Add substitutions

CHANGELOG.md

@@ -13,6 +13,13 @@ The **third number** is for emergencies when we need to start branches for older
 
 ## [Unreleased](https://github.com/hynek/hatch-fancy-pypi-readme/compare/22.3.0...HEAD)
 
+### Added
+
+- It is now possible to run regexp-based substitutions over the final readme.
+  [#9](https://github.com/hynek/hatch-fancy-pypi-readme/issues/9)
+  [#11](https://github.com/hynek/hatch-fancy-pypi-readme/issues/11)
+
+
 ## [22.3.0](https://github.com/hynek/hatch-fancy-pypi-readme/compare/22.2.0...22.3.0) - 2022-08-06
 
 ### Added

README.md

@@ -175,6 +175,38 @@ to your readme.
 For a complete example, please see our [example configuration][example-config].
 
 
+## Substitutions
+
+After a readme is assembled out of fragments, it's possible to run an arbitrary number of [regexp](https://docs.python.org/3/library/re.html)-based substitutions over it:
+
+```toml
+[[tool.hatch.metadata.hooks.fancy-pypi-readme.substitutions]]
+pattern = "This is a (.*) that we'll replace later."
+replacement = "It was a '\\1'!"
+ignore_case = true  # optional; false by default
+```
+
+---
+
+Substitutions are for instance useful for replacing relative links with absolute ones:
+
+```toml
+[[tool.hatch.metadata.hooks.fancy-pypi-readme.substitutions]]
+# Literal TOML strings (single quotes) need no escaping of backslashes.
+pattern = '\[(.+?)\]\(((?!https?://)\S+?)\)'
+replacement = '[\1](https://github.com/hynek/hatch-fancy-pypi-readme/tree/main\g<2>)'
+```
+
+or expanding GitHub issue/pull request IDs to links:
+
+```toml
+[[tool.hatch.metadata.hooks.fancy-pypi-readme.substitutions]]
+# Regular TOML strings (double quotes) do.
+pattern = "#(\\d+)"
+replacement = "[#\\1](https://github.com/hynek/hatch-fancy-pypi-readme/issues/\\1)"
+```
+
+
 ## CLI Interface
 
 For faster feedback loops, *hatch-fancy-pypi-readme* comes with a CLI interface that takes a `pyproject.toml` file as an argument and renders out the readme that would go into respective package.

src/hatch_fancy_pypi_readme/_builder.py

@@ -5,11 +5,19 @@
 from __future__ import annotations
 
 from ._fragments import Fragment
+from ._substitutions import Substituter
 
 
-def build_text(fragments: list[Fragment]) -> str:
+def build_text(
+    fragments: list[Fragment], substitutions: list[Substituter]
+) -> str:
     rv = []
     for f in fragments:
         rv.append(f.render())
 
-    return "".join(rv)
+    text = "".join(rv)
+
+    for sub in substitutions:
+        text = sub.substitute(text)
+
+    return text

src/hatch_fancy_pypi_readme/_cli.py

@@ -45,7 +45,7 @@ def cli_run(pyproject: dict[str, Any], out: TextIO) -> None:
             + "\n".join(f"- {msg}" for msg in e.errors),
         )
 
-    print(build_text(config.fragments), file=out)
+    print(build_text(config.fragments, config.substitutions), file=out)
 
 
 def _fail(msg: str) -> NoReturn:

src/hatch_fancy_pypi_readme/_config.py

@@ -8,13 +8,15 @@
 from typing import Any
 
 from ._fragments import Fragment, load_fragments
+from ._substitutions import Substituter, load_substitutions
 from .exceptions import ConfigurationError
 
 
 @dataclass
 class Config:
     content_type: str
     fragments: list[Fragment]
+    substitutions: list[Substituter]
 
 
 def load_and_validate_config(config: dict[str, Any]) -> Config:
@@ -41,7 +43,12 @@ def load_and_validate_config(config: dict[str, Any]) -> Config:
     except ConfigurationError as e:
         errs.extend(e.errors)
 
+    try:
+        subs = load_substitutions(config.get("substitutions", []))
+    except ConfigurationError as e:
+        errs.extend(e.errors)
+
     if errs:
         raise ConfigurationError(errs)
 
-    return Config(config["content-type"], frags)
+    return Config(config["content-type"], frags, subs)

src/hatch_fancy_pypi_readme/_substitutions.py

@@ -0,0 +1,64 @@
+# SPDX-FileCopyrightText: 2022 Hynek Schlawack <[email protected]>
+#
+# SPDX-License-Identifier: MIT
+
+from __future__ import annotations
+
+import re
+
+from dataclasses import dataclass
+
+from hatch_fancy_pypi_readme.exceptions import ConfigurationError
+
+
+def load_substitutions(config: list[dict[str, str]]) -> list[Substituter]:
+    errs = []
+    subs = []
+
+    for cfg in config:
+        try:
+            subs.append(Substituter.from_config(cfg))
+        except ConfigurationError as e:
+            errs.extend(e.errors)
+
+    if errs:
+        raise ConfigurationError([f"substitution: {e}" for e in errs])
+
+    return subs
+
+
+@dataclass
+class Substituter:
+    pattern: re.Pattern[str]
+    replacement: str
+
+    @classmethod
+    def from_config(cls, cfg: dict[str, str]) -> Substituter:
+        errs = []
+        flags = 0
+
+        ignore_case = cfg.get("ignore_case", False)
+        if not isinstance(ignore_case, bool):
+            errs.append("`ignore_case` must be a bool.")
+        if ignore_case:
+            flags += re.IGNORECASE
+
+        try:
+            pattern = re.compile(cfg["pattern"], flags=flags)
+        except KeyError:
+            errs.append("missing `pattern` key.")
+        except re.error as e:
+            errs.append(f"can't compile pattern: {e}")
+
+        try:
+            replacement = cfg["replacement"]
+        except KeyError:
+            errs.append("missing `replacement` key.")
+
+        if errs:
+            raise ConfigurationError(errs)
+
+        return cls(pattern, replacement)
+
+    def substitute(self, text: str) -> str:
+        return self.pattern.sub(self.replacement, text)

src/hatch_fancy_pypi_readme/hooks.py

@@ -25,7 +25,7 @@ def update(self, metadata: dict[str, Any]) -> None:
 
         metadata["readme"] = {
             "content-type": config.content_type,
-            "text": build_text(config.fragments),
+            "text": build_text(config.fragments, config.substitutions),
         }
 
 

tests/example_changelog.md

@@ -3,29 +3,33 @@
 This is a long-winded preamble that explains versioning and backwards-compatibility guarantees.
 Your don't want this as part of your PyPI readme!
 
+Note that there's issue/PR IDs behind the changelog entries.
+Wouldn't it be nice if they were links in your PyPI readme?
+
 <!-- changelog follows -->
 
 
 ## 1.1.0 - 2022-08-04
 
 ### Added
 
-- Neat features.
+- Neat features. #4
+- Here's a [GitHub-relative link](README.md) -- that would make no sense in a PyPI readme!
 
 ### Fixed
 
-- Nasty bugs.
+- Nasty bugs. #3
 
 
 ## 1.0.0 - 2021-12-16
 
 ### Added
 
-- Everything.
+- Everything. #2
 
 
 ## 0.0.1 - 2020-03-01
 
 ### Removed
 
-- Precedency.
+- Precedency. #1

tests/example_pyproject.toml

@@ -40,3 +40,11 @@ pattern = "<!-- changelog follows -->\n\n\n(.*?)\n\n## "
 
 [[tool.hatch.metadata.hooks.fancy-pypi-readme.fragments]]
 text = "\n---\n\nPretty **cool**, huh? ✨"
+
+[[tool.hatch.metadata.hooks.fancy-pypi-readme.substitutions]]
+pattern = "#(\\d+)"
+replacement = "[#\\1](https://github.com/hynek/hatch-fancy-pypi-readme/issues/\\1)"
+
+[[tool.hatch.metadata.hooks.fancy-pypi-readme.substitutions]]
+pattern = '\[(.+?)\]\(((?!https?://)\S+?)\)'
+replacement = '[\1](https://github.com/hynek/hatch-fancy-pypi-readme/tree/main/\g<2>)'

tests/test_builder.py

@@ -12,7 +12,7 @@ def test_single_text_fragment(self):
         A single text fragment becomes the readme.
         """
         assert "This is the README!" == build_text(
-            [TextFragment("This is the README!")]
+            [TextFragment("This is the README!")], []
         )
 
     def test_multiple_text_fragment(self):
@@ -24,5 +24,6 @@ def test_multiple_text_fragment(self):
             [
                 TextFragment("# Level 1\n\n"),
                 TextFragment("This is the README!"),
-            ]
+            ],
+            [],
         )

tests/test_cli.py

@@ -54,6 +54,16 @@ def test_ok(self):
         assert out.startswith("# Level 1 Header")
         assert "1.0.0" not in out
 
+        # Check substitutions
+        assert (
+            "[GitHub-relative link](https://github.com/hynek/"
+            "hatch-fancy-pypi-readme/tree/main/README.md)" in out
+        )
+        assert (
+            "Neat features. [#4](https://github.com/hynek/"
+            "hatch-fancy-pypi-readme/issues/4)" in out
+        )
+
     def test_ok_redirect(self, tmp_path):
         """
         It's possible to redirect output into a file.

tests/test_config.py

@@ -68,3 +68,21 @@ def test_missing_fragments(self):
             == ei.value.errors
             == ei.value.args[0]
         )
+
+    def test_invalid_substitution(self):
+        """
+        Invalid substitutions are caught and reported.
+        """
+        with pytest.raises(ConfigurationError) as ei:
+            load_and_validate_config(
+                {
+                    "content-type": "text/markdown",
+                    "fragments": [{"text": "foo"}],
+                    "substitutions": [{"foo": "bar"}],
+                }
+            )
+
+        assert [
+            "substitution: missing `pattern` key.",
+            "substitution: missing `replacement` key.",
+        ] == ei.value.errors

tests/test_substitutions.py

@@ -0,0 +1,91 @@
+# SPDX-FileCopyrightText: 2022 Hynek Schlawack <[email protected]>
+#
+# SPDX-License-Identifier: MIT
+
+from __future__ import annotations
+
+import pytest
+
+from hatch_fancy_pypi_readme._substitutions import (
+    Substituter,
+    load_substitutions,
+)
+from hatch_fancy_pypi_readme.exceptions import ConfigurationError
+
+
+class TestLoadSubstitutions:
+    def test_empty(self):
+        """
+        Having no substitutions is fine.
+        """
+        assert [] == load_substitutions([])
+
+    def test_error(self):
+        """
+        Invalid substitutions are caught and reported.
+        """
+        with pytest.raises(ConfigurationError) as ei:
+            load_substitutions([{"in": "valid"}])
+
+        assert [
+            "substitution: missing `pattern` key.",
+            "substitution: missing `replacement` key.",
+        ] == ei.value.errors
+
+
+VALID = {"pattern": "f(o)o", "replacement": r"bar\g<1>bar"}
+
+
+def cow_valid(**kw):
+    d = VALID.copy()
+    d.update(**kw)
+
+    return d
+
+
+class TestSubstituter:
+    def test_ok(self):
+        """
+        Valid pattern leads to correct behavior.
+        """
+        sub = Substituter.from_config(VALID)
+
+        assert "xxx barobar yyy" == sub.substitute("xxx foo yyy")
+
+    @pytest.mark.parametrize(
+        "cfg, errs",
+        [
+            ({}, ["missing `pattern` key.", "missing `replacement` key."]),
+            (cow_valid(ignore_case=42), ["`ignore_case` must be a bool."]),
+            (
+                cow_valid(pattern="???"),
+                ["can't compile pattern: nothing to repeat at position 0"],
+            ),
+        ],
+    )
+    def test_catches_all_errors(self, cfg, errs):
+        """
+        All errors are caught and reported.
+        """
+        with pytest.raises(ConfigurationError) as ei:
+            Substituter.from_config(cfg)
+
+        assert errs == ei.value.errors
+
+    def test_twisted(self):
+        """
+        Twisted example works.
+
+        https://github.com/twisted/twisted/blob/eda9d29dc7fe34e7b207781e5674dc92f798bffe/setup.py#L19-L24
+        """
+        assert (
+            "For information on changes in this release, see the `NEWS <https://github.com/twisted/twisted/blob/trunk/NEWS.rst>`_ file."  # noqa
+        ) == Substituter.from_config(
+            {
+                "pattern": r"`([^`]+)\s+<(?!https?://)([^>]+)>`_",
+                "replacement": r"`\1 <https://github.com/twisted/twisted/blob/trunk/\2>`_",  # noqa
+                "ignore_case": True,
+            }
+        ).substitute(
+            "For information on changes in this release, see the `NEWS <NEWS.rst>`_ file."  # noqa
+        )