1278 - support before/after tangle directives

No way to only insert code at a label in a specific recipe. Let's see
how that goes.

1 files changed, 198 insertions, 0 deletions

diff --git a/077tangle.cc b/077tangle.cc
new file mode 100644
index 00000000..9ec03f68
--- /dev/null
+++ b/077tangle.cc
@@ -0,0 +1,198 @@
+//: Allow code for recipes to be pulled in from multiple places.
+//:
+//: TODO: switch recipe.steps to a more efficient data structure.
+
+:(scenario tangle_before)
+recipe main [
+  1:integer <- copy 0:literal
+  +label1
+  3:integer <- copy 0:literal
+]
+
+before +label1 [
+  2:integer <- copy 0:literal
+]
++mem: storing 0 in location 1
++mem: storing 0 in location 2
++mem: storing 0 in location 3
+# nothing else
+$mem: 3
+
+//: while loading recipes, load before/after fragments
+
+:(before "End Globals")
+map<string /*label*/, recipe> Before_fragments, After_fragments;
+:(before "End Setup")
+Before_fragments.clear();
+After_fragments.clear();
+
+:(before "End Command Handlers")
+else if (command == "before") {
+  string label = next_word(in);
+  recipe tmp = slurp_recipe(in);
+  Before_fragments[label].steps.insert(Before_fragments[label].steps.end(), tmp.steps.begin(), tmp.steps.end());
+}
+else if (command == "after") {
+  string label = next_word(in);
+  recipe tmp = slurp_recipe(in);
+  After_fragments[label].steps.insert(After_fragments[label].steps.begin(), tmp.steps.begin(), tmp.steps.end());
+}
+
+//: after all recipes are loaded, insert fragments at appropriate labels
+
+:(after "int main")
+  Transform.push_back(insert_fragments);
+
+:(code)
+void insert_fragments(const recipe_number r) {
+  // Copy into a new vector because insertions invalidate iterators.
+  // But this way we can't insert into labels created inside before/after.
+  vector<instruction> result;
+  for (index_t i = 0; i < Recipe[r].steps.size(); ++i) {
+    const instruction inst = Recipe[r].steps[i];
+    if (!inst.is_label) {
+      result.push_back(inst);
+      continue;
+    }
+    if (Before_fragments.find(inst.label) != Before_fragments.end()) {
+      result.insert(result.end(), Before_fragments[inst.label].steps.begin(), Before_fragments[inst.label].steps.end());
+    }
+    result.push_back(inst);
+    if (After_fragments.find(inst.label) != After_fragments.end()) {
+      result.insert(result.end(), After_fragments[inst.label].steps.begin(), After_fragments[inst.label].steps.end());
+    }
+  }
+//?   for (index_t i = 0; i < result.size(); ++i) { //? 1
+//?     cout << result[i].to_string() << '\n'; //? 1
+//?   } //? 1
+  Recipe[r].steps.swap(result);
+}
+
+:(scenario tangle_before_and_after)
+recipe main [
+  1:integer <- copy 0:literal
+  +label1
+  4:integer <- copy 0:literal
+]
+before +label1 [
+  2:integer <- copy 0:literal
+]
+after +label1 [
+  3:integer <- copy 0:literal
+]
++mem: storing 0 in location 1
++mem: storing 0 in location 2
+# label1
++mem: storing 0 in location 3
++mem: storing 0 in location 4
+# nothing else
+$mem: 4
+
+:(scenario tangle_keeps_labels_separate)
+recipe main [
+  1:integer <- copy 0:literal
+  +label1
+  +label2
+  6:integer <- copy 0:literal
+]
+before +label1 [
+  2:integer <- copy 0:literal
+]
+after +label1 [
+  3:integer <- copy 0:literal
+]
+before +label2 [
+  4:integer <- copy 0:literal
+]
+after +label2 [
+  5:integer <- copy 0:literal
+]
++mem: storing 0 in location 1
++mem: storing 0 in location 2
+# label1
++mem: storing 0 in location 3
+# 'after' fragments for earlier label always go before 'before' fragments for later label
++mem: storing 0 in location 4
+# label2
++mem: storing 0 in location 5
++mem: storing 0 in location 6
+# nothing else
+$mem: 6
+
+:(scenario tangle_stacks_multiple_fragments)
+recipe main [
+  1:integer <- copy 0:literal
+  +label1
+  6:integer <- copy 0:literal
+]
+before +label1 [
+  2:integer <- copy 0:literal
+]
+after +label1 [
+  3:integer <- copy 0:literal
+]
+before +label1 [
+  4:integer <- copy 0:literal
+]
+after +label1 [
+  5:integer <- copy 0:literal
+]
++mem: storing 0 in location 1
+# 'before' fragments stack in order
++mem: storing 0 in location 2
++mem: storing 0 in location 4
+# label1
+# 'after' fragments stack in reverse order
++mem: storing 0 in location 5
++mem: storing 0 in location 3
++mem: storing 0 in location 6
+# nothing else
+$mem: 6
+
+:(scenario tangle_supports_fragments_with_multiple_instructions)
+recipe main [
+  1:integer <- copy 0:literal
+  +label1
+  6:integer <- copy 0:literal
+]
+before +label1 [
+  2:integer <- copy 0:literal
+  3:integer <- copy 0:literal
+]
+after +label1 [
+  4:integer <- copy 0:literal
+  5:integer <- copy 0:literal
+]
++mem: storing 0 in location 1
++mem: storing 0 in location 2
++mem: storing 0 in location 3
+# label1
++mem: storing 0 in location 4
++mem: storing 0 in location 5
++mem: storing 0 in location 6
+# nothing else
+$mem: 6
+
+:(scenario tangle_tangles_into_all_labels_with_same_name)
+recipe main [
+  1:integer <- copy 0:literal
+  +label1
+  +label1
+  4:integer <- copy 0:literal
+]
+before +label1 [
+  2:integer <- copy 0:literal
+]
+after +label1 [
+  3:integer <- copy 0:literal
+]
++mem: storing 0 in location 1
++mem: storing 0 in location 2
+# label1
++mem: storing 0 in location 3
++mem: storing 0 in location 2
+# label1
++mem: storing 0 in location 3
++mem: storing 0 in location 4
+# nothing else
+$mem: 6