Variant

An ExessVariant is a tagged union that can hold any supported datatype.

• Constructors
• Accessors
• Comparison
• Datatype coercion

union ExessValue

ExessStatus as_status

ExessBlob as_blob

bool as_bool

double as_double

float as_float

int64_t as_long

int32_t as_int

int16_t as_short

int8_t as_byte

uint64_t as_ulong

uint32_t as_uint

uint16_t as_ushort

uint8_t as_ubyte

ExessDuration as_duration

ExessDateTime as_datetime

ExessTime as_time

ExessDate as_date

struct ExessVariant

Any supported value.

A variant is either nothing, or a value of a specific supported type. The nothing variant has datatype ExessDatatype.EXESS_NOTHING.

The value fields (everything other than datatype) are stored in an anonymous union, only the field corresponding to the datatype is active. This should not be used for type punning, use exess_coerce() for that instead.

ExessDatatype datatype

ExessValue value

ExessResult exess_read_variant(ExessVariant *out, ExessDatatype datatype, const char *str)

Read any supported datatype from a string.

For reading binary blobs from base64 or hex, the as_blob field of out must have the size of the available buffer in bytes, and a pointer to the buffer. On return, the size will be set to the exact size of the decoded data, which may be smaller than the initial available size. Only these first bytes are written, the rest of the buffer is not modified.

Parameters

• out – Set to the parsed value, or nothing on error.

• datatype – The datatype to read the string as.

• str – String input.

Returns

The count of characters read, and a status code.

ExessResult exess_write_variant(ExessVariant value, size_t buf_size, char *buf)

Write any supported xsd datatype to a canonical string.

Parameters

• value – Value to write.

• buf_size – The size of buf in bytes.

• buf – Output buffer, or null to only measure.

Returns

The count of characters in the output, and status ExessStatus.EXESS_SUCCESS, or ExessStatus.EXESS_NO_SPACE if the buffer is too small.

ExessResult exess_write_canonical(const char *value, ExessDatatype datatype, size_t buf_size, char *buf)

Rewrite a supported xsd datatype in canonical form.

Parameters

• value – Input value string.

• datatype – Datatype of value.

• buf_size – The size of buf in bytes.

• buf – Output buffer, or null to only measure.

Returns

The count of characters in the output, and a status code. The status may be an error from reading or writing, but the count always refers to the number of characters written.