.travis.yml

language: cpp
dist: trusty
sudo: false
os: linux
compiler: gcc-7
notifications:
  email: false

addons:
  apt:
    sources:
      - ubuntu-toolchain-r-test
      - kubuntu-backports
    packages:
      - g++-7
      - libglu1-mesa-dev
      - libxxf86vm-dev
      - libxrandr-dev
      - libxinerama-dev
      - libxcursor-dev
      - libxi-dev
      - libx11-dev
      - cmake

cache:
  directories:
    - build

install:
  - echo ${PATH}
  - echo ${CXX}
  - ${CXX} --version
  - ${CXX} -v
  - mkdir -p "${TRAVIS_BUILD_DIR}/build"

# Incremental builds script from:
# https://blog.esciencecenter.nl/travis-caching-and-incremental-builds-6518b89ee889
# https://github.com/roofit-dev/root/blob/2cc63b8b3d0a7c3acca4381e1bc5a7ef3e01a94c/.travis.yml
script:
  # ----- Build phase
  # Two cases:
  # 1. There was a previous build, which was restored from the cache.
  #    Use `touch_order.txt` to update the 'last modified' timestamp
  #    of each file. Finally, update 'last modified' of files that have
  #    changed since the last build.
  # 2. No previous build available, run `cmake`.
  - cd "${TRAVIS_BUILD_DIR}/build"
  - |
    if [[ -f touch_order.txt ]]; then
      while read fn; do
        touch $fn || true
      done < touch_order.txt
      # Now, touch changed git files to trigger their rebuild
      read PREVIOUS_GIT_COMMIT < previous_git_commit.txt
      changed_files=`git diff --name-only $PREVIOUS_GIT_COMMIT HEAD`
      echo "Previously cached Travis build based on git commit ${PREVIOUS_GIT_COMMIT}."
      echo "Files changed since then:"
      echo $changed_files
      cd ..
      touch `echo $changed_files` || true
    else
      cmake ${CMAKE_OPTIONS} -DCMAKE_CXX_COMPILER=g++-7 -DCMAKE_C_COMPILER=gcc-7 ..
    fi
  # Either way, run `make` to build newest changes.
  - cd "${TRAVIS_BUILD_DIR}/build"
  - make -j2
  # ----- Test phase
  - cd .. && python run_tests.py

before_cache:
  # Save the order of timestamps of the files so we can recreate it with touch in
  # the next build. N.B.: just tarring the build files doesn't work, since the
  # git clone will still be newer.
  # The build tools (`make` at least) only care about order, not about
  # absolute timestamps.
  - cd "${TRAVIS_BUILD_DIR}/build"
  - find . -type f -printf "%T+\t%p\n" | sort | cut -f 2 > ./touch_order.txt
  # Also store the SHA of the commit that was just built, so that we can figure
  # out which files have changed since.
  - cd "${TRAVIS_BUILD_DIR}" && git rev-parse HEAD > ./build/previous_git_commit.txt