BF generator

Below a generator for BrainFuck where you can define the grammar of the input language and a program in that language and generate a BrainFuck programma with it. A default grammar and a default program have been provided. The default program is a BrainFuck program that could replace the POSIX x86 seed for oriansj/stage0 github repository for a BrainFuck interpreter that returns 0 for End-Of-File. The generator does not yet implement all the node types as mentioned between square brackets in the grammar. See below for a list of types that have been implemented.

Enter the grammar:

unary_expr
        : "!" primary_expr [not]
        | primary_expr
        .

l_expr1 : l_expr1 "*" unary_expr  [times]
        | l_expr1 "/" unary_expr  [div]
        | l_expr1 "%" unary_expr  [mod]
        | unary_expr
        .
l_expr2 : l_expr2 "+" l_expr1  [add]
        | l_expr2 "-" l_expr1  [sub]
        | l_expr1
        .
l_expr3 : l_expr3 "<=" l_expr2  [le]
        | l_expr3 ">=" l_expr2  [ge]
        | l_expr3 "<"  l_expr2  [lt]
        | l_expr3 ">"  l_expr2  [gt]
        | l_expr3 "==" l_expr2  [eq]
        | l_expr3 "!=" l_expr2  [ne]
        | l_expr2
        .
l_expr4 : l_expr4 "&&" l_expr3 [and]  | l_expr3 .
l_expr5 : l_expr5 "||" l_expr4 [or] | l_expr4 .

expr
        : l_expr5 "?" l_expr5 ":" expr  [condternary]
        | l_expr5
        .

The input to be parsed by the grammar:
var ch, output, mode; ch = read; while ch do if '0' <= ch && ch <= '9' then if mode then write (ch - '0') + output; dec mode; else output = (ch - '0') * 16; inc mode; fi else if 'A' <= ch && ch <= 'F' then if mode then write (ch - ('A' - 10)) + output; dec mode; else output = (ch - ('A' - 10)) * 16; inc mode; fi else if 'a' <= ch && ch <= 'f' then if mode then write (ch - ('a' - 10)) + output; dec mode; else output = (ch - ('a' - 10)) * 16; inc mode; fi else if ch == ';' || ch == '#' then ch = read; while ch && ch != 10 do ch = read; od fi fi fi fi ch = read; od

Implemented node types

The following node types have been implemented so far:

add: Adds the two child trees.
sub: Substract the two child trees.
times: Multiplies the two child trees.
le: Value larger than zero means first child is smaller or equal to second child, otherwise zero.
eq: Value larger than zero means first child is equal to second child, otherwise zero.
ne: Value larger than zero means first child is not equal to second child, otherwise zero.
or: Value larger than zero when any child tree is larger than zero, otherwise zero.
and: Value larger than zero when both child trees are larger than zero, otherwise zero.
not: Value larger than zero when child tree is zero, otherwise zero.
ass: Assignemt value of second child to variable names in as first child tree.
read: Read value from input.
clear: Clear variable named as child tree.
inc: Increment variable named as child tree.
dec: Decrement variable named as child tree.
write: Write value of variable named as child tree to the output as byte.
ifthen: If-then statment: execute tree of second child tree when value of first child tree is larger than zero.
ifthenelse: If-then statment: execute tree of second child tree when value of first child tree is larger than zero, otherwise execute tree of third child.
while: While statment: execute tree of second child tree while value of first child tree is larger than zero.

Not yet implemented are:

div
mod
lt
ge
gt
condternary