start of protocol for discrete value ranges

src/challenge/discrete_value_range.clj

@@ -0,0 +1,30 @@
+(ns challenge.discrete-value-range)
+
+(defprotocol DiscreteValueRange
+  "A protocol for generic behavior on Ranges over
+  discrete values.
+
+  This is for discrete values as we want to be
+  able to determine the value before the range
+  start and the value immediately after the range end.
+
+  By using discrete values we:
+   1. Determine if two ranges abut (touch) each other, and
+      can therefore be combined into a single range
+   2. Can combine overlapping by listing all ranges' start
+      and end values, and using a stack's push/pop functionality
+      to know if we are in a larger composite range, similiar
+      to parenthesis matching. e.g. If I encounter two range
+      start items, I know I should be expecting two end values,
+      even if the range is 'unbounded', there should be a MIN/MAX
+      value specified.
+   3. Know the discrete values for both before and or after the range
+      (even if a MIN/MAX marker) value that we can use to compare
+      that before/after values against other values that the range
+      is over.
+  "
+  (abuts [this ^DiscreteValueRange other])
+  (value-before [this])
+  (value-after [this])
+  (start [this])
+  (end [this]))