/**
* Authors: k.inaba
* License: NYSL 0.9982 http://www.kmonos.net/nysl/
*
* Evaluator for Polemy programming language.
*/
module polemy.eval;
import polemy._common;
import polemy.failure;
import polemy.ast;
import polemy.parse;
import polemy.value;
import polemy.layer;
import polemy.value;
import polemy.valueconv;
/// Objects for maitaining global environment and evaluation of expression on it
class Evaluator
{
public:
/// Initialize evaluator with empty context
this() { theContext = new Table; }
/// Evaluate the AST
Value evalAST(AST e)
{
return macroAndEval(e, ValueLayer, theContext, OverwriteCtx)[0];
}
/// Evaluate the string
Value evalString(S,T...)(S str, T fn_ln_cn)
{
return evalAST(parseString(str,fn_ln_cn));
}
/// Evaluate the file
Value evalFile(S,T...)(S filename, T ln_cn)
{
return evalAST(parseFile(filename,ln_cn));
}
/// Get the global context
Table globalContext()
{
return theContext;
}
private:
Table theContext;
enum : bool { CascadeCtx=false, OverwriteCtx=true };
Value eval( AST e, Layer lay, Table ctx, bool overwriteCtx=CascadeCtx )
{
// dynamic-overload-resolution-pattern: modify here
enum funName = "eval";
alias TypeTuple!(e,lay,ctx,overwriteCtx) params;
// dynamic-overload-resolution-pattern: dispatch
alias typeof(__traits(getOverloads, this, funName)) ovTypes;
alias staticMap!(firstParam, ovTypes) fstTypes;
alias DerivedToFront!(fstTypes) fstTypes_sorted;
foreach(i, T; fstTypes_sorted)
static if( is(T == typeof(params[0])) ) {} else if( auto _x = cast(T)params[0] )
return __traits(getOverloads, this, funName)[i](_x, params[1..$]);
// dynamic-overload-resolution-pattern: default behavior
assert(false, text("eval() for ",typeid(e)," [",e.pos,"] is not defined"));
}
Value eval( Str e, Layer lay, Table ctx, bool overwriteCtx=CascadeCtx )
{
if( isASTLayer(lay) )
return ast2table(e, (AST e){return eval(e,lay,ctx);});
if( isUserDefinedLayer(lay) )
return lift(new StrValue(e.data), lay, ctx, e.pos);
return new StrValue(e.data);
}
Value eval( Int e, Layer lay, Table ctx, bool overwriteCtx=CascadeCtx )
{
if( isASTLayer(lay) )
return ast2table(e, (AST e){return eval(e,lay,ctx);});
if( isUserDefinedLayer(lay) )
return lift(new IntValue(e.data), lay, ctx, e.pos);
return new IntValue(e.data);
}
Value eval( Var e, Layer lay, Table ctx, bool overwriteCtx=CascadeCtx )
{
if( isASTLayer(lay) )
if( isMacroLayer(lay) && ctx.has(e.name,MacroLayer) )
return ctx.get(e.name, MacroLayer, e.pos);
else
return ast2table(e, (AST e){return eval(e,lay,ctx);});
if( isUserDefinedLayer(lay) && !ctx.has(e.name, lay) )
return lift(ctx.get(e.name, ValueLayer, e.pos), lay, ctx, e.pos);
return ctx.get(e.name, lay, e.pos);
}
Value eval( App e, Layer lay, Table ctx, bool overwriteCtx=CascadeCtx )
{
Value f = eval( e.fun, lay, ctx );
if( isASTLayer(lay) ) {
auto ff = cast(FunValue)f;
if( ff !is null && isMacroLayer(lay) )
return invokeFunction(ff, e.args, lay, ctx, e.pos, getNameIfPossible(e.fun));
else
return ast2table(e, (AST e){return eval(e,lay,ctx);});
}
return invokeFunction(f, e.args, lay, ctx, e.pos, getNameIfPossible(e.fun));
}
Value eval( Fun e, Layer lay, Table ctx, bool overwriteCtx=CascadeCtx )
{
if( isASTLayer(lay) )
{
// need this for correct scoping (outer scope macro variables must be hidden!)
Table newCtx = new Table(ctx, Table.Kind.NotPropagateSet);
foreach(p; e.params)
newCtx.set(p.name, ValueLayer, new UndefinedValue);
return ast2table(e, (AST e){return eval(e,lay,newCtx);});
}
else
return createNewFunction(e, ctx);
}
Value eval( Lay e, Layer lay, Table ctx, bool overwriteCtx=CascadeCtx )
{
if( isNoLayerChangeLayer(lay) )
return ast2table(e, (AST e){return eval(e,lay,ctx);});
else
return eval(e.expr, e.layer, ctx);
}
Value eval( Let e, Layer lay, Table ctx, bool overwriteCtx=CascadeCtx )
{
Table newCtx = overwriteCtx ? ctx : new Table(ctx, Table.Kind.NotPropagateSet);
if( isASTLayer(lay) )
return ast2table(e, (AST ee){
// need this for correct scoping (outer scope macro variables must be hidden!)
if(ee is e.expr)
newCtx.set(e.name, ValueLayer, new UndefinedValue);
return eval(ee,lay,newCtx);
});
else
{
Value ri = eval(e.init, lay, newCtx);
newCtx.set(e.name, e.layer.empty ? lay : e.layer, ri);
return eval(e.expr, lay, newCtx, OverwriteCtx);
}
}
private:
// little little bit incremental macro defining version.
// enables @macro foo(x)=... in ... foo ..., only at the top level of the
// interpreter and functions. better than nothing :P
Tuple!(Value,AST) macroAndEval( AST e_, Layer lay, Table ctx, bool overwriteCtx=CascadeCtx )
{
assert( !isASTLayer(lay) );
AST decodeAST(Value v, LexPosition pos)
{
// [TODO] more informative error message
return polemy2d!(AST)(v, pos);
}
if(auto e = cast(Let)e_)
{
AST ai = decodeAST(eval(e.init, RawMacroLayer, ctx), e.init.pos);
Value vi = eval(ai, lay, ctx);
if( !overwriteCtx )
ctx = new Table(ctx, Table.Kind.NotPropagateSet);
string theLayer = e.layer.empty ? lay : e.layer;
ctx.set(e.name, theLayer, vi);
auto ave = macroAndEval( e.expr, lay, ctx, OverwriteCtx );
AST a = new Let(e.pos, e.name, e.layer, ai, ave[1]);
return tuple(ave[0], a);
}
else
{
AST a = decodeAST(eval(e_, RawMacroLayer, ctx), e_.pos);
Value v = eval(a, lay, ctx);
return tuple(v, a);
}
}
private:
string getNameIfPossible(AST e)
{
if(auto v = cast(Var)e)
return v.name;
return "";
}
Value invokeFunction(Value _f, AST[] args, Layer lay, Table ctx, LexPosition pos, string callstackmsg)
{
if(auto f = cast(FunValue)_f)
{
Table newCtx = new Table(f.definitionContext(), Table.Kind.NotPropagateSet);
foreach(i,p; f.params())
if( p.layers.empty )
newCtx.set(p.name, isMacroLayer(lay)?MacroLayer:lay, eval(args[i], lay, ctx));
else
foreach(argLay; p.layers)
newCtx.set(p.name, argLay, eval(args[i], argLay, ctx));
scope _ = new PushCallStack(pos, callstackmsg);
return f.invoke(isMacroLayer(lay)?MacroLayer:lay, newCtx, pos);
}
throw genex!RuntimeException(pos, text("tried to call non-function: ",_f));
}
Value lift(Value v, Layer lay, Table ctx, LexPosition pos)
{
assert( !isASTLayer(lay), "lift to the @macro layer should never happen" );
// functions are automatically lifterd
if( cast(FunValue) v )
return v;
if( !ctx.has(lay, SystemLayer) )
throw genex!RuntimeException(pos, "lift function for "~lay~" is not registered" );
// similar to invokeFunction, but with only one argument bound to ValueLayer
auto _f = ctx.get(lay, SystemLayer, pos);
if(auto f = cast(FunValue)_f)
{
Table newCtx = new Table(f.definitionContext(), Table.Kind.NotPropagateSet);
auto ps = f.params();
if( ps.length != 1 )
throw genex!RuntimeException(pos,
text("lift function for", lay, " must take exactly one argument of ", ValueLayer));
if( ps[0].layers.length==0 || ps[0].layers.length==1 && ps[0].layers[0]==ValueLayer )
{
newCtx.set(ps[0].name, ValueLayer, v);
scope _ = new PushCallStack(pos, lay);
return f.invoke(ValueLayer, newCtx, pos);
}
else
throw genex!RuntimeException(pos,
text("lift function for", lay, " must take exactly one argument of ", ValueLayer));
}
throw genex!RuntimeException(pos,
text("non-function ", _f, " is registered as the lift function for ", lay));
}
Value createNewFunction(Fun e, Table ctx)
{
class UserDefinedFunValue : FunValue
{
Fun ast;
Table defCtx;
override const(Parameter[]) params() { return ast.params; }
override Table definitionContext() { return defCtx; }
this(Fun ast, Table defCtx) { this.ast=ast; this.defCtx=defCtx; }
override string toString() const
{ return sprintf!"(function:%x:%x)"(cast(void*)ast, cast(void*)defCtx); }
override int opCmp(Object rhs) {
if(auto r = cast(UserDefinedFunValue)rhs) {
auto a = cast(void*)this.ast;
auto b = cast(void*)r.ast;
if(a<b) return -1;
if(a>b) return +1; // [TODO] avoid using pointer value...
return this.defCtx.opCmp(r.defCtx);
}
if(auto r = cast(Value)rhs) return typeid(this).opCmp(typeid(r));
throw genex!RuntimeException("comparison with value and something other");
}
mixin SimpleToHash;
AST afterMacroAST;
override Value invoke(Layer lay, Table ctx, LexPosition pos)
{
if( isASTLayer(lay) )
return eval(ast.funbody, lay, ctx);
if( afterMacroAST is null )
{
auto va = macroAndEval(e.funbody, lay, ctx);
afterMacroAST = va[1];
return va[0];
}
else
return eval(afterMacroAST, lay, ctx);
}
}
return new UserDefinedFunValue(e,ctx);
}
public:
/// Add primitive function to the global context
void addPrimitive(R,T...)(string name, Layer defLay, R delegate (T) dg)
{
class NativeFunValue : FunValue
{
override const(Parameter[]) params() { return params_data; }
override Table definitionContext() { return theContext; }
override string toString() { return sprintf!"(native:%x)"(dg.funcptr); }
override int opCmp(Object rhs) {
if(auto r = cast(NativeFunValue)rhs) return typeid(typeof(dg)).compare(&dg,&r.dg);
if(auto r = cast(Value)rhs) return typeid(this).opCmp(typeid(r));
throw genex!RuntimeException("comparison with value and something other");
}
mixin SimpleToHash;
R delegate(T) dg;
Parameter[] params_data;
this(R delegate(T) dg)
{
this.dg = dg;
foreach(i, Ti; T)
params_data ~= new Parameter(text(i), []);
}
override Value invoke(Layer lay, Table ctx, LexPosition pos)
{
if( lay != defLay )
throw genex!RuntimeException(pos,
text("only ", defLay, " layer can call native function: ", name));
T typed_args;
foreach(i, Ti; T) {
typed_args[i] = cast(Ti) ctx.get(text(i), ValueLayer, pos);
if( typed_args[i] is null )
throw genex!RuntimeException(pos,
sprintf!"type mismatch on the argument %d of native function: %s"(i+1,name));
}
try {
return dg(typed_args);
} catch( RuntimeException e ) {
throw e.pos is null ? new RuntimeException(pos, e.msg, e.file, e.line) : e;
}
}
}
theContext.set(name, defLay, new NativeFunValue(dg));
}
}
version(unittest) import polemy.runtime;
unittest
{
auto e = new Evaluator;
enrollRuntimeLibrary(e);
auto r = assert_nothrow( e.evalString(`var x = 21; x + x*x;`) );
assert_eq( r, new IntValue(BigInt(21+21*21)) );
assert_eq( e.globalContext.get("x",ValueLayer), new IntValue(BigInt(21)) );
assert_nothrow( e.globalContext.get("x",ValueLayer) );
assert_throw!RuntimeException( e.globalContext.get("y",ValueLayer) );
}
unittest
{
auto e = new Evaluator;
enrollRuntimeLibrary(e);
auto r = assert_nothrow( e.evalString(`var x = 21; var x = x + x*x;`) );
assert_eq( r, new IntValue(BigInt(21+21*21)) );
assert_eq( e.globalContext.get("x",ValueLayer), new IntValue(21+21*21) );
assert_nothrow( e.globalContext.get("x",ValueLayer) );
assert_throw!RuntimeException( e.globalContext.get("y",ValueLayer) );
}
unittest
{
auto e = new Evaluator;
enrollRuntimeLibrary(e);
assert_eq( e.evalString(`let x=1; let y=(let x=2); x`), new IntValue(1) );
assert_eq( e.evalString(`let x=1; let y=(let x=2;fun(){x}); y()`), new IntValue(2) );
}
unittest
{
auto e = new Evaluator;
enrollRuntimeLibrary(e);
assert_eq( e.evalString(`@a x=1; @b x=2; @a(x)`), new IntValue(BigInt(1)) );
assert_eq( e.evalString(`@a x=1; @b x=2; @b(x)`), new IntValue(BigInt(2)) );
assert_eq( e.evalString(`let x=1; let _ = (@a x=2;2); x`), new IntValue(BigInt(1)) );
e = new Evaluator;
assert_throw!Throwable( e.evalString(`let x=1; let _ = (@a x=2;2); @a(x)`) );
}
unittest
{
auto e = new Evaluator;
enrollRuntimeLibrary(e);
assert_eq( e.evalString(`
@@s(x){x};
@s "+" = fun(x, y) {@value(
@s(x) - @s(y)
)};
@s(1 + 2)
`), new IntValue(BigInt(-1)) );
}
unittest
{
auto e = new Evaluator;
enrollRuntimeLibrary(e);
assert_eq( e.evalString(`
@@3(x){x};
def incr(x) { x+1 };
@ 3 incr(x) {@value( if @ 3(x)+1< 3 then @3(x)+1 else 0 )};
def fb(n @value @3) { @3(n) };
fb(incr(incr(incr(0))))
`), new IntValue(BigInt(0)) );
}
unittest
{
auto e = new Evaluator;
enrollRuntimeLibrary(e);
assert_nothrow( e.evalString(`
@macro twice(x) { x; x };
def main() { twice(1) };
main()
`) );
}
/*
unittest
{
assert_eq( evalString(`var fac = fun(x){
if(x)
{ x*fac(x-1); }
else
{ 1; };
};
fac(10);`).val, new IntValue(BigInt(10*9*8*5040)));
assert_eq( evalString(`var fib = fun(x){
if(x<2)
{ 1; }
else
{ fib(x-1) + fib(x-2); };
};
fib(5);`).val, new IntValue(BigInt(8)));
}
unittest
{
assert_eq( evalString(`@@t = fun(x){x+1}; @t(123)`).val, new IntValue(BigInt(124)) );
// there was a bug that declaration in the first line of function definition
// cannot be recursive
assert_nothrow( evalString(`def foo() {
def bar(y) { if(y<1) {0} else {bar(0)} };
bar(1)
}; foo()`) );
}
*/