Merge pull request #58 from moggers87/24-external

External command filter

docs/exhibition.filters.external.rst

@@ -0,0 +1,7 @@
+exhibition.filters.external module
+==================================
+
+.. automodule:: exhibition.filters.external
+    :members:
+    :undoc-members:
+    :show-inheritance:

docs/exhibition.filters.rst

@@ -6,6 +6,7 @@ Submodules
 
 .. toctree::
 
+   exhibition.filters.external
    exhibition.filters.jinja2
 
 Module contents

docs/meta.rst

@@ -131,6 +131,19 @@ If specified, this will wrap the file content in ``{% block %}``.
 Markdown options as specified in the `Markdown documentation
 <https://python-markdown.github.io/reference/#markdown>`_.
 
+External Command
+^^^^^^^^^^^^^^^^
+
+external_cmd
+~~~~~~~~~~~~
+
+The command to run. This should use the placeholders ``{INPUT}`` and
+``{OUTPUT}`` for the input and output files respectively. For example:
+
+.. code-block: yaml
+
+   external_cmd: "cat {INPUT} | sort > {OUTPUT}"
+
 Cache busting
 -------------
 

exhibition/filters/external.py

@@ -0,0 +1,74 @@
+##
+#
+# Copyright (C) 2018 Matt Molyneaux
+#
+# This file is part of Exhibition.
+#
+# Exhibition is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Exhibition is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Exhibition.  If not, see <https://www.gnu.org/licenses/>.
+#
+##
+
+"""
+External command filter
+
+Use an external command to process a file, like so:
+
+.. code-block:: yaml
+
+   filter: exhibition.filters.external
+   external_cmd: sed 's/this/that/g' {INPUT} > {OUTPUT}
+"""
+
+from tempfile import TemporaryDirectory
+import pathlib
+import subprocess
+
+DEFAULT_GLOB = "*.*"
+
+INPUT_NAME = "input"
+OUTPUT_NAME = "output"
+
+INPUT_KEY = "INPUT"
+OUTPUT_KEY = "OUTPUT"
+
+
+def content_filter(node, content):
+    """
+    This is the actual content filter called by :class:`exhibition.main.Node`
+    on appropiate nodes.
+
+    :param node:
+        The node being rendered
+    :param content:
+        The content of the node, stripped of any YAML frontmatter
+    """
+    tmp_dir = TemporaryDirectory()
+    input_file = pathlib.Path(tmp_dir.name, INPUT_NAME)
+    output_file = pathlib.Path(tmp_dir.name, OUTPUT_NAME)
+
+    cmd = node.meta["external_cmd"]
+    cmd = cmd.format(**{
+        INPUT_KEY: input_file,
+        OUTPUT_KEY: output_file,
+    })
+
+    with input_file.open("w") as f:
+        f.write(content)
+
+    subprocess.run(cmd, shell=True)
+
+    with output_file.open("r") as f:
+        output = f.read()
+
+    return output

exhibition/tests/test_filters.py

@@ -21,11 +21,13 @@
 
 from tempfile import TemporaryDirectory
 from unittest import TestCase, mock
+import base64
 import pathlib
 
 from jinja2.exceptions import TemplateRuntimeError
 from jinja2 import Markup
 
+from exhibition.filters.external import content_filter as external_filter
 from exhibition.filters.jinja2 import content_filter as jinja_filter
 from exhibition.node import Node
 
@@ -92,6 +94,38 @@
 """.strip()
 
 
+class ExternalCommandTestCase(TestCase):
+    def test_input_output(self):
+        content = "hello, how are you?"
+        node = Node(mock.Mock(), None, meta={"external_cmd": "cat {INPUT} | base64 > {OUTPUT}"})
+        node._content_start = 0
+        output = external_filter(node, content)
+
+        expected_output = base64.b64encode(content.encode()).decode() + "\n"
+        self.assertEqual(output, expected_output)
+
+    def test_filter_glob(self):
+        with TemporaryDirectory() as content_path, TemporaryDirectory() as deploy_path:
+            # default glob is *.*
+            for filename in ["blog.html", "mytext.txt"]:
+                content = "hello {}, how are you?".format(filename)
+                path = pathlib.Path(content_path, "blog.htm")
+                with path.open("w") as f:
+                    f.write(content)
+
+                node = Node(path, Node(path.parent, None,
+                            {"content_path": content_path,
+                             "deploy_path": deploy_path,
+                             "filter": "exhibition.filters.external",
+                             "external_cmd": "cat {INPUT} | base64 > {OUTPUT}"}))
+                node.render()
+                with pathlib.Path(deploy_path, "blog.htm").open("r") as f:
+                    output = f.read()
+
+                expected_output = base64.b64encode(content.encode()).decode() + "\n"
+                self.assertEqual(output, expected_output)
+
+
 class Jinja2TestCase(TestCase):
     def test_template(self):
         node = Node(mock.Mock(), None, meta={"templates": []})