From 6a64ed40c9f37715854fc02824e754a912fd7983 Mon Sep 17 00:00:00 2001
From: "Tristan B. Velloza Kildaire" <deavmi@redxen.eu>
Date: Sun, 11 Dec 2022 21:41:15 +0200
Subject: [PATCH] CodeEmitter

- Added `finalize()` method, this is to be called whenever the emitting is done and a compiler is to be called on the code

DGen

- Implemented a gcc-based finalization method
- Added `emitEntryPoint()` to emit a main() function which is to be called in libc's `_start` symbol

VariableDeclaration

- Added note we may need a symbol table lookup system actually, rather than just a simple `symbolRename`

Compiler

- Call the `finalize()` method on the DGen code emitter

----

Test cases

- Added `simple_variables_only_decs.t` to test code generation
---
 source/tlang/compiler/codegen/emit/core.d     |  2 +
 source/tlang/compiler/codegen/emit/dgen.d     | 42 +++++++++++++++++++
 source/tlang/compiler/codegen/instruction.d   |  2 +
 source/tlang/compiler/compiler.d              |  2 +
 .../testing/simple_variables_only_decs.t      |  5 +++
 5 files changed, 53 insertions(+)
 create mode 100644 source/tlang/testing/simple_variables_only_decs.t

diff --git a/source/tlang/compiler/codegen/emit/core.d b/source/tlang/compiler/codegen/emit/core.d
index 28042890..4a3e1d57 100644
--- a/source/tlang/compiler/codegen/emit/core.d
+++ b/source/tlang/compiler/codegen/emit/core.d
@@ -41,4 +41,6 @@ public abstract class CodeEmitter
     }
 
     public abstract void emit();
+
+    public abstract void finalize();
 }
\ No newline at end of file
diff --git a/source/tlang/compiler/codegen/emit/dgen.d b/source/tlang/compiler/codegen/emit/dgen.d
index dda73ff3..763b8ed0 100644
--- a/source/tlang/compiler/codegen/emit/dgen.d
+++ b/source/tlang/compiler/codegen/emit/dgen.d
@@ -11,6 +11,7 @@ import std.string : cmp;
 import gogga;
 import std.range : walkLength;
 import std.string : wrap;
+import std.process : spawnProcess, Pid, ProcessException, wait;
 
 public final class DCodeEmitter : CodeEmitter
 {
@@ -19,6 +20,31 @@ public final class DCodeEmitter : CodeEmitter
         super(typeChecker, file);
     }
 
+    public override void finalize()
+    {
+        try
+        {
+            //NOTE: Change to system compiler (maybe, we need to choose a good C compiler)
+            Pid ccPID = spawnProcess(["gcc", "-o", "tlang.out", file.name()]);
+
+            //NOTE: Case where it exited and Pid now inavlid (if it happens it would throw processexception surely)?
+            int code = wait(ccPID);
+            gprintln(code);
+
+            if(code)
+            {
+                //NOTE: Make this a TLang exception
+                throw new Exception("The CC exited with a non-zero exit code");
+            }
+        }
+        catch(ProcessException e)
+        {
+            gprintln("NOTE: Case where it exited and Pid now inavlid (if it happens it would throw processexception surely)?", DebugType.ERROR);
+            assert(false);
+
+        }
+    }
+
     public override void emit()
     {
         // Emit header comment (NOTE: Change this to a useful piece of text)
@@ -29,6 +55,11 @@ public final class DCodeEmitter : CodeEmitter
 
         gprintln("Code emittings needed: "~to!(string)(walkLength(codeQueue[])));
         emitCodeQueue(codeQueue);
+
+        //TODO: Emit function definitions
+
+        //TODO: Emit main (entry point)
+        emitEntryPoint();
     }
 
     /** 
@@ -83,4 +114,15 @@ public final class DCodeEmitter : CodeEmitter
             file.writeln(currentInstruction.emit());
         }
     }
+
+    private void emitEntryPoint()
+    {
+        //TODO: Implement me
+
+        file.writeln(`
+int main()
+{
+    return 0;
+}`);
+    }
 }
\ No newline at end of file
diff --git a/source/tlang/compiler/codegen/instruction.d b/source/tlang/compiler/codegen/instruction.d
index bfa88b1d..be56e8de 100644
--- a/source/tlang/compiler/codegen/instruction.d
+++ b/source/tlang/compiler/codegen/instruction.d
@@ -104,6 +104,8 @@ public final class VariableDeclaration : StorageDeclaration
         // a custom CodeEmitter should be allowed, so let's call it a general rule)
         //
         //simple_variables.x -> simple_variables_x
+        //NOTE: We may need to create a symbol table actually and add to that and use that as these names
+        //could get out of hand (too long)
         string renamedSymbol = symbolRename(typedEntityVariableName);
 
         return varType~" "~renamedSymbol~";";
diff --git a/source/tlang/compiler/compiler.d b/source/tlang/compiler/compiler.d
index 1b10222a..1282ea6f 100644
--- a/source/tlang/compiler/compiler.d
+++ b/source/tlang/compiler/compiler.d
@@ -80,6 +80,8 @@ void beginCompilation(string[] sourceFiles)
             emitter.emit();
             outFile.close();
 
+            // Cause the generation to happen
+            emitter.finalize();
         }
         // catch(CollidingNameException e)
         // {
diff --git a/source/tlang/testing/simple_variables_only_decs.t b/source/tlang/testing/simple_variables_only_decs.t
new file mode 100644
index 00000000..b0d4c34a
--- /dev/null
+++ b/source/tlang/testing/simple_variables_only_decs.t
@@ -0,0 +1,5 @@
+module simple_variables_only_decs;
+
+
+int x;
+int y;
\ No newline at end of file