scripts: add build-gh-pages script

Author: daviddrysdale

scripts/build-gh-pages.sh

@@ -0,0 +1,70 @@
+#!/usr/bin/env bash
+# Copyright 2020 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+set -o errexit
+set -o nounset
+set -o xtrace
+set -o pipefail
+
+# Update the gh-pages branch. Note that `cargo doc` is **not deterministic** so
+# this should only be done when there is a real change.
+readonly RUST_BRANCH=${1:-main}
+readonly RUST_GH_BRANCH=gh-pages
+
+if [ -z "${FORCE+x}" ]; then
+  readonly PREV_COMMIT=$(git log --oneline -n 1 ${RUST_GH_BRANCH} | sed 's/.*branch at \([0-9a-f]*\)/\1/')
+  readonly CHANGES=$(git diff "${PREV_COMMIT}..${RUST_BRANCH}" | grep -e '[+-]//[/!]')
+
+  if [ -z "${CHANGES}" ]; then
+    echo "No doc comment changes found in ${PREV_COMMIT}..${RUST_BRANCH} subdir rust/"
+    exit 0
+  fi
+fi
+
+git switch "${RUST_BRANCH}"
+readonly RUST_BRANCH_SHA1=$(git rev-parse --short HEAD)
+readonly RUST_BRANCH_SUBJECT=$(git log -n 1 --format=format:%s)
+readonly COMMIT_MESSAGE=$(cat <<-END
+Update Rust docs to ${RUST_BRANCH} branch at ${RUST_BRANCH_SHA1}
+
+Auto-generated from commit ${RUST_BRANCH_SHA1} ("${RUST_BRANCH_SUBJECT}").
+END
+)
+
+readonly TGZ_FILE="/tmp/coset-doc-${RUST_BRANCH_SHA1}.tgz"
+# Build Cargo docs and save them off outside the repo
+(
+    rm -rf target/doc
+    cargo doc --no-deps
+    cargo deadlinks
+    cd target/doc || exit
+    tar czf "${TGZ_FILE}" ./*
+)
+
+# Shift to ${RUST_GH_BRANCH} branch and replace contents of (just) ./rust/
+git switch ${RUST_GH_BRANCH}
+
+readonly DOC_DIR=rust
+rm -rf ${DOC_DIR}
+mkdir ${DOC_DIR}
+(
+    cd "${DOC_DIR}" || exit
+    tar xzf "${TGZ_FILE}"
+)
+
+# Commit any differences
+git add "${DOC_DIR}"
+git commit --message="${COMMIT_MESSAGE}"
+git switch "${RUST_BRANCH}"