Add support for running commands from default template processor

In a default template, "{% command something arg1 ... argN %}" will be
replaced by the first line output from the command "something" run with
the given arguments (#452).

.github/workflows/test.yml

@@ -43,6 +43,7 @@ jobs:
         if: ${{ runner.os == 'macOS' }}
         run: |
           command -v expect || brew install expect
+          command -v sha1sum || brew install md5sha1sum
 
       - name: Install dependencies on Windows (WSL)
         if: ${{ runner.os == 'Windows' }}

test/test_unit_template_default.py

@@ -1,5 +1,6 @@
 """Unit tests: template_default"""
 
+import hashlib
 import os
 
 FILE_MODE = 0o754
@@ -169,6 +170,18 @@ Include basic again:
 basic
 """
 
+TEMPLATE_COMMAND = """\
+sha1="{% command sha1sum "{{ yadm.filename }}" | cut -d' ' -f1 %}"
+{% command sha1sum "no endtag"
+{% command echo foobar | tr oa OA %}
+"""
+
+EXPECTED_COMMAND = """\
+sha1="{SHA1}"
+{{% command sha1sum "no endtag"
+fOObAr
+"""
+
 TEMPLATE_NESTED_IFS = """\
 {% if yadm.user == "me" %}
     print1
@@ -296,6 +309,26 @@ def test_include(runner, yadm, tmpdir):
     assert os.stat(output_file).st_mode == os.stat(input_file).st_mode
 
 
+def test_command(runner, yadm, tmpdir):
+    """Test custom commands"""
+
+    input_file = tmpdir.join("input with space")
+    input_file.write(TEMPLATE_COMMAND, ensure=True)
+    output_file = tmpdir.join("output")
+
+    expected = EXPECTED_COMMAND.format(SHA1=hashlib.sha1(TEMPLATE_COMMAND.encode(), usedforsecurity=False).hexdigest())
+
+    script = f"""
+        YADM_TEST=1 source {yadm}
+        set_awk
+        template default "{input_file}" "{output_file}"
+    """
+    run = runner(command=["bash"], inp=script)
+    assert run.success
+    assert run.err == ""
+    assert output_file.read() == expected
+
+
 def test_nested_ifs(runner, yadm, tmpdir):
     """Test nested if statements"""
 

yadm

@@ -436,7 +436,19 @@ BEGIN {
           filename[++current] = include
           line[current] = 0
         }
-        else { print }
+        else {
+          if (match($0, /\{%[ \t]*command[ \t]+/)) {
+            prefix = substr($0, 0, RSTART - 1)
+            command = substr($0, RSTART + RLENGTH)
+            if (match(command, /[ \t]*%\}/) && RSTART > 1) {
+              suffix = substr(command, RSTART + RLENGTH)
+              command = substr(command, 0, RSTART - 1)
+              command | getline
+              $0 = prefix $0 suffix
+            }
+          }
+          print
+        }
       }
     }
     if (res >= 0) { close(filename[current]) }

yadm.1

@@ -739,6 +739,7 @@ with the following content
 
   {% if yadm.user == "harvey" %}
   config={{yadm.class}}-{{yadm.os}}
+  user={% command echo "{{ yadm.user }}" | tr a-z A-Z %}
   {% else %}
   config=dev-whatever
   {% include "whatever.extra" %}
@@ -749,6 +750,7 @@ would output a file named
 with the following content if the user is "harvey":
 
   config=work-Linux
+  user=HARVEY
 
 and the following otherwise (if
 .I whatever.extra
@@ -763,6 +765,7 @@ would look like:
 
   {% if YADM_USER == 'harvey' -%}
   config={{YADM_CLASS}}-{{YADM_OS}}
+  user={{ YADM_USER | upper }}
   {% else -%}
   config=dev-whatever
   {% include 'whatever.extra' %}
@@ -774,6 +777,7 @@ would look like:
 
   <% if [ "$YADM_USER" = "harvey" ]; then -%>
   config=<%= $YADM_CLASS %>-<%= $YADM_OS %>
+  user=<% echo "$YADM_USER" | tr a-z A-Z %>
   <% else -%>
   config=dev-whatever
   <%+ whatever.extra %>