# Grammar for parsing lambdascript, with integer constants.  This grammar,
# when used with my LR(1) parser generater produced 70 states.  It creates
# 3 files:  lambdaplusparser.java, lambdaplus.flex and Mylambdapluslexer.java.
# The lambdaplus.flex file will create a lexical analyzer based on the the
# terminal symbols of the grammar, and Mylambdapluslexer is an object adapter
# that allows the lexical analyzer to be used in the parser.  See the 
# file kam.java for usage.

# This block contains code that will be added to the parser class verbatim:
{%
  kam machine;
  public void setup(kam m) {machine=m;}
  /* kam.java extras */
%}

terminal lambda ( ) [ ] DOT let = in define ;
typedterminal INTEGER Integer
typedterminal ID String
nonterminal T term
nonterminal Vars ArrayList<String>
nonterminal Moreargs ArrayList<term>
nonterminal Ts ArrayList<term>
topsym Ts

# automatically enables genflex option:
flexname DOT .

Ts --> T:x ;  { ArrayList<term> S = new ArrayList<term>(); S.add(x); return S; }
Ts --> Ts:y T:x ;  { y.add(x); return y; }

T --> ID:x { return new var(x); }
T --> INTEGER:x { return new iconst(x); }
T --> ( T:a Moreargs:ts ) {: 
  if (ts.size()<1) return a;
  term t = new app(a,ts.get(0));
  for(int i=1;i<ts.size();i++) t = new app(t,ts.get(i));
  return t; :}
T --> lambda Vars:vs DOT T:b  {: term t = b;
  for(int i=vs.size()-1;i>=0;i--) t = new abs(vs.get(i),t); 
  return t; :}
T --> let ID:x = T:v in T:b { return new app(new abs(x,b),v); }

# define evaluate to the term being defined, but also affects global env
T --> define ID:x = T:v {: 
  machine.Defs = new Binding(new var(x),new Closure(v,machine.Defs),machine.Defs); return v; :}

Moreargs --> { ArrayList<term> s = new ArrayList<term>(); return s; }
Moreargs --> Moreargs:ts T:b { ts.add(b); return ts; }

Vars --> ID:x {: ArrayList<String> A = new ArrayList<String>(); 
  A.add(x); return A; :}
Vars --> Vars:vs ID:y {vs.add(y); return vs;}

EOF