423f308350 2010-11-07        kinaba: module polemy.eval;
423f308350 2010-11-07        kinaba: import polemy._common;
423f308350 2010-11-07        kinaba: /*
423f308350 2010-11-07        kinaba:  * Author:  k.inaba
423f308350 2010-11-07        kinaba:  * License: NYSL 0.9982 (http://www.kmonos.net/nysl/
423f308350 2010-11-07        kinaba:  *   Evaluator for the polemy programming language
423f308350 2010-11-07        kinaba:  */
423f308350 2010-11-07        kinaba: import polemy.ast;
423f308350 2010-11-07        kinaba: import polemy.runtime;
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: Context eval(Program prog)
423f308350 2010-11-07        kinaba: {
423f308350 2010-11-07        kinaba: 	return eval(prog, new Context);
423f308350 2010-11-07        kinaba: }
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: Context eval(Program prog, Context ctx)
423f308350 2010-11-07        kinaba: {
423f308350 2010-11-07        kinaba: 	foreach(s; prog)
423f308350 2010-11-07        kinaba: 		ctx = eval(s, ctx);
423f308350 2010-11-07        kinaba: 	return ctx;
423f308350 2010-11-07        kinaba: }
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: Context eval(Statement _s, Context ctx)
423f308350 2010-11-07        kinaba: {
423f308350 2010-11-07        kinaba: 	if( auto s = cast(DeclStatement)_s )
423f308350 2010-11-07        kinaba: 	{
423f308350 2010-11-07        kinaba: 		auto v = eval(s.expr, ctx);
423f308350 2010-11-07        kinaba: 		ctx.add(s.var, v);
423f308350 2010-11-07        kinaba: 		return ctx;
423f308350 2010-11-07        kinaba: 	}
423f308350 2010-11-07        kinaba: 	else
423f308350 2010-11-07        kinaba: 	if( auto s = cast(ExprStatement)_s )
423f308350 2010-11-07        kinaba: 	{
423f308350 2010-11-07        kinaba: 		eval(s.expr, ctx);
423f308350 2010-11-07        kinaba: 		return ctx;
423f308350 2010-11-07        kinaba: 	}
423f308350 2010-11-07        kinaba: 	throw new PolemyRuntimeException(sprintf!"Unknown Kind of Statement %s at [%s]"(typeid(_s), _s.pos));
423f308350 2010-11-07        kinaba: }
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: Value eval(Expression _e, Context ctx)
423f308350 2010-11-07        kinaba: {
423f308350 2010-11-07        kinaba: 	if( auto e = cast(StrLiteralExpression)_e )
423f308350 2010-11-07        kinaba: 	{
423f308350 2010-11-07        kinaba: 		return new StrValue(e.data);
423f308350 2010-11-07        kinaba: 	}
423f308350 2010-11-07        kinaba: 	else
423f308350 2010-11-07        kinaba: 	if( auto e = cast(IntLiteralExpression)_e )
423f308350 2010-11-07        kinaba: 	{
423f308350 2010-11-07        kinaba: 		return new IntValue(e.data);
423f308350 2010-11-07        kinaba: 	}
423f308350 2010-11-07        kinaba: 	else
423f308350 2010-11-07        kinaba: 	if( auto e = cast(VarExpression)_e )
423f308350 2010-11-07        kinaba: 	{
423f308350 2010-11-07        kinaba: 		return ctx[e.var];
423f308350 2010-11-07        kinaba: 	}
423f308350 2010-11-07        kinaba: 	else
423f308350 2010-11-07        kinaba: 	if( auto e = cast(BinOpExpression)_e )
423f308350 2010-11-07        kinaba: 	{
423f308350 2010-11-07        kinaba: 		if( e.op == "=" )
423f308350 2010-11-07        kinaba: 		{
423f308350 2010-11-07        kinaba: 			if( auto ev = cast(VarExpression)e.lhs )
423f308350 2010-11-07        kinaba: 			{
423f308350 2010-11-07        kinaba: 				Value r = eval(e.rhs, ctx);
423f308350 2010-11-07        kinaba: 				ctx[ev.var] = r;
423f308350 2010-11-07        kinaba: 				return r;
423f308350 2010-11-07        kinaba: 			}
423f308350 2010-11-07        kinaba: 			throw new PolemyRuntimeException(sprintf!"Lhs of assignment must be a variable: %s"(e.pos));
423f308350 2010-11-07        kinaba: 		}
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: 		Value l = eval(e.lhs, ctx);
423f308350 2010-11-07        kinaba: 		Value r = eval(e.rhs, ctx);
423f308350 2010-11-07        kinaba: 		if( auto lv = cast(IntValue)l )
423f308350 2010-11-07        kinaba: 			if( auto rv = cast(IntValue)r )
423f308350 2010-11-07        kinaba: 				final switch(e.op)
423f308350 2010-11-07        kinaba: 				{
423f308350 2010-11-07        kinaba: 				case "+": return new IntValue(lv.data+rv.data);
423f308350 2010-11-07        kinaba: 				case "-": return new IntValue(lv.data-rv.data);
423f308350 2010-11-07        kinaba: 				case "*": return new IntValue(lv.data*rv.data);
423f308350 2010-11-07        kinaba: 				case "/": return new IntValue(lv.data/rv.data);
423f308350 2010-11-07        kinaba: 				}
423f308350 2010-11-07        kinaba: 			else
423f308350 2010-11-07        kinaba: 				throw new PolemyRuntimeException(sprintf!"rhs of %s must be an integer but was %s at [%s]"(e.op, typeid(r), e.rhs.pos));
423f308350 2010-11-07        kinaba: 		else
423f308350 2010-11-07        kinaba: 			throw new PolemyRuntimeException(sprintf!"lhs of %s must be an integer but was %s at [%s]"(e.op, typeid(l), e.lhs.pos));
423f308350 2010-11-07        kinaba: 	}
423f308350 2010-11-07        kinaba: 	throw new PolemyRuntimeException(sprintf!"Unknown Kind of Expression %s at [%s]"(typeid(_e), _e.pos));
423f308350 2010-11-07        kinaba: }
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: version(unittest) import polemy.parse;
423f308350 2010-11-07        kinaba: version(unittest) import std.stdio;
423f308350 2010-11-07        kinaba: version(unittest) import std.exception;
423f308350 2010-11-07        kinaba: unittest
423f308350 2010-11-07        kinaba: {
423f308350 2010-11-07        kinaba: 	auto parser = parserFromString(`var x = 21; x = x + x*x;`);
423f308350 2010-11-07        kinaba: 	auto prog = parser.parseProgram();
423f308350 2010-11-07        kinaba: 	auto ctx = eval(prog);
423f308350 2010-11-07        kinaba: 	assert( ctx["x"] == new IntValue(BigInt(21+21*21)) );
423f308350 2010-11-07        kinaba: 	assert( !collectException(ctx["x"]) );
423f308350 2010-11-07        kinaba: 	assert( collectException(ctx["y"]) );
423f308350 2010-11-07        kinaba: }
423f308350 2010-11-07        kinaba: unittest
423f308350 2010-11-07        kinaba: {
423f308350 2010-11-07        kinaba: 	auto parser = parserFromString(`var x = 21; x = x + x*y;`);
423f308350 2010-11-07        kinaba: 	auto prog = parser.parseProgram();
423f308350 2010-11-07        kinaba: 	assert( collectException(eval(prog)) );
423f308350 2010-11-07        kinaba: }
423f308350 2010-11-07        kinaba: unittest
423f308350 2010-11-07        kinaba: {
423f308350 2010-11-07        kinaba: 	auto parser = parserFromString(`var x = 21; y = x + x*x;`);
423f308350 2010-11-07        kinaba: 	auto prog = parser.parseProgram();
423f308350 2010-11-07        kinaba: 	assert( collectException(eval(prog)) );
423f308350 2010-11-07        kinaba: }