# SI413 Unit 2 Languages

language_name: Arrr!

notes_from_prof: |
    Language designed by LCDR Norine.

    It is a prefix language, meaning the operation name always comes
    before the arguments, and parentheses are usually not necessary.

    The language has a lot of keywords as opposed to operator
    characters.

    The grammar is designed to support static type checking, by
    separating boolean from string expressions.


example_program: |
    !Blimey! Stash the true password ye land lubber! Scallywag!
    Stash Booty correctPass ~~backwards~~

    !Blimey! Get the secret input from the user. They should type in "sdrawkcab" Scallywag!
    Avast Booty ~~Enter the password or walk the plank!~~
    Stash Booty userInput Savvy?

    !Blimey!
        Now, we check if the REVERSED user input is the same as the correct password!
        Swab userInput --> should become "backwards" if typed correctly
        Cog ![ Swab userInput ]! correctPass --> should return true (Aye!)
    Scallywag!
    Avast Loot Cog ![ Swab userInput ]! correctPass

    !Blimey! Now that we know they have the right password, we need to check if they know where our treasure is!
    Scallywag!
    Avast Booty ~~Where is the treasure located?~~
    Restash Booty userInput Savvy?
    !Blimey!
        We know it's under the tree, and the location is larger than "Port Royale"
    Scallywag!
    Avast Loot Chantey ![ Spyglass userInput ~~tree~~ ]! ![ SmallerCog ~~Port Royale~~ userInput ]!

    !Blimey! But is their name lucky? We need to know! x marks the lucky spot! Scallywag!
    Avast Booty ~~What is your first name?~~
    Stash Booty firstName Savvy?
    Avast Booty ~~What is your last name?~~
    Stash Booty lastName Savvy?
    Stash Booty fullName Ahoy firstName lastName
    Avast Booty fullName
    Avast Loot Spyglass fullName ~~X~~

    !Blimey! Let's sail the seven seas with lots of tildes
             by putting dots in the string delimiters.  Scallywag!
    Avast Booty ~.~~~~~~~~~~~~~~~~~~~~~.~


example_input_1: |
    sdrawkcab
    under the tree!
    Chancho
    the Mad

example_output_1: |
    Aye
    Aye
    Nay

example_input_2: |
    hunter2
    out past Zombie Island!
    Xanadu
    the Insane

example_output_2: |
    Nay
    Nay
    Aye


tokens: |
    LP:           !\[
    RP:           \]!
    LOGIC_OP:     Chantey|Parley
    LOGIC_NOT:    Scuttle
    STR_CONTAIN:  Spyglass
    STR_CMP:      (Smaller)?Cog
    CONCAT:       Ahoy
    REVERSE:      Swab
    INPUT:        Savvy\?
    PRINT:        Avast
    ASSIGN:       Stash|Restash
    STR_LIT:      (~\.*~).*?\1
    BOOL_LIT:     Aye|Nay
    STR_TYPE:     Booty
    BOOL_TYPE:    Loot
    ID:           [a-zA-Z][a-zA-Z0-9]*
    ignore:       [ \t\r\n]
    ignore:       !Blimey![\s\S]*?Scallywag!


grammar: |
    program -> stmt program
            -> ε

    stmt -> ASSIGN STR_TYPE ID str_expr
         -> ASSIGN BOOL_TYPE ID bool_expr
         -> PRINT STR_TYPE str_expr
         -> PRINT BOOL_TYPE bool_expr

    str_expr -> LP str_expr RP
             -> CONCAT str_expr str_expr
             -> REVERSE str_expr
             -> INPUT
             -> STR_LIT
             -> ID

    bool_expr -> LP bool_expr RP
              -> LOGIC_OP bool_expr bool_expr
              -> LOGIC_NOT bool_expr
              -> STR_CONTAIN str_expr str_expr
              -> STR_CMP str_expr str_expr
              -> BOOL_LIT
              -> ID


semantics: |
    -I adopted a prefix notation for the language, for better or worse. The
    operators all work on arguments passed AFTER them, so string concatenate
    takes the two expressions after "Ahoy" and returns a single string.

    -True and False will remain like that under the hood, but in my language they are
    Aye and Nay. Those words outside of a string will be treated as boolean literals
    and not strings. If printed, they will output Aye and Nay respectively.

    -There are no escape characters in string literals. The delimiters
    can be ~~ or ~.~ or ~..~ or ~...~ etc., but must match on the left
    and right of each string literal.

    -Chantey means logical AND, Parley means logical OR.

    -Cog means string equality, SmallerCog means string less-than.