https://github.com/akkartik/mu/blob/master/019type_abbreviations.cc
  1 //: For convenience, allow Mu types to be abbreviated.
  2 
  3 :(scenarios transform)
  4 :(scenario type_abbreviations)
  5 type foo = number
  6 def main [
  7   a:foo <- copy 34
  8 ]
  9 +transform: product type after expanding abbreviations: "number"
 10 
 11 :(before "End Globals")
 12 map<string, type_tree*> Type_abbreviations, Type_abbreviations_snapshot;
 13 
 14 //:: Defining type abbreviations.
 15 
 16 :(before "End Command Handlers")
 17 else if (command == "type") {
 18   load_type_abbreviations(in);
 19 }
 20 
 21 :(code)
 22 void load_type_abbreviations(istream& in) {
 23   string new_type_name = next_word(in);
 24   assert(has_data(in) || !new_type_name.empty());
 25   if (!has_data(in) || new_type_name.empty()) {
 26     raise << "incomplete 'type' statement; must be of the form 'type <new type name> = <type expression>'\n" << end();
 27     return;
 28   }
 29   string arrow = next_word(in);
 30   assert(has_data(in) || !arrow.empty());
 31   if (arrow.empty()) {
 32     raise << "incomplete 'type' statement 'type " << new_type_name << "'\n" << end();
 33     return;
 34   }
 35   if (arrow != "=") {
 36     raise << "'type' statements must be of the form 'type <new type name> = <type expression>' but got 'type " << new_type_name << ' ' << arrow << "'\n" << end();
 37     return;
 38   }
 39   if (!has_data(in)) {
 40     raise << "incomplete 'type' statement 'type " << new_type_name << " ='\n" << end();
 41     return;
 42   }
 43   string old = next_word(in);
 44   if (old.empty()) {
 45     raise << "incomplete 'type' statement 'type " << new_type_name << " ='\n" << end();
 46     raise << "'type' statements must be of the form 'type <new type name> = <type expression>' but got 'type " << new_type_name << ' ' << arrow << "'\n" << end();
 47     return;
 48   }
 49   if (contains_key(Type_abbreviations, new_type_name)) {
 50     raise << "'type' conflict: '" << new_type_name << "' defined as both '" << names_to_string_without_quotes(get(Type_abbreviations, new_type_name)) << "' and '" << old << "'\n" << end();
 51     return;
 52   }
 53   trace(9990, "type") << "alias " << new_type_name << " = " << old << end();
 54   type_tree* old_type = new_type_tree(old);
 55   put(Type_abbreviations, new_type_name, old_type);
 56 }
 57 
 58 type_tree* new_type_tree(const string& x) {
 59   string_tree* type_names = starts_with(x, "(") ? parse_string_tree(x) : parse_string_list(x);
 60   type_tree* result = new_type_tree(type_names);
 61   delete type_names;
 62   expand_type_abbreviations(result);
 63   return result;
 64 }
 65 
 66 string_tree* parse_string_list(const string& s) {
 67   istringstream in(s);
 68   in >> std::noskipws;
 69   return parse_property_list(in);
 70 }
 71 
 72 :(scenario type_error1)
 73 % Hide_errors = true;
 74 type foo
 75 +error: incomplete 'type' statement 'type foo'
 76 
 77 :(scenario type_error2)
 78 % Hide_errors = true;
 79 type foo =
 80 +error: incomplete 'type' statement 'type foo ='
 81 
 82 :(scenario type_error3)
 83 % Hide_errors = true;
 84 type foo bar baz
 85 +error: 'type' statements must be of the form 'type <new type name> = <type expression>' but got 'type foo bar'
 86 
 87 :(scenario type_conflict_error)
 88 % Hide_errors = true;
 89 type foo = bar
 90 type foo = baz
 91 +error: 'type' conflict: 'foo' defined as both 'bar' and 'baz'
 92 
 93 :(scenario type_abbreviation_for_compound)
 94 type foo = address:number
 95 def main [
 96   1:foo <- copy null
 97 ]
 98 +transform: product type after expanding abbreviations: ("address" "number")
 99 
100 //: cleaning up type abbreviations between tests and before exiting
101 
102 :(before "End save_snapshots")
103 Type_abbreviations_snapshot = Type_abbreviations;
104 :(before "End restore_snapshots")
105 restore_type_abbreviations();
106 :(before "End One-time Setup")
107 atexit(clear_type_abbreviations);
108 :(code)
109 void restore_type_abbreviations() {
110   for (map<string, type_tree*>::iterator p = Type_abbreviations.begin();  p != Type_abbreviations.end();  ++p) {
111     if (!contains_key(Type_abbreviations_snapshot, p->first))
112       delete p->second;
113   }
114   Type_abbreviations.clear();
115   Type_abbreviations = Type_abbreviations_snapshot;
116 }
117 void clear_type_abbreviations() {
118   for (map<string, type_tree*>::iterator p = Type_abbreviations.begin();  p != Type_abbreviations.end();  ++p)
119     delete p->second;
120   Type_abbreviations.clear();
121 }
122 
123 //:: A few default abbreviations.
124 
125 :(before "End Mu Types Initialization")
126 put(Type_abbreviations, "&", new_type_tree("address"));
127 put(Type_abbreviations, "@", new_type_tree("array"));
128 put(Type_abbreviations, "num", new_type_tree("number"));
129 put(Type_abbreviations, "bool", new_type_tree("boolean"));
130 put(Type_abbreviations, "char", new_type_tree("character"));
131 
132 :(scenario use_type_abbreviations_when_declaring_type_abbreviations)
133 type foo = &:num
134 def main [
135   1:foo <- copy null
136 ]
137 +transform: product type after expanding abbreviations: ("address" "number")
138 
139 //:: Expand type aliases before running.
140 //: We'll do this in a transform so that we don't need to define abbreviations
141 //: before we use them.
142 
143 :(scenario abbreviations_for_address_and_array)
144 def main [
145   f 1:&:num  # abbreviation for 'address:number'
146   f 2:@:num  # abbreviation for 'array:number'
147   f 3:&:@:num  # combining '&' and '@'
148   f 4:&:&:@:&:@:num  # ..any number of times
149   f {5: (array (& num) 3)}  # support for dilated reagents and more complex parse trees
150 ]
151 def f [
152 ]
153 +transform: --- expand type abbreviations in recipe 'main'
154 +transform: ingredient type after expanding abbreviations: ("address" "number")
155 +transform: ingredient type after expanding abbreviations: ("array" "number")
156 +transform: ingredient type after expanding abbreviations: ("address" "array" "number")
157 +transform: ingredient type after expanding abbreviations: ("address" "address" "array" "address" "array" "number")
158 +transform: ingredient type after expanding abbreviations: ("array" ("address" "number") "3")
159 
160 :(before "Transform.push_back(update_instruction_operations)")
161 Transform.push_back(expand_type_abbreviations);  // idempotent
162 // Begin Type Modifying Transforms
163 // End Type Modifying Transforms
164 
165 :(code)
166 void expand_type_abbreviations(const recipe_ordinal r) {
167   expand_type_abbreviations(get(Recipe, r));
168 }
169 
170 void expand_type_abbreviations(const recipe& caller) {
171   trace(9991, "transform") << "--- expand type abbreviations in recipe '" << caller.name << "'" << end();
172   for (int i = 0;  i < SIZE(caller.steps);  ++i) {
173     const instruction& inst = caller.steps.at(i);
174     trace(9991, "transform") << "instruction '" << to_original_string(inst) << end();
175     for (long int i = 0;  i < SIZE(inst.ingredients);  ++i) {
176       expand_type_abbreviations(inst.ingredients.at(i).type);
177       trace(9992, "transform") << "ingredient type after expanding abbreviations: " << names_to_string(inst.ingredients.at(i).type) << end();
178     }
179     for (long int i = 0;  i < SIZE(inst.products);  ++i) {
180       expand_type_abbreviations(inst.products.at(i).type);
181       trace(9992, "transform") << "product type after expanding abbreviations: " << names_to_string(inst.products.at(i).type) << end();
182     }
183   }
184   // End Expand Type Abbreviations(caller)
185 }
186 
187 void expand_type_abbreviations(type_tree* type) {
188   if (!type) return;
189   if (!type->atom) {
190     expand_type_abbreviations(type->left);
191     expand_type_abbreviations(type->right);
192     return;
193   }
194   if (contains_key(Type_abbreviations, type->name))
195     *type = type_tree(*get(Type_abbreviations, type->name));
196 }