Feature/file system cache (#692)

* First pass at caching file system.

* default-file-system -> slang-file-system
fix problem with location("build.linux") confusing windows build for now.

* Added CompressedResult
Fix problem in Result construction with it being unsigned

* Add support for Path simplification.

* Testing for Path::Simplify.

* Refactored CacheFileSystem - automatically handles ISlangFileSystem or ISlangFileSystemExt appropriately.
Removed WrapFileSystem - because wasn't possible to emulate some of the behavior if just loadFile is implemented.
Split out StringBlob - so that no need to convert between ISlangBlob and String repeatidly.

* Remove unwanted code in ~CompileRequest

6 files changed, 191 insertions, 3 deletions

diff --git a/source/core/core.vcxproj b/source/core/core.vcxproj
index d1ed4715f..2d0c67342 100644
--- a/source/core/core.vcxproj
+++ b/source/core/core.vcxproj
@@ -213,7 +213,7 @@
     <ClCompile Include="token-reader.cpp" />
   </ItemGroup>
   <ItemGroup>
-    <Natvis Include="core.natvis" />
+    <None Include="core.natvis" />
   </ItemGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
   <ImportGroup Label="ExtensionTargets">
diff --git a/source/core/core.vcxproj.filters b/source/core/core.vcxproj.filters
index 7936ca11b..1548217b4 100644
--- a/source/core/core.vcxproj.filters
+++ b/source/core/core.vcxproj.filters
@@ -130,8 +130,8 @@
     </ClCompile>
   </ItemGroup>
   <ItemGroup>
-    <Natvis Include="core.natvis">
+    <None Include="core.natvis">
       <Filter>Source Files</Filter>
-    </Natvis>
+    </None>
   </ItemGroup>
 </Project>
\ No newline at end of file
diff --git a/source/core/slang-io.cpp b/source/core/slang-io.cpp
index 2b443a62b..f1948200c 100644
--- a/source/core/slang-io.cpp
+++ b/source/core/slang-io.cpp
@@ -123,6 +123,105 @@ namespace Slang
 		return sb.ProduceString();
 	}
 
+    /* static */ bool Path::IsDriveSpecification(const UnownedStringSlice& element)
+    {
+        switch (element.size())
+        {
+            case 0:     
+            {
+                // We'll just assume it is
+                return true;
+            }
+            case 2:
+            {
+                // Look for a windows like drive spec
+                const char firstChar = element[0]; 
+                return element[1] == ':' && ((firstChar >= 'a' && firstChar <= 'z') || (firstChar >= 'A' && firstChar <= 'Z'));
+            }
+            default:    return false;
+        }
+        
+    }
+
+    /* static */void Path::Split(const UnownedStringSlice& path, List<UnownedStringSlice>& splitOut)
+    {
+        splitOut.Clear();
+
+        const char* start = path.begin();
+        const char* end = path.end();
+
+        while (start < end)
+        {
+            const char* cur = start;
+            // Find the split
+            while (cur < end && !IsDelimiter(*cur)) cur++;
+
+            splitOut.Add(UnownedStringSlice(start, cur));
+           
+            // Next
+            start = cur + 1;
+        }
+
+        // Okay if the end is empty. And we aren't with a spec like // or c:/ , then drop the final slash 
+        if (splitOut.Count() > 1 && splitOut.Last().size() == 0)
+        {
+            if (splitOut.Count() == 2 && IsDriveSpecification(splitOut[0]))
+            {
+                return;
+            }
+            // Remove the last 
+            splitOut.RemoveLast();
+        }
+    }
+
+    /* static */String Path::Simplify(const UnownedStringSlice& path)
+    {
+        List<UnownedStringSlice> split;
+        Split(path, split);
+
+        // Strictly speaking we could do something about case on platforms like window, but here we won't worry about that
+        for (int i = 0; i < int(split.Count()); i++)
+        {
+            const UnownedStringSlice& cur = split[i];
+            if (cur == "." && split.Count() > 1)
+            {
+                // Just remove it 
+                split.RemoveAt(i);
+                i--;
+            }
+            else if (cur == ".." && i > 0)
+            {
+                // Can we remove this and the one before ?
+                UnownedStringSlice& before = split[i - 1];
+                if (before == ".." || (i == 1 && IsDriveSpecification(before)))
+                {
+                    // Can't do it
+                    continue;
+                }
+                split.RemoveRange(i - 1, 2);
+                i -= 2;
+            }
+        }
+
+        // If its empty it must be .
+        if (split.Count() == 0)
+        {
+            split.Add(UnownedStringSlice::fromLiteral("."));
+        }
+
+        // Reconstruct the string
+        StringBuilder builder;
+        for (int i = 0; i < int(split.Count()); i++)
+        {
+            if (i > 0)
+            {
+                builder.Append(PathDelimiter);
+            }
+            builder.Append(split[i]);
+        }
+        return builder;
+    }
+
 	bool Path::CreateDir(const String & path)
 	{
 #if defined(_WIN32)
diff --git a/source/core/slang-io.h b/source/core/slang-io.h
index ff287254c..3703aee08 100644
--- a/source/core/slang-io.h
+++ b/source/core/slang-io.h
@@ -32,6 +32,17 @@ namespace Slang
 		static String Combine(const String & path1, const String & path2, const String & path3);
 		static bool CreateDir(const String & path);
 
+            /// Accept either style of delimiter
+        SLANG_FORCE_INLINE static bool IsDelimiter(char c) { return c == '/' || c == '\\'; }
+
+        static bool IsDriveSpecification(const UnownedStringSlice& element);
+
+            /// Splits the path into it's individual bits
+        static void Split(const UnownedStringSlice& path, List<UnownedStringSlice>& splitOut);
+            /// Strips .. and . as much as it can 
+        static String Simplify(const UnownedStringSlice& path);
+        static String Simplify(const String& path) { return Simplify(path.getUnownedSlice()); }
+
         static SlangResult GetPathType(const String & path, SlangPathType* pathTypeOut);
 
         static SlangResult GetCanonical(const String & path, String& canonicalPathOut);
diff --git a/source/core/slang-string-util.cpp b/source/core/slang-string-util.cpp
index 29f8dc0ca..6d0d896a1 100644
--- a/source/core/slang-string-util.cpp
+++ b/source/core/slang-string-util.cpp
@@ -2,6 +2,19 @@
 
 namespace Slang {
 
+// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! StringBlob !!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+// Allocate static const storage for the various interface IDs that the Slang API needs to expose
+static const Guid IID_ISlangUnknown = SLANG_UUID_ISlangUnknown;
+static const Guid IID_ISlangBlob = SLANG_UUID_ISlangBlob;
+
+/* static */ISlangUnknown* StringBlob::getInterface(const Guid& guid)
+{
+    return (guid == IID_ISlangUnknown || guid == IID_ISlangBlob) ? static_cast<ISlangBlob*>(this) : nullptr;
+}
+
+// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! StringUtil !!!!!!!!!!!!!!!!!!!!!!!!!!!
+
 /* static */void StringUtil::split(const UnownedStringSlice& in, char splitChar, List<UnownedStringSlice>& slicesOut)
 {
     slicesOut.Clear();
@@ -74,4 +87,28 @@ namespace Slang {
     return builder;
 }
 
+/* static */String StringUtil::getString(ISlangBlob* blob)
+{
+    if (blob)
+    {
+        size_t size = blob->getBufferSize();
+        if (size > 0)
+        {
+            const char* contents = (const char*)blob->getBufferPointer();
+            // Check it has terminating 0, if not we must construct as if it does
+            if (contents[size - 1] == 0)
+            {
+                size--;
+            }
+            return String(contents, contents + size);
+        }
+    }
+    return String();
+}
+
+ComPtr<ISlangBlob> StringUtil::createStringBlob(const String& string)
+{
+    return ComPtr<ISlangBlob>(new StringBlob(string));
+}
+
 } // namespace Slang
diff --git a/source/core/slang-string-util.h b/source/core/slang-string-util.h
index fc3258490..47d92f2fe 100644
--- a/source/core/slang-string-util.h
+++ b/source/core/slang-string-util.h
@@ -6,8 +6,41 @@
 
 #include <stdarg.h>
 
+#include "../../slang-com-helper.h"
+#include "../../slang-com-ptr.h"
+
 namespace Slang {
 
+/** A blob that uses a `String` for its storage.
+*/
+class StringBlob : public ISlangBlob
+{
+public:
+    // ISlangUnknown
+    SLANG_IUNKNOWN_ALL
+
+        // ISlangBlob
+    SLANG_NO_THROW void const* SLANG_MCALL getBufferPointer() SLANG_OVERRIDE { return m_string.Buffer(); }
+    SLANG_NO_THROW size_t SLANG_MCALL getBufferSize() SLANG_OVERRIDE { return m_string.Length(); }
+
+        /// Get the contained string
+    SLANG_FORCE_INLINE const String& getString() const { return m_string; }
+
+    explicit StringBlob(String const& string)
+        : m_string(string)
+    {}
+
+    /// Need virtual dtor, because BlobBase is derived from and release impl used is the one in the base class (that doesn't know the derived type)
+    /// Alternatively could be implemented by always using SLANG_IUNKNOWN_RELEASE in derived types - this would make derived types slightly smaller/faster
+    virtual ~StringBlob() {}
+
+protected:
+    ISlangUnknown* getInterface(const Guid& guid);
+
+    String m_string;
+    uint32_t m_refCount = 0;
+};
+
 struct StringUtil
 {
         /// Split in, by specified splitChar into slices out
@@ -22,6 +55,14 @@ struct StringUtil
 
         /// Create a string from the format string applying args (like sprintf)
     static String makeStringWithFormat(const char* format, ...);
+
+        /// Given a string held in a blob, returns as a String
+        /// Returns an empty string if blob is nullptr 
+    static String getString(ISlangBlob* blob);
+
+        /// Create a blob from a string
+    static ComPtr<ISlangBlob> createStringBlob(const String& string);
+
 };
 
 } // namespace Slang