Many options now have additive effect

For example, -A and -V used to override each other, whereas now:

  -A    report the average amount
  -V    report all amounts at current value
  -AV   report the current value of the average
  -VA   report the average of all current values

8 files changed, 63 insertions, 62 deletions

diff --git a/src/chain.cc b/src/chain.cc
index 400b8f26..f8f0aeff 100644
--- a/src/chain.cc
+++ b/src/chain.cc
@@ -118,6 +118,10 @@ post_handler_ptr chain_post_handlers(post_handler_ptr base_handler,
   expr_t& expr(report.HANDLER(amount_).expr);
   expr.set_context(&report);
 
+  report.HANDLER(total_).expr.set_context(&report);
+  report.HANDLER(display_amount_).expr.set_context(&report);
+  report.HANDLER(display_total_).expr.set_context(&report);
+
   if (! for_accounts_report) {
     // Make sure only forecast postings which match are allowed through
     if (report.HANDLED(forecast_while_)) {
diff --git a/src/filters.h b/src/filters.h
index 22f2d2cb..7be3acb9 100644
--- a/src/filters.h
+++ b/src/filters.h
@@ -65,14 +65,14 @@ protected:
   value_to_posts_map         posts_map;
   post_handler_ptr           post_chain;
   report_t&                  report;
-  expr_t                     group_by_expr;
+  expr_t&                    group_by_expr;
   custom_flusher_t           preflush_func;
   optional<custom_flusher_t> postflush_func;
 
 public:
   post_splitter(post_handler_ptr _post_chain,
                 report_t&        _report,
-                expr_t           _group_by_expr)
+                expr_t&          _group_by_expr)
     : post_chain(_post_chain), report(_report),
       group_by_expr(_group_by_expr) {
     TRACE_CTOR(post_splitter, "scope_t&, post_handler_ptr, expr_t");
@@ -521,8 +521,8 @@ class display_filter_posts : public item_handler<post_t>
   // later in the chain.
 
   report_t&     report;
-  expr_t        display_amount_expr;
-  expr_t        display_total_expr;
+  expr_t&       display_amount_expr;
+  expr_t&       display_total_expr;
   bool          show_rounding;
   value_t       last_display_total;
   temporaries_t temps;
@@ -569,8 +569,8 @@ class changed_value_posts : public item_handler<post_t>
   // later in the chain.
 
   report_t&     report;
-  expr_t        total_expr;
-  expr_t        display_total_expr;
+  expr_t&       total_expr;
+  expr_t&       display_total_expr;
   bool          changed_values_only;
   bool          for_accounts_report;
   bool          show_unrealized;
diff --git a/src/global.cc b/src/global.cc
index 5b7bb1c1..cc14c99e 100644
--- a/src/global.cc
+++ b/src/global.cc
@@ -70,6 +70,7 @@ global_scope_t::global_scope_t(char ** envp)
   // generated.
   report_stack.push_front(new report_t(*session_ptr));
   scope_t::default_scope = &report();
+  scope_t::empty_scope   = &empty_scope;
 
   // Read the user's options, in the following order:
   //
diff --git a/src/global.h b/src/global.h
index ce0534b0..7429b1f5 100644
--- a/src/global.h
+++ b/src/global.h
@@ -50,6 +50,7 @@ class global_scope_t : public noncopyable, public scope_t
 {
   shared_ptr<session_t> session_ptr;
   ptr_list<report_t>    report_stack;
+  empty_scope_t         empty_scope;
 
 public:
   global_scope_t(char ** envp);
diff --git a/src/op.cc b/src/op.cc
index a8b71468..a5db1690 100644
--- a/src/op.cc
+++ b/src/op.cc
@@ -89,8 +89,9 @@ namespace {
 expr_t::ptr_op_t expr_t::op_t::compile(scope_t& scope, const int depth,
                                        scope_t * param_scope)
 {
-  scope_t *        scope_ptr = &scope;
-  expr_t::ptr_op_t result;
+  scope_t *           scope_ptr = &scope;
+  unique_ptr<scope_t> bound_scope;
+  expr_t::ptr_op_t    result;
 
 #if defined(DEBUG_ON)
   if (SHOW_DEBUG("expr.compile")) {
@@ -129,9 +130,10 @@ expr_t::ptr_op_t expr_t::op_t::compile(scope_t& scope, const int depth,
     }
   }
   else if (is_scope()) {
-    shared_ptr<scope_t> subscope(new symbol_scope_t(scope));
+    shared_ptr<scope_t> subscope(new symbol_scope_t(*scope_t::empty_scope));
     set_scope(subscope);
-    scope_ptr = subscope.get();
+    bound_scope.reset(new bind_scope_t(*scope_ptr, *subscope.get()));
+    scope_ptr = bound_scope.get();
   }
   else if (kind < TERMINALS) {
     result = this;
@@ -153,8 +155,8 @@ expr_t::ptr_op_t expr_t::op_t::compile(scope_t& scope, const int depth,
         node->set_left(left()->right());
         node->set_right(right());
 
-        empty_scope_t empty_scope;
-        symbol_scope_t params(param_scope ? *param_scope : empty_scope);
+        symbol_scope_t params(param_scope ?
+                              *param_scope : *scope_t::empty_scope);
         for (ptr_op_t sym = node->left();
              sym;
              sym = sym->has_right() ? sym->right() : NULL) {
@@ -330,8 +332,7 @@ value_t expr_t::op_t::calc(scope_t& scope, ptr_op_t * locus, const int depth)
     call_scope_t&  call_args(find_scope<call_scope_t>(scope, true));
     std::size_t    args_count(call_args.size());
     std::size_t    args_index(0);
-    empty_scope_t  empty_scope;
-    symbol_scope_t args_scope(empty_scope);
+    symbol_scope_t args_scope(*scope_t::empty_scope);
 
     for (ptr_op_t sym = left();
          sym;
diff --git a/src/report.h b/src/report.h
index 9541da43..f50bdc28 100644
--- a/src/report.h
+++ b/src/report.h
@@ -366,12 +366,9 @@ public:
 
   OPTION__
   (report_t, amount_, // -t
-   expr_t expr;
-   CTOR(report_t, amount_) {
-     set_expr(none, "amount");
-   }
+   DECL1(report_t, amount_, merged_expr_t, expr, ("amount_expr", "amount")) {}
    void set_expr(const optional<string>& whence, const string& str) {
-     expr = str;
+     expr.append(str);
      on(whence, str);
    }
    DO_(args) {
@@ -384,7 +381,7 @@ public:
 
   OPTION_(report_t, average, DO() { // -A
       parent->HANDLER(display_total_)
-        .set_expr(string("--average"), "count>0?(total_expr/count):0");
+        .set_expr(string("--average"), "count>0?(display_total/count):0");
     });
 
   OPTION__(report_t, balance_format_, CTOR(report_t, balance_format_) {
@@ -405,7 +402,7 @@ public:
 
   OPTION_(report_t, basis, DO() { // -B
       parent->HANDLER(revalued).on_only(string("--basis"));
-      parent->HANDLER(amount_).set_expr(string("--basis"), "rounded(cost)");
+      parent->HANDLER(amount_).expr.set_base_expr("rounded(cost)");
     });
 
   OPTION_(report_t, begin_, DO_(args) { // -b
@@ -438,20 +435,20 @@ public:
 
   OPTION__(report_t, budget_format_, CTOR(report_t, budget_format_) {
       on(none,
-         "%(justify(scrub(get_at(total_expr, 0)), 12, -1, true, color))"
-         " %(justify(-scrub(get_at(total_expr, 1)), 12, "
+         "%(justify(scrub(get_at(display_total, 0)), 12, -1, true, color))"
+         " %(justify(-scrub(get_at(display_total, 1)), 12, "
          "           12 + 1 + 12, true, color))"
-         " %(justify(scrub(get_at(total_expr, 1) + "
-         "                 get_at(total_expr, 0)), 12, "
+         " %(justify(scrub(get_at(display_total, 1) + "
+         "                 get_at(display_total, 0)), 12, "
          "           12 + 1 + 12 + 1 + 12, true, color))"
          " %(ansify_if("
-         "   justify((get_at(total_expr, 1) ? "
-         "            (100% * scrub(get_at(total_expr, 0))) / "
-         "             -scrub(get_at(total_expr, 1)) : 0), "
+         "   justify((get_at(display_total, 1) ? "
+         "            (100% * scrub(get_at(display_total, 0))) / "
+         "             -scrub(get_at(display_total, 1)) : 0), "
          "           5, -1, true, false),"
-         "   magenta if (color and get_at(total_expr, 1) and "
-         "               (abs(quantity(scrub(get_at(total_expr, 0))) / "
-         "                    quantity(scrub(get_at(total_expr, 1)))) >= 1))))"
+         "   magenta if (color and get_at(display_total, 1) and "
+         "               (abs(quantity(scrub(get_at(display_total, 0))) / "
+         "                    quantity(scrub(get_at(display_total, 1)))) >= 1))))"
          "  %(!options.flat ? depth_spacer : \"\")"
          "%-(ansify_if(partial_account(options.flat), blue if color))\n"
          "%/%$1 %$2 %$3 %$4\n%/"
@@ -467,8 +464,8 @@ public:
 
   OPTION__(report_t, cleared_format_, CTOR(report_t, cleared_format_) {
       on(none,
-         "%(justify(scrub(get_at(total_expr, 0)), 16, 16 + prepend_width, "
-         " true, color))  %(justify(scrub(get_at(total_expr, 1)), 18, "
+         "%(justify(scrub(get_at(display_total, 0)), 16, 16 + prepend_width, "
+         " true, color))  %(justify(scrub(get_at(display_total, 1)), 18, "
          " 36 + prepend_width, true, color))"
          "    %(latest_cleared ? format_date(latest_cleared) : \"         \")"
          "    %(!options.flat ? depth_spacer : \"\")"
@@ -524,7 +521,7 @@ public:
 
   OPTION_(report_t, deviation, DO() {
       parent->HANDLER(display_total_)
-        .set_expr(string("--deviation"), "amount_expr-total_expr/count");
+        .set_expr(string("--deviation"), "display_amount-display_total");
     });
 
   OPTION__
@@ -541,12 +538,10 @@ public:
 
   OPTION__
   (report_t, display_amount_,
-   expr_t expr;
-   CTOR(report_t, display_amount_) {
-     set_expr(none, "amount_expr");
-   }
+   DECL1(report_t, display_amount_, merged_expr_t, expr,
+         ("display_amount", "amount_expr")) {}
    void set_expr(const optional<string>& whence, const string& str) {
-     expr = str;
+     expr.append(str);
      on(whence, str);
    }
    DO_(args) {
@@ -555,12 +550,10 @@ public:
 
   OPTION__
   (report_t, display_total_,
-   expr_t expr;
-   CTOR(report_t, display_total_) {
-     set_expr(none, "total_expr");
-   }
+   DECL1(report_t, display_total_, merged_expr_t, expr,
+         ("display_total", "total_expr")) {}
    void set_expr(const optional<string>& whence, const string& str) {
-     expr = str;
+     expr.append(str);
      on(whence, str);
    }
    DO_(args) {
@@ -608,7 +601,10 @@ public:
 
   OPTION_(report_t, gain, DO() { // -G
       parent->HANDLER(revalued).on_only(string("--gain"));
-      parent->HANDLER(amount_).set_expr(string("--gain"), "(amount, cost)");
+
+      parent->HANDLER(amount_).expr.set_base_expr("(amount, cost)");
+      parent->HANDLER(total_).expr.set_base_expr("total");
+
       // Since we are displaying the amounts of revalued postings, they
       // will end up being composite totals, and hence a pair of pairs.
       parent->HANDLER(display_amount_)
@@ -676,10 +672,10 @@ public:
       parent->HANDLER(revalued).on_only(string("--market"));
       parent->HANDLER(display_amount_)
         .set_expr(string("--market"),
-                  "market(amount_expr, value_date, exchange)");
+                  "market(display_amount, value_date, exchange)");
       parent->HANDLER(display_total_)
         .set_expr(string("--market"),
-                  "market(total_expr, value_date, exchange)");
+                  "market(display_total, value_date, exchange)");
     });
 
   OPTION(report_t, meta_);
@@ -802,10 +798,7 @@ public:
     });
 
   OPTION_(report_t, price, DO() { // -I
-      parent->HANDLER(display_amount_)
-        .set_expr(string("--price"), "price(amount_expr)");
-      parent->HANDLER(display_total_)
-        .set_expr(string("--price"), "price(total_expr)");
+      parent->HANDLER(amount_).expr.set_base_expr("price");
     });
 
   OPTION__(report_t, prices_format_, CTOR(report_t, prices_format_) {
@@ -823,8 +816,8 @@ public:
 
   OPTION_(report_t, quantity, DO() { // -O
       parent->HANDLER(revalued).off();
-      parent->HANDLER(amount_).set_expr(string("--quantity"), "amount");
-      parent->HANDLER(total_).set_expr(string("--quantity"), "total");
+      parent->HANDLER(amount_).expr.set_base_expr("amount");
+      parent->HANDLER(total_).expr.set_base_expr("total");
     });
 
   OPTION_(report_t, quarterly, DO() {
@@ -919,12 +912,9 @@ public:
 
   OPTION__
   (report_t, total_, // -T
-   expr_t expr;
-   CTOR(report_t, total_) {
-     set_expr(none, "total");
-   }
+   DECL1(report_t, total_, merged_expr_t, expr, ("total_expr", "total")) {}
    void set_expr(const optional<string>& whence, const string& str) {
-     expr = str;
+     expr.append(str);
      on(whence, str);
    }
    DO_(args) {
@@ -961,9 +951,9 @@ public:
   OPTION(report_t, unrealized_losses_);
 
   OPTION_(report_t, unround, DO() {
-      parent->HANDLER(display_amount_)
+      parent->HANDLER(amount_)
         .set_expr(string("--unround"), "unrounded(amount_expr)");
-      parent->HANDLER(display_total_)
+      parent->HANDLER(total_)
         .set_expr(string("--unround"), "unrounded(total_expr)");
     });
 
diff --git a/src/scope.cc b/src/scope.cc
index 160a97c9..00327159 100644
--- a/src/scope.cc
+++ b/src/scope.cc
@@ -35,7 +35,8 @@
 
 namespace ledger {
 
-scope_t * scope_t::default_scope = NULL;
+scope_t *       scope_t::default_scope = NULL;
+empty_scope_t * scope_t::empty_scope   = NULL;
 
 void symbol_scope_t::define(const symbol_t::kind_t kind,
                             const string& name, expr_t::ptr_op_t def)
diff --git a/src/scope.h b/src/scope.h
index 75dc2c0f..31ef61cb 100644
--- a/src/scope.h
+++ b/src/scope.h
@@ -99,10 +99,13 @@ private:
 #endif // HAVE_BOOST_SERIALIZATION
 };
 
+class empty_scope_t;
+
 class scope_t
 {
 public:
-  static scope_t * default_scope;
+  static scope_t *       default_scope;
+  static empty_scope_t * empty_scope;
 
   explicit scope_t() {
     TRACE_CTOR(scope_t, "");