MarkQL

MarkQL is a C++20 SQL-style query engine for HTML. It treats HTML elements as rows and lets you query them with familiar SELECT ... FROM ... WHERE ... syntax.

Quick Start

Prerequisites:

• CMake 3.16+
• A C++20 compiler
• Boost (multiprecision); set -DXSQL_ENABLE_KHMER_NUMBER=OFF to skip Boost
• Optional dependencies: libxml2, curl, nlohmann_json, arrow/parquet

Ubuntu/Debian/WSL (minimal packages):

sudo apt update
sudo apt install -y \
  git ca-certificates pkg-config \
  build-essential cmake ninja-build \
  libboost-dev

Optional feature packages:

sudo apt install -y libxml2-dev libcurl4-openssl-dev nlohmann-json3-dev

Arrow/Parquet packages (often missing on older distros):

sudo apt install -y libarrow-dev libparquet-dev

macOS (Homebrew):

xcode-select --install
brew install cmake ninja pkg-config boost

Optional feature packages:

brew install libxml2 curl nlohmann-json

Arrow/Parquet:

brew install apache-arrow

Build (project default):

./build.sh

Minimal build when optional dependencies are unavailable:

cmake -S . -B build \
  -DXSQL_WITH_LIBXML2=OFF \
  -DXSQL_WITH_CURL=OFF \
  -DXSQL_WITH_ARROW=OFF \
  -DXSQL_WITH_NLOHMANN_JSON=OFF
cmake --build build

To build without Boost, add -DXSQL_ENABLE_KHMER_NUMBER=OFF.

Run one query:

./build/markql --query "SELECT div FROM doc LIMIT 5;" --input ./data/index.html

Run interactive REPL:

./build/markql --interactive --input ./data/index.html

CLI Notes

• Primary CLI binary is ./build/markql.
• Legacy compatibility binary ./build/xsql is still generated.
• doc and document are both valid sources in FROM.
• If --input is omitted, the CLI reads HTML from stdin.
• URL sources (FROM 'https://...') require XSQL_WITH_CURL=ON.
• TO PARQUET(...) requires XSQL_WITH_ARROW=ON.
• INNER_HTML(...) returns minified HTML by default. Use RAW_INNER_HTML(...) for unmodified raw output.
• TO TABLE(...) supports explicit trimming/sparse options: TRIM_EMPTY_ROWS, TRIM_EMPTY_COLS, EMPTY_IS, STOP_AFTER_EMPTY_ROWS, FORMAT, SPARSE_SHAPE, and HEADER_NORMALIZE.

Testing

C++ tests:

cmake --build build --target xsql_tests
ctest --test-dir build --output-on-failure

Benchmark harness (inner_html minified vs raw):

./build/markql_bench_inner_html 10000

Python package/tests (optional):

./install_python.sh
./test_python.sh

Documentation

• Book (chapter path + verified examples): docs/book/SUMMARY.md
• Canonical tutorial: docs/markql-tutorial.md
• CLI guide: docs/markql-cli-guide.md
• Docs index: docs/README.md
• Changelog: CHANGELOG.md

License

Apache License 2.0. See LICENSE.