1 files changed, 246 insertions, 13 deletions
diff --git a/walk/walk.go b/walk/walk.go
index 1073c67..65fac6e 100644
--- a/walk/walk.go
+++ b/walk/walk.go
@@ -1,17 +1,232 @@
 package walk
 
 import (
-	"strings"
+	"fmt"
 	"math"
+	"strings"
 	"unicode/utf8"
 )
 
+type valueIter struct {
+	values []Value
+	index int
+}
+func (iter *valueIter) Next() Edible {
+	if iter.index >= len(iter.values) {
+		return nil
+	}
+	iter.index += 1
+	return iter.values[iter.index - 1]
+}
+
+func NewValueIter(values []Value) StructureIter {
+	return &valueIter {
+		values: values,
+		index: 0,
+	}
+}
+
+type OutputList interface {
+	outputList()
+}
+
+type StructureIter interface {
+	Next() Edible
+}
+
+type Edible interface {
+	edible()
+}
+
+type Atom interface {
+	Edible
+	atom()
+}
+
+type Scalar interface {
+	Atom
+	Value
+}
+
+type Structure interface {
+	Value
+	structure()
+	Iter() StructureIter
+}
+
+type Value interface {
+	Edible
+	value()
+	Debug() string
+}
+
+type Terminal interface {
+	Atom
+	terminal()
+}
+
+type ValueList []Value
+func (_ ValueList) outputList() {}
+
+type RuneList []StringRuneAtom
+func (_ RuneList) outputList() {}
+
+type NullScalar struct{}
+func (_ NullScalar) edible() {}
+func (_ NullScalar) atom() {}
+func (_ NullScalar) value() {}
+func (_ NullScalar) Debug() string {
+	return "null"
+}
+
+type BoolScalar bool
+func (_ BoolScalar) edible() {}
+func (_ BoolScalar) atom() {}
+func (_ BoolScalar) value() {}
+func (b BoolScalar) Debug() string {
+	if b {
+		return "true"
+	}
+	return "false"
+}
+
+type NumberScalar float64
+func (_ NumberScalar) edible() {}
+func (_ NumberScalar) atom() {}
+func (_ NumberScalar) value() {}
+func (n NumberScalar) Debug() string {
+	return fmt.Sprintf("%v", float64(n))
+}
+
+type StringStructure string
+func (_ StringStructure) edible() {}
+func (_ StringStructure) value() {}
+func (_ StringStructure) structure() {}
+func (s StringStructure) Iter() StructureIter {
+	return &stringStructureIter {
+		string: string(s),
+		position: 0,
+	}
+}
+func (s StringStructure) Debug() string {
+	return fmt.Sprintf("%q", string(s))
+}
+
+type stringStructureIter struct {
+	string string
+	position int
+}
+func (iter *stringStructureIter) Next() Edible {
+	if iter.position == -1 {
+		return nil
+	}
+	r, width := utf8.DecodeRuneInString(iter.string[iter.position:])
+	if width == 0 {
+		iter.position = -1
+		return StringEndTerminal{}
+	}
+	iter.position += width
+	return StringRuneAtom(r)
+}
+
+type StringBeginTerminal struct{}
+func (_ StringBeginTerminal) edible() {}
+func (_ StringBeginTerminal) atom() {}
+func (_ StringBeginTerminal) terminal() {}
+
+type StringEndTerminal struct{}
+func (_ StringEndTerminal) edible() {}
+func (_ StringEndTerminal) atom() {}
+func (_ StringEndTerminal) terminal() {}
+
+type StringRuneAtom rune
+func (_ StringRuneAtom) edible() {}
+func (_ StringRuneAtom) atom() {}
+
+type ArrayStructure []Value
+func (_ ArrayStructure) edible() {}
+func (_ ArrayStructure) value() {}
+func (_ ArrayStructure) structure() {}
+func (array ArrayStructure) Iter() StructureIter {
+	return &arrayStructureIter {
+		array: []Value(array),
+		index: 0,
+	}
+}
+func (array ArrayStructure) Debug() string {
+	builder := strings.Builder{}
+	builder.WriteRune('[')
+	var sep string
+	for _, element := range array {
+		builder.WriteString(sep)
+		builder.WriteString(fmt.Sprintf("%v", element))
+		sep = ", "
+	}
+	builder.WriteRune(']')
+	return builder.String()
+}
+
+type arrayStructureIter struct {
+	array []Value
+	index int
+}
+func (iter *arrayStructureIter) Next() Edible {
+	if iter.index > len(iter.array) {
+		return nil
+	}
+	if iter.index == len(iter.array) {
+		iter.index += 1
+		return ArrayEndTerminal{}
+	}
+	iter.index += 1
+	return iter.array[iter.index - 1]
+}
+
+type ArrayBeginTerminal struct{}
+func (_ ArrayBeginTerminal) edible() {}
+func (_ ArrayBeginTerminal) atom() {}
+func (_ ArrayBeginTerminal) terminal() {}
+
+type ArrayEndTerminal struct{}
+func (_ ArrayEndTerminal) edible() {}
+func (_ ArrayEndTerminal) atom() {}
+func (_ ArrayEndTerminal) terminal() {}
+
+type MapStructure map[string]Value
+func (_ MapStructure) edible() {}
+func (_ MapStructure) value() {}
+func (_ MapStructure) structure() {}
+func (m MapStructure) Debug() string {
+	builder := strings.Builder{}
+	builder.WriteRune('{')
+	var sep string
+	for key, value := range m {
+		builder.WriteString(sep)
+		builder.WriteString(fmt.Sprintf("%q", key))
+		builder.WriteString(": ")
+		builder.WriteString(fmt.Sprintf("%q", value))
+		sep = ", "
+	}
+	builder.WriteRune('}')
+	return builder.String()
+}
+
+type MapBeginTerminal struct{}
+func (_ MapBeginTerminal) edible() {}
+func (_ MapBeginTerminal) atom() {}
+func (_ MapBeginTerminal) terminal() {}
+
+type MapEndTerminal struct{}
+func (_ MapEndTerminal) edible() {}
+func (_ MapEndTerminal) atom() {}
+func (_ MapEndTerminal) terminal() {}
+
 // int or string
 type PathSegment interface {}
 
 type Path []PathSegment
-func (path Path) ToWalkValues() []Value {
-	var values []Value
+func (path Path) ToWalkValues() []ValueOLD {
+	var values []ValueOLD
 	for _, segment := range path {
 		switch s := segment.(type) {
 			case int:
@@ -25,7 +240,7 @@ func (path Path) ToWalkValues() []Value {
 	return values
 }
 
-func PathFromWalkValues(values []Value) Path {
+func PathFromWalkValues(values []ValueOLD) Path {
 	var segments []PathSegment
 	for _, value := range values {
 		switch v := value.(type) {
@@ -41,18 +256,36 @@ func PathFromWalkValues(values []Value) Path {
 }
 
 type WalkItem struct {
-	Value []Atom
-	Path []Atom
+	Value ValueList
+	Path ValueList
+}
+
+func (item WalkItem) Debug() string {
+	builder := strings.Builder{}
+	var sep string
+	for _, pathSegment := range item.Path {
+		builder.WriteString(sep)
+		builder.WriteString(fmt.Sprintf("%s", pathSegment.Debug()))
+		sep = "."
+	}
+	builder.WriteString(": ")
+	sep = ""
+	for _, value := range item.Value {
+		builder.WriteString(sep)
+		builder.WriteString(fmt.Sprintf("%s", value.Debug()))
+		sep = ", "
+	}
+	return builder.String()
 }
 
-func ConcatData(first []Atom, second []Atom) []Atom {
-	res := make([]Atom, 0, len(first) + len(second))
+func ConcatData(first []AtomOLD, second []AtomOLD) []AtomOLD {
+	res := make([]AtomOLD, 0, len(first) + len(second))
 	res = append(res, first...)
 	res = append(res, second...)
 	return res
 }
 
-func Atomise(in []Value) (out []Atom) {
+func Atomise(in []ValueOLD) (out []AtomOLD) {
 	numAtoms := 0
 	for _, value := range in {
 		switch v := value.(type) {
@@ -64,7 +297,7 @@ func Atomise(in []Value) (out []Atom) {
 				panic("Invalid WalkValue")
 		}
 	}
-	out = make([]Atom, 0, numAtoms)
+	out = make([]AtomOLD, 0, numAtoms)
 	for _, value := range in {
 		out = value.Atomise(out)
 	}
@@ -96,11 +329,11 @@ func (err CompoundError) Error() string {
 }
 
 type CompoundResult struct {
-	value Value
+	value ValueOLD
 	error error
 }
 
-func Compound(in []Atom) (out []Value, error error) {
+func Compound(in []AtomOLD) (out []ValueOLD, error error) {
 	numValues := 0
 	i := 0
 	inString := false
@@ -118,7 +351,7 @@ func Compound(in []Atom) (out []Value, error error) {
 		}
 	}
 	i = 0
-	out = make([]Value, 0, numValues)
+	out = make([]ValueOLD, 0, numValues)
 	for {
 		if i >= len(in) {
 			break