regular expression to replace ~ in code

Question

Robert Alvarez 2013-7-11

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/81818-regular-expression-to-replace-in-code

Edit: wrote new function StripTildes.m (see below) that works with all cases including output list on multiple lines

Edit: Modified the StripTildes function to use Daniel's regular expression from FEX function. This still does not work with modified TestFunction that uses a line continuation in the output argument list.

My version of Matlab does not support the use of ~ in an output argument list so it is giving syntax errors when I try to use some downloaded code.

My regular expressions are extremely rusty so I would appreciate a regular expression to use with regexprep to replace the ~ in an output argument enclosed in brackets but not replace ~= and other uses of the symbol.

responding to Azzi's comment: I would like to replace ~ with a regular variable name like 'dummy' so it will not cause a syntax error. The rest of the code should then work OK so long as there is no collision with an existing variable name.

My idea is to write a Matlab function to scan the downloaded code file, replace the ~'s, and then write the output to another file.

My editor 'Editpad' allows regular expression search and replace so I can also use the regular expression with it but for definiteness please stick with regexprep and I will take it from there.

Question: I am no clear the allowable syntax. Are only spaces between output arguments allowed such as?

[~ ~ y3 ] = NewFunction(foo);

TIA.

I created a function to implement the filtering and a test function as follows:

1. the filtering function

    function StripTildes(filename)
    % replace tildes in output parameter lists with 'the_dummy'
    %  in Matlab file filename
    % outputs new file named filename_notilde.m to same directory as original file
    pattern='~(?=[^\]\[='']*\][\s(\.\.\.)]*=[^=])'; % regular expression to find tildes
    fid = fopen(filename); % open for read only
    assert( fid ~= -1);
       % read all file into one long string (including line break chars) so regexprep can work across lines
    filetext = [];
    while 1
        tline = fgets(fid);
        if ~ischar(tline),   break,   end % quit at end of file
        filetext = [filetext tline];
    end
    fclose(fid);
    filetext = regexprep(filetext,pattern,'the_dummy');
       % output the file
    [path,name,ext] = fileparts(filename);
    out_name = [path filesep name '_notilde' ext];
    fidout = fopen(out_name,'w');
    assert( fid ~= -1);
    fwrite(fidout,filetext);
    fclose(fidout);

2. the function to test

    function TestFunction
    if 1 ~= 0
        [~,~,y] = LocalFunction;
    elseif ~(true) or ~exist(foo,'dir')
        [~ ~ y ] = LocalFunction;
    end
    tf = [~true, 1~=0, ...
        ];
    [~,~, ...
        y] = LocalFunction;
    function [y1,y2,y3] = LocalFunction
    y1 = 0;
    y2 = 0;
    y3 = 0

p.s. I cannot afford to upgrade my Matlab version so please do not suggest it as a solution

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per isakson 2013-7-11

编辑：per isakson 2013-7-11

I modified the expression below to handle [~,~,y] and [~,a,~]

Robert Alvarez 2013-7-11

I fixed a bug in StripTildes function and modified TestFunction.

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Answer 1

per isakson 2013-7-11

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https://ww2.mathworks.cn/matlabcentral/answers/81818-regular-expression-to-replace-in-code#answer_91522

编辑：per isakson 2013-7-11

在 MATLAB Online 中打开

regexprep( '[ a, ~, b ]', '(?<=\[.+?,[ ]*)\~(?=.+?])', 'dummy' )

returns

[ a, dummy, b ]

Firstly, backup all your files

and make more tests

.

Always check the FEX. See replaceTildes

.

Bugfix:

    str = '[~,~,y] = LocalFunction;';
    regexprep( str, '(?<=\[(.+?,)|([ ]*)[ ]*)\~(?=.+?])', 'dummy' )

returns

    ans =
    [dummy,dummy,y] = LocalFunction;

.

and another bugfix

    str = '[~,a,~] = LocalFunction;';
    regexprep( str, '(?<=\[(.+?,)|([ ]*)[ ]*)\~(?=.*?])', 'dummy' )

returns

    ans =
    [dummy,a,dummy] = LocalFunction;

and more test needed

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per isakson 2013-7-11

编辑：per isakson 2013-7-11

在 MATLAB Online 中打开

Try this

    reg = '(?<=\[(.+?,)|([ ]*)[ ]*)\~(?=.*?][ ]*(=|(\.\.\.)))'; 
    str = '[~,a,~] = LocalFunction;';
    regexprep( str, reg, 'dummy' )
    str = 'tf = [~true, 1~=0, ...';
    regexprep( str, reg, 'dummy' )
    str = '[~,a,~] ...';
    regexprep( str, reg, 'dummy' )

The expression looks at one line. Thus, I give up on this one

     [~,~, ...
            y] = LocalFunction;

and after that we will face

     [y,~, ...
            ~] = LocalFunction;

You could

concatenate the continuation lines
search&replace
restore the continuation lines

per isakson 2013-7-11

FileLocator Lite is a free really good find_in_files_program. It will help you find the remaining cases, which you should edit interactively.

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Answer 2

Azzi Abdelmalek 2013-7-11

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/81818-regular-expression-to-replace-in-code#answer_91520

编辑：Azzi Abdelmalek 2013-7-11

在 MATLAB Online 中打开

str='one ~ two ~= three ~'
pattern='~(?!\S)'
regexprep(str,pattern,'dummy')

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Daniel Shub 2013-7-11

I think this will fail if the ~ is in a string. It is possibly better to also include [] since I think that is a requirement. I think counting opening/closing quoutes might be hard.

Azzi Abdelmalek 2013-7-11

编辑：Azzi Abdelmalek 2013-7-11

在 MATLAB Online 中打开

str=' z~d one ~ two ~= three ~'
pattern='~(?!\=)'
regexprep(str,pattern,'dummy')

%or

str=strrep(str,'~=','obma')
str=strrep(str,'~','dummy')
str=strrep(str,'obma','~=')

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regular expression to replace ~ in code

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