Added ParsePrimitiveValue convenience function for users

Author: daboyuka

parser.go

@@ -11,13 +11,14 @@ import (
 
 // Errors
 var (
-	KeyPathNotFoundError = errors.New("Key path not found")
+	KeyPathNotFoundError  = errors.New("Key path not found")
 	UnknownValueTypeError = errors.New("Unknown value type")
-	MalformedJsonError = errors.New("Malformed JSON error")
-	MalformedStringError = errors.New("Value is string, but can't find closing '\"' symbol")
-	MalformedArrayError = errors.New("Value is array, but can't find closing ']' symbol")
-	MalformedObjectError = errors.New("Value looks like object, but can't find closing '}' symbol")
-	MalformedValueError = errors.New("Value looks like Number/Boolean/None, but can't find its end: ',' or '}' symbol")
+	MalformedJsonError    = errors.New("Malformed JSON error")
+	MalformedStringError  = errors.New("Value is string, but can't find closing '\"' symbol")
+	MalformedArrayError   = errors.New("Value is array, but can't find closing ']' symbol")
+	MalformedObjectError  = errors.New("Value looks like object, but can't find closing '}' symbol")
+	MalformedValueError   = errors.New("Value looks like Number/Boolean/None, but can't find its end: ',' or '}' symbol")
+	NotAPrimitiveError    = errors.New("Cannot parse a non-primitive value in ParsePrimitiveValue")
 )
 
 func tokenEnd(data []byte) int {
@@ -31,7 +32,6 @@ func tokenEnd(data []byte) int {
 	return -1
 }
 
-
 // Find position of next character which is not ' ', ',', '}' or ']'
 func nextToken(data []byte, skipComma bool) int {
 	for i, c := range data {
@@ -133,10 +133,10 @@ func searchKeys(data []byte, keys ...string) int {
 			i += valueOffset
 
 			// if string is a Key, and key level match
-			if data[i] == ':'{
+			if data[i] == ':' {
 				key := unsafeBytesToString(data[keyBegin:keyEnd])
 
-			 	if keyLevel == level-1 && // If key nesting level match current object nested level
+				if keyLevel == level-1 && // If key nesting level match current object nested level
 					keys[level-1] == key {
 					keyLevel++
 					// If we found all keys in path
@@ -462,3 +462,34 @@ func unsafeBytesToString(data []byte) string {
 	sh := reflect.StringHeader{Data: h.Data, Len: h.Len}
 	return *(*string)(unsafe.Pointer(&sh))
 }
+
+// ParsePrimitiveValue takes a []byte value returned by Get(), passed to ArrayEach() callback, etc.
+// and parses/converts it into a Go type (wrapped in an interface{}) as follows:
+//
+// Null -> nil
+// Boolean -> bool
+// String -> string (unescaped)
+// Number -> float64
+// anything else -> error
+//
+// This function will likely a memory allocation to return an interface{}, but often user code
+// needs an interface{} value, so we provide an efficient implementation for when it is needed.
+//
+func ParsePrimitiveValue(vbytes []byte, jtype ValueType) (interface{}, error) {
+	switch jtype {
+	case Null:
+		return nil, nil
+	case Boolean:
+		return (vbytes[0] == 't'), nil // assumes value is already validated by Get(), etc. since we're given jtype == Boolean
+	case String:
+		return string(vbytes), nil // TODO: this does not unescape the string; use unescaper whenever it becomes available
+	case Number:
+		if v, err := strconv.ParseFloat(unsafeBytesToString(vbytes), 64); err != nil { // TODO: use better BytesParseFloat in PR #25
+			return nil, MalformedValueError
+		} else {
+			return v, nil
+		}
+	default:
+		return nil, NotAPrimitiveError
+	}
+}