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yap-6.3/library/lineutils.yap
2014-11-25 12:03:48 +00:00

332 lines
7.5 KiB
Prolog

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