ExternalData: Add support for custom algorithm-to-URL mapping

Allow URL templates to contain a %(algo:<key>) placeholder that is
replaced by mapping the canonical hash algorithm name through a map
defined by the <key>.

Extend the Module.ExternalData test to cover the behavior.
Extend the RunCMake.ExternalData test to cover error cases.

Tests/Module/ExternalData/Alt/MyAlgoMap1-md5/dded55e43cd6529ee35d24113dfc87a3

@@ -0,0 +1 @@
+DataAlgoMap

Tests/Module/ExternalData/Alt/SHA1/85158f0c1996837976e858c42a9a7634bfe91b93

@@ -0,0 +1 @@
+DataAlgoMap

Tests/Module/ExternalData/CMakeLists.txt

@@ -10,8 +10,10 @@ if(NOT "${CMAKE_CURRENT_SOURCE_DIR}" MATCHES "^/")
 endif()
 set(ExternalData_URL_TEMPLATES
   "file://${slash}${CMAKE_CURRENT_SOURCE_DIR}/%(algo)/%(hash)"
+  "file://${slash}${CMAKE_CURRENT_SOURCE_DIR}/Alt/%(algo:MyAlgoMap1)/%(hash)"
   "ExternalDataCustomScript://MyScript1/%(algo)/%(hash)"
   )
+set(ExternalData_URL_ALGO_MD5_MyAlgoMap1 MyAlgoMap1-md5)
 set(ExternalData_CUSTOM_SCRIPT_MyScript1 "${CMAKE_CURRENT_SOURCE_DIR}/MyScript1.cmake")
 set(ExternalData_BINARY_ROOT "${CMAKE_CURRENT_BINARY_DIR}/ExternalData")
 file(REMOVE_RECURSE ${ExternalData_BINARY_ROOT}) # clean test
@@ -26,6 +28,8 @@ ExternalData_Add_Test(Data1
     -D Data=DATA{Data.dat}
     ${Data1CheckSpaces}
     -D DataScript=DATA{DataScript.dat}
+    -D DataAlgoMapA=DATA{DataAlgoMapA.dat}
+    -D DataAlgoMapB=DATA{DataAlgoMapB.dat}
     -D DataMissing=DATA{DataMissing.dat}
     -D DataMissingWithAssociated=DATA{DataMissing.dat,Data.dat}
     -D SeriesA=DATA{SeriesA.dat,:}

Tests/Module/ExternalData/Data1Check.cmake

@@ -12,6 +12,14 @@ file(STRINGS "${DataScript}" lines LIMIT_INPUT 1024)
 if(NOT "x${lines}" STREQUAL "xDataScript")
   message(SEND_ERROR "Input file:\n  ${DataScript}\ndoes not have expected content, but [[${lines}]]")
 endif()
+file(STRINGS "${DataAlgoMapA}" lines LIMIT_INPUT 1024)
+if(NOT "x${lines}" STREQUAL "xDataAlgoMap")
+  message(SEND_ERROR "Input file:\n  ${DataAlgoMapA}\ndoes not have expected content, but [[${lines}]]")
+endif()
+file(STRINGS "${DataAlgoMapB}" lines LIMIT_INPUT 1024)
+if(NOT "x${lines}" STREQUAL "xDataAlgoMap")
+  message(SEND_ERROR "Input file:\n  ${DataAlgoMapB}\ndoes not have expected content, but [[${lines}]]")
+endif()
 if(DataMissing)
   if(EXISTS "${DataMissing}")
     message(SEND_ERROR

Tests/Module/ExternalData/DataAlgoMapA.dat.md5

@@ -0,0 +1 @@
+dded55e43cd6529ee35d24113dfc87a3

Tests/Module/ExternalData/DataAlgoMapB.dat.sha1

@@ -0,0 +1 @@
+85158f0c1996837976e858c42a9a7634bfe91b93