update cfg module docs

Author: bygu4

pyformlang/cfg/cfg.py

@@ -1,4 +1,4 @@
-"""A CFG Variable Converter"""
+"""A converter into CFG variables."""
 
 from typing import Dict, List, AbstractSet, Tuple, Optional, Hashable
 
@@ -7,11 +7,12 @@
 
 
 class CFGVariableConverter:
-    """A CFG Variable Converter"""
+    """A converter into CFG variables."""
 
     def __init__(self,
                  states: AbstractSet[FormalObject],
                  stack_symbols: AbstractSet[FormalObject]) -> None:
+        """Initializes the converter."""
         self._counter = 0
         self._inverse_states_d: Dict[FormalObject, int] = {}
         self._counter_state = 0
@@ -31,7 +32,7 @@ def __init__(self,
                range(len(states))]
 
     def _get_state_index(self, state: FormalObject) -> int:
-        """Get the state index"""
+        """Gets the state index."""
         if state.index is None:
             if state not in self._inverse_states_d:
                 self._inverse_states_d[state] = self._counter_state
@@ -40,7 +41,7 @@ def _get_state_index(self, state: FormalObject) -> int:
         return state.index
 
     def _get_symbol_index(self, symbol: FormalObject) -> int:
-        """Get the symbol index"""
+        """Gets the symbol index."""
         if symbol.index is None:
             if symbol not in self._inverse_stack_symbol_d:
                 self._inverse_stack_symbol_d[symbol] = self._counter_symbol
@@ -52,7 +53,7 @@ def to_cfg_combined_variable(self,
                                  state0: FormalObject,
                                  stack_symbol: FormalObject,
                                  state1: FormalObject) -> Variable:
-        """ Conversion used in the to_pda method """
+        """Conversion used in the PDA to CFG transformation."""
         i_stack_symbol, i_state0, i_state1 = self._get_indexes(
             stack_symbol, state0, state1)
         prev = self._conversions[i_state0][i_stack_symbol][i_state1]
@@ -78,7 +79,7 @@ def set_valid(self,
                   state0: FormalObject,
                   stack_symbol: FormalObject,
                   state1: FormalObject) -> None:
-        """Set valid"""
+        """Set valid."""
         i_stack_symbol, i_state0, i_state1 = self._get_indexes(
             stack_symbol, state0, state1)
         prev = self._conversions[i_state0][i_stack_symbol][i_state1]
@@ -88,7 +89,7 @@ def is_valid_and_get(self,
                          state0: FormalObject,
                          stack_symbol: FormalObject,
                          state1: FormalObject) -> Optional[Variable]:
-        """Check if valid and get"""
+        """Check if valid and get."""
         i_state0 = self._get_state_index(state0)
         i_stack_symbol = self._get_symbol_index(stack_symbol)
         i_state1 = self._get_state_index(state1)

pyformlang/cfg/cfg_variable_converter.py

@@ -1,6 +1,4 @@
-"""
-Representation of a CYK table
-"""
+"""Representation of a CYK parsing table."""
 
 from typing import Dict, List, Set, Iterable, Tuple, Any
 
@@ -13,17 +11,18 @@
 
 
 class CYKTable:
-    """
-    A CYK table
+    """Representation of a CYK parsing table.
 
     Parameters
     ----------
-    cfg : A context-free grammar
-    word : iterable of Terminals
-        The word from which we construct the CYK table
+    grammar:
+        A grammar to create CYK table from.
+    word:
+        A word from which we construct the CYK table.
     """
 
     def __init__(self, grammar: FormalGrammar, word: List[Terminal]) -> None:
+        """Initializes the CYK table."""
         self._normal_form: FormalGrammar = grammar.to_normal_form()
         self._generate_epsilon: bool = grammar.generate_epsilon()
         self._word: List[Terminal] = word
@@ -83,12 +82,11 @@ def _initialize_cyk_table(self) -> None:
                     (start_window, start_window + window_size)] = set()
 
     def generate_word(self) -> bool:
-        """
-        Checks is the word is generated
+        """Checks is the word is generated by the grammar.
+
         Returns
         -------
-        is_generated : bool
-
+        Whether the grammar contains the word.
         """
         if not self._word:
             return self._generate_epsilon
@@ -103,12 +101,16 @@ def _generates_all_terminals(self) -> bool:
         return generate_all_terminals
 
     def get_parse_tree(self) -> ParseTree:
-        """
-        Give the parse tree associated with this CYK Table
+        """Gets the parse tree associated with this CYK Table.
 
         Returns
         -------
-        parse_tree : :class:`~pyformlang.cfg.ParseTree`
+        A parsing tree of the word in the CNF.
+
+        Raises
+        ------
+        DerivationDoesNotExistError
+            If the word cannot be derived.
         """
         if not self._normal_form.start_symbol or not self.generate_word():
             raise DerivationDoesNotExistError
@@ -122,12 +124,13 @@ def get_parse_tree(self) -> ParseTree:
 
 
 class CYKNode(ParseTree):
-    """A node in the CYK table"""
+    """A node in the CYK table."""
 
     def __init__(self,
                  value: CFGObject,
                  left_son: "CYKNode" = None,
                  right_son: "CYKNode" = None) -> None:
+        """Initializes the node."""
         super().__init__(value)
         self.value = value
         self.left_son = left_son
@@ -138,9 +141,11 @@ def __init__(self,
             self.sons.append(right_son)
 
     def __eq__(self, other: Any) -> bool:
+        """Checks if the node is equal to the given object."""
         if isinstance(other, CYKNode):
             return self.value == other.value
         return self.value == other
 
     def __hash__(self) -> int:
+        """Gets the hash of the node."""
         return hash(self.value)