c('PL_is_id_start')

Availability:C-language interface function

int PL_is_id_start(int chr)

int PL_is_id_continue(int chr)

int PL_is_uppercase(int chr)

int PL_is_decimal(int chr)

int PL_is_layout(int chr)

Unicode classification predicates. Each returns non-zero iff the 32-bit code point chr carries the corresponding property as defined by the data files in src/Unicode/ and consulted by the Prolog reader. Provided so foreign extensions and embedded toolkits (notably xpce) classify code points exactly as SWI-Prolog does, locale- independently. id_start and id_continue follow Prolog's identifier syntax (close to UAX #31 XID_Start / XID_Continue, adjusted for Prolog). layout matches the reader's whitespace set (white_space/1 in src/Unicode/derived_core_properties.pl).