Initial support for documentation extraction in C++ (#2156)

* #include an absolute path didn't work - because paths were taken to always be relative.

* Split doc extractor such that can be used in C++ extractor.

* Compiles. Update the stdlib docs.

* Fix issue on release builds.

* Add support for extracting documentation to C++ extractor.

* Dump out markup.
Make enum value backing type take tokens.

* Node::Type -> Node::Kind

* More improvements around Node::Type -> Node::Kind

2 files changed, 1027 insertions, 0 deletions

diff --git a/source/compiler-core/slang-doc-extractor.cpp b/source/compiler-core/slang-doc-extractor.cpp
new file mode 100644
index 000000000..d26ed01d1
--- /dev/null
+++ b/source/compiler-core/slang-doc-extractor.cpp
@@ -0,0 +1,864 @@
+// slang-doc-extractor.cpp
+#include "slang-doc-extractor.h"
+
+#include "../core/slang-string-util.h"
+
+namespace Slang {
+
+/* TODO(JS):
+
+* If Decls hand SourceRange, then we could use the range to simplify getting the Post markup, as will be trivial to get to the 'end'
+* Need to handle preceeding * in some markup styles
+* If we want to be able to disable markup we need a mechanism to do this. Probably define source ranges.
+
+* Need a way to take the extracted markup and produce suitable markdown
+** This will need to display the decoration appropriately
+*/
+
+/* static */UnownedStringSlice DocMarkupExtractor::removeStart(MarkupType type, const UnownedStringSlice& comment)
+{
+    switch (type)
+    {
+        case MarkupType::BlockBefore:
+        {
+            if (comment.startsWith(UnownedStringSlice::fromLiteral("/**")) ||
+                comment.startsWith(UnownedStringSlice::fromLiteral("/*!")))
+            {
+                /// /**  */ or /*!  */.
+                return comment.tail(3);
+            }
+            return comment;
+        }   
+        case MarkupType::BlockAfter:
+        {
+            
+            if (comment.startsWith(UnownedStringSlice::fromLiteral("/**<")) ||
+                comment.startsWith(UnownedStringSlice::fromLiteral("/*!<")))
+            {
+                /// /*!< */ or /**< */
+                return comment.tail(4);
+            }
+            return comment;
+        }
+
+        case MarkupType::LineBangBefore:
+        {
+            return comment.startsWith(UnownedStringSlice::fromLiteral("//!")) ? comment.tail(3) : comment;
+        }
+        case MarkupType::LineSlashBefore:
+        {
+            return comment.startsWith(UnownedStringSlice::fromLiteral("///")) ? comment.tail(3) : comment;
+        }
+
+        case MarkupType::LineBangAfter:
+        {
+            /// //!< Can be multiple lines
+            return comment.startsWith(UnownedStringSlice::fromLiteral("//!<")) ? comment.tail(4) : comment;
+        }
+        case MarkupType::LineSlashAfter:
+        {
+            return comment.startsWith(UnownedStringSlice::fromLiteral("///<")) ? comment.tail(4) : comment;
+        }
+        default: break;
+    }
+    return comment;
+}
+
+static Index _findTokenIndex(SourceLoc loc, const Token* toks, Index numToks)
+{
+    // Use a binary search to find the token
+    Index lo = 0;
+    Index hi = numToks;
+
+    while (lo + 1 < hi)
+    {
+        const Index mid = (hi + lo) >> 1;
+        const Token& midToken = toks[mid];
+
+        if (midToken.loc == loc)
+        {
+            return mid;
+        }
+
+        if (midToken.loc.getRaw() <= loc.getRaw())
+        {
+            lo = mid;
+        }
+        else
+        {
+            hi = mid;
+        }
+    }
+
+    // Not found
+    return -1;
+}
+
+/* static */DocMarkupExtractor::MarkupFlags DocMarkupExtractor::getFlags(MarkupType type)
+{
+    switch (type)
+    {
+        default:
+        case MarkupType::None:              return 0;
+        case MarkupType::BlockBefore:      return MarkupFlag::Before | MarkupFlag::IsBlock; 
+        case MarkupType::BlockAfter:       return MarkupFlag::After  | MarkupFlag::IsBlock;
+
+        case MarkupType::LineBangBefore:     return MarkupFlag::Before | MarkupFlag::IsMultiToken; 
+        case MarkupType::LineSlashBefore:    return MarkupFlag::Before | MarkupFlag::IsMultiToken; 
+
+        case MarkupType::LineBangAfter:      return MarkupFlag::After | MarkupFlag::IsMultiToken; 
+        case MarkupType::LineSlashAfter:     return MarkupFlag::After | MarkupFlag::IsMultiToken;
+    }
+}
+
+/* static */DocMarkupExtractor::MarkupType DocMarkupExtractor::findMarkupType(const Token& tok)
+{
+    switch (tok.type)
+    {
+        case TokenType::BlockComment:
+        {
+            UnownedStringSlice slice = tok.getContent();
+            if (slice.getLength() >= 3 && (slice[2] == '!' || slice[2] == '*'))
+            {
+                return (slice.getLength() >= 4 && slice[3] == '<') ? MarkupType::BlockAfter : MarkupType::BlockBefore;
+            }
+            break;
+        }
+        case TokenType::LineComment:
+        {
+            UnownedStringSlice slice = tok.getContent();
+            if (slice.getLength() >= 3)
+            {
+                if (slice[2] == '!')
+                {
+                    return (slice.getLength() >= 4 && slice[3] == '<') ? MarkupType::LineBangAfter : MarkupType::LineBangBefore;
+                }
+                else if (slice[2] == '/')
+                {
+                    return (slice.getLength() >= 4 && slice[3] == '<') ? MarkupType::LineSlashAfter : MarkupType::LineSlashBefore;
+                }
+            }
+            break;
+        }
+        default: break;
+    }
+    return MarkupType::None;
+}
+
+static Index _calcWhitespaceIndent(const UnownedStringSlice& line)
+{
+    // TODO(JS): For now we ignore tabs and just work out indentation based on spaces/assume ASCII
+    Index indent = 0;
+    const Index count = line.getLength();
+    for (; indent < count && line[indent] == ' '; indent++);
+    return indent;
+}
+
+static Index _calcIndent(const UnownedStringSlice& line)
+{
+    // TODO(JS): For now we just assume no tabs, and that every char is ASCII
+    return line.getLength();
+}
+
+static void _appendUnindenttedLine(const UnownedStringSlice& line, Index maxIndent, StringBuilder& out)
+{
+    Index indent = _calcWhitespaceIndent(line);
+
+    // We want to remove indenting remove no more than maxIndent
+    if (maxIndent >= 0)
+    {
+        indent = (indent > maxIndent) ? maxIndent : indent;
+    }
+
+    // Remove the indenting, and append to out
+    out.append(line.tail(indent));
+}
+
+SlangResult DocMarkupExtractor::_extractMarkup(const FindInfo& info, const FoundMarkup& foundMarkup, StringBuilder& out)
+{
+    SourceView* sourceView = info.sourceView;
+    SourceFile* sourceFile = sourceView->getSourceFile();
+
+    // Here we want to produce the text that is implied by the markup tokens.
+    // We want to removing surrounding markup, and to also keep appropriate indentation
+    
+    switch (foundMarkup.type)
+    {
+        case MarkupType::BlockBefore:
+        case MarkupType::BlockAfter:
+        {
+            // We should only have a single line
+            SLANG_ASSERT(foundMarkup.range.getCount() == 1);
+
+            const auto& tok = info.tokenList->m_tokens[foundMarkup.range.start];
+            uint32_t offset = sourceView->getRange().getOffset(tok.loc);
+
+            const UnownedStringSlice startLine = sourceFile->getLineContainingOffset(offset);
+
+            UnownedStringSlice content = tok.getContent();
+
+            // Split into lines
+            List<UnownedStringSlice> lines;
+
+            StringUtil::calcLines(content, lines);
+
+            Index maxIndent = -1;
+
+            StringBuilder unindentedLine;
+
+            const Index linesCount = lines.getCount();
+            for (Index i = 0; i < linesCount; ++i)
+            {
+                UnownedStringSlice line = lines[i];
+                unindentedLine.Clear();
+
+                if (i == 0)
+                {
+                    if (startLine.isMemoryContained(line.begin()))
+                    {
+                        // For now we'll ignore tabs, and that the indent amount is, the amount of *byte*
+                        // NOTE! This is only appropriate for ASCII without tabs.
+                        maxIndent = _calcIndent(UnownedStringSlice(startLine.begin(), line.begin()));
+
+                        // Let's strip the start stuff
+                        line = removeStart(foundMarkup.type, line);
+                    }
+                }
+
+                if (i == linesCount - 1)
+                {
+                    SLANG_ASSERT(line.tail(line.getLength() - 2) == UnownedStringSlice::fromLiteral("*/"));
+                    // Remove the */ at the end of the line
+                    line = line.head(line.getLength() - 2);
+                }
+
+                if (i > 0)
+                {
+                    _appendUnindenttedLine(line, maxIndent, unindentedLine);
+                }
+                else
+                {
+                    unindentedLine.append(line);
+                }
+                
+                // If the first or last line are all white space, just ignore them
+                if ((i == linesCount - 1 || i == 0) && unindentedLine.getUnownedSlice().trim().getLength() == 0)
+                {
+                    continue;
+                }
+
+                out.append(unindentedLine);
+                out.appendChar('\n');
+            }
+
+            break;
+        }
+        case MarkupType::LineBangBefore:      
+        case MarkupType::LineSlashBefore:
+        case MarkupType::LineBangAfter:
+        case MarkupType::LineSlashAfter:
+        {
+            // Holds the lines extracted, they may have some white space indenting (like the space at the start of //) 
+            List<UnownedStringSlice> lines;
+
+            const auto& range = foundMarkup.range;
+            for (Index i = range.start; i < range.end; ++ i)
+            {
+                const auto& tok = info.tokenList->m_tokens[i];
+                UnownedStringSlice line = tok.getContent();
+                line = removeStart(foundMarkup.type, line);
+
+                // If the first or last line are all white space, just ignore them
+                if ((i == range.start || i == range.end - 1) && line.trim().getLength() == 0)
+                {
+                    continue;
+                }
+                lines.add(line);
+            }
+
+            if (lines.getCount() == 0)
+            {
+                // If there are no lines, theres no content
+                return SLANG_OK;
+            }
+
+            Index minIndent = 0x7fffffff;
+            for (const auto& line : lines)
+            {
+                const Index indent = _calcWhitespaceIndent(line);
+                minIndent = (indent < minIndent) ? indent : minIndent;
+            }
+
+            for (const auto& line : lines)
+            {
+                _appendUnindenttedLine(line, minIndent, out);
+                out.appendChar('\n');
+            }
+
+            break;
+        }
+        default:    return SLANG_FAIL;
+    }
+
+    return SLANG_OK;
+}
+
+Index DocMarkupExtractor::_findStartIndex(const FindInfo& info, Location location)
+{
+    Index openCount = 0;
+
+    const TokenList& toks = *info.tokenList;
+    const Index tokIndex = info.tokenIndex;
+
+    Index direction = isBefore(location) ? -1 : 1;
+
+    const Index count = toks.m_tokens.getCount();
+    for (Index i = tokIndex; i >= 0 && i < count; i += direction)
+    {
+        const Token& tok = toks.m_tokens[i];
+
+        switch (tok.type)
+        {
+            case TokenType::LBrace:
+            case TokenType::LBracket:
+            case TokenType::LParent:
+            case TokenType::OpLess:
+            {
+                openCount += direction;
+                if (openCount < 0) return -1;
+                break;
+            }
+            case TokenType::RBracket:
+            {
+                openCount -= direction;
+                if (openCount < 0) return -1;
+                break;
+            }
+            case TokenType::OpGreater:
+            {
+                if (location == Location::AfterGenericParam && openCount == 0)
+                {
+                    return i + 1;
+                }
+
+                openCount -= direction;
+                if (openCount < 0) return -1;
+
+                break;
+            }
+            case TokenType::RParent:
+            {
+                if (openCount == 0 && location == Location::AfterParam)
+                {
+                    return i + 1;
+                }
+
+                openCount -= direction;
+                if (openCount < 0) return -1;
+                break;
+            }
+            case TokenType::RBrace:
+            {
+                // If we haven't hit a candidate yet before hitting } it's not going to work
+                if (location == Location::Before || location == Location::AfterEnumCase)
+                {
+                    return -1;
+                }
+                break;
+            }
+            case TokenType::BlockComment:
+            case TokenType::LineComment:
+            {
+                if (openCount == 0)
+                {
+                    // Determine the markup type
+                    const MarkupType markupType = findMarkupType(tok);
+                    // If the location wanted is before and the markup is, we'll assume this is it
+                    if (isBefore(location) && isBefore(markupType))
+                    {
+                        return i;
+                    }
+                    // If we are looking for enum cases, and the markup is after, we'll assume this is it
+                    if (isAfter(location) && isAfter(markupType))
+                    {
+                        return i;
+                    }
+                }
+                break;
+            }
+            case TokenType::Comma:
+            {
+                if (openCount == 0)
+                {   
+                    if (location == Location::AfterParam || location == Location::AfterEnumCase || location == Location::AfterGenericParam)
+                    {
+                        return i + 1;
+                    }
+
+                    if (location == Location::Before)
+                    {
+                        return -1;
+                    }
+                }
+
+                break;
+            }
+            case TokenType::Semicolon:
+            {
+                // If we haven't hit a candidate yet it's not going to work
+                if (location == Location::Before)
+                {
+                    return -1;
+                }
+                if (openCount == 0 && location == Location::AfterSemicolon)
+                {
+                    return i + 1;
+                }
+                break;
+            }
+            default: break;
+        }
+    }
+
+    return -1;
+}
+
+/* static */bool DocMarkupExtractor::_isTokenOnLineIndex(SourceView* sourceView, MarkupType type, const Token& tok, Index lineIndex)
+{
+    SourceFile* sourceFile = sourceView->getSourceFile();
+    const int offset = sourceView->getRange().getOffset(tok.loc);
+
+    auto const flags = getFlags(type);
+
+    if (flags & MarkupFlag::IsBlock)
+    {
+        // Either the start or the end of the block have to be on the specified line
+        return sourceFile->isOffsetOnLine(offset, lineIndex) || sourceFile->isOffsetOnLine(offset + tok.charsCount, lineIndex);
+    }
+    else
+    {
+        // Has to be exactly on the specified line
+        return sourceFile->isOffsetOnLine(offset, lineIndex);
+    }
+}
+
+SlangResult DocMarkupExtractor::_findMarkup(const FindInfo& info, Location location, FoundMarkup& out)
+{
+    out.reset();
+
+    const auto& toks = info.tokenList->m_tokens;
+    const Index tokIndex = info.tokenIndex;
+
+    // The starting token index
+    Index startIndex = _findStartIndex(info, location);
+    if (startIndex <= 0)
+    {
+        return SLANG_E_NOT_FOUND;
+    }
+
+    SourceView* sourceView = info.sourceView;
+    SourceFile* sourceFile = sourceView->getSourceFile();
+
+    // Let's lookup the line index where this occurred
+    const int startOffset = sourceView->getRange().getOffset(toks[startIndex - 1].loc);
+
+    // The line index that the markoff starts from 
+    Index lineIndex = sourceFile->calcLineIndexFromOffset(startOffset);
+    if (lineIndex < 0)
+    {
+        return SLANG_E_NOT_FOUND;
+    }
+
+    const Index searchDirection = isBefore(location) ? -1 : 1;
+    
+    // Get the type and flags
+    const MarkupType type = findMarkupType(toks[startIndex]);
+    const MarkupFlags flags = getFlags(type);
+
+    const MarkupFlag::Enum requiredFlag = isBefore(location) ? MarkupFlag::Before : MarkupFlag::After;
+    if ((flags & requiredFlag) == 0)
+    {
+        return SLANG_E_NOT_FOUND;
+    }
+
+#if 0
+    // The token still isn't accepted, unless it's on the expected line
+    if (_isTokenOnLineIndex(info.sourceView, type, toks[startIndex], expectedLineIndex))
+    {
+        return SLANG_E_NOT_FOUND;
+    }
+#endif
+
+    Index endIndex = startIndex;
+
+    // If it's multiline, so look for the end index
+    if (flags & MarkupFlag::IsMultiToken)
+    {
+        Index expectedLineIndex = lineIndex;
+
+        // TODO(JS):
+        // We should probably do the work here to confirm  indentation - but that
+        // requires knowing something about tabs, so for now we leave.
+
+        while (true)
+        {
+            endIndex += searchDirection;
+            expectedLineIndex += searchDirection;
+
+            if (endIndex < 0 || endIndex >= toks.getCount())
+            {
+                break;
+            }
+
+            // Do we find a token of the right type?
+            if (findMarkupType(toks[endIndex]) != type)
+            {
+                break;
+            }
+
+            // Is it on the right line?
+            if (_isTokenOnLineIndex(info.sourceView, type, toks[startIndex], expectedLineIndex))
+            {
+                break;
+            }
+        }
+
+        // Fix the end index (it's the last one that worked)
+        endIndex -= searchDirection;
+    }
+
+    // Put start < end order
+    if (endIndex < startIndex)
+    {
+        Swap(endIndex, startIndex);
+    }
+    // The range excludes end so increase
+    endIndex++;
+
+    // Okay we've found the markup
+    out.type = type;
+    out.location = location;
+    out.range = IndexRange{ startIndex, endIndex };
+
+    SLANG_ASSERT(out.range.getCount() > 0);
+
+    return SLANG_OK;
+}
+
+SlangResult DocMarkupExtractor::_findFirstMarkup(const FindInfo& info, const Location* locs, Index locCount, FoundMarkup& out, Index& outIndex)
+{
+    Index i = 0;
+    for (; i < locCount; ++i)
+    {
+        SlangResult res = _findMarkup(info, locs[i], out);
+        if (SLANG_SUCCEEDED(res) || (SLANG_FAILED(res) && res != SLANG_E_NOT_FOUND))
+        {
+            outIndex = i;
+            return res;
+        }
+    }
+    return SLANG_E_NOT_FOUND;
+}
+
+SlangResult DocMarkupExtractor::_findMarkup(const FindInfo& info, const Location* locs, Index locCount, FoundMarkup& out)
+{
+    Index foundIndex;
+    SLANG_RETURN_ON_FAIL(_findFirstMarkup(info, locs, locCount, out, foundIndex));
+
+    // Lets see if the remaining ones match
+    {
+        FoundMarkup otherMarkup;
+        for (Index i = foundIndex + 1; i < locCount; ++i)
+        {
+            SlangResult res = _findMarkup(info, locs[i], otherMarkup);
+            if (SLANG_SUCCEEDED(res))
+            {
+                // TODO(JS): Warning found markup in another location
+            }
+        }
+    }
+
+    return SLANG_OK;
+}
+
+
+SlangResult DocMarkupExtractor::_findMarkup(const FindInfo& info, SearchStyle searchStyle, FoundMarkup& out)
+{
+    switch (searchStyle)
+    {
+        default:
+        case SearchStyle::None:
+        {
+            return SLANG_E_NOT_FOUND;
+        }
+        case SearchStyle::EnumCase:
+        {
+            Location locs[] = { Location::Before, Location::AfterEnumCase };
+            return _findMarkup(info, locs, SLANG_COUNT_OF(locs), out);
+        }
+        case SearchStyle::Param:
+        {
+            Location locs[] = { Location::Before, Location::AfterParam };
+            return _findMarkup(info, locs, SLANG_COUNT_OF(locs), out);
+        }
+        case SearchStyle::Before:
+        {
+            return _findMarkup(info, Location::Before, out);
+        }
+        case SearchStyle::Function:
+        {
+            return _findMarkup(info, Location::Before, out);
+        }
+        case SearchStyle::Variable:
+        {
+            Location locs[] = { Location::Before, Location::AfterSemicolon };
+            return _findMarkup(info, locs, SLANG_COUNT_OF(locs), out);
+        }
+        case SearchStyle::GenericParam:
+        {
+            Location locs[] = { Location::Before, Location::AfterGenericParam };
+            return _findMarkup(info, locs, SLANG_COUNT_OF(locs), out);
+        }
+    }
+}
+
+static void _calcLineVisibility(SourceView* sourceView, const TokenList& toks, List<MarkupVisibility>& outLineVisibility)
+{
+    SourceFile* sourceFile = sourceView->getSourceFile();
+    const auto& lineOffsets = sourceFile->getLineBreakOffsets();
+
+    outLineVisibility.setCount(lineOffsets.getCount() + 1);
+
+    MarkupVisibility lastVisibility = MarkupVisibility::Public;
+    Index lastLine = 0;
+
+    for (const auto& tok : toks)
+    {
+        if (tok.type == TokenType::LineComment)
+        {
+            UnownedStringSlice contents = tok.getContent();
+
+            MarkupVisibility newVisibility = lastVisibility;
+
+            // Distinct from other markup
+            if (contents.startsWith(toSlice("//@")))
+            {
+                UnownedStringSlice access = contents.tail(3).trim();
+                if (access == "hidden:" || access == "private:")
+                {
+                    newVisibility = MarkupVisibility::Hidden;
+                }
+                else if (access == "internal:")
+                {
+                    newVisibility = MarkupVisibility::Internal;
+                }
+                else if (access == "public:")
+                {
+                    newVisibility = MarkupVisibility::Public;
+                }
+            }
+
+            if (newVisibility != lastVisibility)
+            {
+                // Work up the line it's on
+                const int offset = sourceView->getRange().getOffset(tok.loc);
+                Index line = sourceFile->calcLineIndexFromOffset(offset);
+
+                // Fill in the span
+                for (Index i = lastLine; i < line; ++i)
+                {
+                    outLineVisibility[i] = lastVisibility;
+                }
+
+                // Record the new access and where we are up to
+                lastLine = line;
+                lastVisibility = newVisibility;
+            }
+        }
+    }
+
+    // Fill in the remaining
+    for (Index i = lastLine; i < outLineVisibility.getCount(); ++ i)
+    {
+        outLineVisibility[i] = lastVisibility;
+    }
+}
+
+SlangResult DocMarkupExtractor::extract(const SearchItemInput* inputs, Index inputCount, SourceManager* sourceManager, DiagnosticSink* sink, List<SourceView*>& outViews, List<SearchItemOutput>& out)
+{
+    struct Entry
+    {
+        typedef Entry ThisType;
+
+        Index viewIndex;                    ///< The view/file index this loc is found in
+        SourceLoc::RawValue locOrOffset;    ///< Can be a loc or an offset into the file
+
+        SearchStyle searchStyle;            ///< The search style when looking for an item
+        Index inputIndex;                   ///< The index to this item in the input
+    };
+
+    List<Entry> entries;
+
+    {
+        entries.setCount(inputCount);
+        for (Index i = 0; i < inputCount; ++i)
+        {
+            const auto& input = inputs[i];
+            Entry& entry = entries[i];
+            entry.inputIndex = i;
+            entry.viewIndex = -1;            //< We don't know what file/view it's in
+            entry.locOrOffset = input.sourceLoc.getRaw();
+            entry.searchStyle = input.searchStyle;
+        }
+    }
+
+    // Sort them into loc order
+    entries.sort([](const Entry& a, const Entry& b) -> bool { return a.locOrOffset < b.locOrOffset; });
+
+    {
+        SourceView* sourceView = nullptr;
+        Index viewIndex = -1;
+
+        for (auto& entry : entries)
+        {
+            if (entry.searchStyle == SearchStyle::None)
+            {
+                continue;
+            }
+
+            const SourceLoc loc = SourceLoc::fromRaw(entry.locOrOffset);
+
+            if (sourceView == nullptr || !sourceView->getRange().contains(loc))
+            {
+                // Find the new view
+                sourceView = sourceManager->findSourceView(loc);
+                SLANG_ASSERT(sourceView);
+
+                // We want only one view per SourceFile
+                SourceFile* sourceFile = sourceView->getSourceFile();
+
+                // NOTE! The view found might be different than sourceView. 
+                viewIndex = outViews.findFirstIndex([&](SourceView* currentView) -> bool { return currentView->getSourceFile() == sourceFile; });
+
+                if (viewIndex < 0)
+                {
+                    viewIndex = outViews.getCount();
+                    outViews.add(sourceView);
+                }
+            }
+
+            SLANG_ASSERT(viewIndex >= 0);
+            SLANG_ASSERT(sourceView && sourceView->getRange().contains(loc));
+
+            // Set the file index
+            entry.viewIndex = viewIndex;
+            // Set as the offset within the file 
+            entry.locOrOffset = sourceView->getRange().getOffset(loc);
+        }
+
+        // Sort into view/file and then offset order
+        entries.sort([](const Entry& a, const Entry& b) -> bool { return (a.viewIndex < b.viewIndex) || ((a.viewIndex == b.viewIndex) && a.locOrOffset < b.locOrOffset); });
+    }
+
+    {
+        TokenList tokens;
+        List<MarkupVisibility> lineVisibility;
+
+        MemoryArena memoryArena(4096);
+
+        RootNamePool rootNamePool;
+        NamePool namePool;
+        namePool.setRootNamePool(&rootNamePool);
+
+        Index viewIndex = -1;
+        SourceView* sourceView = nullptr;
+
+        const Int entryCount = entries.getCount();
+
+        out.setCount(entryCount);
+
+        for (Index i = 0; i < entryCount; ++i)
+        {
+            const auto& entry = entries[i];
+            auto& dst = out[i];
+
+            dst.viewIndex = -1;
+            dst.inputIndex = entry.inputIndex;
+            dst.visibilty = MarkupVisibility::Public;
+
+            // If there isn't a mechanism to search with, just move on
+            if (entry.searchStyle == SearchStyle::None)
+            {
+                continue;
+            }
+
+            if (viewIndex != entry.viewIndex)
+            {
+                viewIndex = entry.viewIndex;
+                sourceView = outViews[viewIndex];
+
+                // Make all memory free again
+                memoryArena.reset();
+
+                // Run the lexer
+                Lexer lexer;
+                lexer.initialize(sourceView, sink, &namePool, &memoryArena);
+
+                // Lex everything
+                tokens = lexer.lexAllMarkupTokens();
+
+                // Let's work out the access
+
+                _calcLineVisibility(sourceView, tokens, lineVisibility);
+            }
+
+            dst.viewIndex = viewIndex;
+
+            // Get the offset within the source file
+            const uint32_t offset = entry.locOrOffset;
+
+            // We need to get the loc in the source views space, so we look up appropriately in the list of tokens (which uses the views loc range)
+            const SourceLoc loc = sourceView->getRange().getSourceLocFromOffset(offset);
+
+            // Work out the line number
+            SourceFile* sourceFile = sourceView->getSourceFile();
+            const Index lineIndex = sourceFile->calcLineIndexFromOffset(int(offset));
+
+            dst.visibilty = lineVisibility[lineIndex];
+
+            // Okay, lets find the token index with a binary chop
+            Index tokenIndex = _findTokenIndex(loc, tokens.m_tokens.getBuffer(), tokens.m_tokens.getCount());
+            if (tokenIndex >= 0 && lineIndex >= 0)
+            {
+                FindInfo findInfo;
+                findInfo.tokenIndex = tokenIndex;
+                findInfo.lineIndex = lineIndex;
+                findInfo.tokenList = &tokens;
+                findInfo.sourceView = sourceView;
+
+                // Okay let's see if we extract some documentation then for this.
+                FoundMarkup foundMarkup;
+                SlangResult res = _findMarkup(findInfo, entry.searchStyle, foundMarkup);
+
+                if (SLANG_SUCCEEDED(res))
+                {
+                    // We need to extract
+                    StringBuilder buf;
+                    SLANG_RETURN_ON_FAIL(_extractMarkup(findInfo, foundMarkup, buf));
+
+                    // Save the extracted text in the output
+                    dst.text = buf;
+
+                }
+                else if (res != SLANG_E_NOT_FOUND)
+                {
+                    return res;
+                }
+            }
+        }
+    }
+
+    return SLANG_OK;
+}
+
+} // namespace Slang
diff --git a/source/compiler-core/slang-doc-extractor.h b/source/compiler-core/slang-doc-extractor.h
new file mode 100644
index 000000000..5b4c67782
--- /dev/null
+++ b/source/compiler-core/slang-doc-extractor.h
@@ -0,0 +1,163 @@
+// slang-doc.h
+#ifndef SLANG_DOC_EXTRACTOR_H
+#define SLANG_DOC_EXTRACTOR_H
+
+#include "../core/slang-basic.h"
+
+#include "slang-source-loc.h"
+#include "slang-lexer.h"
+
+namespace Slang {
+
+enum class MarkupVisibility : uint8_t
+{
+    Public,                 ///< Always available
+    Internal,               ///< Can be available in more verbose 'internal' documentation
+    Hidden,                 ///< Not generally available
+};
+
+/* Extracts 'markup' from comments in Slang source core. The comments are extracted and associated in declarations. The association
+is held in DocMarkup type. The comment style follows the doxygen style */
+class DocMarkupExtractor
+{
+public:
+
+    typedef uint32_t MarkupFlags;
+    struct MarkupFlag
+    {
+        enum Enum : MarkupFlags
+        {
+            Before = 0x1,
+            After = 0x2,
+            IsMultiToken = 0x4,          ///< Can use more than one token
+            IsBlock = 0x8,          ///< 
+        };
+    };
+
+    // NOTE! Don't change order without fixing isBefore and isAfter
+    enum class MarkupType
+    {
+        None,
+
+        BlockBefore,        /// /**  */ or /*!  */.
+        LineBangBefore,      /// //! Can be multiple lines
+        LineSlashBefore,     /// /// Can be multiple lines
+
+        BlockAfter,         /// /*!< */ or /**< */
+        LineBangAfter,       /// //!< Can be multiple lines
+        LineSlashAfter,      /// ///< Can be multiple lines
+    };
+
+    static bool isBefore(MarkupType type) { return Index(type) >= Index(MarkupType::BlockBefore) && Index(type) <= Index(MarkupType::LineSlashBefore); }
+    static bool isAfter(MarkupType type) { return Index(type) >= Index(MarkupType::BlockAfter); }
+
+    struct IndexRange
+    {
+        SLANG_FORCE_INLINE Index getCount() const { return end - start; }
+
+        Index start;
+        Index end;
+    };
+
+    enum class Location
+    {
+        None,                           ///< No defined location
+        Before,
+        AfterParam,                     ///< Can have trailing , or )
+        AfterSemicolon,                 ///< Can have a trailing ;
+        AfterEnumCase,                  ///< Can have a , or before }
+        AfterGenericParam,              ///< Can have trailing , or > 
+    };
+
+    static bool isAfter(Location location) { return Index(location) >= Index(Location::AfterParam); }
+    static bool isBefore(Location location) { return location == Location::Before; }
+
+    struct FoundMarkup
+    {
+        void reset()
+        {
+            location = Location::None;
+            type = MarkupType::None;
+            range = IndexRange{ 0, 0 };
+        }
+
+        Location location = Location::None;
+        MarkupType type = MarkupType::None;
+        IndexRange range;
+    };
+
+    enum SearchStyle
+    {
+        None,               ///< Cannot be searched for
+        EnumCase,           ///< An enum case
+        Param,              ///< A parameter in a function/method
+        Variable,           ///< A variable-like declaration
+        Before,             ///< Only allows before
+        Function,           ///< Function/method
+        GenericParam,       ///< Generic parameter
+    };
+
+        /// An input search item
+    struct SearchItemInput
+    {
+        SourceLoc sourceLoc;
+        SearchStyle searchStyle;            ///< The search style when looking for an item
+    };
+
+        /// The items will be in source order
+    struct SearchItemOutput
+    {
+        Index viewIndex;                    ///< Index into the array of views on the output
+        Index inputIndex;                   ///< The index to this item in the input
+        String text;                        ///< The found text
+        MarkupVisibility visibilty;         ///< Visibility of the item
+    };
+
+    struct FindInfo
+    {
+        SourceView* sourceView;         ///< The source view the tokens were generated from
+        TokenList* tokenList;           ///< The token list
+        Index tokenIndex;               ///< The token index location (where searches start from)
+        Index lineIndex;                ///< The line number for the decl
+    };
+
+    
+        /// Extracts 'markup' doc information for the specified input items
+        /// The output is placed in out - with the items now in the source order *not* the order of the input items
+        /// The inputIndex on the output holds the input item index
+        /// The outViews holds the views specified in viewIndex in the output, which may be useful for determining where the documentation was placed in source
+    SlangResult extract(const SearchItemInput* inputItems, Index inputCount, SourceManager* sourceManager, DiagnosticSink* sink, List<SourceView*>& outViews, List<SearchItemOutput>& out);
+
+    static MarkupFlags getFlags(MarkupType type);
+    static MarkupType findMarkupType(const Token& tok);
+    static UnownedStringSlice removeStart(MarkupType type, const UnownedStringSlice& comment);
+
+protected:
+    /// returns SLANG_E_NOT_FOUND if not found, SLANG_OK on success else an error
+    SlangResult _findMarkup(const FindInfo& info, Location location, FoundMarkup& out);
+
+    /// Locations are processed in order, and the first successful used. If found in another location will issue a warning.
+    /// returns SLANG_E_NOT_FOUND if not found, SLANG_OK on success else an error
+    SlangResult _findFirstMarkup(const FindInfo& info, const Location* locs, Index locCount, FoundMarkup& out, Index& outIndex);
+
+    SlangResult _findMarkup(const FindInfo& info, const Location* locs, Index locCount, FoundMarkup& out);
+
+    /// Given the decl, the token stream, and the decls tokenIndex, try to find some associated markup
+    SlangResult _findMarkup(const FindInfo& info, SearchStyle searchStyle, FoundMarkup& out);
+
+    /// Given a found markup location extracts the contents of the tokens into out
+    SlangResult _extractMarkup(const FindInfo& info, const FoundMarkup& foundMarkup, StringBuilder& out);
+
+    /// Given a location, try to find the first token index that could potentially be markup
+    /// Will return -1 if not found
+    Index _findStartIndex(const FindInfo& info, Location location);
+
+    /// True if the tok is 'on' lineIndex. Interpretation of 'on' depends on the markup type.
+    static bool _isTokenOnLineIndex(SourceView* sourceView, MarkupType type, const Token& tok, Index lineIndex);
+
+    DiagnosticSink* m_sink;
+};
+
+} // namespace Slang
+
+#endif