Add graphrag (#1793)

### What problem does this PR solve?

#1594

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

graphrag/utils.py

@@ -0,0 +1,74 @@
+#
+#  Copyright 2024 The InfiniFlow Authors. All Rights Reserved.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+#
+"""
+Reference:
+ - [graphrag](https://github.com/microsoft/graphrag)
+"""
+
+import html
+import re
+from collections.abc import Callable
+from typing import Any
+
+ErrorHandlerFn = Callable[[BaseException | None, str | None, dict | None], None]
+
+
+def perform_variable_replacements(
+    input: str, history: list[dict]=[], variables: dict | None ={}
+) -> str:
+    """Perform variable replacements on the input string and in a chat log."""
+    result = input
+
+    def replace_all(input: str) -> str:
+        result = input
+        if variables:
+            for entry in variables:
+                result = result.replace(f"{{{entry}}}", variables[entry])
+        return result
+
+    result = replace_all(result)
+    for i in range(len(history)):
+        entry = history[i]
+        if entry.get("role") == "system":
+            history[i]["content"] = replace_all(entry.get("content") or "")
+
+    return result
+
+
+def clean_str(input: Any) -> str:
+    """Clean an input string by removing HTML escapes, control characters, and other unwanted characters."""
+    # If we get non-string input, just give it back
+    if not isinstance(input, str):
+        return input
+
+    result = html.unescape(input.strip())
+    # https://stackoverflow.com/questions/4324790/removing-control-characters-from-a-string-in-python
+    return re.sub(r"[\"\x00-\x1f\x7f-\x9f]", "", result)
+
+
+def dict_has_keys_with_types(
+    data: dict, expected_fields: list[tuple[str, type]]
+) -> bool:
+    """Return True if the given dictionary has the given keys with the given types."""
+    for field, field_type in expected_fields:
+        if field not in data:
+            return False
+
+        value = data[field]
+        if not isinstance(value, field_type):
+            return False
+    return True
+