Convert structure to _dub_ build system

3 files changed, 231 insertions, 0 deletions

diff --git a/source/primitives/conditional.d b/source/primitives/conditional.d
new file mode 100644
index 0000000..678f516
--- /dev/null
+++ b/source/primitives/conditional.d
@@ -0,0 +1,77 @@
+module primitives.conditional;
+
+import std.variant;
+import std.typecons;
+import std.container : DList;
+
+import base.stack;
+
+Nullable!(DList!Token) buffer;
+bool                   concluded = true;
+bool                   drop_mode = false;
+
+void capture(Token token) {
+	if ( !drop_mode ) {
+		buffer.insertBack(token);
+	}
+}
+
+bool drop(Token token) {
+	if ( concluded && buffer.isNull ) {
+		return false;
+	}
+
+	if ( token.type == typeid(string) ) {
+		switch ( *token.peek!string ) {
+			case "if"   : eval_if;        break;
+			case "then" : eval_then;      break;
+			case "else" : eval_else;      break;
+			default     : capture(token); break; 
+		}
+	} else {
+		capture(token);
+	}
+
+	return true;
+}
+
+void eval_if() {
+	if ( concluded ) {
+		buffer    = DList!Token();
+		drop_mode = !stack.pop.get!bool;
+		concluded = false;
+	} else {
+		throw new Exception("conditionals may not be nested directly");
+	}
+}
+
+void eval_then() {
+	if ( concluded  ) {
+		throw new Exception("`then` without preceding `if`");
+	} else {
+		drop_mode = !drop_mode;
+	}
+}
+
+void eval_else() {
+	if ( concluded ) {
+		throw new Exception("`else` without preceding `if`");	
+	} else {
+		drop_mode = false;
+		concluded = true;
+	}
+}
+
+bool dischargeable() {
+	return concluded && !buffer.isNull;
+}
+
+Stack!Token discharge() {
+	if ( concluded ) {
+		Stack!Token result = buffer[];
+		buffer.nullify;
+		return result;
+	} else {
+		throw new Exception("unconcluded conditional may not be discharged");	
+	}
+}
diff --git a/source/primitives/core.d b/source/primitives/core.d
new file mode 100644
index 0000000..45bbeac
--- /dev/null
+++ b/source/primitives/core.d
@@ -0,0 +1,101 @@
+module primitives.core;
+
+import std.stdio;
+
+import base.stack;
+import definition = base.definition;
+
+Token[string] variables;
+
+void definition_start() {
+	definition.start;
+}
+
+void binary_op_variable_bind() {
+	string name     = stack.pop.get!string;
+	Token  value    = stack.pop;
+	variables[name] = value;
+}
+
+void unary_op_variable_resolve() {
+	string name = stack.pop.get!string;
+
+	if ( name in variables ) {
+		stack.push(variables[name]);
+	}
+}
+
+void binary_op_add() {
+	int b = stack.pop.get!int;
+	int a = stack.pop.get!int;
+
+	stack.push(a + b);
+}
+
+void binary_op_multiply() {
+	int b = stack.pop.get!int;
+	int a = stack.pop.get!int;
+
+	stack.push(a * b);
+}
+
+void binary_op_divide() {
+	int b = stack.pop.get!int;
+	int a = stack.pop.get!int;
+
+	if ( b == 0 ) {
+		throw new Exception("division by 0 undefined");
+	} else {
+		stack.push(a / b);
+	}
+}
+
+void binary_op_modulo() {
+	int b = stack.pop.get!int;
+	int a = stack.pop.get!int;
+
+	if ( b == 0 ) {
+		throw new Exception("modulo 0 undefined");
+	} else {
+		stack.push(a % b);
+	}
+}
+
+void unary_op_io_print() {
+	writeln(stack.top);
+}
+
+void unary_op_stack_pop() {
+	stack.pop;
+}
+
+void unary_op_stack_dup() {
+	stack.push(stack.top);
+}
+
+void binary_op_stack_swp() {
+	auto b = stack.pop;
+	auto a = stack.pop;
+
+	stack.push(b);
+	stack.push(a);
+
+}
+
+void binary_cond_lt() {
+	int b = stack.pop.get!int;
+	int a = stack.pop.get!int;
+
+	stack.push(a < b);
+}
+
+void binary_cond_eq() {
+	auto b = stack.pop;
+	auto a = stack.pop;
+
+	stack.push(a == b);
+}
+
+void integral_value_bool(bool value) {
+	stack.push(Token(value));
+}
diff --git a/source/primitives/eval.d b/source/primitives/eval.d
new file mode 100644
index 0000000..0ddd65a
--- /dev/null
+++ b/source/primitives/eval.d
@@ -0,0 +1,53 @@
+module primitives.eval;
+
+import std.variant;
+
+import base.stack;
+import primitives.core;
+import conditional = primitives.conditional;
+
+bool evaluate_primitive(string word) {
+	switch ( word ) {
+		case     "§"     : definition_start;           break;
+		case     "$"     : binary_op_variable_bind;    break;
+		case     "@"     : unary_op_variable_resolve;  break;
+		case     "if"    : conditional.eval_if;        break;
+		case     "then"  : conditional.eval_then;      break;
+		case     "else"  : conditional.eval_else;      break;
+		case     "+"     : binary_op_add;              break;
+		case     "*"     : binary_op_multiply;         break;
+		case     "/"     : binary_op_divide;           break;
+		case     "%"     : binary_op_modulo;           break;
+		case     "."     : unary_op_io_print;          break;
+		case     "pop"   : unary_op_stack_pop;         break;
+		case     "dup"   : unary_op_stack_dup;         break;
+		case     "swp"   : binary_op_stack_swp;        break;
+		case     "true"  : integral_value_bool(true);  break;
+		case     "false" : integral_value_bool(false); break;
+		case     "<"     : binary_cond_lt;             break;
+		case     "="     : binary_cond_eq;             break;
+		default          : return false;
+	}
+
+	return true;
+}
+
+bool evaluate(Token token) {
+	if ( conditional.drop(token) ) {
+		return true;
+	} else {
+		return token.visit!(
+			(int    value) => false,
+			(bool   value) => false,
+			(string word ) => evaluate_primitive(word)
+		);
+	}
+}
+
+Stack!Token result() {
+	if ( conditional.dischargeable ) {
+		return conditional.discharge;
+	} else {
+		return Stack!Token();
+	}
+}