Implemented dict renderer to resolve assets

utils/dict_renderer.py

@@ -0,0 +1,119 @@
+import re
+import time
+from typing import Any, Dict, Union, List, Set
+
+class DictRenderer:
+    """
+    Resolves placeholders in the form << path >> within nested dictionaries,
+    supporting hyphens, numeric list indexing, and quoted keys via ['key'] or ["key"].
+    """
+    # Match << path >> where path contains no whitespace or closing >
+    PATTERN = re.compile(r"<<\s*(?P<path>[^\s>]+)\s*>>")
+    # Tokenizes a path into unquoted keys, single-quoted, double-quoted keys, or numeric indices
+    TOKEN_REGEX = re.compile(
+        r"(?P<key>[\w\-]+)"
+        r"|\['(?P<qkey>[^']+)'\]"
+        r"|\[\"(?P<dkey>[^\"]+)\"\]"
+        r"|\[(?P<idx>\d+)\]"
+    )
+
+    def __init__(self, verbose: bool = False, timeout: float = 10.0):
+        self.verbose = verbose
+        self.timeout = timeout
+
+    def render(self, data: Union[Dict[str, Any], List[Any]]) -> Union[Dict[str, Any], List[Any]]:
+        start = time.monotonic()
+        self.root = data
+        rendered = data
+        pass_num = 0
+
+        while True:
+            pass_num += 1
+            if self.verbose:
+                print(f"[DictRenderer] Pass {pass_num} starting...")
+            rendered, changed = self._render_pass(rendered)
+            if not changed:
+                if self.verbose:
+                    print(f"[DictRenderer] No more placeholders after pass {pass_num}.")
+                break
+            if time.monotonic() - start > self.timeout:
+                raise TimeoutError(f"Rendering exceeded timeout of {self.timeout} seconds")
+
+        # After all passes, raise error on unresolved placeholders
+        unresolved = self.find_unresolved(rendered)
+        if unresolved:
+            raise ValueError(f"Unresolved placeholders: {', '.join(sorted(unresolved))}")
+
+        return rendered
+
+    def _render_pass(self, obj: Any) -> (Any, bool):
+        if isinstance(obj, dict):
+            new = {}
+            changed = False
+            for k, v in obj.items():
+                nv, ch = self._render_pass(v)
+                new[k] = nv
+                changed = changed or ch
+            return new, changed
+        if isinstance(obj, list):
+            new_list = []
+            changed = False
+            for item in obj:
+                ni, ch = self._render_pass(item)
+                new_list.append(ni)
+                changed = changed or ch
+            return new_list, changed
+        if isinstance(obj, str):
+            def repl(m):
+                path = m.group('path')
+                val = self._lookup(path)
+                if val is not None:
+                    if self.verbose:
+                        print(f"[DictRenderer] Resolving <<{path}>> -> {val}")
+                    return str(val)
+                return m.group(0)
+            new_str = self.PATTERN.sub(repl, obj)
+            return new_str, new_str != obj
+        return obj, False
+
+    def _lookup(self, path: str) -> Any:
+        current = self.root
+        for m in self.TOKEN_REGEX.finditer(path):
+            if m.group('key') is not None:
+                if isinstance(current, dict):
+                    current = current.get(m.group('key'))
+                else:
+                    return None
+            elif m.group('qkey') is not None:
+                if isinstance(current, dict):
+                    current = current.get(m.group('qkey'))
+                else:
+                    return None
+            elif m.group('dkey') is not None:
+                if isinstance(current, dict):
+                    current = current.get(m.group('dkey'))
+                else:
+                    return None
+            elif m.group('idx') is not None:
+                idx = int(m.group('idx'))
+                if isinstance(current, list) and 0 <= idx < len(current):
+                    current = current[idx]
+                else:
+                    return None
+            if current is None:
+                return None
+        return current
+
+    def find_unresolved(self, data: Any) -> Set[str]:
+        """Return all paths of unresolved << placeholders in data."""
+        unresolved: Set[str] = set()
+        if isinstance(data, dict):
+            for v in data.values():
+                unresolved |= self.find_unresolved(v)
+        elif isinstance(data, list):
+            for item in data:
+                unresolved |= self.find_unresolved(item)
+        elif isinstance(data, str):
+            for m in self.PATTERN.finditer(data):
+                unresolved.add(m.group('path'))
+        return unresolved