Added true recursive template interpolation and cleaned up

config.yaml

@@ -18,7 +18,7 @@ sites:
     git_repo: ssh://gitea/jim/resume.git
     build_cache: ./build/resume
     assets: 
-      - '{build_cache}/shepich_resume.pdf'
+      - 'shepich_resume.pdf'
   dogma_jimfinium:
     base_url: http://localhost:8080/dogma-jimfinium
     git_repo: ssh://gitea/jim/dogma-jimfinium.git

jimsite.py

@@ -1,4 +1,5 @@
 import os
+import re
 import glob
 import shutil
 import subprocess
@@ -23,6 +24,59 @@ def filepath_or_string(s: str) -> str:
         return s
     
 
+def extract_placeholders(s: str) -> set:
+    '''Extracts placeholder variables in the format `{variable}` from
+    an unformatted template string.'''
+
+    # Regex pattern to match placeholders with alphanumerics, dots, and underscores.
+    placeholder_pattern = r'\{([\w\.]+)\}'
+    
+    # Find all matches in the string.
+    matches = re.findall(placeholder_pattern, s)
+    
+    # Return the set of distinct placeholders.
+    return set(matches)
+
+
+def find_cyclical_placeholders(s: str, _parents: tuple = None, _cycles: set = None, **kwargs) -> set[tuple]:
+    '''Recursively interpolates supplied kwargs into a template string to validate
+    that there are no cyclical dependencies that would cause infinite recursion.
+    
+    Returns a list of paths (expressed as tuples of nodes) of cyclical placeholders.
+    '''
+
+    # Track the lineage of each placeholder so we can see if it is its own ancestor.
+    if _parents is None:
+        _parents = tuple()
+
+    # Keep track of any cycles encountered.
+    if _cycles is None:
+        _cycles = set()
+
+    # Extract the placeholders from the input.
+    placeholders = extract_placeholders(s)
+
+    # Recursion will naturally end once there are no more nested placeholders.
+    for p in placeholders:
+
+        # Any placeholder that has itself in its ancestry forms a cycle.
+        if p in _parents:
+            _cycles.add(_parents + (p,))
+        
+        # For placeholders that are not their own ancestor, recursively 
+        # interpolate the kwargs into the nested placeholders until we reach
+        # strings without placeholders.
+        else:
+            find_cyclical_placeholders(
+                ('{'+p+'}').format(**kwargs),
+                _parents = _parents+(p,),
+                _cycles = _cycles,
+                **kwargs
+            )
+
+    return _cycles
+    
+
 with open('config.yaml', 'r') as config_file:
     config = yaml.safe_load(config_file.read())
     
@@ -69,20 +123,36 @@ def load_markdown(md: str) -> tuple[ArticleMetadata|None, str]:
 
 def format_html_template(template: str, **kwargs) -> str:
     '''Interpolates variables specified as keyword arguments 
-    into the given HTML template.'''
+    into the given HTML template.
+    
+    # Example
+
+    ```python
+    kwargs = {'a': '1', 'b': '2', 'c': '{d}+{e}', 'd': '3', 'e': '{c}'}
+    s = '{a} + {b} = {c}'
+    find_cyclical_placeholders(s, **kwargs)
+
+    >>> {('c', 'e', 'c')}
+    ```
+    '''
 
     # Load the template if a filepath is given.
     template = filepath_or_string(template)
 
-    # Interpolate the kwargs into the HTML template.
+    # Ensure the template does not have cyclical placeholder references.
-    # Apply global variables twice in case a partial used
+    cycles = find_cyclical_placeholders(template, globalvars = GlobalVars(), **kwargs)
-    # by the first call of .format() uses a variable.
+
-    html = template.format(
+    if len(cycles) > 0:
-        globalvars = GlobalVars(), **kwargs
+        raise ValueError('Template has cyclical dependencies: {cycles}')
-    ).format(globalvars = GlobalVars())
+
+    # Iteratively interpolate global variables and the kwargs into the template until
+    # there are no more placeholders. The loop is used to account for nested template references.
+    formatted_html = template
+    while len(extract_placeholders(formatted_html)) > 0:
+        formatted_html = formatted_html.format(globalvars = GlobalVars(), **kwargs)
 
     # Return the formatted HTML.
-    return html
+    return formatted_html
 
 
 run = lambda cmd: subprocess.run(cmd.split(' '), stdout = subprocess.PIPE, stderr = subprocess.PIPE)
@@ -212,7 +282,7 @@ def build_index(site: SiteConfig) -> dict:
 
     # Expand any globbed expressions.
     expanded_article_list = []
-    for a in site.articles:
+    for a in site.articles or {}:
         expanded_article_list.extend(
             # Article paths are defined relative to the build cache; construct the full path.
             glob.glob(f'{site.build_cache}/{a.lstrip("/")}')
@@ -259,10 +329,6 @@ def map_templates(dir: str, parent = '') -> DotMap:
         with open(full_path, 'r') as file:
             html = file.read()
 
-        # # Interpolate global variables into partials.
-        # if 'partials' in full_path:
-        #     html = html.format(globalvars = GlobalVars())
-
         output[filestem] = html
             
     return DotMap(output)