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Basic input/output

Author(s): Daniel Cabeza, Mats Carlsson.

Version: 1.10#7 (2006/4/26, 19:22:13 CEST)

Version of last change: 1.9#285 (2004/2/13, 17:36:9 CET)

This module provides predicates for character input/output and for canonical term output. From the ISO-Prolog predicates for character input/output, only the _code versions are provided, the rest are given by library(iso_byte_char), using these. Most predicates are provided in two versions: one that specifies the input or output stream as the first argument and a second which omits this argument and uses the current input or output stream.

Usage and interface (io_basic)

Documentation on exports (io_basic)

PREDICATE: get_code/2:

get_code(Stream, Code)

Reads from Stream the next character and unifies Code with its character code. At end of stream, unifies Code with the integer -1.

Usage: get_code(+stream, ?int) * ISO *

PREDICATE: get_code/1:

get_code(Code)

Behaves like current_input(S), get_code(S,Code).

Usage: get_code(?int) * ISO *

PREDICATE: get1_code/2:

get1_code(Stream, Code)

Reads from Stream the next non-layout character (see code_class/2) and unifies Code with its character code. At end of stream, unifies Code with the integer -1.

Usage: get1_code(+stream, ?int)

PREDICATE: get1_code/1:

get1_code(Code)

Behaves like current_input(S), get1_code(S,Code).

Usage: get1_code(?int)

PREDICATE: peek_code/2:

peek_code(Stream, Code)

Unifies Code with the character code of the next character of Stream, leaving the stream position unaltered. At end of stream, unifies Code with the integer -1.

PREDICATE: peek_code/1:

peek_code(Code)

Behaves like current_input(S), peek_code(S,Code).

PREDICATE: skip_code/2:

skip_code(Stream, Code)

Skips just past the next character code Code from Stream.

PREDICATE: skip_code/1:

skip_code(Code)

Behaves like current_input(S), skip_code(S,Code).

PREDICATE: skip_line/1:

skip_line(Stream)

Skips from Stream the remaining input characters on the current line. If the end of the stream is reached, the stream will stay at its end. Portable among different operating systems.

PREDICATE: skip_line/0:

skip_line(skip_line

Behaves like current_input(S), skip_line(S).

PREDICATE: put_code/2:

put_code(Stream, Code)

Outputs to Stream the character corresponding to character code Code.

Usage: put_code(+stream, +int) * ISO *

PREDICATE: put_code/1:

put_code(Code)

Behaves like current_output(S), put_code(S,Code).

Usage: put_code(+int) * ISO *

PREDICATE: nl/1:

nl(Stream)

Outputs a newline character to Stream. Equivalent to put_code(Stream, 0'\n).

Usage: nl(+stream) * ISO *

PREDICATE: nl/0:

nl(nl

Behaves like current_output(S), nl(S).

Usage: * ISO *

PREDICATE: tab/2:

tab(Stream, Num)

Outputs Num spaces to Stream.

Usage: tab(+stream, +int)

PREDICATE: tab/1:

tab(Num)

Behaves like current_output(S), tab(S,Num).

Usage: tab(+int)

PREDICATE: code_class/2:

code_class(Code, Class)

Unifies Class with an integer corresponding to the lexical class of the character whose code is Code, with the following correspondence: 

    0 - layout (includes space, newline, tab)
    1 - small letter
    2 - capital letter (including '_')
    3 - digit
    4 - graphic (includes #$&*+-./:<=>?@^\`~ )
    5 - punctuation (includes !;"'%(),[]{|} )

Note that in ISO-Prolog the back quote ` is a punctuation character, whereas in Ciao it is a graphic character. Thus, if compatibility with ISO-Prolog is desired, the programmer should not use this character in unquoted names.

PREDICATE: getct/2:

getct(Code, Type)

Reads from the current input stream the next character, unifying Code with its character code, and Type with its lexical class. At end of stream, unifies both Code and Type with the integer -1. Equivalent to 

   get(Code), (Code = -1 -> Type = -1 ; code_class(Code,Type))

PREDICATE: getct1/2:

getct1(Code, Type)

Reads from the current input stream the next non-layout character, unifying Code with its character code, and Type with its lexical class (which will be nonzero). At end of stream, unifies both Code and Type with the integer -1. Equivalent to 

   get1(Code), (Code = -1 -> Type = -1 ; code_class(Code,Type))

PREDICATE: display/2:

display(Stream, Term)

Displays Term onto Stream. Lists are output using list notation, the other compound terms are output in functional notation. Similar to write_term(Stream, Term, [ignore_ops(ops)]), except that curly bracketed notation is not used with {}/1, and the write_strings flag is not honored.

Usage: display(+stream, @term)

PREDICATE: display/1:

display(Term)

Behaves like current_output(S), display(S,Term).

Usage: display(@term)

PREDICATE: displayq/2:

displayq(Stream, Term)

Similar to display(Stream, Term), but atoms and functors that can't be read back by read_term/3 are quoted. Thus, similar to write_term(Stream, Term, [quoted(true), ignore_ops(ops)]), with the same exceptions as display/2.

PREDICATE: displayq/1:

displayq(Term)

Behaves like current_output(S), displayq(S,Term).

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