|
}
|
|
|
|
default:
|
|
{
|
|
error_message = "invalid number; expected digit after exponent sign";
|
|
return token_type::parse_error;
|
|
}
|
|
}
|
|
|
|
scan_number_any2:
|
|
// we just parsed a number after the exponent or exponent sign
|
|
switch (get())
|
|
{
|
|
case '0':
|
|
case '1':
|
|
case '2':
|
|
case '3':
|
|
case '4':
|
|
case '5':
|
|
case '6':
|
|
case '7':
|
|
case '8':
|
|
case '9':
|
|
{
|
|
add(current);
|
|
goto scan_number_any2;
|
|
}
|
|
|
|
default:
|
|
goto scan_number_done;
|
|
}
|
|
|
|
scan_number_done:
|
|
// unget the character after the number (we only read it to know that
|
|
// we are done scanning a number)
|
|
unget();
|
|
|
|
char* endptr = nullptr;
|
|
errno = 0;
|
|
|
|
// try to parse integers first and fall back to floats
|
|
if (number_type == token_type::value_unsigned)
|
|
{
|
|
const auto x = std::strtoull(token_buffer.data(), &endptr, 10);
|
|
|
|
// we checked the number format before
|
|
assert(endptr == token_buffer.data() + token_buffer.size());
|
|
|
|
if (errno == 0)
|
|
{
|
|
value_unsigned = static_cast<number_unsigned_t>(x);
|
|
if (value_unsigned == x)
|
|
{
|
|
return token_type::value_unsigned;
|
|
}
|
|
}
|
|
}
|
|
else if (number_type == token_type::value_integer)
|
|
{
|
|
const auto x = std::strtoll(token_buffer.data(), &endptr, 10);
|
|
|
|
// we checked the number format before
|
|
assert(endptr == token_buffer.data() + token_buffer.size());
|
|
|
|
if (errno == 0)
|
|
{
|
|
value_integer = static_cast<number_integer_t>(x);
|
|
if (value_integer == x)
|
|
{
|
|
return token_type::value_integer;
|
|
}
|
|
}
|
|
}
|
|
|
|
// this code is reached if we parse a floating-point number or if an
|
|
// integer conversion above failed
|
|
strtof(value_float, token_buffer.data(), &endptr);
|
|
|
|
// we checked the number format before
|
|
assert(endptr == token_buffer.data() + token_buffer.size());
|
|
|
|
return token_type::value_float;
|
|
}
|
|
|
|
/*!
|
|
@param[in] literal_text the literal text to expect
|
|
@param[in] length the length of the passed literal text
|
|
@param[in] return_type the token type to return on success
|
|
*/
|
|
token_type scan_literal(const char* literal_text, const std::size_t length,
|
|
token_type return_type)
|
|
{
|
|
assert(current == literal_text[0]);
|
|
for (std::size_t i = 1; i < length; ++i)
|
|
{
|
|
if (JSON_UNLIKELY(get() != literal_text[i]))
|
|
{
|
|
error_message = "invalid literal";
|
|
return token_type::parse_error;
|
|
}
|
|
}
|
|
return return_type;
|
|
}
|
|
|
|
/////////////////////
|
|
// input management
|
|
/////////////////////
|
|
|
|
/// reset token_buffer; current character is beginning of token
|
|
void reset() noexcept
|
|
{
|
|
token_buffer.clear();
|
|
token_string.clear();
|
|
token_string.push_back(std::char_traits<char>::to_char_type(current));
|
|
}
|
|
|
|
/*
|
|
@brief get next character from the input
|
|
|
|
This function provides the interface to the used input adapter. It does
|
|
not throw in case the input reached EOF, but returns a
|
|
`std::char_traits<char>::eof()` in that case. Stores the scanned characters
|
|
for use in error messages.
|
|
|
|
@return character read from the input
|
|
*/
|
|
std::char_traits<char>::int_type get()
|
|
{
|
|
++chars_read;
|
|
current = ia->get_character();
|
|
if (JSON_LIKELY(current != std::char_traits<char>::eof()))
|
|
{
|
|
token_string.push_back(std::char_traits<char>::to_char_type(current));
|
|
}
|
|
return current;
|
|
}
|
|
|
|
/// unget current character (return it again on next get)
|
|
void unget()
|
|
{
|
|
--chars_read;
|
|
if (JSON_LIKELY(current != std::char_traits<char>::eof()))
|
|
{
|
|
ia->unget_character();
|
|
assert(token_string.size() != 0);
|
|
token_string.pop_back();
|
|
}
|
|
}
|
|
|
|
/// add a character to token_buffer
|
|
void add(int c)
|
|
{
|
|
token_buffer.push_back(std::char_traits<char>::to_char_type(c));
|
|
}
|
|
|
|
public:
|
|
/////////////////////
|
|
// value getters
|
|
/////////////////////
|
|
|
|
/// return integer value
|
|
constexpr number_integer_t get_number_integer() const noexcept
|
|
{
|
|
return value_integer;
|
|
}
|
|
|
|
/// return unsigned integer value
|
|
constexpr number_unsigned_t get_number_unsigned() const noexcept
|
|
{
|
|
return value_unsigned;
|
|
}
|
|
|
|
/// return floating-point value
|
|
constexpr number_float_t get_number_float() const noexcept
|
|
{
|
|
return value_float;
|
|
}
|
|
|
|
/// return current string value (implicitly resets the token; useful only once)
|
|
std::string&& move_string()
|
|
{
|
|
return std::move(token_buffer);
|
|
}
|
|
|
|
/////////////////////
|
|
// diagnostics
|
|
/////////////////////
|
|
|
|
/// return position of last read token
|
|
constexpr std::size_t get_position() const noexcept
|
|
{
|
|
return chars_read;
|
|
}
|
|
|
|
/// return the last read token (for errors only). Will never contain EOF
|
|
/// (an arbitrary value that is not a valid char value, often -1), because
|
|
/// 255 may legitimately occur. May contain NUL, which should be escaped.
|
|
std::string get_token_string() const
|
|
{
|
|
// escape control characters
|
|
std::string result;
|
|
for (const auto c : token_string)
|
|
{
|
|
if ('\x00' <= c and c <= '\x1F')
|
|
{
|
|
// escape control characters
|
|
std::stringstream ss;
|
|
ss << "<U+" << std::setw(4) << std::uppercase << std::setfill('0')
|
|
<< std::hex << static_cast<int>(c) << ">";
|
|
result += ss.str();
|
|
}
|
|
else
|
|
{
|
|
// add character as is
|
|
result.push_back(c);
|
|
}
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
/// return syntax error message
|
|
constexpr const char* get_error_message() const noexcept
|
|
{
|
|
return error_message;
|
|
}
|
|
|
|
/////////////////////
|
|
// actual scanner
|
|
/////////////////////
|
|
|
|
token_type scan()
|
|
{
|
|
// read next character and ignore whitespace
|
|
do
|
|
{
|
|
get();
|
|
}
|
|
while (current == ' ' or current == '\t' or current == '\n' or current == '\r');
|
|
|
|
switch (current)
|
|
{
|
|
// structural characters
|
|
case '[':
|
|
return token_type::begin_array;
|
|
case ']':
|
|
return token_type::end_array;
|
|
case '{':
|
|
return token_type::begin_object;
|
|
case '}':
|
|
return token_type::end_object;
|
|
case ':':
|
|
return token_type::name_separator;
|
|
case ',':
|
|
return token_type::value_separator;
|
|
|
|
// literals
|
|
case 't':
|
|
return scan_literal("true", 4, token_type::literal_true);
|
|
case 'f':
|
|
return scan_literal("false", 5, token_type::literal_false);
|
|
case 'n':
|
|
return scan_literal("null", 4, token_type::literal_null);
|
|
|
|
// string
|
|
case '\"':
|
|
return scan_string();
|
|
|
|
// number
|
|
case '-':
|
|
case '0':
|
|
case '1':
|
|
case '2':
|
|
case '3':
|
|
case '4':
|
|
case '5':
|
|
case '6':
|
|
case '7':
|
|
case '8':
|
|
case '9':
|
|
return scan_number();
|
|
|
|
// end of input (the null byte is needed when parsing from
|
|
// string literals)
|
|
case '\0':
|
|
case std::char_traits<char>::eof():
|
|
return token_type::end_of_input;
|
|
|
|
// error
|
|
default:
|
|
error_message = "invalid literal";
|
|
return token_type::parse_error;
|
|
}
|
|
}
|
|
|
|
private:
|
|
/// input adapter
|
|
detail::input_adapter_t ia = nullptr;
|
|
|
|
/// the current character
|
|
std::char_traits<char>::int_type current = std::char_traits<char>::eof();
|
|
|
|
/// the number of characters read
|
|
std::size_t chars_read = 0;
|
|
|
|
/// raw input token string (for error messages)
|
|
std::vector<char> token_string {};
|
|
|
|
/// buffer for variable-length tokens (numbers, strings)
|
|
std::string token_buffer {};
|
|
|
|
/// a description of occurred lexer errors
|
|
const char* error_message = "";
|
|
|
|
// number values
|
|
number_integer_t value_integer = 0;
|
|
number_unsigned_t value_unsigned = 0;
|
|
number_float_t value_float = 0;
|
|
|
|
/// the decimal point
|
|
const char decimal_point_char = '.';
|
|
};
|
|
}
|
|
}
|