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1 # Copyright (C) 1996 Kurt Hornik |
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2 # |
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3 # This file is part of Octave. |
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4 # |
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5 # Octave is free software; you can redistribute it and/or modify it |
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6 # under the terms of the GNU General Public License as published by the |
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7 # Free Software Foundation; either version 2, or (at your option) any |
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8 # later version. |
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9 # |
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10 # Octave is distributed in the hope that it will be useful, but WITHOUT |
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11 # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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12 # FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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13 # for more details. |
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14 # |
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15 # You should have received a copy of the GNU General Public License |
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16 # along with Octave; see the file COPYING. If not, write to the Free |
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17 # Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
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18 |
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19 function v = findstr (s, t, overlap) |
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20 |
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21 # usage: findstr (s, t [, overlap]) |
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22 # |
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23 # Returns the vector of all positions in the longer of the two strings |
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24 # S and T where an occurence of the shorter of the two starts. |
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25 # |
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26 # If the optional argument OVERLAP is nonzero, the returned vector |
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27 # can include overlapping positions (this is the default). |
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28 # |
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29 # For example, |
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30 # |
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31 # findstr ("abababa", "aba") => [1, 3, 5] |
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32 # findstr ("abababa", "aba", 0) => [1, 5] |
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33 |
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34 # Original version by Kurt Hornik <Kurt.Hornik@ci.tuwien.ac.at>. |
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35 |
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36 if (nargin < 2 || nargin > 3) |
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37 usage ("findstr (s, t [, overlap])"); |
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38 endif |
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39 |
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40 if (nargin == 2) |
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41 overlap = 1; |
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42 endif |
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43 |
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44 if (isstr (s) && isstr (t)) |
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45 |
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46 # Make S be the longer string. |
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47 |
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48 if (length (s) < length (t)) |
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49 tmp = s; |
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50 s = t; |
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51 t = tmp; |
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52 endif |
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53 |
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54 s = toascii (s); |
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55 t = toascii (t); |
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56 |
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57 l_t = length (t); |
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58 |
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59 ind = 1 : l_t; |
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60 limit = length (s) - l_t + 1; |
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61 v = zeros (1, limit); |
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62 i = 0; |
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63 |
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64 k = 1; |
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65 while (k <= limit) |
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66 if (s (ind + k - 1) == t) |
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67 v (++i) = k; |
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68 if (! overlap) |
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69 k = k + l_t - 1; |
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70 endif |
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71 endif |
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72 k++; |
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73 endwhile |
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74 |
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75 if (i > 0) |
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76 v = v (1:i); |
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77 else |
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78 v = []; |
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79 endif |
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80 |
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81 else |
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82 error ("findstr: expecting first two arguments to be strings"); |
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83 endif |
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84 |
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85 endfunction |
