Use general approach for rendering in commonmark

Instead of supporting graphviz and any other possible text-to-diagram providers directly, let's build a general approach instead where a user can specify whatever executable they want to pipe the content of the code block through it, and replace the whole node w/ its output. This drops direct graphviz support in favor of built-in 'exec' pipe.
ikalnytskyi · Nov 2, 2023 · 0358dd8 · 0358dd8
1 parent 1d13f7b
commit 0358dd8
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Showing 4 changed files with 30 additions and 81 deletions.
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -32,8 +32,5 @@ jobs:
         with:
           python-version: "3.10"
 
-      - name: Set up prerequisites
-        run: sudo apt-get install graphviz libgraphviz-dev
-
       - name: Run tests
         run: pipx run -- hatch run test:run
diff --git a/pyproject.toml b/pyproject.toml
@@ -23,6 +23,7 @@ classifiers = [
     "Programming Language :: Python",
     "Programming Language :: Python :: 3",
     "Programming Language :: Python :: 3.10",
+    "Programming Language :: Python :: 3.11",
 ]
 dependencies = [
     "Jinja2 >= 3.1",
@@ -33,7 +34,6 @@ dependencies = [
     "Markdown >= 3.4",
     "docutils >= 0.19",
     "feedgen >= 0.9",
-    "pygraphviz >= 1.10",
     "termcolor >= 1.1",
     "colorama >= 0.4",
     "markdown-it-py >= 2.1",
@@ -58,7 +58,6 @@ source = "vcs"
 sources = ["src"]
 
 [tool.hatch.envs.test]
-python = "3.10"
 dependencies = [
     "mock >= 4.0",
     "coverage >= 6.4",

diff --git a/src/holocron/_processors/commonmark.py b/src/holocron/_processors/commonmark.py
@@ -2,7 +2,8 @@
 
 import json
 import logging
-import pathlib
+import subprocess
+import typing as t
 
 import markdown_it
 import markdown_it.renderer
@@ -11,13 +12,10 @@
 import pygments.formatters.html
 import pygments.lexers
 import pygments.util
-import pygraphviz
 from mdit_py_plugins.container import container_plugin
 from mdit_py_plugins.deflist import deflist_plugin
 from mdit_py_plugins.footnote import footnote_plugin
 
-import holocron
-
 from ._misc import parameters
 
 _LOGGER = logging.getLogger("holocron")
@@ -28,22 +26,35 @@ def __init__(self, parser):
         super().__init__(parser)
         self._parser = parser
 
-    def fence(self, tokens, idx, options, env):
+    def fence(self, tokens, idx, options, env) -> str:
         token = tokens[idx]
+
         match token.info.split(maxsplit=1):
-            case ["dot", params]:
-                env.setdefault("diagrams", [])
+            case [language, params]:
                 params = json.loads(params)
-                diagram_name = f"diagram-{len(env['diagrams'])}.svg"
-                diagram_data = pygraphviz.AGraph(token.content).draw(
-                    format=params["format"],
-                    prog=params.get("engine", "dot"),
-                )
-                env["diagrams"].append((diagram_name, diagram_data))
-                return self._parser.render(f"![]({diagram_name})")
+                if "exec" in params:
+                    return _exec_pipe(params["exec"], token.content.encode("UTF-8")).decode("UTF-8")
+
         return super().fence(tokens, idx, options, env)
 
 
+def _exec_pipe(args: t.List[str], input_: t.ByteString, timeout: int = 1000) -> bytes:
+    try:
+        completed_process = subprocess.run(
+            args,
+            shell=True,
+            input=input_,
+            capture_output=True,
+            timeout=timeout,
+            check=True
+        )
+    except subprocess.TimeoutExpired:
+        return b"timed out executing the command"
+    except subprocess.CalledProcessError as exc:
+        return exc.stderr
+    return completed_process.stdout
+
+
 def _pygmentize(code: str, language: str, _: str) -> str:
     if not language:
         return code
@@ -118,13 +129,3 @@ def process(
         item["content"] = commonmark.renderer.render(tokens, commonmark.options, env)
         item["destination"] = item["destination"].with_suffix(".html")
         yield item
-
-        for diagram_name, diagram_bytes in env.get("diagrams", []):
-            yield holocron.WebSiteItem(
-                {
-                    "source": pathlib.Path("dot://", str(item["source"]), diagram_name),
-                    "destination": item["destination"].with_name(diagram_name),
-                    "baseurl": app.metadata["url"],
-                    "content": diagram_bytes,
-                }
-            )
diff --git a/tests/_processors/test_commonmark.py b/tests/_processors/test_commonmark.py
@@ -407,7 +407,7 @@ def test_args_pygmentize_unknown_language(testapp, language):
     ]
 
 
-def test_item_dot_render(testapp):
+def test_item_exec(testapp):
     """Commonmark has to render DOT snippets into SVG if asked to render."""
 
     stream = commonmark.process(
@@ -417,10 +417,8 @@ def test_item_dot_render(testapp):
                 {
                     "content": textwrap.dedent(
                         """
-                        ```dot {"format": "svg"}
-                        graph yoda {
-                            a -- b -- c
-                        }
+                        ```text {"exec": "sed --expression 's/ a / the /g'"}
+                        yoda, a jedi grandmaster
                         ```
                         """
                     ),
@@ -435,57 +433,11 @@ def test_item_dot_render(testapp):
     assert list(stream) == [
         holocron.Item(
             {
-                "content": '<p><img src="diagram-0.svg" alt="" /></p>\n',
+                "content": "yoda, the jedi grandmaster\n",
                 "source": pathlib.Path("1.md"),
                 "destination": pathlib.Path("1.html"),
             },
         ),
-        holocron.WebSiteItem(
-            {
-                "content": _pytest_regex(rb".*</svg>\s*", re.DOTALL | re.MULTILINE),
-                "source": pathlib.Path("dot://1.md/diagram-0.svg"),
-                "destination": pathlib.Path("diagram-0.svg"),
-                "baseurl": "https://yoda.ua",
-            }
-        ),
-    ]
-
-
-def test_item_dot_not_rendered(testapp):
-    """Commonmark has to preserve DOT snippet if not asked to render."""
-
-    stream = commonmark.process(
-        testapp,
-        [
-            holocron.Item(
-                {
-                    "content": textwrap.dedent(
-                        """
-                        ```dot
-                        graph yoda {
-                            a -- b -- c
-                        }
-                        ```
-                        """
-                    ),
-                    "destination": pathlib.Path("1.md"),
-                }
-            )
-        ],
-    )
-
-    assert isinstance(stream, collections.abc.Iterable)
-    assert list(stream) == [
-        holocron.Item(
-            {
-                "content": (
-                    '<pre><code class="language-dot">graph yoda {\n'
-                    "    a -- b -- c\n"
-                    "}\n</code></pre>\n"
-                ),
-                "destination": pathlib.Path("1.html"),
-            }
-        )
     ]