Added lexer/parser skeleton

lexer_parser.py

@@ -0,0 +1,76 @@
+from enum import Enum
+
+class Tokens(Enum):
+    QUOTE = 1,
+    CHAR = 2,
+    NEWLINE = 3,
+    SPACE = 4
+
+class Lexer:
+    tokens = list()
+    def __init__(self):
+        pass
+    def lex(self, str):
+        for c in str:
+            if c == "'" or c == '"':
+                self.tokens.append(Tokens.QUOTE)
+                print("Token: QUOTE")
+            elif c == "\n":
+                self.tokens.append(Tokens.NEWLINE)
+                print("Token: NEWLINE")
+            elif c == " ":
+                self.tokens.append(Tokens.SPACE)
+                print("Token: SPACE")
+            else:
+                self.tokens.append(Tokens.CHAR)
+                print("Token: CHAR")
+    def __str__(self):
+        return ",".join(Tokens(token).name for token in self.tokens)
+
+class States(Enum):
+    INITIAL = 0,
+    BEGINQUOTE = 1
+    
+class Parser:
+    def __init__(self):
+        self.state = States.INITIAL
+        self.line = 1
+
+    def transition(self, state):
+        print(f"{States(self.state).name} -> {States(state).name}")
+        self.state = state
+
+    def parse(self, tokens):
+        for token in tokens:
+            if self.state == States.INITIAL:
+                if token == Tokens.QUOTE:
+                    self.transition(States.BEGINQUOTE)
+                elif token == Tokens.NEWLINE:
+                    self.line += 1
+                continue
+            if self.state == States.BEGINQUOTE:
+                if token == Tokens.QUOTE:
+                    self.transition(States.INITIAL)
+                elif token == Tokens.CHAR or token == Tokens.SPACE:
+                    pass                    
+                elif token == Tokens.NEWLINE:
+                    raise ValueError(f"Unterminated string on line {self.line}")
+                continue
+
+if __name__ == "__main__":
+    test1 = """abcdefg
+    "abcde
+    'a'
+    bareword
+"""
+
+    lexer = Lexer()
+    lexer.lex(test1)
+    # print(lexer)
+    parser = Parser()
+    try:
+        parser.parse(lexer.tokens)
+    except ValueError as error:
+        print(error)
+
+