Tidyparse

START -> X
    X -> I | F | P | B
    P -> I | P O I | ( P ) | - P
    F -> IF | BF
   IF -> if B then I else I
   BF -> if B then B else B
    O -> + | - | * | /
    I -> 1 | 2 | 3 | I I | IF | P
    B -> true | false | B BO B | ( B ) | BF | N B
   BO -> and | or | xor | nand
    N -> !
---

_ true _ _ false _ _ true _ _

_ _ _ )

- ( 1 + 1 )

( _ _ _ _ _ _

if ( true ) + then

true or false

( if true then else true )

if true or false and false then 1 else 2 else

if true then if true then 1 else 3 else true

if then if true then true else 2 1 else 1

if ( true ) then if true <BO> true then else 1 else 1

( true and false )

if ( true or false ) xor then true else true

if ( true or false ) then true else ! false

_ true _

if ( true or true ) then 1 else 1

_ _ _ _ true _ _ _ _

true 1 or false 3

true 1 or false 2

true <BO> or false <BO> <N>

if ( false ) then if true then 3 else 2 else false

if ( true or false ) then true else false

if ( true or false ) then 1 else 3 2 3 2

if ( true or false ) then true else 3 2 3 2

if _ _ _ _ _ _ <BO> _ _ _ _ _ _

if then else ( <BO> <BO> <BO> )

if ( true or false ) then true else 1

if true then if true then 1 else 2 else 3

Usage Tips: • To trigger an update, modify the editor to the left. • All tokens must be separated by one or more whitespaces. • Invalid snippets are marked with a squiggly underline. • Unparseable fragments are colored orange and unknown terminals are colored red inside invalid snippets. • Nonterminal stubs are enclosed in angle brackets, <F>. • Any symbol to the left of -> is considered a nonterminal and all other symbols are considered terminals in a CFG. • --- and -> are reserved for the following scenarios: • --- is used to separate the CFG from the test cases. • -> separates the left and right sides of a production. • The symbol ε is reserved and must not be used anywhere. • Any line in the CFG that does not contain -> is ignored. • Tidyparse adds ε-productions, {V} -> ε {V} | {V} ε, and literals {V} -> <V> for each nonterminal, V, in the CFG. • If the grammar contains no nonterminal named START, then Tidyparse will add START -> {V} for every nonterminal, V.

Tidyparse Browser Demonstration