10 files changed, 140 insertions, 4 deletions

diff --git a/src/StringConsumer/BaseConsumers/BinaryOperatorConsumer.cl b/src/StringConsumer/BaseConsumers/BinaryOperatorConsumer.cl
new file mode 100644
index 0000000..8e7288c
--- /dev/null
+++ b/src/StringConsumer/BaseConsumers/BinaryOperatorConsumer.cl
@@ -0,0 +1,18 @@
+class BinaryOperatorConsumer inherits IWordsConsumer {
+	init() : IStringConsumer {{
+		matched_words <- matched_words
+			.push("+")
+			.push("-")
+			.push("*")
+			.push("/")
+			.push("<")
+			.push("<=")
+			.push("=")
+			;
+		self;
+	}};
+
+	token() : IToken {
+		new BinaryOperatorToken
+	};
+};
diff --git a/src/StringConsumer/BaseConsumers/IntegerConsumer.cl b/src/StringConsumer/BaseConsumers/IntegerConsumer.cl
new file mode 100644
index 0000000..5b4cd82
--- /dev/null
+++ b/src/StringConsumer/BaseConsumers/IntegerConsumer.cl
@@ -0,0 +1,21 @@
+class IntegerConsumer inherits IWordsConsumer {
+	init() : IStringConsumer {{
+		matched_words <- matched_words
+			.push("0")
+			.push("1")
+			.push("2")
+			.push("3")
+			.push("4")
+			.push("5")
+			.push("6")
+			.push("7")
+			.push("8")
+			.push("9")
+			;
+		self;
+	}};
+
+	token() : IToken {
+		new IntegerToken
+	};
+};
diff --git a/src/StringConsumer/BaseConsumers/KeywordsIfConsumer.cl b/src/StringConsumer/BaseConsumers/KeywordsIfConsumer.cl
new file mode 100644
index 0000000..9bd76e9
--- /dev/null
+++ b/src/StringConsumer/BaseConsumers/KeywordsIfConsumer.cl
@@ -0,0 +1,15 @@
+class KeywordsIfConsumer inherits IWordsConsumer {
+	init() : IStringConsumer {{
+		matched_words <- matched_words
+			.push("if")
+			.push("then")
+			.push("else")
+			.push("fi")
+			;
+		self;
+	}};
+
+	token() : IToken {
+		new KeywordToken
+	};
+};
diff --git a/src/StringConsumer/WhitespaceConsumer.cl b/src/StringConsumer/BaseConsumers/WhitespaceConsumer.cl
index 3a8c4dc..3a8c4dc 100644
--- a/src/StringConsumer/WhitespaceConsumer.cl
+++ b/src/StringConsumer/BaseConsumers/WhitespaceConsumer.cl
diff --git a/src/StringConsumer/HigherOrderConsumers/ExpressionConsumer.cl b/src/StringConsumer/HigherOrderConsumers/ExpressionConsumer.cl
new file mode 100644
index 0000000..592611e
--- /dev/null
+++ b/src/StringConsumer/HigherOrderConsumers/ExpressionConsumer.cl
@@ -0,0 +1,19 @@
+class ExpressionConsumer inherits IHigherOrderConsumer {
+	integerc: IStringConsumer <- (new IntegerConsumer).init();
+	binaryopc: IStringConsumer <- (new BinaryOperatorConsumer).init();
+
+	consume(s: String) : Int {{
+		consumed_length <- 0;
+		if did(integerc.consume(s))
+		then
+			token <- integerc.token()
+		else if did(binaryopc.consume(s))
+		then
+			token <- binaryopc.token()
+		else
+			void
+		fi
+		fi;
+		consumed_length;
+	}};
+};
diff --git a/src/StringConsumer/HigherOrderConsumers/IfConsumer.cl b/src/StringConsumer/HigherOrderConsumers/IfConsumer.cl
new file mode 100644
index 0000000..431f79b
--- /dev/null
+++ b/src/StringConsumer/HigherOrderConsumers/IfConsumer.cl
@@ -0,0 +1,14 @@
+class IfConsumer inherits IHigherOrderConsumer {
+	ifc: IStringConsumer <- (new KeywordsIfConsumer).init();
+
+	consume(s: String) : Int {{
+		consumed_length <- 0;
+		if did(ifc.consume(s))
+		then
+			token <- ifc.token()
+		else
+			void
+		fi;
+		consumed_length;
+	}};
+};
diff --git a/src/StringConsumer/IHigherOrderConsumer.cl b/src/StringConsumer/IHigherOrderConsumer.cl
new file mode 100644
index 0000000..e7325d2
--- /dev/null
+++ b/src/StringConsumer/IHigherOrderConsumer.cl
@@ -0,0 +1,11 @@
+class IHigherOrderConsumer inherits IStringConsumer {
+	token: IToken;
+
+	token() : IToken {
+		token
+	};
+
+	did(length: Int) : Bool {
+		0 < (consumed_length <- consumed_length + length)
+	};
+};
diff --git a/src/StringConsumer/IWordConsumer.cl b/src/StringConsumer/IWordConsumer.cl
new file mode 100644
index 0000000..a809cd2
--- /dev/null
+++ b/src/StringConsumer/IWordConsumer.cl
@@ -0,0 +1,13 @@
+class IWordConsumer inherits IStringConsumer {
+	word: String;
+
+	consume(s: String) : Int {{
+		consumed_length <- 0;
+		if s.substr(0, word.length()) = word
+		then
+			consumed_length <- word.length()
+		else
+			consumed_length
+		fi;
+	}};
+};
diff --git a/src/StringConsumer/IWordsConsumer.cl b/src/StringConsumer/IWordsConsumer.cl
index 4c184bf..a1c22ba 100644
--- a/src/StringConsumer/IWordsConsumer.cl
+++ b/src/StringConsumer/IWordsConsumer.cl
@@ -37,16 +37,37 @@ class WordList inherits System {
 
 	any_starts(s: String, start: Int) : Int {
 		if or(word = "", s.length() <= start)
-		then 0
+		then
+			0
+		else if and(s.length() < start + word.length(), not isvoid next)
+		then
+			next.any_starts(s, start)
 		else if s.substr(start, word.length()) = word
-		then word.length()
+		then
+			word.length()
 		else if isvoid next
-		then 0
-		else next.any_starts(s, start)
+		then
+			0
+		else
+			next.any_starts(s, start)
+		fi
 		fi
 		fi
 		fi
 	};
+
+	empty() : Bool {
+		if not (word = "")
+		then
+			false
+		else if isvoid next
+		then
+			true
+		else
+			next.empty()
+		fi
+		fi
+	};
 };
 
 class IWordsConsumer inherits IStringConsumer {
@@ -56,6 +77,8 @@ class IWordsConsumer inherits IStringConsumer {
 	let
 		word_length: Int <- 0
 	in {
+		assert(not matched_words.empty(), "consume", "object of class hasn't been initialised!");
+
 		consumed_length <- 0;
 		while 0 < (word_length <- matched_words.any_starts(s, consumed_length))
 		loop
diff --git a/src/StringConsumer/StringConsumerEngine.cl b/src/StringConsumer/StringConsumerEngine.cl
index 6f07d2e..4f4f65f 100644
--- a/src/StringConsumer/StringConsumerEngine.cl
+++ b/src/StringConsumer/StringConsumerEngine.cl
@@ -1,6 +1,8 @@
 class StringConsumerEngine inherits System {
 	consumers: ConsumerList <- (new ConsumerList)
 		.push((new WhitespaceConsumer).init())
+		.push((new ExpressionConsumer).init())
+		.push((new IfConsumer).init())
 		;
 
 	str: String;