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--- lfa:2024:lab04 [2024/10/27 23:22]
cata_chiru
+++ lfa:2024:lab04 [2024/10/29 09:27] (current)
cata_chiru
@@ Line 62: / Line 62: @@
     crt_lst = list(set(lst))
     return sorted(crt_lst, key = lambda x: (len(x), x))
 # Global variable used to threshold the number of Star items
 INNER_STAR_NO_ITEMS = 3
 class Regex:
     '''Base class for Regex ADT'''
     def __str__(self) -> str:
         '''Returns the string representation of the regular expression'''
         pass
     def gen(self) -> [str]:
         '''Return a representative set of strings that the regular expression can generate'''
         pass
+    def __len__(self) -> str:
+        '''Returns the length of the regular expression'''
+        pass
     def eval_gen(self):
         '''Prints the set of strings that the regular expression can generate'''
         pass
 # TODO 0: Implementati Clasa Void dupa blueprint-ul de mai sus
 class Void(Regex):
     '''Represents the empty regular expression'''
     # Va returna Void ca string
     def __str__(self) -> str:
         pass
     # Va genera un obiect din Python corespunzatoar clasei void
     def gen(self) -> [str]:
         pass
+    def __len__(self):
+        return 0
     def eval_gen(self):
         print("Void generates nothing")
 # TODO 1: Implementati Clasa Epsilon-String (Empty) dupa blueprint-ul de mai sus
 class Empty(Regex):
     '''Represents the empty string regular expression'''
     # Va returna Empty ca string
     def __str__(self) -> str:
         pass
     # Va returna o lista corespunzatoare a ce stringuri produce sirul vid
     def gen(self) -> [str]:
         pass
+    # Va returna lungimea corespunzatoare sirului vid
+    def __len__(self) -> int:
+        pass
     def eval_gen(self):
-        print("Empty string generates ''.")
+        print(f"Empty string has length {len(self)} generates ''.")
 # TODO 2: Implementati functionalitatile necesare pentru Clasa Symbol dupa blueprint-ul de mai sus
 class Symbol(Regex):
     '''Represents a symbol in the regular expression'''
     def __init__(self, char: str):
         self.char = char
     # TODO 2: Completati metodele __str__ si gen pentru clasa Symbol
     def __str__(self) -> str:
         pass
     def gen(self) -> [str]:
         pass
+    def __len__(self) -> int:
+        return 1
     def eval_gen(self):
         self.gen()
 	# Dorim sa pastram in atributul words al clasei curente stringurile generate cu gen(self)
-        return "Symbol {self.char} generates {self.words}"
+        return f"Symbol {self.char} has length {len(self)} generates {self.words}"
 # TODO 3: Implementati functionalitatile necesare pentru Clasa Union dupa blueprint-ul de mai sus
 class Union(Regex):
@@ Line 137: / Line 151: @@
     def __init__(self, *arg: [Regex]):
         self.components = arg
+    # TODO 3: Completati metodele __str__, gen, __len__ si eval_gen pentru clasa Union
-    # TODO 3: Completati metodele __str__, gen si eval_gen pentru clasa Union
+    # Hint: Look at the str.join method to create (expr1|expr2|...)
     def __str__(self) -> str:
         pass
     def gen(self) -> [str]:
-	pass
+        pass
+    # We will consider the len of a Union as the max length of its components
+    def __len__(self) -> int:
+        pass
     # Dupa modelul de la Symbol, vom dori ca urmatoarele eval sa implementeze
-    # return "Class {varianta toString() a clasei) generates {self.words}"
+    # return "Class {varianta toString() a clasei) has length {len(self)} and generates {self.words}"
     def eval_gen(self) -> str:
-	pass
+	    pass
 # TODO 4: Implementati functionalitatile necesare pentru Clasa Concat dupa blueprint-ul de mai sus
 class Concat(Regex):
     '''Represents the concatenation of two regular expressions'''
     def __init__(self, *arg : [Regex]):
         self.components = arg
-    # TODO 4: Completati metodele __str__, gen si eval_gen pentru clasa Concat
+    # TODO 4: Completati metodele __str__, gen, __len__ si eval_gen pentru clasa Concat
     def __str__(self) -> str:
         pass
     def gen(self) -> [str]:
-	pass
+        pass
-    def eval_gen(self) -> str:
-	pass
+    def __len__(self) -> int:
+        pass
+    def eval_gen(self) -> str:
+	    pass
 # TODO 5: Implementati functionalitatile necesare pentru Clasa Star dupa blueprint-ul de mai sus
 class Star(Regex):
@@ Line 172: / Line 195: @@
     def __init__(self, regex: Regex):
         self.regex = regex
+        # To memorize the base words generated by the regex inside the star, we store them in a list
         self.base_words = [""]
-        self.base_gen()
         self.words = []
+    # TODO 5: Completati metodele __str__, gen, __len__, eval_gen pentru clasa Star
-    # TODO 5: Completati metodele __str__, gen, eval_gen pentru clasa Star
+    def __str__(self) -> str:
-    def __str__(self):
+        pass
+    def gen(self, no_items = 10) -> [str]:
         pass
-    def base_gen(self):
+    # To ease your implementation we will consider a big number e.g. 1000000 as Infinity
-        '''To memorize the base words generated by the regex inside the star, we store them in a list'''
+    def __len__(self) -> int:
-        if type(self.regex) == Star:
+        pass
-	    # Implement Star.gen with a limiting threshold
+    def eval_gen(self, no_items = 10):
 	    pass
-	# Implement Regex.gen for the rest
-	pass
-    def gen(self, no_items = 10):
-	pass
-    def eval_gen(self, no_items = 10):
-	pass
 if __name__ == "__main__":
-    # Example usage
     r1 = Symbol('a')
     r2 = Symbol('b')
     regex_union = Union(r1, r2)
     regex_union.eval_gen()
     e2 = Union(Symbol('a'),Symbol('b'), Symbol('c'))
     e4 = Concat(r1, e2)
     e4.eval_gen()
     e5 = Concat(e2, e2, r2)
     e5.eval_gen()
     star_ex = Star(r1)
     star_ex.eval_gen()
     regex_concat = Concat(regex_union, star_ex)
     regex_concat.eval_gen()
     last_expr = Concat(Star(Union(Symbol('a'), Symbol('b'))), Symbol('b'), Star(Symbol('c')))
     last_expr.eval_gen()
-    </code>
+</code>
 The output should be similar to:
 <code>
-Union (a | b) generates ['a', 'b'].
+Union (a | b) has length 1 and generates ['a', 'b'].
-Concat (a(a | b | c)) generates ['aa', 'ab', 'ac'].
+Concat (a(a | b | c)) has length 2 and generates ['aa', 'ab', 'ac'].
-Concat ((a | b | c)(a | b | c)b) generates ['aab', 'abb', 'acb', 'bab', 'bbb', 'bcb', 'cab', 'cbb', 'ccb'].
+Concat ((a | b | c)(a | b | c)b) has length 3 and generates ['aab', 'abb', 'acb', 'bab', 'bbb', 'bcb', 'cab', 'cbb', 'ccb'].
-Star (a*) generates ['', 'a', 'aa', 'aaa', 'aaaa', 'aaaaa', 'aaaaaa', 'aaaaaaa', 'aaaaaaaa', 'aaaaaaaaa', 'aaaaaaaaaa', '...'].
+Star (a*) has length 10000000 generates ['', 'a', 'aa', 'aaa', 'aaaa', 'aaaaa', 'aaaaaa', 'aaaaaaa', 'aaaaaaaa', 'aaaaaaaaa', 'aaaaaaaaaa', '...'].
-Concat ((a | b)(a*)) generates ['a', 'b', 'aa', 'ba', 'aaa', 'baa', 'aaaa', 'baaa'].
+Concat ((a | b)(a*)) has length 10000001 and generates ['a', 'b', 'aa', 'ba', 'aaa', 'baa', 'aaaa', 'baaa', '...'].
-Concat (((a | b)*)b(c*)) generates ['b', 'ab', 'bb', 'bc', 'aab', 'abb', 'abc', 'bab', 'bbb', 'bbc', 'bcc', 'aaab', 'aabb', 'aabc', 'abab', 'abbb', 'abbc', 'abcc', 'baab', 'babb', 'babc', 'bbab', 'bbbb', 'bbbc', 'bbcc', 'bccc', 'aaaab', 'aaabb', '...'].
+Concat (((a | b)*)b(c*)) has length 20000001 and generates ['b', 'ab', 'bb', 'bc', 'aab', 'abb', 'abc', 'bab', 'bbb', 'bbc', 'bcc', 'aaab', 'aabb', 'aabc', 'abab', 'abbb', 'abbc', 'abcc', 'baab', 'babb', 'babc', 'bbab', 'bbbb', 'bbbc', 'bbcc', 'bccc', '...'].
 </code>