Add docstrings to core modules and helper functions

Co-authored-by: varun-r-mallya <100590632+varun-r-mallya@users.noreply.github.com>

pythonbpf/structs/struct_type.py

@@ -2,18 +2,64 @@ from llvmlite import ir
 
 
 class StructType:
+    """
+    Wrapper class for LLVM IR struct types with field access helpers.
+    
+    Attributes:
+        ir_type: The LLVM IR struct type
+        fields: Dictionary mapping field names to their types
+        size: Total size of the struct in bytes
+    """
+    
     def __init__(self, ir_type, fields, size):
+        """
+        Initialize a StructType.
+        
+        Args:
+            ir_type: The LLVM IR struct type
+            fields: Dictionary mapping field names to their types
+            size: Total size of the struct in bytes
+        """
         self.ir_type = ir_type
         self.fields = fields
         self.size = size
 
     def field_idx(self, field_name):
+        """
+        Get the index of a field in the struct.
+        
+        Args:
+            field_name: The name of the field
+        
+        Returns:
+            The zero-based index of the field
+        """
         return list(self.fields.keys()).index(field_name)
 
     def field_type(self, field_name):
+        """
+        Get the LLVM IR type of a field.
+        
+        Args:
+            field_name: The name of the field
+        
+        Returns:
+            The LLVM IR type of the field
+        """
         return self.fields[field_name]
 
     def gep(self, builder, ptr, field_name):
+        """
+        Generate a GEP (GetElementPtr) instruction to access a struct field.
+        
+        Args:
+            builder: LLVM IR builder
+            ptr: Pointer to the struct
+            field_name: Name of the field to access
+        
+        Returns:
+            A pointer to the field
+        """
         idx = self.field_idx(field_name)
         return builder.gep(
             ptr,
@@ -22,6 +68,18 @@ class StructType:
         )
 
     def field_size(self, field_name):
+        """
+        Calculate the size of a field in bytes.
+        
+        Args:
+            field_name: The name of the field
+        
+        Returns:
+            The size of the field in bytes
+        
+        Raises:
+            TypeError: If the field type is not supported
+        """
         fld = self.fields[field_name]
         if isinstance(fld, ir.ArrayType):
             return fld.count * (fld.element.width // 8)

pythonbpf/structs/structs_pass.py

@@ -26,6 +26,15 @@ def structs_proc(tree, module, chunks):
 
 
 def is_bpf_struct(cls_node):
+    """
+    Check if a class node is decorated with @struct.
+    
+    Args:
+        cls_node: The AST class node to check
+    
+    Returns:
+        True if the class is decorated with @struct, False otherwise
+    """
     return any(
         isinstance(decorator, ast.Name) and decorator.id == "struct"
         for decorator in cls_node.decorator_list
@@ -33,7 +42,16 @@ def is_bpf_struct(cls_node):
 
 
 def process_bpf_struct(cls_node, module):
-    """Process a single BPF struct definition"""
+    """
+    Process a single BPF struct definition and create its LLVM IR representation.
+    
+    Args:
+        cls_node: The AST class node representing the struct
+        module: The LLVM IR module (not used in current implementation)
+    
+    Returns:
+        A StructType object containing the struct's type information
+    """
 
     fields = parse_struct_fields(cls_node)
     field_types = list(fields.values())
@@ -44,7 +62,18 @@ def process_bpf_struct(cls_node, module):
 
 
 def parse_struct_fields(cls_node):
-    """Parse fields of a struct class node"""
+    """
+    Parse fields of a struct class node.
+    
+    Args:
+        cls_node: The AST class node representing the struct
+    
+    Returns:
+        A dictionary mapping field names to their LLVM IR types
+    
+    Raises:
+        TypeError: If a field has an unsupported type annotation
+    """
     fields = {}
 
     for item in cls_node.body:
@@ -57,7 +86,18 @@ def parse_struct_fields(cls_node):
 
 
 def get_type_from_ann(annotation):
-    """Convert an AST annotation node to an LLVM IR type for struct fields"""
+    """
+    Convert an AST annotation node to an LLVM IR type for struct fields.
+    
+    Args:
+        annotation: The AST annotation node (e.g., c_int64, str(32))
+    
+    Returns:
+        The corresponding LLVM IR type
+    
+    Raises:
+        TypeError: If the annotation type is not supported
+    """
     if isinstance(annotation, ast.Call) and isinstance(annotation.func, ast.Name):
         if annotation.func.id == "str":
             # Char array
@@ -72,7 +112,15 @@ def get_type_from_ann(annotation):
 
 
 def calc_struct_size(field_types):
-    """Calculate total size of the struct with alignment and padding"""
+    """
+    Calculate total size of the struct with alignment and padding.
+    
+    Args:
+        field_types: List of LLVM IR types for each field
+    
+    Returns:
+        The total size of the struct in bytes
+    """
     curr_offset = 0
     for ftype in field_types:
         if isinstance(ftype, ir.IntType):