JSON's skeleton is punctuation - braces wrap objects, brackets wrap arrays, colons and commas separate. Today you teach the scanner to recognize those six single-character tokens, the frame every value hangs on.
Scan each of the six structural characters into its own distinct token kind.
An object is written { ... }, an array [ ... ], a key and value are joined by
:, and siblings are separated by ,. Those six characters are the structural
tokens - the load-bearing frame of every JSON document. They are the easiest
tokens to scan because each is exactly one character and maps to exactly one kind,
with no value to decode.
Walk the input one byte at a time and, for each of these six characters, append the
matching token. Append the final EOF when you run off the end. You are building the
punctuation vocabulary now; the literals, strings, and numbers that fill the gaps
between this punctuation come next. Keep the loop simple - a switch on the current
byte is all it takes today.
// add one Kind per punctuator alongside EOFconst (EOF Kind = iotaLBrace; RBrace; LBracket; RBracket; Colon; Comma)// walk byte by byte; each of these maps to exactly one token// switch input[i] { case '{': ... '}': ... '[': ... etc }