Warning: This is the manual of the legacy Guile 2.2 series. You may want to read the manual of the current stable series instead.

6.6.4.2 Iterating Over Character Sets

Character set cursors are a means for iterating over the members of a character sets. After creating a character set cursor with char-set-cursor, a cursor can be dereferenced with char-set-ref, advanced to the next member with char-set-cursor-next. Whether a cursor has passed past the last element of the set can be checked with end-of-char-set?.

Additionally, mapping and (un-)folding procedures for character sets are provided.

Scheme Procedure: char-set-cursor cs

C Function: scm_char_set_cursor (cs)

Return a cursor into the character set cs.

Scheme Procedure: char-set-ref cs cursor

C Function: scm_char_set_ref (cs, cursor)

Return the character at the current cursor position cursor in the character set cs. It is an error to pass a cursor for which end-of-char-set? returns true.

Scheme Procedure: char-set-cursor-next cs cursor

C Function: scm_char_set_cursor_next (cs, cursor)

Advance the character set cursor cursor to the next character in the character set cs. It is an error if the cursor given satisfies end-of-char-set?.

Scheme Procedure: end-of-char-set? cursor

C Function: scm_end_of_char_set_p (cursor)

Return #t if cursor has reached the end of a character set, #f otherwise.

Scheme Procedure: char-set-fold kons knil cs

C Function: scm_char_set_fold (kons, knil, cs)

Fold the procedure kons over the character set cs, initializing it with knil.

Scheme Procedure: char-set-unfold p f g seed [base_cs]

C Function: scm_char_set_unfold (p, f, g, seed, base_cs)

This is a fundamental constructor for character sets.

• g is used to generate a series of “seed” values from the initial seed: seed, (g seed), (g^2 seed), (g^3 seed), …
• p tells us when to stop – when it returns true when applied to one of the seed values.
• f maps each seed value to a character. These characters are added to the base character set base_cs to form the result; base_cs defaults to the empty set.

Scheme Procedure: char-set-unfold! p f g seed base_cs

C Function: scm_char_set_unfold_x (p, f, g, seed, base_cs)

This is a fundamental constructor for character sets.

• g is used to generate a series of “seed” values from the initial seed: seed, (g seed), (g^2 seed), (g^3 seed), …
• p tells us when to stop – when it returns true when applied to one of the seed values.
• f maps each seed value to a character. These characters are added to the base character set base_cs to form the result; base_cs defaults to the empty set.

Scheme Procedure: char-set-for-each proc cs

C Function: scm_char_set_for_each (proc, cs)

Apply proc to every character in the character set cs. The return value is not specified.

Scheme Procedure: char-set-map proc cs

C Function: scm_char_set_map (proc, cs)

Map the procedure proc over every character in cs. proc must be a character -> character procedure.