Fix Many hanging when wrapped parser never fails

3 files changed, 38 insertions, 23 deletions

diff --git a/spec/parcom_spec.cr b/spec/parcom_spec.cr
index 11d2446..dde6f21 100644
--- a/spec/parcom_spec.cr
+++ b/spec/parcom_spec.cr
@@ -494,6 +494,16 @@ describe Many do
       result.value.should eq("aaa".chars)
       result.tokens.should eq(tokens[3..])
     end
+
+    it "stops parsing when the wapped parser succeeds without consuming any input" do
+      a_optional : Parser(Char, Char?)
+      a_optional = Optional.new(Token.new('a'))
+      tokens = Tokens.from_string("aaa")
+      result = Many(Char, Char?).new(a_optional).parse(tokens)
+
+      result.value.should eq("aaa".chars)
+      result.tokens.should eq(tokens[3..])
+    end
   end
 end
 
diff --git a/src/parcom.cr b/src/parcom.cr
index 6715e07..c7dde7b 100644
--- a/src/parcom.cr
+++ b/src/parcom.cr
@@ -119,29 +119,6 @@ module Parcom
     end
   end
 
-  class Many(T, V) < Parser(T, Array(V))
-    def initialize(@p : Parser(T, V))
-    end
-
-    def parse(tokens : Tokens(T)) : Result(T, Array(V))
-      parsed = [] of V
-
-      loop do
-        result = @p.parse?(tokens)
-        if result.nil?
-          break
-        else
-          parsed << result.value
-          tokens = result.tokens
-        end
-      end
-
-      Result.new(tokens, parsed)
-    rescue ex : ParserFail
-      raise ParserFail.new("Many: #{ex.message}")
-    end
-  end
-
   class Some(T, V) < Parser(T, Array(V))
     @p : Assert(T, Array(V))
 
diff --git a/src/parcom/many.cr b/src/parcom/many.cr
new file mode 100644
index 0000000..dbe3b13
--- /dev/null
+++ b/src/parcom/many.cr
@@ -0,0 +1,28 @@
+require "./parser.cr"
+
+module Parcom
+  class Many(T, V) < Parser(T, Array(V))
+    def initialize(@p : Parser(T, V))
+    end
+
+    def parse(tokens : Tokens(T)) : Result(T, Array(V))
+      parsed = [] of V
+
+      loop do
+        result = @p.parse?(tokens)
+
+        if !result.nil? && result.tokens != tokens
+          parsed << result.value
+          tokens = result.tokens
+        else
+          break
+        end
+      end
+
+      Result.new(tokens, parsed)
+    rescue ex : ParserFail
+      raise ParserFail.new("Many: #{ex.message}")
+    end
+  end
+end
+