Implemented alternate Python 'stringify' tool

This simplifies build dependencies when cross-compiling
or when building multi-architecture binaries.

For backward compatibility with earlier releases, the compiled
C++ version of this tool is used when no Python interpreter is found.

CMakeLists.txt

@@ -394,6 +394,9 @@ else()
     set(DOXYGEN_EXECUTABLE )
 endif()
 
+# Python is used optionally to process source and documentation source files.
+find_package(Python COMPONENTS Interpreter)
+
 set(BUILD_SHARED_LIBS "${build_shared_libs}")
 
 # Warn about missing dependencies that will cause parts of OpenSubdiv to be
@@ -717,11 +720,27 @@ macro(osd_add_doxy_headers headers)
 endmacro()
 
 # Kernel Stringification
-# We want to use preprocessor include directives to include GLSL and OpenCL
+# We want to use preprocessor include directives to include GLSL, OpenCL, etc.
 # kernel source files in cpp files, but since the sources contain newline
 # characters we would need raw string literals from C++11 to do this directly.
-# To avoid depending on C++11 we instead use a small tool called "line_quote"
+# To avoid depending on C++11 we instead use a small tool called "stringify"
 # to generate source files that are suitable for direct inclusion.
+
+# We provide a Python implementation for configurability, e.g. to
+# use when cross compiling or building multi-architecture binaries.
+# We also provide a C++ binary implementation so that Python is not
+# required (for backward compatibility).
+if (OPENGL_FOUND OR OPENCL_FOUND OR DXSDK_FOUND OR METAL_FOUND)
+    if(Python_Interpreter_FOUND)
+        set(OSD_STRINGIFY_TOOL ${CMAKE_CURRENT_SOURCE_DIR}/tools/stringify/stringify.py)
+        set(OSD_STRINGIFY ${Python_EXECUTABLE} ${OSD_STRINGIFY_TOOL})
+    else()
+        set(OSD_STRINGIFY_TOOL stringify)
+        set(OSD_STRINGIFY ${OSD_STRINGIFY_TOOL})
+        set(OSD_USES_STRINGIFY_TOOL_BINARY TRUE)
+    endif()
+endif()
+
 function(osd_stringify src_files varname)
 
     set(inc_files "")
@@ -737,9 +756,9 @@ function(osd_stringify src_files varname)
             OUTPUT
                 "${CMAKE_CURRENT_BINARY_DIR}/${inc_file}"
             COMMAND
-                stringify "${CMAKE_CURRENT_SOURCE_DIR}/${src_file}" "${CMAKE_CURRENT_BINARY_DIR}/${inc_file}"
+                ${OSD_STRINGIFY} "${CMAKE_CURRENT_SOURCE_DIR}/${src_file}" "${CMAKE_CURRENT_BINARY_DIR}/${inc_file}"
             DEPENDS
-                stringify "${CMAKE_CURRENT_SOURCE_DIR}/${src_file}"
+                ${OSD_STRINGIFY_TOOL} "${CMAKE_CURRENT_SOURCE_DIR}/${src_file}"
         )
 
     endforeach()
@@ -837,6 +856,10 @@ if (NOT NO_OPENGL)
     add_subdirectory(glLoader)
 endif()
 
+if (OSD_USES_STRINGIFY_TOOL_BINARY)
+    add_subdirectory(tools/stringify)
+endif()
+
 add_subdirectory(opensubdiv)
 
 if (NOT ANDROID) # XXXdyu

documentation/CMakeLists.txt

@@ -54,8 +54,6 @@ else()
 
 endif()
 
-find_package(Python COMPONENTS Interpreter)
-
 # ReST - HTML documentation
 if (DOCUTILS_FOUND AND Python_Interpreter_FOUND)
 

opensubdiv/CMakeLists.txt

@@ -55,10 +55,6 @@ if (NOT NO_LIB)
         )
     endif()
 
-    if(OPENGL_FOUND OR OPENCL_FOUND OR DXSDK_FOUND OR METAL_FOUND)
-        add_subdirectory(tools/stringify)
-    endif()
-
     if( OPENGL_FOUND )
         include_directories(${OPENGL_LOADER_INCLUDE_DIRS})
         list(APPEND PLATFORM_GPU_LIBRARIES

tools/stringify/stringify.py

@@ -0,0 +1,61 @@
+#
+#   Copyright 2022 Pixar
+#
+#   Licensed under the Apache License, Version 2.0 (the "Apache License")
+#   with the following modification; you may not use this file except in
+#   compliance with the Apache License and the following modification to it:
+#   Section 6. Trademarks. is deleted and replaced with:
+#
+#   6. Trademarks. This License does not grant permission to use the trade
+#      names, trademarks, service marks, or product names of the Licensor
+#      and its affiliates, except as required to comply with Section 4(c) of
+#      the License and to reproduce the content of the NOTICE file.
+#
+#   You may obtain a copy of the Apache License at
+#
+#       http://www.apache.org/licenses/LICENSE-2.0
+#
+#   Unless required by applicable law or agreed to in writing, software
+#   distributed under the Apache License with the above modification is
+#   distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+#   KIND, either express or implied. See the Apache License for the specific
+#   language governing permissions and limitations under the Apache License.
+#
+
+from __future__ import print_function
+import sys
+
+def stringify(s):
+    withinStringConstant = False
+
+    result = ""
+    for i in range(len(s)-1):
+        # escape double quotes
+        if s[i] == '"':
+            result += '\\'
+            withinStringConstant = not withinStringConstant
+
+        if s[i] == '\\' and i == len(s)-2:
+            return '"' + result + '"\n'
+
+        # escape backslash
+        if withinStringConstant and s[i] == '\\':
+            result += '\\'
+
+        result += s[i]
+
+    return '"' + result + '\\n"\n'
+
+def stringifyFile(inputFilename, outputFilename):
+    with open(inputFilename, "r") as inputFile, \
+         open(outputFilename, "w") as outputFile:
+        for line in inputFile:
+            outputFile.write(stringify(line))
+        outputFile.write('"\\n"\n')
+
+if len(sys.argv) != 3:
+    print("Usage: stringify input-file output-file")
+    sys.exit(1)
+
+stringifyFile(sys.argv[1], sys.argv[2])
+