diff --git a/parse.go b/parse.go
new file mode 100644
index 0000000..ab37a07
--- /dev/null
+++ b/parse.go
@@ -0,0 +1,147 @@
+package bond
+
+import (
+	"strings"
+	"fmt"
+	"net/url"
+)
+
+func ParseStr(encodedString string, result map[string]interface{}) error {
+	// build nested map.
+	var build func(map[string]interface{}, []string, interface{}) error
+
+	build = func(result map[string]interface{}, keys []string, value interface{}) error {
+		length := len(keys)
+		// trim ',"
+		key := strings.Trim(keys[0], "'\"")
+		if length == 1 {
+			result[key] = value
+			return nil
+		}
+
+		// The end is slice. like f[], f[a][]
+		if keys[1] == "" && length == 2 {
+			// todo nested slice
+			if key == "" {
+				return nil
+			}
+			val, ok := result[key]
+			if !ok {
+				result[key] = []interface{}{value}
+				return nil
+			}
+			children, ok := val.([]interface{})
+			if !ok {
+				return fmt.Errorf("expected type '[]interface{}' for key '%s', but got '%T'", key, val)
+			}
+			result[key] = append(children, value)
+			return nil
+		}
+
+		// The end is slice + map. like f[][a]
+		if keys[1] == "" && length > 2 && keys[2] != "" {
+			val, ok := result[key]
+			if !ok {
+				result[key] = []interface{}{}
+				val = result[key]
+			}
+			children, ok := val.([]interface{})
+			if !ok {
+				return fmt.Errorf("expected type '[]interface{}' for key '%s', but got '%T'", key, val)
+			}
+			if l := len(children); l > 0 {
+				if child, ok := children[l-1].(map[string]interface{}); ok {
+					if _, ok := child[keys[2]]; !ok {
+						_ = build(child, keys[2:], value)
+						return nil
+					}
+				}
+			}
+			child := map[string]interface{}{}
+			_ = build(child, keys[2:], value)
+			result[key] = append(children, child)
+
+			return nil
+		}
+
+		// map. like f[a], f[a][b]
+		val, ok := result[key]
+		if !ok {
+			result[key] = map[string]interface{}{}
+			val = result[key]
+		}
+		children, ok := val.(map[string]interface{})
+		if !ok {
+			return fmt.Errorf("expected type 'map[string]interface{}' for key '%s', but got '%T'", key, val)
+		}
+
+		return build(children, keys[1:], value)
+	}
+
+	// split encodedString.
+	parts := strings.Split(encodedString, "&")
+	for _, part := range parts {
+		pos := strings.Index(part, "=")
+		if pos <= 0 {
+			continue
+		}
+		key, err := url.QueryUnescape(part[:pos])
+		if err != nil {
+			return err
+		}
+		for key[0] == ' ' {
+			key = key[1:]
+		}
+		if key == "" || key[0] == '[' {
+			continue
+		}
+		value, err := url.QueryUnescape(part[pos+1:])
+		if err != nil {
+			return err
+		}
+
+		// split into multiple keys
+		var keys []string
+		left := 0
+		for i, k := range key {
+			if k == '[' && left == 0 {
+				left = i
+			} else if k == ']' {
+				if left > 0 {
+					if len(keys) == 0 {
+						keys = append(keys, key[:left])
+					}
+					keys = append(keys, key[left+1:i])
+					left = 0
+					if i+1 < len(key) && key[i+1] != '[' {
+						break
+					}
+				}
+			}
+		}
+		if len(keys) == 0 {
+			keys = append(keys, key)
+		}
+		// first key
+		first := ""
+		for i, chr := range keys[0] {
+			if chr == ' ' || chr == '.' || chr == '[' {
+				first += "_"
+			} else {
+				first += string(chr)
+			}
+			if chr == '[' {
+				first += keys[0][i+1:]
+				break
+			}
+		}
+		keys[0] = first
+
+		// build nested map
+		if err := build(result, keys, value); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}