[CMake] SUBSTRING - STRING - shorten a string variable

[Brandon Van Every]

On Dec 3, 2007 12:56 PM, Sören Freudiger <muffmolch at gmx.de> wrote:
>
>
>
>
> Hello
>
> Following problem:
>
>
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> My CMakeList.txt file is somewhere like:
>
> E:/LBM_subversion/source/topology/amr3d/lbmd3q19/singlephase/testcases/RCF/all_in_one
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>
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> Now I want to have only the substring:
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> E:/LBM_subversion/source
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> Is it possible to get last string with the help of CMAKE_CURRENT_SOURCE_DIR?
> I just want to know the position of "source".  Thus I can shorten the string
> stored in CMAKE_CURRENT_SOURCE_DIR very easy. I do not always  know the path
> behind source/…

If you know the string contains "${CMAKE_CURRENT_SOURCE_DIR}" then you can do:

string(REPLACE
  "${CMAKE_CURRENT_SOURCE_DIR}"
  ""
  relative_path "${absolute_path}")

If you need to find out whether the string contains
"${CMAKE_CURRENT_SOURCE_DIR}" then the following will work as long as
"${CMAKE_CURRENT_SOURCE_DIR}" doesn't contain regex special
characters.

if(absolute_path MATCHES "^${CMAKE_CURRENT_SOURCE_DIR}")
  # blah blah blah

If "${CMAKE_CURRENT_SOURCE_DIR}" contains regex special characters,
you'll have to double escape them.

string(REPLACE
  "\\"
  "\\\\"
  escaped_path "${toplevel_path}")
string(REGEX REPLACE
  "([][.?*+|()$^-])"
  "\\\\\\1"
  escaped_path "${escaped_path}")
if(absolute_path MATCHES "^${escaped_path}")
   string(REPLACE
      "${toplevel_path}"
      ""
      relative_path "${absolute_path}")



Cheers,
Brandon Van Every