Initial work on match data values management

src/spectator/matchers/generic_match_data_value.cr

@@ -0,0 +1,15 @@
+require "./match_data_value"
+
+module Spectator::Matchers
+  # Wraps a value for used in match data.
+  private struct GenericMatchDataValue(T) < MatchDataValue
+    # Creates the wrapper.
+    def initialize(@value : T)
+    end
+
+    # Stringifies the value.
+    def to_s(io)
+      @value.inspect(io)
+    end
+  end
+end

src/spectator/matchers/match_data.cr

@@ -12,9 +12,9 @@ module Spectator::Matchers
     end
 
     # Information about the match.
-    # Returned value and type will differ by sub-type,
-    # but all will return a set of key-value pairs.
-    abstract def values
+    # Returned elments will differ by matcher,
+    # but all will return a set of labeled values.
+    abstract def values : Array(MatchDataLabeledValue)
 
     # Describes the condition that satisfies the matcher.
     # This is informational and displayed to the end-user.

src/spectator/matchers/match_data_labeled_value.cr

@@ -0,0 +1,15 @@
+module Spectator::Matchers
+  # A value from match data with a label.
+  private struct MatchDataLabeledValue
+    # Label tied to the value.
+    # This annotates what the value is.
+    getter label : String
+
+    # The actual value from the match data.
+    getter value : MatchDataValue
+
+    # Creates a new labeled value.
+    def initialize(@label, @value)
+    end
+  end
+end

src/spectator/matchers/match_data_value.cr

@@ -0,0 +1,6 @@
+module Spectator::Matchers
+  # Abstract base for all match data values.
+  # All sub-classes are expected to implement their own `#to_s`.
+  private abstract struct MatchDataValue
+  end
+end