332 lines
7.5 KiB
Prolog
332 lines
7.5 KiB
Prolog
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:- module(line_utils,
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[search_for/2,
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search_for/3,
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scan_natural/3,
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scan_integer/3,
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natural/3,
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integer/3,
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blank/3,
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split/2,
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split/3,
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fields/2,
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fields/3,
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glue/3,
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copy_line/2,
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filter/3,
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file_filter/3,
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file_filter_with_initialization/5,
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process/2
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]).
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/** @defgroup LineUtilities Line Manipulation Utilities
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@ingroup YAPLibrary
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@{
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This package provides a set of useful predicates to manipulate
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sequences of characters codes, usually first read in as a line. It is
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available by loading the
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~~~~
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:- use_module(library(lineutils)).
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~~~~
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*/
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:- meta_predicate
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filter(+,+,2),
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file_filter(+,+,2),
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file_filter_with_initialization(+,+,2,+,:),
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process(+,1).
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:- use_module(library(lists),
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[member/2,
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append/3]).
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:- use_module(library(readutil),
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[read_line_to_codes/2]).
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/**
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@pred search_for(+ _Char_,+ _Line_)
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Search for a character _Char_ in the list of codes _Line_.
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*/
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search_for(C,L) :-
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search_for(C, L, []).
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search_for(C) --> [C], !.
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search_for(C) --> [_],
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search_for(C).
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/** @pred scan_integer(? _Int_,+ _Line_,+ _RestOfLine_)
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Scan the list of codes _Line_ for an integer _Nat_, either a
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positive, zero, or negative integer, and unify _RestOfLine_ with
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the remainder of the line.
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*/
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scan_integer(N) -->
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"-", !,
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scan_natural(0, N0),
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N is -N0.
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scan_integer(N) -->
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scan_natural(0, N).
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/** @pred integer(? _Int_,+ _Line_,+ _RestOfLine_)
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Scan the list of codes _Line_ for an integer _Nat_, either a
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positive, zero, or negative integer, and unify _RestOfLine_ with
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the remainder of the line.
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*/
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integer(N) -->
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"-", !,
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natural(0, N0),
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N is -N0.
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integer(N) -->
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natural(0, N).
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/** @pred scan_natural(? _Nat_,+ _Line_,+ _RestOfLine_)
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Scan the list of codes _Line_ for a natural number _Nat_, zero
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or a positive integer, and unify _RestOfLine_ with the remainder
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of the line.
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*/
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scan_natural(N) -->
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scan_natural(0, N).
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scan_natural(N0,N) -->
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[C],
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{C >= 0'0, C =< 0'9 }, !,
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{ N1 is N0*10+(C-0'0) }, %'
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get_natural(N1,N).
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scan_natural(N,N) --> [].
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/** @pred natural(? _Nat_,+ _Line_,+ _RestOfLine_)
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Scan the list of codes _Line_ for a natural number _Nat_, zero
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or a positive integer, and unify _RestOfLine_ with the remainder
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of the line.
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*/
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natural(N) -->
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natural(0, N).
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natural(N0,N) -->
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[C],
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{C >= 0'0, C =< 0'9 }, !,
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{ N1 is N0*10+(C-0'0) }, %'
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get_natural(N1,N).
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natural(N,N) --> [].
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/** @pred skip_whitespace(+ _Line_,+ _RestOfLine_)
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Scan the list of codes _Line_ for white space, namely for tabbing and space characters.
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*/
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skip_whitespace([0' |Blanks]) -->
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" ",
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skip_whitespace( Blanks ).
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skip_whitespace([0' |Blanks]) -->
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" ",
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skip_whitespace( Blanks ).
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skip_whitespace( [] ) -->
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!.
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/** @pred blank(+ _Line_,+ _RestOfLine_)
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The list of codes _Line_ is formed by white space, namely by tabbing and space characters.
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*/
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blank([0' |Blanks]) -->
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" ",
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blank( Blanks ).
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blank([0' |Blanks]) -->
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" ",
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blank( Blanks ).
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blank( [] ) -->
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[].
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/** @pred split(+ _Line_,- _Split_)
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Unify _Words_ with a set of strings obtained from _Line_ by
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using the blank characters as separators.
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*/
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split(String, Strings) :-
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split_at_blank(" ", Strings, String, []).
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/** @pred split(+ _Line_,+ _Separators_,- _Split_)
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Unify _Words_ with a set of strings obtained from _Line_ by
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using the character codes in _Separators_ as separators. As an
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example, consider:
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~~~~~{.prolog}
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?- split("Hello * I am free"," *",S).
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S = ["Hello","I","am","free"] ?
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no
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~~~~~
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*/
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split(String, SplitCodes, Strings) :-
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split_at_blank(SplitCodes, Strings, String, []).
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split_at_blank(SplitCodes, More) -->
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[C],
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{ member(C, SplitCodes) }, !,
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split_at_blank(SplitCodes, More).
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split_at_blank(SplitCodes, [[C|New]| More]) -->
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[C], !,
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split(SplitCodes, New, More).
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split_at_blank(_, []) --> [].
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split(SplitCodes, [], More) -->
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[C],
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{ member(C, SplitCodes) }, !,
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split_at_blank(SplitCodes, More).
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split(SplitCodes, [C|New], Set) -->
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[C], !,
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split(SplitCodes, New, Set).
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split(_, [], []) --> [].
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/** @pred fields(+ _Line_,- _Split_)
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Unify _Words_ with a set of strings obtained from _Line_ by
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using the blank characters as field separators.
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*/
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fields(String, Strings) :-
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fields(" ", Strings, String, []).
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/** @pred fields(+ _Line_,+ _Separators_,- _Split_)
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Unify _Words_ with a set of strings obtained from _Line_ by
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using the character codes in _Separators_ as separators for
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fields. If two separators occur in a row, the field is considered
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empty. As an example, consider:
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~~~~~{.prolog}
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?- fields("Hello I am free"," *",S).
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S = ["Hello","","I","am","","free"] ?
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~~~~~
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*/
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fields(String, FieldsCodes, Strings) :-
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dofields(FieldsCodes, First, More, String, []),
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(
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First = [], More = []
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->
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Strings = []
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;
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Strings = [First|More]
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).
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dofields(FieldsCodes, [], New.More) -->
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[C],
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{ member(C, FieldsCodes) }, !,
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dofields(FieldsCodes, New, More).
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dofields(FieldsCodes, [C|New], Set) -->
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[C], !,
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dofields(FieldsCodes, New, Set).
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dofields(_, [], []) --> [].
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/** @pred glue(+ _Words_,+ _Separator_,- _Line_)
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Unify _Line_ with string obtained by glueing _Words_ with
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the character code _Separator_.
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*/
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glue([], _, []).
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glue([A], _, A) :- !.
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glue([H|T], [B|_], Merged) :-
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append(H, [B|Rest], Merged),
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glue(T, [B], Rest).
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/** @pred copy_line(+ _StreamInput_,+ _StreamOutput_)
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Copy a line from _StreamInput_ to _StreamOutput_.
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*/
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copy_line(StreamInp, StreamOut) :-
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read_line_to_codes(StreamInp, Line),
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format(StreamOut, '~s~n', [Line]).
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/** @pred filter(+ _StreamInp_, + _StreamOut_, + _Goal_)
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For every line _LineIn_ in stream _StreamInp_, execute
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`call(Goal,LineIn,LineOut)`, and output _LineOut_ to
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stream _StreamOut_. If `call(Goal,LineIn,LineOut)` fails,
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nothing will be output but execution continues with the next
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line. As an example, consider a procedure to select the second and
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fifth field of a CSV table :
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~~~~~{.prolog}
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select(Sep, In, Out) :-
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fields(In, Sep, [_,F2,_,_,F5|_]),
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fields(Out,Sep, [F2,F5]).
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select :-
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filter(",",
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~~~~~
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*/
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filter(StreamInp, StreamOut, Command) :-
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repeat,
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read_line_to_codes(StreamInp, Line),
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(
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Line == end_of_file
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->
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!
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;
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call(Command, Line, NewLine),
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format(StreamOut, '~s~n', [NewLine]),
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fail
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).
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/** @pred process(+ _StreamInp_, + _Goal_) is meta
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For every line _LineIn_ in stream _StreamInp_, call
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`call(Goal,LineIn)`.
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*/
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process(StreamInp, Command) :-
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repeat,
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read_line_to_codes(StreamInp, Line),
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(
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Line == end_of_file
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->
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!
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;
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call(Command, Line),
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fail
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).
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/** @pred file_filter(+ _FileIn_, + _FileOut_, + _Goal_) is meta
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For every line _LineIn_ in file _FileIn_, execute
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`call(Goal,LineIn,LineOut)`, and output _LineOut_ to file
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_FileOut_.
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The input stream is accessible through the alias `filter_input`, and the output
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stream is accessible through `filter_output`.
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*/
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file_filter(Inp, Out, Command) :-
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open(Inp, read, StreamInp, [alias(filter_input)]),
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open(Out, write, StreamOut),
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filter(StreamInp, StreamOut, Command),
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close(StreamInp),
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close(StreamOut).
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/** @pred file_filter_with_initialization(+ _FileIn_, + _FileOut_, + _Goal_, + _FormatCommand_, + _Arguments_)
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Same as file_filter/3, but before starting the filter execute
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`format/3` on the output stream, using _FormatCommand_ and
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_Arguments_.
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*/
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file_filter_with_initialization(Inp, Out, Command, FormatString, Parameters) :-
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open(Inp, read, StreamInp, [alias(filter_input)]),
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open(Out, write, StreamOut, [alias(filter_output)]),
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format(StreamOut, FormatString, Parameters),
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filter(StreamInp, StreamOut, Command),
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close(StreamInp),
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close(StreamOut).
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/**
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@}
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*/
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