feat!: Add basic lexer components

4 files changed, 123 insertions, 0 deletions

diff --git a/src/StringConsumer/ConsumerList.cl b/src/StringConsumer/ConsumerList.cl
new file mode 100644
index 0000000..526996c
--- /dev/null
+++ b/src/StringConsumer/ConsumerList.cl
@@ -0,0 +1,52 @@
+class ConsumerList inherits System {
+	item: IStringConsumer;
+	next: ConsumerList;
+
+	init(value: IStringConsumer, tail: Object) : ConsumerList {{
+		assert(not (isvoid value), "init", "value argument cannot be void!");
+		assert(isvoid item, "init", "List has already been initialised!");
+
+		item <- value;
+		if isvoid tail then
+			void
+		else
+			case tail of
+				cl: ConsumerList => next <- cl;
+				o: Object => assert(false, "init", "tail argument can be either a ConsumerList or void!");
+			esac
+		fi;
+
+		self;
+	}};
+
+	push(value: IStringConsumer) : ConsumerList {{
+		assert(not (isvoid value), "push", "value argument cannot be void!");
+
+		if isvoid item
+		then
+			item <- value
+		else if isvoid next
+		then
+			next <- (new ConsumerList).init(value, void)
+		else
+			next.push(value)
+		fi
+		fi;
+		self;
+	}};
+
+	find(s: String) : Object {{
+		assert(not (isvoid item), "find", "list isn't initialised!");
+
+		if 0 < item.consume(s)
+		then
+			item
+		else if isvoid next
+		then
+			void
+		else
+			next.find(s)
+		fi
+		fi;
+	}};
+};
diff --git a/src/StringConsumer/IStringConsumer.cl b/src/StringConsumer/IStringConsumer.cl
new file mode 100644
index 0000000..20a4f3a
--- /dev/null
+++ b/src/StringConsumer/IStringConsumer.cl
@@ -0,0 +1,20 @@
+class IStringConsumer inherits System {
+	consume(s: String) : Int {
+		not_implemented_retint("consume")
+	};
+
+	token() : IToken {{
+		not_implemented("token");
+		new IToken;
+	}};
+
+	out() : Object {
+		not_implemented("out")
+	};
+
+---
+	consumed_length: Int;
+	consumed_length() : Int {
+		consumed_length
+	};
+};
diff --git a/src/StringConsumer/StringConsumerEngine.cl b/src/StringConsumer/StringConsumerEngine.cl
new file mode 100644
index 0000000..dc7e202
--- /dev/null
+++ b/src/StringConsumer/StringConsumerEngine.cl
@@ -0,0 +1,36 @@
+class StringConsumerEngine inherits System {
+	consumers: ConsumerList <- (new ConsumerList)
+		.push(new WhitespaceConsumer)
+		;
+
+	str: String;
+
+	init(code: String) : Object {{
+		assert(not (code = ""), "init", "input code cannot be empty!");
+		assert(str = "", "init", "already initialised!");
+
+		str <- code;
+	}};
+
+	try_consume() : Bool {
+		let
+			consumer: Object <- consumers.find(str)
+		in
+			if isvoid consumer
+			then
+				false
+			else
+				case consumers.find(str) of
+					c: IStringConsumer => {
+						str <- str.substr(c.consumed_length(), str.length() - c.consumed_length());
+						true;
+					};
+					o: Object => false;
+				esac
+			fi
+	};
+
+	out() : Object {
+		out_string(str)
+	};
+};
diff --git a/src/StringConsumer/WhitespaceConsumer.cl b/src/StringConsumer/WhitespaceConsumer.cl
new file mode 100644
index 0000000..4c0b8b5
--- /dev/null
+++ b/src/StringConsumer/WhitespaceConsumer.cl
@@ -0,0 +1,15 @@
+class WhitespaceConsumer inherits IStringConsumer {
+	consume(s: String) : Int {{
+		consumed_length <- 0;
+		while or(s.substr(consumed_length, 1) = " ",
+		         s.substr(consumed_length, 1) = "\t")
+		loop
+			consumed_length <- consumed_length + 1
+		pool;
+		consumed_length;
+	}};
+
+	token() : IToken {
+		new WhitespaceToken
+	};
+};