Ensure README is synched with code

.pre-commit-config.yaml

@@ -40,3 +40,11 @@ repos:
     hooks:
       - id: ruff
         args: [--fix, --exit-non-zero-on-fix]
+
+  - repo: local
+    hooks:
+      - id: readme.py
+        name: readme.py
+        language: system
+        entry: python .tools/readme.py
+        files: "README.md|src/changelist/default_config.toml|.tools/readme.py"

.tools/readme.py

@@ -0,0 +1,20 @@
+import re
+
+with open("README.md") as fh:
+    readme = fh.read()
+
+with open("src/changelist/default_config.toml") as fh:
+    default_config = fh.read()
+
+config_begin = r"<!--- begin default_config.toml --->\n"
+config_end = r"<!--- end default_config.toml --->\n"
+config_section = (
+    config_begin + r"\n````toml\n" + default_config + r"````\n\n" + config_end
+)
+
+rx = re.compile(config_begin + ".*?" + config_end, re.DOTALL)
+readme = rx.sub(config_section, readme)
+
+
+with open("README.md", "w") as fh:
+    fh.write(readme)

README.md

@@ -50,6 +50,8 @@ changelist can be configured from two sources, in order of precedence:
 If a configuration option is not specified in either file above, changelist
 falls back to the following configuration:
 
+<!--- begin default_config.toml --->
+
 ````toml
 # Default changelist configuration as supported in pyproject.toml
 [tool.changelist]
@@ -109,6 +111,8 @@ pr_summary_regex = "^```release-note\\s*(?P<summary>[\\s\\S]*?\\w[\\s\\S]*?)\\s*
 ".*Maintenance.*" = "Maintenance"
 ````
 
+<!--- end default_config.toml --->
+
 ## Set up your repository
 
 To categorize merged PRs in the changelist with the default configuration, each