DirStackFileIncluder.h

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//
// Copyright (C) 2002-2005 3Dlabs Inc. Ltd.
// Copyright (C) 2017 Google, Inc.
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#pragma once

#include <vector>
#include <string>
#include <fstream>
#include <algorithm>

#include "./../glslang/Public/ShaderLang.h"

// Default include class for normal include convention of search backward
// through the stack of active include paths (for nested includes).
// Can be overridden to customize.
class DirStackFileIncluder : public glslang::TShader::Includer {
public:
 DirStackFileIncluder() : externalLocalDirectoryCount(0) { }

 virtual IncludeResult* includeLocal(const char* headerName,
 const char* includerName,
 size_t inclusionDepth) override
 {
 return readLocalPath(headerName, includerName, (int)inclusionDepth);
 }

 virtual IncludeResult* includeSystem(const char* headerName,
 const char* /*includerName*/,
 size_t /*inclusionDepth*/) override
 {
 return readSystemPath(headerName);
 }

 // Externally set directories. E.g., from a command-line -I<dir>.
 // - Most-recently pushed are checked first.
 // - All these are checked after the parse-time stack of local directories
 // is checked.
 // - This only applies to the "local" form of #include.
 // - Makes its own copy of the path.
 virtual void pushExternalLocalDirectory(const std::string& dir)
 {
 directoryStack.push_back(dir);
 externalLocalDirectoryCount = (int)directoryStack.size();
 }

 virtual void releaseInclude(IncludeResult* result) override
 {
 if (result != nullptr) {
 delete [] static_cast<tUserDataElement*>(result->userData);
 delete result;
 }
 }

 virtual ~DirStackFileIncluder() override { }

protected:
 typedef char tUserDataElement;
 std::vector<std::string> directoryStack;
 int externalLocalDirectoryCount;

 // Search for a valid "local" path based on combining the stack of include
 // directories and the nominal name of the header.
 virtual IncludeResult* readLocalPath(const char* headerName, const char* includerName, int depth)
 {
 // Discard popped include directories, and
 // initialize when at parse-time first level.
 directoryStack.resize(depth + externalLocalDirectoryCount);
 if (depth == 1)
 directoryStack.back() = getDirectory(includerName);

 // Find a directory that works, using a reverse search of the include stack.
 for (auto it = directoryStack.rbegin(); it != directoryStack.rend(); ++it) {
 std::string path = *it + '/' + headerName;
 std::replace(path.begin(), path.end(), '\\', '/');
 std::ifstream file(path, std::ios_base::binary | std::ios_base::ate);
 if (file) {
 directoryStack.push_back(getDirectory(path));
 return newIncludeResult(path, file, (int)file.tellg());
 }
 }

 return nullptr;
 }

 // Search for a valid <system> path.
 // Not implemented yet; returning nullptr signals failure to find.
 virtual IncludeResult* readSystemPath(const char* /*headerName*/) const
 {
 return nullptr;
 }

 // Do actual reading of the file, filling in a new include result.
 virtual IncludeResult* newIncludeResult(const std::string& path, std::ifstream& file, int length) const
 {
 char* content = new tUserDataElement [length];
 file.seekg(0, file.beg);
 file.read(content, length);
 return new IncludeResult(path, content, length, content);
 }

 // If no path markers, return current working directory.
 // Otherwise, strip file name and return path leading up to it.
 virtual std::string getDirectory(const std::string path) const
 {
 size_t last = path.find_last_of("/\\");
 return last == std::string::npos ? "." : path.substr(0, last);
 }
};