1 files changed, 23 insertions, 0 deletions
diff --git a/src/__OLD_parcom/peek.cr b/src/__OLD_parcom/peek.cr
new file mode 100644
index 0000000..2b6f657
--- /dev/null
+++ b/src/__OLD_parcom/peek.cr
@@ -0,0 +1,23 @@
+require "./parser.cr"
+
+module Parcom
+  # `Peek` is a `Parser` that runs another `Parser` while
+  # leaving the input stream unmodified.
+  class Peek(T, V) < Parser(T, V)
+    # Accepts the parser to run.
+    def initialize(@p : Parser(T, V)) 
+    end 
+
+    # Runs the parser it was initialized with, and returns
+    # that parser's result along with the original input.
+    #
+    # Re-raises a `ParserFail` exception if the other parser fails.
+    def parse(tokens : Tokens(T)) : Result(T, V)
+      result = @p.parse(tokens)
+      Result.new(tokens, result.value)
+    rescue ex : ParserFail
+      raise ParserFail.new("Peek: #{ex.message}")
+    end 
+  end
+end
+