From 007c89501bd77e40b44edda7f914077831dac1c4 Mon Sep 17 00:00:00 2001
From: Danila Fedorin <danila.fedorin@gmail.com>
Date: Tue, 8 Oct 2019 23:46:35 -0700
Subject: [PATCH] Implement ast_case::compile for compiler series and reference
 code

---
 06/ast.cpp         | 44 ++++++++++++++++++++++++++++++++++++++++++++
 06/instruction.hpp |  7 +++++++
 2 files changed, 51 insertions(+)

diff --git a/06/ast.cpp b/06/ast.cpp
index 3954a8a..ad85a09 100644
--- a/06/ast.cpp
+++ b/06/ast.cpp
@@ -176,7 +176,51 @@ void ast_case::resolve(const type_mgr& mgr) const {
 }
 
 void ast_case::compile(const env_ptr& env, std::vector<instruction_ptr>& into) const {
+    type_data* type = dynamic_cast<type_data*>(node_type.get());
 
+    of->compile(env, into);
+    into.push_back(instruction_ptr(new instruction_eval()));
+
+    instruction_jump* jump_instruction = new instruction_jump();
+    into.push_back(instruction_ptr(jump_instruction));
+    for(auto& branch : branches) {
+        std::vector<instruction_ptr> branch_instructions;
+        pattern_var* vpat;
+        pattern_constr* cpat;
+
+        if((vpat = dynamic_cast<pattern_var*>(branch->pat.get()))) {
+            branch->expr->compile(env_ptr(new env_offset(1, env)), branch_instructions);
+
+            for(auto& constr_pair : type->constructors) {
+                if(jump_instruction->tag_mappings.find(constr_pair.second.tag) !=
+                        jump_instruction->tag_mappings.end())
+                    break;
+
+                jump_instruction->tag_mappings[constr_pair.second.tag] =
+                    jump_instruction->branches.size();
+            }
+            jump_instruction->branches.push_back(std::move(branch_instructions));
+        } else if((cpat = dynamic_cast<pattern_constr*>(branch->pat.get()))) {
+            branch_instructions.push_back(instruction_ptr(new instruction_split()));
+            branch->expr->compile(env_ptr(new env_offset(cpat->params.size(), env)),
+                branch_instructions);
+
+            int new_tag = type->constructors[cpat->constr].tag;
+            if(jump_instruction->tag_mappings.find(new_tag) !=
+                    jump_instruction->tag_mappings.end())
+                throw type_error("technically not a type error: duplicate pattern");
+
+            jump_instruction->tag_mappings[new_tag] =
+                jump_instruction->branches.size();
+            jump_instruction->branches.push_back(std::move(branch_instructions));
+        }
+    }
+
+    for(auto& constr_pair : type->constructors) {
+        if(jump_instruction->tag_mappings.find(constr_pair.second.tag) ==
+                jump_instruction->tag_mappings.end())
+            throw type_error("non-total pattern");
+    }
 }
 
 void pattern_var::print(std::ostream& to) const {
diff --git a/06/instruction.hpp b/06/instruction.hpp
index 8d846e0..40196e4 100644
--- a/06/instruction.hpp
+++ b/06/instruction.hpp
@@ -2,6 +2,8 @@
 #include <string>
 #include <memory>
 #include "binop.hpp"
+#include <vector>
+#include <map>
 
 struct instruction {
     virtual ~instruction() = default;
@@ -53,6 +55,11 @@ struct instruction_split : public instruction {
     
 };
 
+struct instruction_jump : public instruction {
+    std::vector<std::vector<instruction_ptr>> branches;
+    std::map<int, int> tag_mappings;
+};
+
 struct instruction_slide : public instruction {
     int offset;