Stop options with implicit value from consuming separate tokens.

The current documentation states that if an option has implicit
value, it will only consume adjacent token.

Author: mjdecker

include/boost/program_options/value_semantic.hpp

@@ -39,6 +39,11 @@ namespace boost { namespace program_options {
             should be present on the command line. */
         virtual unsigned max_tokens() const = 0;
 
+        /** Returns true if the option should only take adjacent token,
+            not one from further command-line arguments.
+        */
+        virtual bool adjacent_tokens_only() const = 0;
+
         /** Returns true if values from different sources should be composed.
             Otherwise, value from the first source is used and values from
             other sources are discarded.
@@ -49,7 +54,7 @@ namespace boost { namespace program_options {
 
         */
         virtual bool is_required() const = 0;
-        
+
         /** Parses a group of tokens that specify a value of option.
             Stores the result in 'value_store', using whatever representation
             is desired. May be be called several times if value of the same
@@ -135,6 +140,7 @@ namespace boost { namespace program_options {
 
         unsigned min_tokens() const;
         unsigned max_tokens() const;
+        bool adjacent_tokens_only() const { return false; }
 
         bool is_composing() const { return false; }
 
@@ -322,6 +328,8 @@ namespace boost { namespace program_options {
             }
         }
 
+        bool adjacent_tokens_only() const { return !m_implicit_value.empty(); }
+
         bool is_required() const { return m_required; }
 
         /** Creates an instance of the 'validator' class and calls

src/cmdline.cpp

@@ -313,6 +313,9 @@ namespace boost { namespace program_options { namespace detail {
             if (!xd)
                 continue;
 
+            if (xd->semantic()->adjacent_tokens_only())
+                continue;
+
             unsigned min_tokens = xd->semantic()->min_tokens();
             unsigned max_tokens = xd->semantic()->max_tokens();
             if (min_tokens < max_tokens && opt.value.size() < max_tokens)