Mercurial > octave
changeset 24460:892f7f096ffb
erase.m: New string function for deleting substrings with a string.
* scripts/strings/erase.m: New function.
* scripts/strings/module.mk: Add erase.m to build system.
* NEWS: Announce new function in list for 4.4 release.
* strings.txi: Add erase docstring to manual.
| author | Sahil Yadav |
|---|---|
| date | Mon, 25 Dec 2017 08:33:52 -0800 |
| parents | b728b7ac1601 |
| children | 0a034d34a686 |
| files | NEWS doc/interpreter/strings.txi scripts/strings/erase.m scripts/strings/module.mk |
| diffstat | 4 files changed, 143 insertions(+), 0 deletions(-) [+] |
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--- a/NEWS Sat Dec 23 21:04:14 2017 -0800 +++ b/NEWS Mon Dec 25 08:33:52 2017 -0800 @@ -90,6 +90,7 @@ camva camzoom corrcoef + erase getframe gsvd hgtransform
--- a/doc/interpreter/strings.txi Sat Dec 23 21:04:14 2017 -0800 +++ b/doc/interpreter/strings.txi Mon Dec 25 08:33:52 2017 -0800 @@ -452,6 +452,8 @@ @DOCSTRING(strrep) +@DOCSTRING(erase) + @DOCSTRING(substr) @DOCSTRING(regexp)
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/scripts/strings/erase.m Mon Dec 25 08:33:52 2017 -0800 @@ -0,0 +1,139 @@ +## Copyright (C) 2017 Sahil Yadav +## +## This file is part of Octave. +## +## Octave is free software; you can redistribute it and/or modify it +## under the terms of the GNU General Public License as published by +## the Free Software Foundation; either version 3 of the License, or +## (at your option) any later version. +## +## Octave is distributed in the hope that it will be useful, but +## WITHOUT ANY WARRANTY; without even the implied warranty of +## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +## GNU General Public License for more details. +## +## You should have received a copy of the GNU General Public License +## along with Octave; see the file COPYING. If not, see +## <http://www.gnu.org/licenses/>. + +## -*- texinfo -*- +## @deftypefn {} {@var{newstr} =} erase (@var{str}, @var{ptn}) +## Delete all occurrences of @var{ptn} within @var{str}. +## +## @var{str} and @var{ptn} can be ordinary strings, cell array of strings, or +## character arrays. +## +## Examples +## +## @example +## @group +## ## string, single pattern +## erase ("Hello World!", " World") +## @result{} "Hello!" +## +## ## cellstr, single pattern +## erase (@{"Hello", "World!"@}, "World") +## @result{} @{"Hello", "!"@} +## +## ## string, multiple patterns +## erase ("The Octave interpreter is fabulous", @{"interpreter ", "The "@}) +## @result{} "Octave is fabulous" +## +## ## cellstr, multiple patterns +## erase (@{"The ", "Octave interpreter ", "is fabulous"@}, @{"interpreter ", "The "@}) +## @result{} @{"", "Octave ", "is fabulous"@} +## @end group +## @end example +## +## Programming Note: @code{erase} deletes the first instance of a pattern in a +## string when there are overlapping occurrences. For example, +## +## @example +## erase ("abababa", "aba") +## @result{} "b" +## @end example +## +## See @code{strrep} for processing overlaps. +## +## @seealso{strrep, regexprep} +## @end deftypefn + +## Author: Sahil Yadav <yadavsahil5198@gmail.com> + + +function newstr = erase (str, ptn) + + if (nargin != 2) + print_usage (); + endif + + ischarmatrix = false; + if (ischar (str)) + if (rows (str) > 1) + ## Convert to cell. Can't use cellstr which trims spaces. + str = mat2cell (str, ones (1, rows (str))); + ischarmatrix = true; + endif + elseif (! iscellstr (str)) + error ("erase: STR must be a string or cell array of strings"); + endif + + if (ischar (ptn)) + if (rows (ptn) > 1) + ## Convert to cell. Can't use cellstr which trims spaces. + ptn = mat2cell (ptn, ones (1, rows (ptn))); + endif + elseif (! iscellstr (ptn)) + error ("erase: PTN must be a string or cell array of strings"); + endif + + nptn = ifelse (ischar (ptn), 1, numel (ptn)); + if (nptn == 1) + newstr = strrep (str, ptn, "", "overlaps", false); + else + ptn = regexptranslate ("escape", ptn(:).'); + ptn = strjoin (ptn, '|'); + newstr = regexprep (str, ptn, ""); + endif + + if (ischarmatrix) + newstr = char (newstr); + endif + +endfunction + + +%!assert (erase ("Hello World!", " World"), "Hello!") +%!assert (erase ({"Hello World!"}, " World"), {"Hello!"}) +%!assert (erase (char ("Hello", "World!"), "World"), char ("Hello ", "!")) +%!assert (erase ({"Hello", "World!"}, "World"), {"Hello", "!"}) +%!assert (erase ("Hello World!", {"o"; "World"; " "}), "Hell!") + +## Test overlaps +## from https://savannah.gnu.org/bugs/?52647#comment5 +%!assert (erase ('ababa', 'aba'), 'ba') +%!assert (erase ('abababa', 'aba'), 'b') +%!assert (erase ('ababababa', 'aba'), 'bba') +%!assert (erase ('ababababa', {'aba', 'bba'}), 'bba') +%!assert (erase ('ababababa ', {'aba', 'bba'}), 'bba ') +%!assert (erase ({' ababababa '}, {'aba', 'bba'}), {' bba '}) +%!assert (erase (' ababa ', {'aba', 'baba'}), ' ba ') +%!assert (erase (' Hello World t ', {'t';'llo'}), ' He World ') +%!assert (erase ({' Hello World t '}, [ 'o ']), {' HellWorld t '}) +%!assert (erase ( 'Hello World t ', {'ld '; 'o '}), 'HellWort ') +%!assert (erase ('aba', 'aba'), '') +%!assert (erase ({'aba'}, 'aba'), ({""})) +%!assert (erase ('', 'aba'), '') +%!assert (erase ({'abbabbabba'},{'abba'}), {'bb'}) +%!assert (erase ({'ababababa';'abbabbabba'}, 'aba'), {'bba';'abbabbabba'}) +%!assert (erase ({''}, {''}), {''}) +%!assert (erase ({'pppppppp'}, 'p'), {''}) +%!assert (erase ('Hello World t ', {'ld '; 'o '}), 'HellWort ') +%!assert (erase ({'Hello World t '}, {'ld '; 'o '}), {'HellWort '}) + +## Test input validation +%!error erase () +%!error erase ("a") +%!error erase ("a", "b", "c") +%!error <STR must be a string> erase ([1], "foo") +%!error <PTN must be a string> erase ("foo", [1])