h_token: Copy string correctly.

See https://github.com/ffi/ffi/wiki/Core-Concepts#string-memory-allocation for additional information.

src/bindings/ruby/lib/hammer.rb

@@ -72,4 +72,14 @@ p parser.parse 'abcabd'
 p parser.parse 'abdabd'
 p parser.parse 'abd'
 
-$r = parser.parse 'abcabd'
+#$r = parser.parse 'abcabd'
+
+
+# Test multibyte characters
+parser = Hammer::Parser.build {
+  token '今日'
+  end_p
+}
+
+p ($r = parser.parse('今日')) # should succeed
+

src/bindings/ruby/lib/hammer/internal.rb

@@ -70,7 +70,7 @@ module Hammer
     attach_function :h_parse, [:h_parser, :string, :size_t], HParseResult.auto_ptr # TODO: Use :buffer_in instead of :string?
 
     # build a parser
-    attach_function :h_token, [:string, :size_t], :h_parser # TODO: Use :buffer_in instead of :string?
+    attach_function :h_token, [:buffer_in, :size_t], :h_parser
     attach_function :h_ch, [:uint8], :h_parser
     attach_function :h_ch_range, [:uint8, :uint8], :h_parser
     attach_function :h_int_range, [:int64, :int64], :h_parser
@@ -87,8 +87,8 @@ module Hammer
     attach_function :h_left,   [:h_parser, :h_parser], :h_parser
     attach_function :h_right,  [:h_parser, :h_parser], :h_parser
     attach_function :h_middle, [:h_parser, :h_parser, :h_parser], :h_parser
-    #attach_function :h_in, [:string, :size_t], :h_parser # TODO: Use :buffer_in instead of :string?
-    #attach_function :h_not_in, [:string, :size_t], :h_parser # TODO: Use :buffer_in instead of :string?
+    #attach_function :h_in, [:buffer_in, :size_t], :h_parser
+    #attach_function :h_not_in, [:buffer_in, :size_t], :h_parser
     attach_function :h_end_p, [], :h_parser
     attach_function :h_nothing_p, [], :h_parser
     attach_function :h_sequence, [:varargs], :h_parser

src/bindings/ruby/lib/hammer/parser.rb

@@ -6,7 +6,7 @@ module Hammer
     #
     # name: Name of the parser. Should be a symbol.
     # h_parser: The pointer to the parser as returned by hammer.
-    # dont_gc: Pass additional data that's used by the parser and needs to be saved from the garbage collector.
+    # dont_gc: Pass additional data that's used by the parser and needs to be saved from the garbage collector (at least as long this object lives).
     def initialize(name, h_parser, dont_gc)
       @name = name
       @h_parser = h_parser
@@ -34,13 +34,14 @@ module Hammer
     end
 
     def self.token(string)
-      # TODO:
-      # This might fail in JRuby.
-      # See "String Memory Allocation" at https://github.com/ffi/ffi/wiki/Core-Concepts
-      h_string = string.dup
-      h_parser = Hammer::Internal.h_token(h_string, h_string.length)
+      # Need to copy string to a memory buffer (not just string.dup)
+      # * Original string might be modified, this must not affect existing tokens
+      # * We need a constant memory address (Ruby string might be moved around by the Ruby VM)
+      # * Use string.length instead of h_string.size to handle multibyte characters correctly.
+      buffer = FFI::MemoryPointer.from_string(string)
+      h_parser = Hammer::Internal.h_token(buffer, string.length)
 
-      return Hammer::Parser.new(:token, h_parser, h_string)
+      return Hammer::Parser.new(:token, h_parser, buffer)
     end
 
     def self.ch(num)