sexp.pegjs

root
 = elements:(sexp+) {return {type: 'root', elements}}

sexp
 = parenexp
 / delimited
 / id
 
parenexp
 = type:$lparen elements:exp+ rparen {return {type, elements}}
 / type:$lbrace elements:exp+ rbrace {return {type, elements}}
 / type:$lbracket elements:exp+ rbracket {return {type, elements}}
 / type:$rangle elements:exp+ langle {return {type, elements}}

delimited
 = type:$squote elements:(!squote e:exp {return e})+ squote {return {type, elements}}
 / type:$dquote elements:(!dquote e:exp {return e})+ dquote {return {type, elements}}
 / type:$bar elements:(!bar e:exp {return e})+ bar {return {type, elements}}
 
exp
 = id
 / sexp

id
 = c:(!reserved c:. {return c})+ _ {return c.join('')}

reserved = ws / lparen / rparen / lbrace / rbrace / lbracket / rbracket / rangle / langle / dquote / squote / bar

lparen   = '(' _
rparen   = ')' _
lbrace   = '{' _
rbrace   = '}' _
lbracket = '[' _
rbracket = ']' _
langle   = '<' _
rangle   = '>' _
dquote   = '"' _
squote   = "'" _
bar      = '|' _

_ = ws?
ws 'whitespace' = [\r\n\t ]+