Do minor updates to dot files and add license headers (#1598)

* Add license header

* Update to current common version

Changes:
- Add license header
- Add line length setting
- Reduce allowed raw HTML elements

This version matches the current common version of the file I've been
adding to the Quantumlib repos.

* Update to current common version

Changes:
- Add license header
- Add more settings
- Adjust settings to match (apparent) Qualtran project conventions

Except for the changed settings, this version of the file matches the
current common version of the file I've been adding to the Quantumlib
repos.

* Add back max_line_length setting

After more discussion, the conclusion is that despite the issues with
`max_line_length`, it is handled as expected in the editors that many
people have been using.

Author: mhucka

.editorconfig

@@ -1,27 +1,64 @@
-# Summary: coding style configuration for editors that read .editorconfig.
+# Copyright 2025 Google LLC
 #
-# EditorConfig defines a file format for specifying some common coding style
-# parameters. Many editors recognize .editorconfig files automatically, and
-# there exist plugins for other editors. See https://spec.editorconfig.org/.
+# 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
+#
+#     https://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.
+
+# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+# Common editor configurations for this project.
+#
+# EditorConfig is a file format for specifying some common style parameters.
+# Many IDEs & editors read .editorconfig files, either natively or via plugins.
+# We mostly follow Google's style guides (https://google.github.io/styleguide/)
+# with only a few deviations for line length and indentation in some files.
+# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 root = true
 
 [*]
 charset = utf-8
-end_of_line = lf
+indent_style = space
 insert_final_newline = true
 spelling_language = en-US
 trim_trailing_whitespace = true
+max_line_length = 100
+
+[{BUILD,*.BUILD,*.bzl,*.bazel,.bazelrc}]
+# Google doesn't have a style guideline for Bazel files. Most people use 4.
+indent_size = 4
+
+[{*.cc,*.h}]
+# Google style guidelines use 2.
+indent_size = 2
+
+[{*.js,*.ts}]
+# Google style guidelines use 2.
+indent_size = 2
+
+[*.json]
+# Not stated explicitly in Google's guidelines, but the examples use 2.
+indent_size = 2
 
 [*.py]
+# Google style guidelines use 4.
 indent_size = 4
-indent_style = space
-max_line_length = 100
+
+[*.rst]
+# Google doesn't have a style guideline for reStructuredText. Many people use 3.
+indent_size = 3
 
 [*.sh]
+# Google style guidelines use 2.
 indent_size = 4
-indent_style = space
-max_line_length = 100
 
-[*.yml,*.yaml]
+[{*.yaml,*.yml}]
+# Google doesn't have style guidelines for YAML. Most people use indent = 2.
 indent_size = 2

.markdownlintrc

@@ -1,11 +1,28 @@
-{ // Summary: markdownlint config file for Qualtran                -*- jsonc -*-
+{ // -*- jsonc -*-
+  // Copyright 2025 Google LLC
   //
-  // Note: there are multiple programs programs named "markdownlint". For
-  // Qualtran, we use https://github.com/igorshubovych/markdownlint-cli/, which
-  // is the one you get with "brew install markdownlint" on MacOS.
+  // 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
+  //
+  //     https://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.
+
+  // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+  // Markdownlint linter configuration for this project.
+  //
+  // Note: there are multiple programs programs named "markdownlint". We use
+  // https://github.com/igorshubovych/markdownlint-cli/, which is the one you
+  // get with "brew install markdownlint" on MacOS.
   //
   // These settings try to stay close to the Google Markdown Style as
   // described at https://google.github.io/styleguide/docguide/style.html
+  // with very few differences.
   //
   // For a list of configuration options, see the following page:
   // https://github.com/DavidAnson/markdownlint/blob/main/doc/Rules.md
@@ -41,9 +58,13 @@
     "br_spaces": 0
   },
 
-  // Google style exempts some constructs from the line-length limit of 80 chars.
+  // Google style is 80 characters.
+  // Google style exempts some constructs from the line-length limit:
   // https://google.github.io/styleguide/docguide/style.html#exceptions
   "line-length": {
+    "line_length": 100,
+    "code_block_line_length": 100,
+    "heading_line_length": 100,
     "code_blocks": false,
     "headings": false,
     "tables": false
@@ -67,24 +88,20 @@
   "no-bare-urls": false,
 
   // Basic Markdown allows raw HTML. Both GitHub & PyPI support subsets of
-  // HTML, though it's unclear what subset PyPI supports. Google's style
-  // guide doesn't disallow using HTML, although it recommends against it. (C.f.
-  // the bottom of https://google.github.io/styleguide/docguide/style.html)
-  // It's worth noting, though, that Google's guidance has Google's internal
-  // documentation system in mind, and that system extends Markdown with
-  // constructs that make it possible to accomplish things you can't do in
-  // Markdown. Those extensions are also not available outside Google's system.
-  // Thus, although a goal of this markdownlint configuration is to match
-  // Google's style guide as closely as possible, these various factors suggest
-  // it's reasonable to relax the HTML limitation. The list below is based on
-  // https://github.com/github/markup/issues/245#issuecomment-682231577 plus
-  // some things found elsewhere after that was written.
+  // HTML, though it's unclear what subset PyPI supports. Google's style guide
+  // recommends against using raw HTML, but does allow it. (C.f. the bottom of
+  // https://google.github.io/styleguide/docguide/style.html) Google's in-house
+  // documentation system allows many inline and block-level tags, but strips
+  // others that can pose security risks (e.g., <object> and standalone <svg>).
+  // The list below tries to capture the intersection of what GitHub allows
+  // (c.f. https://github.com/github/markup/issues/245#issuecomment-682231577),
+  // what PyPI seems to allow, what Google allows, and what seems likely to be
+  // most useful in situations where someone needs to reach for HTML.
   "html": {
     "allowed_elements": [
       "a",
       "abbr",
       "b",
-      "bdo",
       "blockquote",
       "br",
       "caption",
@@ -106,8 +123,6 @@
       "h4",
       "h5",
       "h6",
-      "h7",
-      "h8",
       "hr",
       "i",
       "img",
@@ -120,16 +135,10 @@
       "picture",
       "pre",
       "q",
-      "rp",
-      "rt",
-      "ruby",
       "s",
       "samp",
       "small",
-      "source",
-      "span",
       "span",
-      "strike",
       "strong",
       "sub",
       "summary",
@@ -145,7 +154,6 @@
       "tt",
       "ul",
       "var",
-      "video",
       "wbr"
     ]
   }

.yamllint.yaml

@@ -1,5 +1,21 @@
-# Summary: yamllint configuration.
+# Copyright 2025 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
+#
+#     https://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.
+
+# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+# Yamllint configuration to match project settings like line length.
 # See https://yamllint.readthedocs.io/ for info about configuration options.
+# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 rules:
   line-length: