Add finishing touches to code for part 6 of compiler series

code/compiler/06/ast.cpp

@@ -176,7 +176,7 @@ 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());
+    type_data* type = dynamic_cast<type_data*>(of->node_type.get());
 
     of->compile(env, into);
     into.push_back(instruction_ptr(new instruction_eval()));
@@ -201,9 +201,15 @@ void ast_case::compile(const env_ptr& env, std::vector<instruction_ptr>& into) c
             }
             jump_instruction->branches.push_back(std::move(branch_instructions));
         } else if((cpat = dynamic_cast<pattern_constr*>(branch->pat.get()))) {
+            env_ptr new_env = env;
+            for(auto it = cpat->params.rbegin(); it != cpat->params.rend(); it++) {
+                new_env = env_ptr(new env_var(*it, new_env));
+            }
+
             branch_instructions.push_back(instruction_ptr(new instruction_split()));
-            branch->expr->compile(env_ptr(new env_offset(cpat->params.size(), env)),
+            branch->expr->compile(new_env, branch_instructions);
-                branch_instructions);
+            branch_instructions.push_back(instruction_ptr(new instruction_slide(
+                            cpat->params.size())));
 
             int new_tag = type->constructors[cpat->constr].tag;
             if(jump_instruction->tag_mappings.find(new_tag) !=

code/compiler/06/ast.hpp

@@ -59,6 +59,7 @@ struct definition {
     virtual void typecheck_first(type_mgr& mgr, type_env& env) = 0;
     virtual void typecheck_second(type_mgr& mgr, const type_env& env) const = 0;
     virtual void resolve(const type_mgr& mgr) = 0;
+    virtual void compile() = 0;
 };
 
 using definition_ptr = std::unique_ptr<definition>;
@@ -168,6 +169,8 @@ struct definition_defn : public definition {
     type_ptr return_type;
     std::vector<type_ptr> param_types;
 
+    std::vector<instruction_ptr> instructions;
+
     definition_defn(std::string n, std::vector<std::string> p, ast_ptr b)
         : name(std::move(n)), params(std::move(p)), body(std::move(b)) {
 
@@ -176,6 +179,7 @@ struct definition_defn : public definition {
     void typecheck_first(type_mgr& mgr, type_env& env);
     void typecheck_second(type_mgr& mgr, const type_env& env) const;
     void resolve(const type_mgr& mgr);
+    void compile();
 };
 
 struct definition_data : public definition {
@@ -188,4 +192,5 @@ struct definition_data : public definition {
     void typecheck_first(type_mgr& mgr, type_env& env);
     void typecheck_second(type_mgr& mgr, const type_env& env) const;
     void resolve(const type_mgr& mgr);
+    void compile();
 };

code/compiler/06/definition.cpp

@@ -41,6 +41,15 @@ void definition_defn::resolve(const type_mgr& mgr) {
     }
 }
 
+void definition_defn::compile() {
+    env_ptr new_env = env_ptr(new env_offset(0, nullptr));
+    for(auto it = params.rbegin(); it != params.rend(); it++) {
+        new_env = env_ptr(new env_var(*it, new_env));
+    }
+    body->compile(new_env, instructions);
+    instructions.push_back(instruction_ptr(new instruction_update(params.size())));
+}
+
 void definition_data::typecheck_first(type_mgr& mgr, type_env& env) {
     type_data* this_type = new type_data(name);
     type_ptr return_type = type_ptr(this_type);
@@ -67,3 +76,6 @@ void definition_data::resolve(const type_mgr& mgr) {
     // Nothing
 }
 
+void definition_data::compile() {
+
+}

code/compiler/06/instruction.cpp

@@ -21,12 +21,12 @@ void instruction_push::print(int indent, std::ostream& to) const {
 
 void instruction_mkapp::print(int indent, std::ostream& to) const {
     print_indent(indent, to);
-    to << "Push()" << std::endl;
+    to << "MkApp()" << std::endl;
 }
 
 void instruction_update::print(int indent, std::ostream& to) const {
     print_indent(indent, to);
-    to << "Offset(" << offset << ")" << std::endl;
+    to << "Update(" << offset << ")" << std::endl;
 }
 
 void instruction_pack::print(int indent, std::ostream& to) const {
@@ -48,6 +48,8 @@ void instruction_jump::print(int indent, std::ostream& to) const {
         }
         to << std::endl;
     }
+    print_indent(indent, to);
+    to << ")" << std::endl;
 }
 
 void instruction_slide::print(int indent, std::ostream& to) const {

code/compiler/06/main.cpp

@@ -42,6 +42,19 @@ void typecheck_program(
     }
 }
 
+void compile_program(const std::vector<definition_ptr>& prog) {
+    for(auto& def : prog) {
+        def->compile();
+
+        definition_defn* defn = dynamic_cast<definition_defn*>(def.get());
+        if(!defn) continue;
+        for(auto& instruction : defn->instructions) {
+            instruction->print(0, std::cout);
+        }
+        std::cout << std::endl;
+    }
+}
+
 int main() {
     yy::parser parser;
     type_mgr mgr;
@@ -60,6 +73,7 @@ int main() {
     }
     try {
         typecheck_program(program, mgr, env);
+        compile_program(program);
     } catch(unification_error& err) {
         std::cout << "failed to unify types: " << std::endl;
         std::cout << "  (1) \033[34m";

content/blog/06_compiler_semantics.md

@@ -168,6 +168,10 @@ first define C++ structs for the instructions of the G-machine:
 
 {{< codeblock "C++" "compiler/06/instruction.hpp" >}}
 
+I omit the implementation of the various (trivial) `print` methods in this post;
+as always, you can look at the full project source code, which is 
+freely available for each post in the series.
+
 We can now envision a method on the `ast` struct that takes an environment 
 (just like our compilation scheme takes the environment \\(\\rho\\\)),
 and compiles the `ast`. Rather than returning a vector
@@ -282,7 +286,7 @@ struct, called `type_data`:
 
 When we create types from `definition_data`, we tag the corresponding constructors:
 
-{{< codelines "C++" "compiler/06/definition.cpp" 35 51 >}}
+{{< codelines "C++" "compiler/06/definition.cpp" 53 69 >}}
 
 Ah, but adding constructor info to the type doesn't solve the problem.
 Once we performed type checking, we don't keep
@@ -339,7 +343,7 @@ of a node. Here's a sample implementation from `ast_binop`:
 
 And here's the implementation of `definition::resolve` on `definition_defn`:
 
-{{< codelines "C++" "compiler/06/definition.cpp" 31 33 >}}
+{{< codelines "C++" "compiler/06/definition.cpp" 32 42 >}}
 
 Finally, we call `resolve` at the end `typecheck_program` in `main.cpp`:
 
@@ -348,7 +352,7 @@ Finally, we call `resolve` at the end `typecheck_program` in `main.cpp`:
 At last, we're ready to implement the code for compiling `ast_case`.
 Here it is, in all its glory:
 
-{{< codelines "C++" "compiler/06/ast.cpp" 178 224 >}}
+{{< codelines "C++" "compiler/06/ast.cpp" 178 230 >}}
 
 There's a lot to unpack here. First of all, just like we said in the compilation
 scheme, we want to build and evaluate the expression that's being analyzed.
@@ -399,4 +403,51 @@ After we're done with all the branches, we also check for non-exhaustive pattern
 since otherwise we could run into runtime errors. With this, the case expression,
 and the last of the AST nodes, can be compiled.
 
+We also add a `compile` method to definitions, since they contain
+our AST nodes. The method is empty for `defn_data`, and
+looks as follows for `definition_defn`:
+
+{{< codelines "C++" "compiler/06/definition.cpp" 44 51 >}}
+
+Finally, we make a function in our `main.cpp` file to compile
+all the definitions:
+
+{{< codelines "C++" "compiler/06/main.cpp" 45 56 >}}
+
+In this method, we also include some extra
+output to help us see the result of our compilation. Since
+at the moment, only the `definition_defn` program has to
+be compiled, we try cast all definitions to it, and if
+we succeed, we print them out.
+
+Let's try it all out! For the below sample program:
+
+{{< rawblock "compiler/06/examples/works1.txt" >}}
+
+Our compiler produces the following new output:
+```
+PushInt(6)
+PushInt(320)
+PushGlobal(plus)
+MkApp()
+MkApp()
+
+Push(1)
+Push(1)
+PushGlobal(+)
+MkApp()
+MkApp()
+```
+
+The first sequence of instructions is clearly `main`. It creates
+an application of `plus` to `320`, and then applies that to
+`6`, which results in `plus 320 6`, which is correct. The
+second sequence of instruction pushes the parameter that
+sits on offset 1 from the top of the stack (`y`). It then
+pushes a parameter from the same offset again, but this time,
+since `y` was previously pushed on the stack, `x` is now
+in that position, so `x` is pushed onto the stack.
+Finally, `+` is pushed, and the application
+`(+) x y` is created, which is equivalent to `x+y`.
+
 {{< todo >}}Backport bugfix in case's typecheck{{< /todo >}}