Parsing tools: added StripPreprocessorDirectives function

Author: TheMostDiligent

Common/interface/ParsingTools.hpp

@@ -32,6 +32,8 @@
 #include <cstring>
 #include <sstream>
 #include <limits>
+#include <vector>
+#include <algorithm>
 
 #include "../../Primitives/interface/BasicTypes.h"
 #include "../../Primitives/interface/FlagEnum.h"
@@ -1225,6 +1227,54 @@ inline int GetArrayIndex(const std::string& Var, std::string& NameWithoutBracket
     return GetArrayIndex(Var.begin(), Var.end(), NameWithoutBrackets);
 }
 
+
+/// Strips all preprocessor directives from the source string.
+inline void StripPreprocessorDirectives(std::string& Source, const std::vector<std::string>& Directives)
+{
+    if (Directives.empty())
+        return;
+
+    auto Pos = Source.begin();
+    while (Pos != Source.end())
+    {
+        // // Comment
+        // ^
+        Pos = SkipDelimitersAndComments(Pos, Source.end());
+        if (Pos == Source.end())
+            break;
+
+        if (*Pos == '#')
+        {
+            const auto DirectiveStart = Pos;
+            // # version 450
+            // ^
+
+            ++Pos;
+            if (Pos == Source.end())
+                break;
+
+            Pos = SkipDelimiters(Pos, Source.end(), " \t");
+            // # version 450
+            //   ^
+
+            if (Pos == Source.end())
+                break;
+
+            const std::string DirectiveIdentifier{Pos, SkipIdentifier(Pos, Source.end())};
+            if (!DirectiveIdentifier.empty() && std::find(Directives.begin(), Directives.end(), DirectiveIdentifier) != Directives.end())
+            {
+                const auto LineEnd = SkipLine(Pos, Source.end(), false);
+
+                Pos = Source.erase(DirectiveStart, LineEnd);
+                if (Pos == Source.end())
+                    break;
+            }
+        }
+
+        Pos = SkipLine(Pos, Source.end(), true);
+    }
+}
+
 } // namespace Parsing
 
 } // namespace Diligent

Tests/DiligentCoreTest/src/Common/ParsingToolsTest.cpp

@@ -1442,4 +1442,122 @@ TEST(Common_ParsingTools, GetArrayIndex)
     Test("xy7[12 ", 3, INT_MIN);
 }
 
+TEST(Common_ParsingTools, StripPreprocessorDirectives)
+{
+    auto Test = [](std::string Source, const std::string& RefSource, const std::vector<std::string>& Directives) {
+        StripPreprocessorDirectives(Source, Directives);
+        EXPECT_STREQ(Source.c_str(), RefSource.c_str());
+    };
+
+    Test("", "", {{"version"}});
+    Test(" ", " ", {{"version"}});
+    Test("// Comment", "// Comment", {{"version"}});
+    Test("/* Comment */", "/* Comment */", {{"version"}});
+    Test("#", "#", {{"version"}});
+    Test("#\n", "#\n", {{"version"}});
+    Test("#\nversion", "#\nversion", {{"version"}});
+    Test("#\n#version XYZ", "#\n", {{"version"}});
+    Test("# ", "# ", {{"version"}});
+    Test("# \n", "# \n", {{"version"}});
+    Test("#extension XYZ", "#extension XYZ", {{"version"}});
+    Test("// #version XYZ", "// #version XYZ", {{"version"}});
+
+    Test(R"(
+void main()
+{
+})",
+         R"(
+void main()
+{
+})",
+         {{"version"}});
+
+
+    Test(R"(
+#version 450
+void main()
+{
+})",
+         R"(
+
+void main()
+{
+})",
+         {{"version"}});
+
+
+    Test(R"(
+// Comment
+#  version 450
+void main()
+{
+})",
+         R"(
+// Comment
+
+void main()
+{
+})",
+         {{"version"}});
+
+
+    Test(R"(
+/* Comment */ #  version 450
+void main()
+{
+})",
+         R"(
+/* Comment */ 
+void main()
+{
+})",
+         {{"version"}});
+
+
+    Test(R"(
+/* #  version 450 */ 
+void main()
+{
+})",
+         R"(
+/* #  version 450 */ 
+void main()
+{
+})",
+         {{"version"}});
+
+
+    Test(R"(
+#version 450
+void main()
+{
+# error Error Message
+})",
+         R"(
+#version 450
+void main()
+{
+
+})",
+         {{"error"}});
+
+    Test(R"(#version 450
+#extension GL_ARB_separate_shader_objects : enable
+#ifndef GL_ARB_shader_draw_parameters
+#error GL_ARB_shader_draw_parameters is not supported.
+#endif
+void main()
+{
+})",
+         R"(
+
+#ifndef GL_ARB_shader_draw_parameters
+
+#endif
+void main()
+{
+})",
+         {{"version"}, {"extension"}, {"error"}});
+}
+
 } // namespace