/*****
* fundec.h
* Andy Hammerlindl 2002/8/29
*
* Defines the semantics for defining functions.  Both the newexp syntax, and
* the abbreviated C-style function definition.
*****/

#include "fundec.h"
#include "errormsg.h"
#include "coenv.h"
#include "stm.h"
#include "runtime.h"

namespace absyntax {

using namespace trans;
using namespace types;
using mem::list;

varinit *Default=new definit(nullPos);

void formal::prettyprint(ostream &out, Int indent)
{
 prettyname(
     out, keywordOnly ? "formal (keyword only)" : "formal", indent, getPos()
 );

 base->prettyprint(out, indent+1);
 if (start) start->prettyprint(out, indent+1);
 if (defval) defval->prettyprint(out, indent+1);
}

types::formal formal::trans(coenv &e, bool encodeDefVal, bool tacit) {
 return types::formal(getType(e,tacit),
                      getName(),
                      encodeDefVal ? (bool) getDefaultValue() : 0,
                      getExplicit());
}

types::ty *formal::getType(coenv &e, bool tacit) {
 types::ty *bt = base->trans(e, tacit);
 types::ty *t = start ? start->getType(bt, e, tacit) : bt;
 if (t->kind == ty_void && !tacit) {
   em.error(getPos());
   em << "cannot declare parameters of type void";
   return primError();
 }

 return t;
}

void formal::addOps(coenv &e, record *r) {
 base->addOps(e, r);
 if (start)
   start->addOps(base->trans(e, true), e, r);
}

void formals::prettyprint(ostream &out, Int indent)
{
 prettyname(out, "formals",indent, getPos());

 for (list<formal *>::iterator p = fields.begin(); p != fields.end(); ++p)
   (*p)->prettyprint(out, indent+1);
}

void formals::addToSignature(signature& sig,
                            coenv &e, bool encodeDefVal, bool tacit)
{
 for (list<formal *>::iterator p = fields.begin(); p != fields.end(); ++p) {
   formal& f=**p;
   types::formal tf = f.trans(e, encodeDefVal, tacit);

   if (f.isKeywordOnly())
     sig.addKeywordOnly(tf);
   else
     sig.add(tf);
 }

 if (rest) {
   if (!tacit && rest->getDefaultValue()) {
     em.error(rest->getPos());
     em << "rest parameters cannot have default values";
   }
   sig.addRest(rest->trans(e, encodeDefVal, tacit));
 }
}

// Returns the types of each parameter as a signature.
// encodeDefVal means that it will also encode information regarding
// the default values into the signature
signature *formals::getSignature(coenv &e, bool encodeDefVal, bool tacit)
{
 signature *sig = new signature;
 addToSignature(*sig,e,encodeDefVal,tacit);
 return sig;
}


// Returns the corresponding function type, assuming it has a return
// value of types::ty *result.
function *formals::getType(types::ty *result, coenv &e,
                          bool encodeDefVal,
                          bool tacit)
{
 function *ft = new function(result);
 addToSignature(ft->sig,e,encodeDefVal,tacit);
 return ft;
}

void formals::addOps(coenv &e, record *r)
{
 for(list<formal *>::iterator p = fields.begin(); p != fields.end(); ++p)
   (*p)->addOps(e, r);

 if (rest)
   rest->addOps(e, r);
}

mem::vector<tySymbolPair> *formals::getFields() {
 auto *lst = new mem::vector<tySymbolPair>();
 for (auto frml : fields) {
   lst->emplace_back(frml->getAbsyntaxType(), frml->getName());
 }
 return lst;
}

// Another helper class. Does an assignment, but relying only on the
// destination for the type.
class basicAssignExp : public exp {
 varEntry *dest;
 varinit *value;
public:
 basicAssignExp(position pos, varEntry *dest, varinit *value)
   : exp(pos), dest(dest), value(value) {}

 void prettyprint(ostream &out, Int indent) {
   prettyname(out, "basicAssignExp", indent, getPos());
 }

 types::ty *getType(coenv &) {
   return dest->getType();
 }

 types::ty *trans(coenv &e) {
   // This doesn't handle overloaded types for the destination.
   value->transToType(e, getType(e));
   dest->encode(WRITE, pos, e.c);
   return getType(e);
 }
};

void transDefault(coenv &e, position pos, varEntry *v, varinit *init) {
 // This roughly translates into the statement
 //   if (isDefault(x))
 //     x=init;
 // where x is the variable in v and isDefault is a function that tests
 // whether x is the default argument token.

 v->encode(READ, pos, e.c);

 label end = e.c.fwdLabel();
 e.c.useLabel(inst::jump_if_not_default, end);

 init->transToType(e, v->getType());
 v->encode(WRITE, pos, e.c);
 e.c.encodePop();

 e.c.defLabel(end);
}

void formal::transAsVar(coenv &e, Int index) {
 symbol name = getName();
 if (name) {
   trans::access *a = e.c.accessFormal(index);
   assert(a);

   // Suppress error messages because they will already be reported
   // when the formals are translated to yield the type earlier.
   types::ty *t = getType(e, true);
   varEntry *v = new varEntry(t, a, 0, getPos());

   // Translate the default argument before adding the formal to the
   // environment, consistent with the initializers of variables.
   if (defval)
     transDefault(e, getPos(), v, defval);

   e.e.addVar(name, v);
 }
}


void formals::trans(coenv &e)
{
 Int index = 0;

 for (list<formal *>::iterator p=fields.begin(); p!=fields.end(); ++p) {
   (*p)->transAsVar(e, index);
   ++index;
 }

 if (rest) {
   rest->transAsVar(e, index);
   ++index;
 }
}

void fundef::prettyprint(ostream &out, Int indent)
{
 result->prettyprint(out, indent+1);
 params->prettyprint(out, indent+1);
 body->prettyprint(out, indent+1);
}

function *fundef::transType(coenv &e, bool tacit) {
 bool encodeDefVal=true;
 return params->getType(result->trans(e, tacit), e, encodeDefVal, tacit);
}

function *fundef::transTypeAndAddOps(coenv &e, record *r, bool tacit) {
 result->addOps(e,r);
 params->addOps(e,r);

 function *ft=transType(e, tacit);
 // No function ops to add.

 return ft;
}

varinit *fundef::makeVarInit(function *ft) {
 struct initializer : public varinit {
   fundef *f;
   function *ft;

   initializer(fundef *f, function *ft)
     : varinit(f->getPos()), f(f), ft(ft) {}

   void prettyprint(ostream &out, Int indent) {
     prettyname(out, "initializer", indent, getPos());
   }

   void transToType(coenv &e, types::ty *target) {
     assert(ft==target);
     f->baseTrans(e, ft);
   }
 };

 return new initializer(this, ft);
}

void fundef::baseTrans(coenv &e, types::function *ft)
{
 string name = id ? string(id) : string("<anonymous function>");

 // Create a new function environment.
 coder fc = e.c.newFunction(getPos(), name, ft);
 coenv fe(fc,e.e);

 // Translate the function.
 fe.e.beginScope();
 params->trans(fe);

 body->trans(fe);

 types::ty *rt = ft->result;
 if (rt->kind != ty_void &&
     rt->kind != ty_error &&
     !body->returns()) {
   em.error(body->getPos());
   em << "function must return a value";
 }

 fe.e.endScope();

 // Put an instance of the new function on the stack.
 vm::lambda *l = fe.c.close();
 e.c.encode(inst::pushclosure);
 e.c.encode(inst::makefunc, l);
}

types::ty *fundef::trans(coenv &e) {
 // We must addOps for the return type and formals.  ex:
 //
 //   new guide[] (guide f(int)) {
 //     return sequence(f, 10);
 //   };
 function *ft=transTypeAndAddOps(e, (record *)0, false);
 assert(ft);

 baseTrans(e, ft);

 return ft;
}

void fundec::prettyprint(ostream &out, Int indent)
{
 prettyindent(out, indent);
 out << "fundec '" << id << "'\n";

 fun.prettyprint(out, indent);
}

void fundec::trans(coenv &e)
{
 transAsField(e,0);
}

void fundec::transAsField(coenv &e, record *r)
{
 function *ft = fun.transTypeAndAddOps(e, r, false);
 assert(ft);

 createVar(getPos(), e, r, id, ft, fun.makeVarInit(ft));
}



} // namespace absyntax

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