Add support for writing ports of Ignition Robotics libraries and ports for ignition-cmake0 and ignition-math4 (#7781)

* Add ignition-modularscript port

Modeled after the qt5-modularscript port, this port just contain
ignition_modular_library, an helper CMake function to simplify the
process of writing port of C++ libraries developed by the Ignition
Robotics project ( https://ignitionrobotics.org ).

* Add ignition-cmake0 port

* Add ignition-math4 port

3 files changed, 117 insertions, 0 deletions

diff --git a/ports/ignition-modularscripts/CONTROL b/ports/ignition-modularscripts/CONTROL
new file mode 100644
index 000000000..fa8a222cd
--- /dev/null
+++ b/ports/ignition-modularscripts/CONTROL
@@ -0,0 +1,3 @@
+Source: ignition-modularscripts

+Version: 2019-08-20

+Description: Vcpkg helpers to package ignition libraries

diff --git a/ports/ignition-modularscripts/ignition_modular_library.cmake b/ports/ignition-modularscripts/ignition_modular_library.cmake
new file mode 100644
index 000000000..8800353d1
--- /dev/null
+++ b/ports/ignition-modularscripts/ignition_modular_library.cmake
@@ -0,0 +1,106 @@
+
+function(ignition_modular_build_library NAME MAJOR_VERSION SOURCE_PATH)
+    vcpkg_configure_cmake(
+        SOURCE_PATH ${SOURCE_PATH}
+        PREFER_NINJA
+        OPTIONS -DBUILD_TESTING=OFF
+    )
+
+    vcpkg_install_cmake()
+
+    vcpkg_fixup_cmake_targets(CONFIG_PATH "lib/cmake/ignition-${NAME}${MAJOR_VERSION}")
+
+    file(GLOB_RECURSE CMAKE_RELEASE_FILES 
+                      "${CURRENT_PACKAGES_DIR}/lib/cmake/ignition-${NAME}${MAJOR_VERSION}/*")
+
+    file(COPY ${CMAKE_RELEASE_FILES} DESTINATION 
+              "${CURRENT_PACKAGES_DIR}/share/ignition-${NAME}${MAJOR_VERSION}/")
+
+    # Remove debug files
+    file(REMOVE_RECURSE ${CURRENT_PACKAGES_DIR}/debug/include 
+                        ${CURRENT_PACKAGES_DIR}/debug/lib/cmake
+                        ${CURRENT_PACKAGES_DIR}/debug/share)
+
+    # Post-build test for cmake libraries 
+    vcpkg_test_cmake(PACKAGE_NAME ignition-${NAME}${MAJOR_VERSION})
+
+    # Find the relevant license file and install it
+    if(EXISTS "${SOURCE_PATH}/LICENSE")
+        set(LICENSE_PATH "${SOURCE_PATH}/LICENSE")
+    elseif(EXISTS "${SOURCE_PATH}/README.md")
+        set(LICENSE_PATH "${SOURCE_PATH}/README.md")
+    endif()
+    file(INSTALL ${LICENSE_PATH} DESTINATION ${CURRENT_PACKAGES_DIR}/share/${PORT} RENAME copyright)
+endfunction()
+
+## # ignition_modular_library
+##
+## Download and build a library from the Ignition Robotics project ( https://ignitionrobotics.org/ ).
+##
+## ## Usage:
+## ```cmake
+## ignition_modular_library(NAME <name>
+##                          VERSION <version>
+##                          SHA512 <sha512>
+##                          [REF <ref>]
+##                          [HEAD_REF <head_ref>]
+##                          [PATCHES <patches>])
+## ```
+##
+## ## Parameters:
+## ### NAME
+## The name of the specific ignition library, i.e. `cmake` for `ignition-cmake0`, `math` for `ignition-math4`.
+##
+## ### VERSION
+## The complete version number.
+##
+## ### SHA512
+## The SHA512 hash that should match the downloaded  archive. This is forwarded to the `vcpkg_from_bitbucket` command.
+##
+## ### REF
+## Reference to the tag of the desired release. This is forwarded to the `vcpkg_from_bitbucket` command.
+## If not specified, defaults to `ignition-${NAME}${MAJOR_VERSION}_${VERSION}`.
+##
+## ### HEAD_REF
+## Reference (tag) to the desired release. This is forwarded to the `vcpkg_from_bitbucket` command.
+## If not specified, defaults to `ign-${NAME}${MAJOR_VERSION}`.
+##
+## ### PATCHES
+## A list of patches to be applied to the extracted sources.
+##  This is forwarded to the `vcpkg_from_bitbucket` command.
+##
+## ## Examples:
+##
+## * [ignition-cmake0](https://github.com/Microsoft/vcpkg/blob/master/ports/ignition-cmake0/portfile.cmake)
+## * [ignition-math4](https://github.com/Microsoft/vcpkg/blob/master/ports/ignition-math4/portfile.cmake)
+function(ignition_modular_library)
+    set(oneValueArgs NAME VERSION SHA512 REF HEAD_REF)
+	set(multiValueArgs PATCHES)
+    cmake_parse_arguments(IML "" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
+    
+    string(REPLACE "." ";" IML_VERSION_LIST ${IML_VERSION})
+    list(GET IML_VERSION_LIST 0 IML_MAJOR_VERSION)
+    
+    # If the REF option is omitted, use the canonical one 
+    if(NOT DEFINED IML_REF)
+        set(IML_REF "ignition-${IML_NAME}${IML_MAJOR_VERSION}_${IML_VERSION}")
+    endif()
+    
+    # If the HEAD_REF option is omitted, use the canonical one 
+    if(NOT DEFINED IML_HEAD_REF)
+        set(IML_HEAD_REF "ign-${IML_NAME}${IML_MAJOR_VERSION}")
+    endif()
+    
+    # Download library from bitbucket, to support also the --head option
+    vcpkg_from_bitbucket(
+        OUT_SOURCE_PATH SOURCE_PATH
+        REPO ignitionrobotics/ign-${IML_NAME}
+        REF ${IML_REF}
+        SHA512 ${IML_SHA512}
+        HEAD_REF ${IML_HEAD_REF}
+        PATCHES ${IML_PATCHES}
+    )
+    
+    # Build library
+    ignition_modular_build_library(${IML_NAME} ${IML_MAJOR_VERSION} ${SOURCE_PATH})
+endfunction()
diff --git a/ports/ignition-modularscripts/portfile.cmake b/ports/ignition-modularscripts/portfile.cmake
new file mode 100644
index 000000000..509240d7d
--- /dev/null
+++ b/ports/ignition-modularscripts/portfile.cmake
@@ -0,0 +1,8 @@
+file(COPY
+    ${CMAKE_CURRENT_LIST_DIR}/ignition_modular_library.cmake
+    DESTINATION
+        ${CURRENT_PACKAGES_DIR}/share/ignitionmodularscripts
+)
+file(WRITE ${CURRENT_PACKAGES_DIR}/share/ignitionmodularscripts/copyright "")
+
+set(VCPKG_POLICY_EMPTY_PACKAGE enabled)