Documentation for Left and Right

3 files changed, 52 insertions, 28 deletions

diff --git a/src/parcom.cr b/src/parcom.cr
index acb0503..e421e5e 100644
--- a/src/parcom.cr
+++ b/src/parcom.cr
@@ -81,34 +81,6 @@ module Parcom
     end
   end
 
-  class Left(T, V, U) < Parser(T, V)
-    @p : Map(T, {V, U}, V)
-
-    def initialize(p1 : Parser(T, V), p2 : Parser(T, U))
-      @p = (p1 + p2).map(&.first)
-    end
-
-    def parse(tokens : Tokens(T)) : Result(T, V)
-      @p.parse(tokens)
-    rescue ex : ParserFail
-      raise ParserFail.new("Left: #{ex.message}")
-    end
-  end
-
-  class Right(T, V, U) < Parser(T, U)
-    @p : Map(T, {V, U}, U)
-
-    def initialize(p1 : Parser(T, V), p2 : Parser(T, U))
-      @p = (p1 + p2).map(&.last)
-    end
-
-    def parse(tokens : Tokens(T)) : Result(T, U)
-      @p.parse(tokens)
-    rescue ex : ParserFail
-      raise ParserFail.new("Right: #{ex.message}")
-    end
-  end
-
   class Recover(T, V) < Parser(T, V)
     @p : Map(T, V?, V)
 
diff --git a/src/parcom/Left.cr b/src/parcom/Left.cr
new file mode 100644
index 0000000..201f497
--- /dev/null
+++ b/src/parcom/Left.cr
@@ -0,0 +1,26 @@
+require "./parser.cr"
+require "./map.cr"
+
+module Parcom
+  # `Left` is a `Parser` that tries to parse with two different
+  # parsers in succession and fails if either of the two parsers fails.
+  # This parser behaves the same as `Plus`, but only returns the result
+  # of the first parser.
+  class Left(T, V, U) < Parser(T, V)
+    @p : Map(T, {V, U}, V)
+
+    # Accepts the two parsers to use, in order.
+    def initialize(p1 : Parser(T, V), p2 : Parser(T, U)) 
+      @p = (p1 + p2).map(&.first)
+    end 
+
+    # Tries to parse with the two given parsers, and returns the
+    # result of the first parser if they both succeed.
+    def parse(tokens : Tokens(T)) : Result(T, V)
+      @p.parse(tokens)
+    rescue ex : ParserFail
+      raise ParserFail.new("Left: #{ex.message}")
+    end 
+  end
+end
+
diff --git a/src/parcom/Right.cr b/src/parcom/Right.cr
new file mode 100644
index 0000000..202754d
--- /dev/null
+++ b/src/parcom/Right.cr
@@ -0,0 +1,26 @@
+require "./parser.cr"
+require "./map.cr"
+
+module Parcom
+  # `Right` is a `Parser` that tries to parse with two different
+  # parsers in succession and fails if either of the two parsers fails.
+  # This parser behaves the same as `Plus`, but only returns the result
+  # of the second parser.
+  class Right(T, V, U) < Parser(T, U)
+    @p : Map(T, {V, U}, V)
+
+    # Accepts the two parsers to use, in order.
+    def initialize(p1 : Parser(T, V), p2 : Parser(T, U)) 
+      @p = (p1 + p2).map(&.last)
+    end
+
+    # Tries to parse with the two given parsers, and returns the
+    # result of the second parser if they both succeed.
+    def parse(tokens : Tokens(T)) : Result(T, U)
+      @p.parse(tokens)
+    rescue ex : ParserFail
+      raise ParserFail.new("Left: #{ex.message}")
+    end 
+  end 
+end
+