Implement AtLeast and AtMost

1 files changed, 22 insertions, 2 deletions

diff --git a/src/parcom.cr b/src/parcom.cr
index c7f4012..0a97e51 100644
--- a/src/parcom.cr
+++ b/src/parcom.cr
@@ -308,10 +308,30 @@ module Parcom
     end
   end
 
-  class AtLeast
+  class AtLeast(T, V) < Parser(T, Array(V))
+    @p : Map(T, {Array(V), Array(V)}, Array(V))
+
+    def initialize(i : Int, p : Parser(T, V))
+      @p = (Exactly.new(i, p) + Many.new(p)).map do |tup|
+        tup[0] + tup[1]
+      end
+    end
+
+    def parse(tokens : TokenStream(T)) : Result(T, Array(V))
+      @p.parse(tokens)
+    end
   end
 
-  class AtMost
+  class AtMost(T, V) < Parser(T, Array(V))
+    @p : Map(T, Array(V?), Array(V))
+
+    def initialize(i : Int, p : Parser(T, V))
+      @p = Exactly.new(i, Optional.new(p)).map(&.compact)
+    end
+
+    def parse(tokens : TokenStream(T)) : Result(T, Array(V))
+      @p.parse(tokens)
+    end
   end
 
   class Between