/ NGNK Parser and Source Code Generator

/ Define AST Structures
ASTNode:{(x;y;z)}
FunctionCall:{(x;y)}
Conditional:{(x;y;z)}
SystemCommand:{(x)}

/ Tokenizer using State Machine with Scan (Right-to-Left)
tokenize:{
  states: ("num"; "id"; "op"; "ws"; "adverb");
  s:();
  x:|x;
  
  classify:{
    ?x in "0123456789": "num"
    ; ?x in "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz": "id"
    ; ?x in "()+-*/%=<>~,:#@.?;[]{}!": "op"
    ; ?x in "' / \\ ': /: \\:": "adverb"
    ; "ws"
  }
  
  tokens:states\:classify x;
  s,::tokens;
  
  if (#(s="ws") > 0) { s::ErrorNode["Invalid token detected"] }
  
  s
}

/ Parsing Table
parseTable:(`+
  `-`*`%`!`&`|`<`>`=`~`,`^`#`_`$`?`@`.
  `binaryOp@)!
  binaryOp@
parseTable[`$[]:`conditionalOp;
parseTable[`\`:systemCommandOp;
parseTable[`'`:adverbOp;
parseTable[`/`:adverbOp;
parseTable[`\\`:adverbOp;
parseTable[`':`:adverbOp;
parseTable[`/:`:adverbOp;
parseTable[`\\:`:adverbOp;

/ Operator Handling
binaryOp:{s::(x@-2;x@-1;*|_2#x); x:_2#x}
monadicOp:{s::(x@-1;*x); x:_1#x}
dyadicOp:{s::(x@-2;x@-1;*|_2#x); x:_2#x}

/ Specialized Operations
conditionalOp:{s::Conditional[x@-3;x@-2;x@-1]; x:_3#x}
systemCommandOp:{s::SystemCommand[x@-1]; x:_1#x}
adverbOp:{s::FunctionCall["adverb"; x@-1]; x:_1#x}

/ Parser
parse:{
  s:();
  x:|x;
  s,::(t in parseTable ? parseTable[t] s : t like "0123456789" | t like '"*"' | t like '`*' ? t : FunctionCall[t;!s] if t like '*]')@\:x;
  *s
}

/ Convert AST back to NGNK source code
generateSource:{
  t:type x;
  $[t=`FunctionCall; x 0, "[", ";" join generateSource each 1_x, "]"
    ;t=`Conditional; "$[", ";" join generateSource each x, "]"
    ;t=`SystemCommand; "\\", x 0
    ;x]
}

/ Example
code:"\\clear; x:2*3+4; while[x<20; x:x+2]; try[1/0]"; tokens:tokenize code; ast:parse tokens; `0:generateSource ast