squash! first attempt

Author: pierrecamilleri

frictionless/schema/fields_info.py

@@ -0,0 +1,47 @@
+from typing import List
+
+from frictionless.schema.field import Field
+
+
+class FieldInfo:
+    """Private class to store additional data to a field"""
+
+    def __init__(self, field: Field, field_number: int):
+        """field_number: 1-indexed rank of the field"""
+        self.field = field
+        self.field_number = field_number
+        self.cell_reader = field.create_cell_reader()
+        self.cell_writer = field.create_cell_writer()
+
+
+class FieldsInfo:
+    def __init__(self, fields: List[Field]):
+        self._fields: List[FieldInfo] = [
+            FieldInfo(field, i + 1) for i, field in enumerate(fields)
+        ]
+
+    def ls(self) -> List[str]:
+        """List all field names"""
+        return [fi.field.name for fi in self._fields]
+
+    def get(self, field_name: str) -> FieldInfo:
+        """Get a Field by its name
+
+        Raises:
+            ValueError: Field with name fieldname does not exist
+        """
+        try:
+            return next(fi for fi in self._fields if fi.field.name == field_name)
+        except StopIteration:
+            raise ValueError(f"'{field_name}' is not in fields data")
+
+    def get_copies(self) -> List[Field]:
+        """Return field copies"""
+        return [fi.field.to_copy() for fi in self._fields]
+
+    def rm(self, field_name: str):
+        try:
+            i = self.ls().index(field_name)
+            del self._fields[i]
+        except ValueError:
+            raise ValueError(f"'{field_name}' is not in fields data")