From 736706604d1ade9b267252726944a1cd15d16620 Mon Sep 17 00:00:00 2001
From: Gabriel Gerlero <gerlero@users.noreply.github.com>
Date: Thu, 22 Aug 2024 22:22:21 -0300
Subject: [PATCH] Add create method to FoamFile

---
 foamlib/_cases/_base.py  |  6 ++----
 foamlib/_files/_files.py | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/foamlib/_cases/_base.py b/foamlib/_cases/_base.py
index 4b42fd0..3e01876 100644
--- a/foamlib/_cases/_base.py
+++ b/foamlib/_cases/_base.py
@@ -62,12 +62,10 @@ def name(self) -> str:
             return self.path.name
 
         def __getitem__(self, key: str) -> FoamFieldFile:
-            if (self.path / key).is_file():
-                return FoamFieldFile(self.path / key)
-            elif (self.path / f"{key}.gz").is_file():
+            if (self.path / f"{key}.gz").is_file() and not (self.path / key).is_file():
                 return FoamFieldFile(self.path / f"{key}.gz")
             else:
-                raise KeyError(key)
+                return FoamFieldFile(self.path / key)
 
         def __contains__(self, obj: object) -> bool:
             if isinstance(obj, FoamFieldFile):
diff --git a/foamlib/_files/_files.py b/foamlib/_files/_files.py
index e159745..37ad0eb 100644
--- a/foamlib/_files/_files.py
+++ b/foamlib/_files/_files.py
@@ -11,6 +11,11 @@
 else:
     from typing import Iterator, Mapping, MutableMapping, Sequence
 
+if sys.version_info >= (3, 11):
+    from typing import Self
+else:
+    from typing_extensions import Self
+
 from .._util import is_sequence
 from ._base import FoamFileBase
 from ._io import _FoamFileIO
@@ -96,6 +101,32 @@ def as_dict(self) -> FoamFileBase._Dict:
 
             return ret
 
+    def create(self, *, exist_ok: bool = False, parents: bool = False) -> Self:
+        """
+        Create the file.
+
+        Parameters
+        ----------
+        exist_ok : bool, optional
+            If False (the default), raise a FileExistsError if the file already exists.
+            If True, do nothing if the file already exists.
+        parents : bool, optional
+            If True, also create parent directories as needed.
+        """
+        if self.path.exists():
+            if not exist_ok:
+                raise FileExistsError(self.path)
+            else:
+                return self
+
+        if parents:
+            self.path.parent.mkdir(parents=True, exist_ok=True)
+
+        self.path.touch()
+        self._write_header()
+
+        return self
+
     @property
     def version(self) -> float:
         """Alias of `self["FoamFile", "version"]`."""
@@ -160,6 +191,7 @@ def object_(self, value: str) -> None:
 
     def _write_header(self) -> None:
         assert "FoamFile" not in self
+        assert not self
 
         self["FoamFile"] = {}
         self.version = 2.0