Experiment: Lazy evaluation of argument lists in evaluation context. Allows e.g. for loop variables to be dependent on each other

9 files changed, 151 insertions, 136 deletions

diff --git a/src/context.cc b/src/context.cc
index 706407c..ea48dad 100644
--- a/src/context.cc
+++ b/src/context.cc
@@ -66,9 +66,9 @@ void Context::setVariables(const AssignmentList &args,
 
 	if (evalctx) {
 		size_t posarg = 0;
-		for (size_t i=0; i<evalctx->eval_arguments.size(); i++) {
-			const std::string &name = evalctx->eval_arguments[i].first;
-			const Value &val = evalctx->eval_arguments[i].second;
+		for (size_t i=0; i<evalctx->numArgs(); i++) {
+			const std::string &name = evalctx->getArgName(i);
+			const Value &val = evalctx->getArgValue(i);
 			if (name.empty()) {
 				if (posarg < args.size()) this->set_variable(args[posarg++].first, val);
 			} else {
diff --git a/src/control.cc b/src/control.cc
index d47eec0..d45ee02 100644
--- a/src/control.cc
+++ b/src/control.cc
@@ -52,9 +52,9 @@ public:
 void for_eval(AbstractNode &node, const ModuleInstantiation &inst, size_t l, 
 							const Context *ctx, const EvalContext *evalctx)
 {
-	if (evalctx->eval_arguments.size() > l) {
-		const std::string &it_name = evalctx->eval_arguments[l].first;
-		const Value &it_values = evalctx->eval_arguments[l].second;
+	if (evalctx->numArgs() > l) {
+		const std::string &it_name = evalctx->getArgName(l);
+		const Value &it_values = evalctx->getArgValue(l, ctx);
 		Context c(ctx);
 		if (it_values.type() == Value::RANGE) {
 			Value::RangeType range = it_values.toRange();
@@ -93,9 +93,9 @@ AbstractNode *ControlModule::evaluate(const Context *ctx, const ModuleInstantiat
 	if (type == CHILD)
 	{
 		int n = 0;
-		if (evalctx->eval_arguments.size() > 0) {
+		if (evalctx->numArgs() > 0) {
 			double v;
-			if (evalctx->eval_arguments[0].second.getDouble(v)) {
+			if (evalctx->getArgValue(0).getDouble(v)) {
 				n = trunc(v);
 				if (n < 0) {
 					PRINTB("WARNING: Negative child index (%d) not allowed", n);
@@ -114,14 +114,14 @@ AbstractNode *ControlModule::evaluate(const Context *ctx, const ModuleInstantiat
         // assert(filectx->evalctx);
 
 				if (filectx->evalctx) {
-					if (n < filectx->evalctx->children.size()) {
-						node = filectx->evalctx->children[n]->evaluate_instance(filectx->evalctx);
+					if (n < filectx->evalctx->numChildren()) {
+						node = filectx->evalctx->getChild(n)->evaluate_instance(filectx->evalctx);
 					}
 					else {
 						// How to deal with negative objects in this case?
             // (e.g. first child of difference is invalid)
 						PRINTB("WARNING: Child index (%d) out of bounds (%d children)", 
-									 n % filectx->evalctx->children.size());
+									 n % filectx->evalctx->numChildren());
 					}
 				}
 				return node;
@@ -142,8 +142,8 @@ AbstractNode *ControlModule::evaluate(const Context *ctx, const ModuleInstantiat
 		msg << "ECHO: ";
 		for (size_t i = 0; i < inst->arguments.size(); i++) {
 			if (i > 0) msg << ", ";
-			if (!evalctx->eval_arguments[i].first.empty()) msg << evalctx->eval_arguments[i].first << " = ";
-			msg << evalctx->eval_arguments[i].second;
+			if (!evalctx->getArgName(i).empty()) msg << evalctx->getArgName(i) << " = ";
+			msg << evalctx->getArgValue(i);
 		}
 		PRINTB("%s", msg.str());
 	}
@@ -151,9 +151,9 @@ AbstractNode *ControlModule::evaluate(const Context *ctx, const ModuleInstantiat
 	if (type == ASSIGN)
 	{
 		Context c(evalctx);
-		for (size_t i = 0; i < evalctx->eval_arguments.size(); i++) {
-			if (!evalctx->eval_arguments[i].first.empty())
-				c.set_variable(evalctx->eval_arguments[i].first, evalctx->eval_arguments[i].second);
+		for (size_t i = 0; i < evalctx->numArgs(); i++) {
+			if (!evalctx->getArgName(i).empty())
+				c.set_variable(evalctx->getArgName(i), evalctx->getArgValue(i));
 		}
 		std::vector<AbstractNode *> evaluatednodes = inst->evaluateChildren(&c);
 		node->children.insert(node->children.end(), evaluatednodes.begin(), evaluatednodes.end());
@@ -167,7 +167,7 @@ AbstractNode *ControlModule::evaluate(const Context *ctx, const ModuleInstantiat
 	if (type == IF)
 	{
 		const IfElseModuleInstantiation *ifelse = dynamic_cast<const IfElseModuleInstantiation*>(inst);
-		if (evalctx->eval_arguments.size() > 0 && evalctx->eval_arguments[0].second.toBool()) {
+		if (evalctx->numArgs() > 0 && evalctx->getArgValue(0).toBool()) {
 			std::vector<AbstractNode *> evaluatednodes = ifelse->evaluateChildren(evalctx);
 			node->children.insert(node->children.end(), evaluatednodes.begin(), evaluatednodes.end());
 		}
diff --git a/src/dxfdim.cc b/src/dxfdim.cc
index fbc24c4..ecdae80 100644
--- a/src/dxfdim.cc
+++ b/src/dxfdim.cc
@@ -52,17 +52,17 @@ Value builtin_dxf_dim(const Context *ctx, const EvalContext *evalctx)
   // FIXME: We don't lookup the file relative to where this function was instantiated
 	// since the path is only available for ModuleInstantiations, not function expressions.
 	// See issue #217
-	for (size_t i = 0; i < evalctx->eval_arguments.size(); i++) {
-		if (evalctx->eval_arguments[i].first == "file")
-			filename = ctx->getAbsolutePath(evalctx->eval_arguments[i].second.toString());
-		if (evalctx->eval_arguments[i].first == "layer")
-			layername = evalctx->eval_arguments[i].second.toString();
-		if (evalctx->eval_arguments[i].first == "origin")
-			evalctx->eval_arguments[i].second.getVec2(xorigin, yorigin);
-		if (evalctx->eval_arguments[i].first == "scale")
-			evalctx->eval_arguments[i].second.getDouble(scale);
-		if (evalctx->eval_arguments[i].first == "name")
-			name = evalctx->eval_arguments[i].second.toString();
+	for (size_t i = 0; i < evalctx->numArgs(); i++) {
+		if (evalctx->getArgName(i) == "file")
+			filename = ctx->getAbsolutePath(evalctx->getArgValue(i).toString());
+		if (evalctx->getArgName(i) == "layer")
+			layername = evalctx->getArgValue(i).toString();
+		if (evalctx->getArgName(i) == "origin")
+			evalctx->getArgValue(i).getVec2(xorigin, yorigin);
+		if (evalctx->getArgName(i) == "scale")
+			evalctx->getArgValue(i).getDouble(scale);
+		if (evalctx->getArgName(i) == "name")
+			name = evalctx->getArgValue(i).toString();
 	}
 
 	std::stringstream keystream;
@@ -146,15 +146,15 @@ Value builtin_dxf_cross(const Context *ctx, const EvalContext *evalctx)
   // FIXME: We don't lookup the file relative to where this function was instantiated
 	// since the path is only available for ModuleInstantiations, not function expressions.
 	// See isse #217
-	for (size_t i = 0; i < evalctx->eval_arguments.size(); i++) {
-		if (evalctx->eval_arguments[i].first == "file")
-			filename = ctx->getAbsolutePath(evalctx->eval_arguments[i].second.toString());
-		if (evalctx->eval_arguments[i].first == "layer")
-			layername = evalctx->eval_arguments[i].second.toString();
-		if (evalctx->eval_arguments[i].first == "origin")
-			evalctx->eval_arguments[i].second.getVec2(xorigin, yorigin);
-		if (evalctx->eval_arguments[i].first == "scale")
-			evalctx->eval_arguments[i].second.getDouble(scale);
+	for (size_t i = 0; i < evalctx->numArgs(); i++) {
+		if (evalctx->getArgName(i) == "file")
+			filename = ctx->getAbsolutePath(evalctx->getArgValue(i).toString());
+		if (evalctx->getArgName(i) == "layer")
+			layername = evalctx->getArgValue(i).toString();
+		if (evalctx->getArgName(i) == "origin")
+			evalctx->getArgValue(i).getVec2(xorigin, yorigin);
+		if (evalctx->getArgName(i) == "scale")
+			evalctx->getArgValue(i).getDouble(scale);
 	}
 
 	std::stringstream keystream;
diff --git a/src/evalcontext.cc b/src/evalcontext.cc
index b7566e3..25b6716 100644
--- a/src/evalcontext.cc
+++ b/src/evalcontext.cc
@@ -7,6 +7,19 @@
 
 #include <boost/foreach.hpp>
 
+const std::string &EvalContext::getArgName(size_t i) const
+{
+	assert(i < this->eval_arguments.size());
+	return this->eval_arguments[i].first;
+}
+
+Value EvalContext::getArgValue(size_t i, const Context *ctx) const
+{
+	assert(i < this->eval_arguments.size());
+	const Assignment &arg = this->eval_arguments[i];
+	return arg.second ? arg.second->evaluate(ctx ? ctx : this) : Value();
+}
+
 #ifdef DEBUG
 void EvalContext::dump(const AbstractModule *mod, const ModuleInstantiation *inst)
 {
@@ -20,9 +33,9 @@ void EvalContext::dump(const AbstractModule *mod, const ModuleInstantiation *ins
 	for (int i=0;i<this->eval_arguments.size();i++) {
 		PRINTB("    %s = %s", this->eval_arguments[i].first % this->eval_arguments[i].second);
 	}
-	if (this->children.size() > 0) {
+	if (this->children && this->children->size() > 0) {
 		PRINT("    children:");
-		BOOST_FOREACH(const ModuleInstantiation *ch, this->children) {
+		BOOST_FOREACH(const ModuleInstantiation *ch, *this->children) {
 			PRINTB("      %s", ch->name());
 		}
 	}
diff --git a/src/evalcontext.h b/src/evalcontext.h
index 3d7d222..26a4a68 100644
--- a/src/evalcontext.h
+++ b/src/evalcontext.h
@@ -10,15 +10,28 @@
 class EvalContext : public Context
 {
 public:
-	EvalContext(const Context *parent = NULL) : Context(parent) {}
+	typedef std::vector<class ModuleInstantiation *> InstanceList;
+
+	EvalContext(const Context *parent, 
+							const AssignmentList &args, const InstanceList *const children = NULL)
+		: Context(parent), eval_arguments(args), children(children) {}
 	virtual ~EvalContext() {}
 
-	std::vector<std::pair<std::string, Value> > eval_arguments;
-	std::vector<class ModuleInstantiation *> children;
+	size_t numArgs() const { return this->eval_arguments.size(); }
+	const std::string &getArgName(size_t i) const;
+	Value getArgValue(size_t i, const Context *ctx = NULL) const;
+
+	size_t numChildren() const { return this->children ? this->children->size() : 0; }
+	ModuleInstantiation *getChild(size_t i) const { return this->children ? (*this->children)[i] : NULL; }
 
 #ifdef DEBUG
 	virtual void dump(const class AbstractModule *mod, const ModuleInstantiation *inst);
 #endif
+
+private:
+	const AssignmentList &eval_arguments;
+	std::vector<std::pair<std::string, Value> > eval_values;
+	const InstanceList *const children;
 };
 
 #endif
diff --git a/src/expr.cc b/src/expr.cc
index 7a8180f..6629bf5 100644
--- a/src/expr.cc
+++ b/src/expr.cc
@@ -127,11 +127,7 @@ Value Expression::evaluate(const Context *context) const
 		return Value();
 	}
 	if (this->type == "F") {
-		EvalContext c(context);
-		for (size_t i=0; i < this->call_arguments.size(); i++) {
-			c.eval_arguments.push_back(std::make_pair(this->call_arguments[i].first, 
-																								this->call_arguments[i].second->evaluate(context)));
-		}
+		EvalContext c(context, this->call_arguments);
 		// Value::VectorType argvalues;
 		// std::transform(this->children.begin(), this->children.end(), 
 		// 							 std::back_inserter(argvalues), 
diff --git a/src/func.cc b/src/func.cc
index 88bf3c8..4377a90 100644
--- a/src/func.cc
+++ b/src/func.cc
@@ -129,35 +129,35 @@ static inline double rad2deg(double x)
 
 Value builtin_abs(const Context *, const EvalContext *evalctx)
 {
-	if (evalctx->eval_arguments.size() == 1 && evalctx->eval_arguments[0].second.type() == Value::NUMBER)
-		return Value(fabs(evalctx->eval_arguments[0].second.toDouble()));
+	if (evalctx->numArgs() == 1 && evalctx->getArgValue(0).type() == Value::NUMBER)
+		return Value(fabs(evalctx->getArgValue(0).toDouble()));
 	return Value();
 }
 
 Value builtin_sign(const Context *, const EvalContext *evalctx)
 {
-	if (evalctx->eval_arguments.size() == 1 && evalctx->eval_arguments[0].second.type() == Value::NUMBER)
-		return Value((evalctx->eval_arguments[0].second.toDouble()<0) ? -1.0 : ((evalctx->eval_arguments[0].second.toDouble()>0) ? 1.0 : 0.0));
+	if (evalctx->numArgs() == 1 && evalctx->getArgValue(0).type() == Value::NUMBER)
+		return Value((evalctx->getArgValue(0).toDouble()<0) ? -1.0 : ((evalctx->getArgValue(0).toDouble()>0) ? 1.0 : 0.0));
 	return Value();
 }
 
 Value builtin_rands(const Context *, const EvalContext *evalctx)
 {
 	bool deterministic = false;
-	if (evalctx->eval_arguments.size() == 3 &&
-			evalctx->eval_arguments[0].second.type() == Value::NUMBER && 
-			evalctx->eval_arguments[1].second.type() == Value::NUMBER && 
-			evalctx->eval_arguments[2].second.type() == Value::NUMBER)
+	if (evalctx->numArgs() == 3 &&
+			evalctx->getArgValue(0).type() == Value::NUMBER && 
+			evalctx->getArgValue(1).type() == Value::NUMBER && 
+			evalctx->getArgValue(2).type() == Value::NUMBER)
 	{
 		deterministic = false;
 	}
-	else if (evalctx->eval_arguments.size() == 4 && 
-					 evalctx->eval_arguments[0].second.type() == Value::NUMBER && 
-					 evalctx->eval_arguments[1].second.type() == Value::NUMBER && 
-					 evalctx->eval_arguments[2].second.type() == Value::NUMBER && 
-					 evalctx->eval_arguments[3].second.type() == Value::NUMBER)
+	else if (evalctx->numArgs() == 4 && 
+					 evalctx->getArgValue(0).type() == Value::NUMBER && 
+					 evalctx->getArgValue(1).type() == Value::NUMBER && 
+					 evalctx->getArgValue(2).type() == Value::NUMBER && 
+					 evalctx->getArgValue(3).type() == Value::NUMBER)
 	{
-		deterministic_rng.seed( (unsigned int) evalctx->eval_arguments[3].second.toDouble() );
+		deterministic_rng.seed( (unsigned int) evalctx->getArgValue(3).toDouble() );
 		deterministic = true;
 	}
 	else
@@ -165,11 +165,11 @@ Value builtin_rands(const Context *, const EvalContext *evalctx)
 		return Value();
 	}
 	
-	double min = std::min( evalctx->eval_arguments[0].second.toDouble(), evalctx->eval_arguments[1].second.toDouble() );
-	double max = std::max( evalctx->eval_arguments[0].second.toDouble(), evalctx->eval_arguments[1].second.toDouble() );
+	double min = std::min( evalctx->getArgValue(0).toDouble(), evalctx->getArgValue(1).toDouble() );
+	double max = std::max( evalctx->getArgValue(0).toDouble(), evalctx->getArgValue(1).toDouble() );
 	boost::uniform_real<> distributor( min, max );
 	Value::VectorType vec;
-	for (int i=0; i<evalctx->eval_arguments[2].second.toDouble(); i++) {
+	for (int i=0; i<evalctx->getArgValue(2).toDouble(); i++) {
 		if ( deterministic ) {
 			vec.push_back( Value( distributor( deterministic_rng ) ) );
 		} else {
@@ -183,11 +183,11 @@ Value builtin_rands(const Context *, const EvalContext *evalctx)
 
 Value builtin_min(const Context *, const EvalContext *evalctx)
 {
-	if (evalctx->eval_arguments.size() >= 1 && evalctx->eval_arguments[0].second.type() == Value::NUMBER) {
-		double val = evalctx->eval_arguments[0].second.toDouble();
-		for (size_t i = 1; i < evalctx->eval_arguments.size(); i++)
-			if (evalctx->eval_arguments[1].second.type() == Value::NUMBER)
-				val = fmin(val, evalctx->eval_arguments[i].second.toDouble());
+	if (evalctx->numArgs() >= 1 && evalctx->getArgValue(0).type() == Value::NUMBER) {
+		double val = evalctx->getArgValue(0).toDouble();
+		for (size_t i = 1; i < evalctx->numArgs(); i++)
+			if (evalctx->getArgValue(1).type() == Value::NUMBER)
+				val = fmin(val, evalctx->getArgValue(i).toDouble());
 		return Value(val);
 	}
 	return Value();
@@ -195,11 +195,11 @@ Value builtin_min(const Context *, const EvalContext *evalctx)
 
 Value builtin_max(const Context *, const EvalContext *evalctx)
 {
-	if (evalctx->eval_arguments.size() >= 1 && evalctx->eval_arguments[0].second.type() == Value::NUMBER) {
-		double val = evalctx->eval_arguments[0].second.toDouble();
-		for (size_t i = 1; i < evalctx->eval_arguments.size(); i++)
-			if (evalctx->eval_arguments[1].second.type() == Value::NUMBER)
-				val = fmax(val, evalctx->eval_arguments[i].second.toDouble());
+	if (evalctx->numArgs() >= 1 && evalctx->getArgValue(0).type() == Value::NUMBER) {
+		double val = evalctx->getArgValue(0).toDouble();
+		for (size_t i = 1; i < evalctx->numArgs(); i++)
+			if (evalctx->getArgValue(1).type() == Value::NUMBER)
+				val = fmax(val, evalctx->getArgValue(i).toDouble());
 		return Value(val);
 	}
 	return Value();
@@ -207,117 +207,117 @@ Value builtin_max(const Context *, const EvalContext *evalctx)
 
 Value builtin_sin(const Context *, const EvalContext *evalctx)
 {
-	if (evalctx->eval_arguments.size() == 1 && evalctx->eval_arguments[0].second.type() == Value::NUMBER)
-		return Value(sin(deg2rad(evalctx->eval_arguments[0].second.toDouble())));
+	if (evalctx->numArgs() == 1 && evalctx->getArgValue(0).type() == Value::NUMBER)
+		return Value(sin(deg2rad(evalctx->getArgValue(0).toDouble())));
 	return Value();
 }
 
 Value builtin_cos(const Context *, const EvalContext *evalctx)
 {
-	if (evalctx->eval_arguments.size() == 1 && evalctx->eval_arguments[0].second.type() == Value::NUMBER)
-		return Value(cos(deg2rad(evalctx->eval_arguments[0].second.toDouble())));
+	if (evalctx->numArgs() == 1 && evalctx->getArgValue(0).type() == Value::NUMBER)
+		return Value(cos(deg2rad(evalctx->getArgValue(0).toDouble())));
 	return Value();
 }
 
 Value builtin_asin(const Context *, const EvalContext *evalctx)
 {
-	if (evalctx->eval_arguments.size() == 1 && evalctx->eval_arguments[0].second.type() == Value::NUMBER)
-		return Value(rad2deg(asin(evalctx->eval_arguments[0].second.toDouble())));
+	if (evalctx->numArgs() == 1 && evalctx->getArgValue(0).type() == Value::NUMBER)
+		return Value(rad2deg(asin(evalctx->getArgValue(0).toDouble())));
 	return Value();
 }
 
 Value builtin_acos(const Context *, const EvalContext *evalctx)
 {
-	if (evalctx->eval_arguments.size() == 1 && evalctx->eval_arguments[0].second.type() == Value::NUMBER)
-		return Value(rad2deg(acos(evalctx->eval_arguments[0].second.toDouble())));
+	if (evalctx->numArgs() == 1 && evalctx->getArgValue(0).type() == Value::NUMBER)
+		return Value(rad2deg(acos(evalctx->getArgValue(0).toDouble())));
 	return Value();
 }
 
 Value builtin_tan(const Context *, const EvalContext *evalctx)
 {
-	if (evalctx->eval_arguments.size() == 1 && evalctx->eval_arguments[0].second.type() == Value::NUMBER)
-		return Value(tan(deg2rad(evalctx->eval_arguments[0].second.toDouble())));
+	if (evalctx->numArgs() == 1 && evalctx->getArgValue(0).type() == Value::NUMBER)
+		return Value(tan(deg2rad(evalctx->getArgValue(0).toDouble())));
 	return Value();
 }
 
 Value builtin_atan(const Context *, const EvalContext *evalctx)
 {
-	if (evalctx->eval_arguments.size() == 1 && evalctx->eval_arguments[0].second.type() == Value::NUMBER)
-		return Value(rad2deg(atan(evalctx->eval_arguments[0].second.toDouble())));
+	if (evalctx->numArgs() == 1 && evalctx->getArgValue(0).type() == Value::NUMBER)
+		return Value(rad2deg(atan(evalctx->getArgValue(0).toDouble())));
 	return Value();
 }
 
 Value builtin_atan2(const Context *, const EvalContext *evalctx)
 {
-	if (evalctx->eval_arguments.size() == 2 && evalctx->eval_arguments[0].second.type() == Value::NUMBER && evalctx->eval_arguments[1].second.type() == Value::NUMBER)
-		return Value(rad2deg(atan2(evalctx->eval_arguments[0].second.toDouble(), evalctx->eval_arguments[1].second.toDouble())));
+	if (evalctx->numArgs() == 2 && evalctx->getArgValue(0).type() == Value::NUMBER && evalctx->getArgValue(1).type() == Value::NUMBER)
+		return Value(rad2deg(atan2(evalctx->getArgValue(0).toDouble(), evalctx->getArgValue(1).toDouble())));
 	return Value();
 }
 
 Value builtin_pow(const Context *, const EvalContext *evalctx)
 {
-	if (evalctx->eval_arguments.size() == 2 && evalctx->eval_arguments[0].second.type() == Value::NUMBER && evalctx->eval_arguments[1].second.type() == Value::NUMBER)
-		return Value(pow(evalctx->eval_arguments[0].second.toDouble(), evalctx->eval_arguments[1].second.toDouble()));
+	if (evalctx->numArgs() == 2 && evalctx->getArgValue(0).type() == Value::NUMBER && evalctx->getArgValue(1).type() == Value::NUMBER)
+		return Value(pow(evalctx->getArgValue(0).toDouble(), evalctx->getArgValue(1).toDouble()));
 	return Value();
 }
 
 Value builtin_round(const Context *, const EvalContext *evalctx)
 {
-	if (evalctx->eval_arguments.size() == 1 && evalctx->eval_arguments[0].second.type() == Value::NUMBER)
-		return Value(round(evalctx->eval_arguments[0].second.toDouble()));
+	if (evalctx->numArgs() == 1 && evalctx->getArgValue(0).type() == Value::NUMBER)
+		return Value(round(evalctx->getArgValue(0).toDouble()));
 	return Value();
 }
 
 Value builtin_ceil(const Context *, const EvalContext *evalctx)
 {
-	if (evalctx->eval_arguments.size() == 1 && evalctx->eval_arguments[0].second.type() == Value::NUMBER)
-		return Value(ceil(evalctx->eval_arguments[0].second.toDouble()));
+	if (evalctx->numArgs() == 1 && evalctx->getArgValue(0).type() == Value::NUMBER)
+		return Value(ceil(evalctx->getArgValue(0).toDouble()));
 	return Value();
 }
 
 Value builtin_floor(const Context *, const EvalContext *evalctx)
 {
-	if (evalctx->eval_arguments.size() == 1 && evalctx->eval_arguments[0].second.type() == Value::NUMBER)
-		return Value(floor(evalctx->eval_arguments[0].second.toDouble()));
+	if (evalctx->numArgs() == 1 && evalctx->getArgValue(0).type() == Value::NUMBER)
+		return Value(floor(evalctx->getArgValue(0).toDouble()));
 	return Value();
 }
 
 Value builtin_sqrt(const Context *, const EvalContext *evalctx)
 {
-	if (evalctx->eval_arguments.size() == 1 && evalctx->eval_arguments[0].second.type() == Value::NUMBER)
-		return Value(sqrt(evalctx->eval_arguments[0].second.toDouble()));
+	if (evalctx->numArgs() == 1 && evalctx->getArgValue(0).type() == Value::NUMBER)
+		return Value(sqrt(evalctx->getArgValue(0).toDouble()));
 	return Value();
 }
 
 Value builtin_exp(const Context *, const EvalContext *evalctx)
 {
-	if (evalctx->eval_arguments.size() == 1 && evalctx->eval_arguments[0].second.type() == Value::NUMBER)
-		return Value(exp(evalctx->eval_arguments[0].second.toDouble()));
+	if (evalctx->numArgs() == 1 && evalctx->getArgValue(0).type() == Value::NUMBER)
+		return Value(exp(evalctx->getArgValue(0).toDouble()));
 	return Value();
 }
 
 Value builtin_length(const Context *, const EvalContext *evalctx)
 {
-	if (evalctx->eval_arguments.size() == 1) {
-		if (evalctx->eval_arguments[0].second.type() == Value::VECTOR) return Value(int(evalctx->eval_arguments[0].second.toVector().size()));
-		if (evalctx->eval_arguments[0].second.type() == Value::STRING) return Value(int(evalctx->eval_arguments[0].second.toString().size()));
+	if (evalctx->numArgs() == 1) {
+		if (evalctx->getArgValue(0).type() == Value::VECTOR) return Value(int(evalctx->getArgValue(0).toVector().size()));
+		if (evalctx->getArgValue(0).type() == Value::STRING) return Value(int(evalctx->getArgValue(0).toString().size()));
 	}
 	return Value();
 }
 
 Value builtin_log(const Context *, const EvalContext *evalctx)
 {
-	if (evalctx->eval_arguments.size() == 2 && evalctx->eval_arguments[0].second.type() == Value::NUMBER && evalctx->eval_arguments[1].second.type() == Value::NUMBER)
-		return Value(log(evalctx->eval_arguments[1].second.toDouble()) / log(evalctx->eval_arguments[0].second.toDouble()));
-	if (evalctx->eval_arguments.size() == 1 && evalctx->eval_arguments[0].second.type() == Value::NUMBER)
-		return Value(log(evalctx->eval_arguments[0].second.toDouble()) / log(10.0));
+	if (evalctx->numArgs() == 2 && evalctx->getArgValue(0).type() == Value::NUMBER && evalctx->getArgValue(1).type() == Value::NUMBER)
+		return Value(log(evalctx->getArgValue(1).toDouble()) / log(evalctx->getArgValue(0).toDouble()));
+	if (evalctx->numArgs() == 1 && evalctx->getArgValue(0).type() == Value::NUMBER)
+		return Value(log(evalctx->getArgValue(0).toDouble()) / log(10.0));
 	return Value();
 }
 
 Value builtin_ln(const Context *, const EvalContext *evalctx)
 {
-	if (evalctx->eval_arguments.size() == 1 && evalctx->eval_arguments[0].second.type() == Value::NUMBER)
-		return Value(log(evalctx->eval_arguments[0].second.toDouble()));
+	if (evalctx->numArgs() == 1 && evalctx->getArgValue(0).type() == Value::NUMBER)
+		return Value(log(evalctx->getArgValue(0).toDouble()));
 	return Value();
 }
 
@@ -325,8 +325,8 @@ Value builtin_str(const Context *, const EvalContext *evalctx)
 {
 	std::stringstream stream;
 
-	for (size_t i = 0; i < evalctx->eval_arguments.size(); i++) {
-		stream << evalctx->eval_arguments[i].second.toString();
+	for (size_t i = 0; i < evalctx->numArgs(); i++) {
+		stream << evalctx->getArgValue(i).toString();
 	}
 	return Value(stream.str());
 }
@@ -334,16 +334,16 @@ Value builtin_str(const Context *, const EvalContext *evalctx)
 Value builtin_lookup(const Context *, const EvalContext *evalctx)
 {
 	double p, low_p, low_v, high_p, high_v;
-	if (evalctx->eval_arguments.size() < 2 ||                     // Needs two args
-			!evalctx->eval_arguments[0].second.getDouble(p) ||                  // First must be a number
-			evalctx->eval_arguments[1].second.toVector().size() < 2 ||       // Second must be a vector of vectors
-			evalctx->eval_arguments[1].second.toVector()[0].toVector().size() < 2)
+	if (evalctx->numArgs() < 2 ||                     // Needs two args
+			!evalctx->getArgValue(0).getDouble(p) ||                  // First must be a number
+			evalctx->getArgValue(1).toVector().size() < 2 ||       // Second must be a vector of vectors
+			evalctx->getArgValue(1).toVector()[0].toVector().size() < 2)
 		return Value();
-	if (!evalctx->eval_arguments[1].second.toVector()[0].getVec2(low_p, low_v) || !evalctx->eval_arguments[1].second.toVector()[0].getVec2(high_p, high_v))
+	if (!evalctx->getArgValue(1).toVector()[0].getVec2(low_p, low_v) || !evalctx->getArgValue(1).toVector()[0].getVec2(high_p, high_v))
 		return Value();
-	for (size_t i = 1; i < evalctx->eval_arguments[1].second.toVector().size(); i++) {
+	for (size_t i = 1; i < evalctx->getArgValue(1).toVector().size(); i++) {
 		double this_p, this_v;
-		if (evalctx->eval_arguments[1].second.toVector()[i].getVec2(this_p, this_v)) {
+		if (evalctx->getArgValue(1).toVector()[i].getVec2(this_p, this_v)) {
 			if (this_p <= p && (this_p > low_p || low_p > p)) {
 				low_p = this_p;
 				low_v = this_v;
@@ -406,12 +406,12 @@ Value builtin_lookup(const Context *, const EvalContext *evalctx)
 */
 Value builtin_search(const Context *, const EvalContext *evalctx)
 {
-	if (evalctx->eval_arguments.size() < 2) return Value();
+	if (evalctx->numArgs() < 2) return Value();
 
-	const Value &findThis = evalctx->eval_arguments[0].second;
-	const Value &searchTable = evalctx->eval_arguments[1].second;
-	unsigned int num_returns_per_match = (evalctx->eval_arguments.size() > 2) ? evalctx->eval_arguments[2].second.toDouble() : 1;
-	unsigned int index_col_num = (evalctx->eval_arguments.size() > 3) ? evalctx->eval_arguments[3].second.toDouble() : 0;
+	const Value &findThis = evalctx->getArgValue(0);
+	const Value &searchTable = evalctx->getArgValue(1);
+	unsigned int num_returns_per_match = (evalctx->numArgs() > 2) ? evalctx->getArgValue(2).toDouble() : 1;
+	unsigned int index_col_num = (evalctx->numArgs() > 3) ? evalctx->getArgValue(3).toDouble() : 0;
 
 	Value::VectorType returnvec;
 
@@ -512,7 +512,7 @@ Value builtin_version(const Context *, const EvalContext *evalctx)
 
 Value builtin_version_num(const Context *ctx, const EvalContext *evalctx)
 {
-	Value val = (evalctx->eval_arguments.size() == 0) ? builtin_version(ctx, evalctx) : evalctx->eval_arguments[0].second;
+	Value val = (evalctx->numArgs() == 0) ? builtin_version(ctx, evalctx) : evalctx->getArgValue(0);
 	double y, m, d = 0;
 	if (!val.getVec3(y, m, d)) {
 		if (!val.getVec2(y, m)) {
diff --git a/src/linearextrude.cc b/src/linearextrude.cc
index f4c1112..a3337e8 100644
--- a/src/linearextrude.cc
+++ b/src/linearextrude.cc
@@ -80,10 +80,10 @@ AbstractNode *LinearExtrudeModule::evaluate(const Context *ctx, const ModuleInst
 	// if height not given, and first argument is a number,
 	// then assume it should be the height.
 	if (c.lookup_variable("height").isUndefined() &&
-			evalctx->eval_arguments.size() > 0 && 
-			evalctx->eval_arguments[0].first == "" &&
-			evalctx->eval_arguments[0].second.type() == Value::NUMBER) {
-		height = Value(evalctx->eval_arguments[0].second);
+			evalctx->numArgs() > 0 && 
+			evalctx->getArgName(0) == "" &&
+			evalctx->getArgValue(0).type() == Value::NUMBER) {
+		height = evalctx->getArgValue(0);
 	}
 
 	node->layername = layer.isUndefined() ? "" : layer.toString();
diff --git a/src/module.cc b/src/module.cc
index 7d83975..3f6dd22 100644
--- a/src/module.cc
+++ b/src/module.cc
@@ -112,14 +112,7 @@ std::string ModuleInstantiation::dump(const std::string &indent) const
 
 AbstractNode *ModuleInstantiation::evaluate_instance(const Context *ctx) const
 {
-	EvalContext c(ctx);
-	BOOST_FOREACH(const Assignment &arg, this->arguments) {
-		c.eval_arguments.push_back(std::make_pair(arg.first,
-																							arg.second ? 
-																							arg.second->evaluate(ctx) : 
-																							Value()));
-	}
-	c.children = this->children;
+	EvalContext c(ctx, this->arguments, &this->children);
 
 #if 0 && DEBUG
 	PRINT("New eval ctx:");