Fix bug with special chars handling in strings, detect package key queries,

arch condition for dependency-like queries.

query/query.go

@@ -1,6 +1,10 @@
 // Package query implements query language for
 package query
 
+import (
+	"github.com/smira/aptly/deb"
+)
+
 /*
 
   Query language resembling Debian dependencies and reprepro
@@ -10,8 +14,16 @@ package query
   A := B | B ',' A
   B := C | '!' B
   C := '(' Query ')' | D
-  D := <field> <condition>
+  D := <field> <condition> <arch_condition> | <pkg>_<version>_<arch>
   field := <package-name> | <field> | $special_field
   condition := '(' <operator> value ')' |
+  arch_condition := '{' arch '}' |
   operator := | << | < | <= | > | >> | >= | = | % | ~
 */
+
+// Parse parses input package query into PackageQuery tree ready for evaluation
+func Parse(query string) (result deb.PackageQuery, err error) {
+	l, _ := lex("", query)
+	result, err = parse(l)
+	return
+}