/*
Binding levels (well...):
0 = lowest
1 = arrows (> lowest)
2 = arrowsr (> arrows)
3 = word (> arrows)
4 = juxta, idword, subword (> word)
*/


static S snlParse_rules = [[
  // highest (strongest binding) level 
  <extidentifier> = idword
  <int> = subword
  <quoted> = subword
  // <ucid> = subword
  
  // random symbols we'd want to use
  // (they don't parse if not listed here)
  ? = symbol
  ! = symbol
  : = symbol
  * = symbol
  "=" = symbol
  + = symbol
  , = symbol
  . = symbol
  <symbol> = idword
  
  <subword> = word
  <idword> = word
  
  // juxtaposition on highest level
  <word> <word> = juxta
  <juxta> = word
  
  // bracketing takes us to highest level
  [ <lowest> ] = square
  ( <lowest> ) = round
  
  <square> = subword
  <round> = subword
  
  // < is intermediate
  <word> = arrowsr
  <word> > <arrowsr> = realarrowr
  <realarrowr> = arrowsr
  
  <arrowsr> < <arrows> = realarrow
  <realarrow> = arrows
  <arrowsr> = arrows
  
  = lowest // allow empty here
  <arrows> = lowest
]];

static Explain snlParse(S input) {
  ret explainFull(snlTok(input), snlParse_rules, "lowest");
}