Initial commit

1 files changed, 114 insertions, 0 deletions

diff --git a/combinator.go b/combinator.go
new file mode 100644
index 0000000..2b6b8a3
--- /dev/null
+++ b/combinator.go
@@ -0,0 +1,114 @@
+package parsec
+
+func Nil(p Pointer) (Node, Pointer) {
+	return nil, p
+}
+
+func Never(p Pointer) (Node, Pointer) {
+	return Error{p.pos, "Never matches"}, p
+}
+
+func And(parsers ...Parserish) Parser {
+	if len(parsers) == 0 {
+		return Nil
+	}
+
+	ps := ParsifyAll(parsers...)
+
+	return func(p Pointer) (Node, Pointer) {
+		var nodes = make([]Node, 0, len(ps))
+		var node Node
+		newP := p
+		for _, parser := range ps {
+			node, newP = parser(newP)
+			if node == nil {
+				continue
+			}
+			if IsError(node) {
+				return node, p
+			}
+			nodes = append(nodes, node)
+		}
+		return NewSequence(p.pos, nodes...), newP
+	}
+}
+
+func Any(parsers ...Parserish) Parser {
+	if len(parsers) == 0 {
+		return Nil
+	}
+
+	ps := ParsifyAll(parsers...)
+
+	return func(p Pointer) (Node, Pointer) {
+		errors := []Error{}
+		for _, parser := range ps {
+			node, newP := parser(p)
+			if err, isErr := node.(Error); isErr {
+				errors = append(errors, err)
+				continue
+			}
+			return node, newP
+		}
+
+		longestError := errors[0]
+		for _, e := range errors[1:] {
+			if e.pos > longestError.pos {
+				longestError = e
+			}
+		}
+
+		return longestError, p
+	}
+}
+
+func Kleene(opScan Parserish, sepScan ...Parserish) Parser {
+	return manyImpl(0, opScan, Never, sepScan...)
+}
+
+func KleeneUntil(opScan Parserish, untilScan Parserish, sepScan ...Parserish) Parser {
+	return manyImpl(0, opScan, untilScan, sepScan...)
+}
+
+func Many(opScan Parserish, sepScan ...Parserish) Parser {
+	return manyImpl(1, opScan, Never, sepScan...)
+}
+
+func ManyUntil(opScan Parserish, untilScan Parserish, sepScan ...Parserish) Parser {
+	return manyImpl(1, opScan, untilScan, sepScan...)
+}
+
+func manyImpl(min int, op Parserish, until Parserish, sep ...Parserish) Parser {
+	opParser := Parsify(op)
+	untilParser := Parsify(until)
+	sepParser := Nil
+	if len(sep) > 0 {
+		sepParser = Parsify(sep[0])
+	}
+
+	return func(p Pointer) (Node, Pointer) {
+		var node Node
+		nodes := make([]Node, 0)
+		newP := p
+		for {
+			if node, _ := untilParser(newP); !IsError(node) {
+				if len(nodes) < min {
+					return NewError(newP.pos, "Unexpected input"), p
+				}
+				break
+			}
+
+			if node, newP = opParser(newP); IsError(node) {
+				if len(nodes) < min {
+					return node, p
+				}
+				break
+			}
+			nodes = append(nodes, node)
+			if node, newP = sepParser(newP); IsError(node) {
+				break
+			}
+		}
+		return NewSequence(p.pos, nodes...), newP
+	}
+}