Convert structure to _dub_ build system

6 files changed, 398 insertions, 0 deletions

diff --git a/source/app.d b/source/app.d
new file mode 100644
index 0000000..7d25f7f
--- /dev/null
+++ b/source/app.d
@@ -0,0 +1,57 @@
+import std.stdio;
+import std.string;
+import std.variant;
+
+import std.container.util : make;
+
+import base.stack;
+
+import definition = base.definition;
+import primitives = primitives.eval;
+
+Stack!Token resolve(Token token) {
+	try {
+		if ( primitives.evaluate(token) ) {
+			return primitives.result;
+		} else {
+			return token.visit!(
+				(int    value) => Stack!Token(Token(value)),
+				(bool   value) => Stack!Token(Token(value)),
+				(string word ) => definition.get(word)
+			);
+		}
+	}
+	catch (Exception ex) {
+		writeln("Error: ", ex.msg);
+		return Stack!Token();
+	}
+}
+
+void process(string value) {
+	auto buffer = make!(Stack!Token)(toToken(value));
+
+	do {
+		Token current = buffer.pop;
+
+		if ( !definition.handle(current) ) {
+			Stack!Token resolved = resolve(current);
+
+			if ( !resolved.empty ) {
+				if ( resolved.front == current ) {
+					stack.push(current);
+				} else {
+					buffer.insertFront(resolved[]);
+				}
+			}
+		}
+	}
+	while ( !buffer.empty );
+}
+
+void main() {
+	while ( !stdin.eof ) {
+		foreach ( token; stdin.readln.split ) {
+			process(token);
+		}
+	}
+}
diff --git a/source/base/definition.d b/source/base/definition.d
new file mode 100644
index 0000000..cf64f3e
--- /dev/null
+++ b/source/base/definition.d
@@ -0,0 +1,62 @@
+module base.definition;
+
+import std.string;
+import std.variant;
+import std.typecons;
+
+import std.container : DList;
+
+import base.stack;
+
+alias Words = Stack!Token[string];
+
+Nullable!(DList!Token) definition;
+Words                  words;
+
+void start() {
+	definition = DList!Token();
+}
+
+void end() {
+	string wordToBeDefined;
+
+	definition.front.visit!(
+		(int    value) => wordToBeDefined = "",
+		(bool   value) => wordToBeDefined = "",
+		(string name ) => wordToBeDefined = name
+	);
+
+	if ( wordToBeDefined == "" ) {
+		throw new Exception("words may not be numeric or boolean");
+	}
+
+	definition.removeFront;
+	words[wordToBeDefined] = Stack!Token(definition[]);
+	definition.nullify;
+}
+
+bool handle(Token token) {
+	if ( definition.isNull ) {
+		return false;
+	} else {
+		if ( token.type == typeid(string) ) {
+			if ( *token.peek!string == ";" ) {
+				end;
+			} else {
+				definition.insertBack(token);
+			}
+		} else {
+			definition.insertBack(token);
+		}
+
+		return true;
+	}
+}
+
+Stack!Token get(string word) {
+	if ( word in words ) {
+		return words[word].dup;
+	} else {
+		return Stack!Token(Token(word));
+	}
+}
diff --git a/source/base/stack.d b/source/base/stack.d
new file mode 100644
index 0000000..253bac0
--- /dev/null
+++ b/source/base/stack.d
@@ -0,0 +1,48 @@
+module base.stack;
+
+import std.conv;
+import std.string;
+import std.variant;
+import std.container : SList;
+
+import definition = base.definition;
+
+alias Token = Algebraic!(int, bool, string);
+alias Stack = SList;
+
+Stack!Token stack;
+
+Token toToken(string value) {
+	if ( value.isNumeric ) {
+		return Token(parse!int(value));
+	} else {
+		return Token(value);
+	}
+}
+
+Token top(ref Stack!Token stack) {
+	if ( stack.empty ) {
+		throw new Exception("stack is empty");
+	} else {
+		return stack.front;
+	}
+}
+
+Token pop(ref Stack!Token stack) {
+	Token token = stack.top;
+	stack.removeFront;
+	return token;
+}
+
+void push(ref Stack!Token stack, Token token) {
+	if ( !definition.handle(token) ) {
+		stack.insertFront(token);
+	}
+}
+
+template push(T)
+if ( is(T == int) || is(T == bool) || is (T == string) ) {
+	void push(ref Stack!Token stack, T value) {
+		stack.push(Token(value));
+	}
+}
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();
+	}
+}