1 //: So far the recipes we define can't run each other. Let's fix that.
  2 
  3 :(scenario calling_recipe)
  4 def main [
  5   f
  6 ]
  7 def f [
  8   3:num <- add 2, 2
  9 ]
 10 +mem: storing 4 in location 3
 11 
 12 :(scenario return_on_fallthrough)
 13 def main [
 14   f
 15   1:num <- copy 0
 16   2:num <- copy 0
 17   3:num <- copy 0
 18 ]
 19 def f [
 20   4:num <- copy 0
 21   5:num <- copy 0
 22 ]
 23 +run: f
 24 # running f
 25 +run: {4: "number"} <- copy {0: "literal"}
 26 +run: {5: "number"} <- copy {0: "literal"}
 27 # back out to main
 28 +run: {1: "number"} <- copy {0: "literal"}
 29 +run: {2: "number"} <- copy {0: "literal"}
 30 +run: {3: "number"} <- copy {0: "literal"}
 31 
 32 :(before "struct routine {")
 33 // Everytime a recipe runs another, we interrupt it and start running the new
 34 // recipe. When that finishes, we continue this one where we left off.
 35 // This requires maintaining a 'stack' of interrupted recipes or 'calls'.
 36 struct call {
 37   recipe_ordinal running_recipe;
 38   int running_step_index;
 39   // End call Fields
 40   call(recipe_ordinal r) {
 41     running_recipe = r;
 42     running_step_index = 0;
 43     // End call Constructor
 44   }
 45   ~call() {
 46     // End call Destructor
 47   }
 48 };
 49 typedef list<call> call_stack;
 50 
 51 :(replace{} "struct routine")
 52 struct routine {
 53   call_stack calls;
 54   // End routine Fields
 55   routine(recipe_ordinal r);
 56   bool completed() const;
 57   const vector<instruction>& steps() const;
 58 };
 59 :(code)
 60 routine::routine(recipe_ordinal r) {
 61   if (Trace_stream) {
 62     ++Trace_stream->callstack_depth;
 63     trace(9999, "trace") << "new routine; incrementing callstack depth to " << Trace_stream->callstack_depth << end();
 64     assert(Trace_stream->callstack_depth < 9000);  // 9998-101 plus cushion
 65   }
 66   calls.push_front(call(r));
 67   // End routine Constructor
 68 }
 69 
 70 :(code)
 71 call& current_call() {
 72   return Current_routine->calls.front();
 73 }
 74 
 75 //:: now update routine's helpers
 76 
 77 :(replace{} "int& current_step_index()")
 78 int& current_step_index() {
 79   assert(!Current_routine->calls.empty());
 80   return current_call().running_step_index;
 81 }
 82 :(replace{} "const string& current_recipe_name()")
 83 const string& current_recipe_name() {
 84   assert(!Current_routine->calls.empty());
 85   return get(Recipe, current_call().running_recipe).name;
 86 }
 87 :(replace{} "const recipe& current_recipe()")
 88 const recipe& current_recipe() {
 89   assert(!Current_routine->calls.empty());
 90   return get(Recipe, current_call().running_recipe);
 91 }
 92 :(replace{} "const instruction& current_instruction()")
 93 const instruction& current_instruction() {
 94   assert(!Current_routine->calls.empty());
 95   return to_instruction(current_call());
 96 }
 97 :(code)
 98 const instruction& to_instruction(const call& call) {
 99   return get(Recipe, call.running_recipe).steps.at(call.running_step_index);
100 }
101 
102 :(after "Defined Recipe Checks")
103 // not a primitive; check that it's present in the book of recipes
104 if (!contains_key(Recipe, inst.operation)) {
105   raise << maybe(get(Recipe, r).name) << "undefined operation in '" << inst.original_string << "'\n" << end();
106   break;
107 }
108 :(replace{} "default:" following "End Primitive Recipe Implementations")
109 default: {
110   const instruction& call_instruction = current_instruction();
111   if (Recipe.find(current_instruction().operation) == Recipe.end()) {  // duplicate from Checks
112     // stop running this instruction immediately
113     ++current_step_index();
114     continue;
115   }
116   // not a primitive; look up the book of recipes
117   if (Trace_stream) {
118     ++Trace_stream->callstack_depth;
119     trace(9999, "trace") << "incrementing callstack depth to " << Trace_stream->callstack_depth << end();
120     assert(Trace_stream->callstack_depth < 9000);  // 9998-101 plus cushion
121   }
122   Current_routine->calls.push_front(call(current_instruction().operation));
123   finish_call_housekeeping(call_instruction, ingredients);
124   continue;  // not done with caller; don't increment step_index of caller
125 }
126 :(code)
127 void finish_call_housekeeping(const instruction& call_instruction, const vector<vector<double> >& ingredients) {
128   // End Call Housekeeping
129 }
130 
131 :(scenario calling_undefined_recipe_fails)
132 % Hide_errors = true;
133 def main [
134   foo
135 ]
136 +error: main: undefined operation in 'foo '
137 
138 :(scenario calling_undefined_recipe_handles_missing_result)
139 % Hide_errors = true;
140 def main [
141   x:num <- foo
142 ]
143 +error: main: undefined operation in 'x:num <- foo '
144 
145 //:: finally, we need to fix the termination conditions for the run loop
146 
147 :(replace{} "bool routine::completed() const")
148 bool routine::completed() const {
149   return calls.empty();
150 }
151 
152 :(replace{} "const vector<instruction>& routine::steps() const")
153 const vector<instruction>& routine::steps() const {
154   assert(!calls.empty());
155   return get(Recipe, calls.front().running_recipe).steps;
156 }
157 
158 :(before "Running One Instruction")
159 // when we reach the end of one call, we may reach the end of the one below
160 // it, and the one below that, and so on
161 while (current_step_index() >= SIZE(Current_routine->steps())) {
162   // Falling Through End Of Recipe
163   if (Trace_stream) {
164     trace(9999, "trace") << "fall-through: exiting " << current_recipe_name() << "; decrementing callstack depth from " << Trace_stream->callstack_depth << end();
165     --Trace_stream->callstack_depth;
166     assert(Trace_stream->callstack_depth >= 0);
167   }
168   Current_routine->calls.pop_front();
169   if (Current_routine->calls.empty()) goto stop_running_current_routine;
170   // Complete Call Fallthrough
171   // todo: fail if no products returned
172   ++current_step_index();
173 }