Inherits nlohmann::detail::lexer_base< BasicJsonType >.
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constexpr number_integer_t | get_number_integer () const noexcept |
| | return integer value
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constexpr number_unsigned_t | get_number_unsigned () const noexcept |
| | return unsigned integer value
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constexpr number_float_t | get_number_float () const noexcept |
| | return floating-point value
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string_t & | get_string () |
| | return current string value (implicitly resets the token; useful only once)
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constexpr position_t | get_position () const noexcept |
| | return position of last read token
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| std::string | get_token_string () const |
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constexpr const JSON_HEDLEY_RETURNS_NON_NULL char * | get_error_message () const noexcept |
| | return syntax error message
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| bool | skip_bom () |
| | skip the UTF-8 byte order mark More...
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| int | get_codepoint () |
| | get codepoint from 4 hex characters following \u More...
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| bool | next_byte_in_range (std::initializer_list< char_int_type > ranges) |
| | check if the next byte(s) are inside a given range More...
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| token_type | scan_string () |
| | scan a string literal More...
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| bool | scan_comment () |
| | scan a comment More...
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| token_type | scan_number () |
| | scan a number literal More...
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| token_type | scan_literal (const char_type *literal_text, const std::size_t length, token_type return_type) |
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void | reset () noexcept |
| | reset token_buffer; current character is beginning of token
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| void | unget () |
| | unget current character (read it again on next get) More...
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void | add (char_int_type c) |
| | add a character to token_buffer
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template<typename BasicJsonType, typename InputAdapterType>
class nlohmann::detail::lexer< BasicJsonType, InputAdapterType >
lexical analysis
This class organizes the lexical analysis during JSON deserialization.
template<typename BasicJsonType , typename InputAdapterType >
get codepoint from 4 hex characters following \u
For input "\u c1 c2 c3 c4" the codepoint is: (c1 * 0x1000) + (c2 * 0x0100) + (c3 * 0x0010) + c4 = (c1 << 12) + (c2 << 8) + (c3 << 4) + (c4 << 0)
Furthermore, the possible characters '0'..'9', 'A'..'F', and 'a'..'f' must be converted to the integers 0x0..0x9, 0xA..0xF, 0xA..0xF, resp. The conversion is done by subtracting the offset (0x30, 0x37, and 0x57) between the ASCII value of the character and the desired integer value.
- Returns
- codepoint (0x0000..0xFFFF) or -1 in case of an error (e.g. EOF or non-hex character)
template<typename BasicJsonType , typename InputAdapterType >
| bool nlohmann::detail::lexer< BasicJsonType, InputAdapterType >::next_byte_in_range |
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std::initializer_list< char_int_type > |
ranges | ) |
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check if the next byte(s) are inside a given range
Adds the current byte and, for each passed range, reads a new byte and checks if it is inside the range. If a violation was detected, set up an error message and return false. Otherwise, return true.
- Parameters
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| [in] | ranges | list of integers; interpreted as list of pairs of inclusive lower and upper bound, respectively |
- Precondition
- The passed list ranges must have 2, 4, or 6 elements; that is, 1, 2, or 3 pairs. This precondition is enforced by an assertion.
- Returns
- true if and only if no range violation was detected
template<typename BasicJsonType , typename InputAdapterType >
scan a string literal
This function scans a string according to Sect. 7 of RFC 7159. While scanning, bytes are escaped and copied into buffer token_buffer. Then the function returns successfully, token_buffer is not null-terminated (as it may contain \0 bytes), and token_buffer.size() is the number of bytes in the string.
- Returns
- token_type::value_string if string could be successfully scanned, token_type::parse_error otherwise
- Note
- In case of errors, variable error_message contains a textual description.
template<typename BasicJsonType , typename InputAdapterType >
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 | decimal2 | [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.
- Returns
- 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.
template<typename BasicJsonType , typename InputAdapterType >
unget current character (read it again on next get)
We implement unget by setting variable next_unget to true. The input is not changed - we just simulate ungetting by modifying chars_read_total, chars_read_current_line, and token_string. The next call to get() will behave as if the unget character is read again.
1.8.17