Fix opt statement productions, start regex for literals

PLATYPUS Grammar Specification.md

@@ -52,6 +52,9 @@ This does not follow standard BNF/EBNF syntax, I will rewrite it once I get all
 <arithmetic identifier> ::=
     <letter> <opt_letters or digits>
 
+<opt_letters or digits> ::=
+    ε | <letters or digits>
+
 <letters or digits> ::=
     <letter or digit> | <letters or digits> <letter or digit>
 
@@ -77,6 +80,9 @@ This does not follow standard BNF/EBNF syntax, I will rewrite it once I get all
 <decimal integer literal> ::=
     0 | <non-zero digit> <opt_digits>
 
+<opt_digits> ::=
+    ε | <digits>
+
 <digits> ::=
     <digit> | <digits> <digit>
 
@@ -103,10 +109,16 @@ This does not follow standard BNF/EBNF syntax, I will rewrite it once I get all
 ```
 ### 2.8 String Literals
 ```
+<opt_string literal> ::=
+    ε | <string literal>
+    
 <string literal> ::=
     "<opt_string characters>"
 
-<string chacters> ::=
+<opt_string characters> ::=
+    ε | <string characters>
+
+<string characters> ::=
     <input character> | <string characters> <input character>
 ```
 ### 2.9 Separators
@@ -142,6 +154,9 @@ This does not follow standard BNF/EBNF syntax, I will rewrite it once I get all
 <program> ::=
     PLATYPUS {<opt_statements>} SEOF
 
+<opt_statements> ::=
+    ε | <statements>
+
 <statements> ::=
     <statement> | <statements> <statement>
 ```
@@ -179,6 +194,9 @@ This does not follow standard BNF/EBNF syntax, I will rewrite it once I get all
 <input statement> ::=
     INPUT (<variable list>);
 
+<opt_variable list> ::=
+    ε | <variable list>
+
 <variable list> ::=
     <variable identifier> | <variable list>,<variable identifier>
 ```

PLATYPUS_Regex.md

@@ -0,0 +1,47 @@
+# Regular Expressions for PLATYPUS 
+## Comments
+```
+L(COMMENT) = !< [^CR]*CR
+```
+
+## Keywords
+```
+L(KEYWORD) = PLATYPUS | IF | THEN | ELSE | USING | REPEAT | INPUT | OUTPUT
+```
+## Variable Identifiers
+```
+L(LETTER) = [a-zA-Z]
+
+L(LETTER_OR_DIGIT) = [a-zA-Z0-9]
+
+L(VID) = AVID | SVID
+
+L(AVID) = [a-zA-Z]([a-zA-Z0-9])*
+
+L(SVID) = AVID#
+
+```
+## Integer Literals
+```
+
+L(DEC_INT_LITERAL) = [0-9]*
+
+L(NON_ZERO_DIGIT) = 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
+
+L(DIGIT) = [0-9]+
+
+L(OCT_DIGIT) = 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7
+
+L(OCT_DIGIT_LITERAL) = 0(OCT_DIGIT)+
+
+L(INT_LITERAL) = (DEC_INT_LITERAL | OCT_INT_LITERAL)
+
+```
+## Floating Point Literal
+```
+L(FLP_LITERAL) = ([0-9]*).([0-9]+)
+```
+## String Literal
+```
+L(STR_LITERAL) = "([a-ZA-Z_0-9])*"
+```