From 09406d74711fd241a16f4e0d4cc76bfa11e42a60 Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Wed, 10 Nov 2021 17:13:56 +0100
Subject: Add initial local definition/access

---
 src/compiler.h | 39 +++++++++++++++++++++++++++++++++++----
 src/main.c     |  2 +-
 src/parser.c   |  5 +++--
 3 files changed, 39 insertions(+), 7 deletions(-)

diff --git a/src/compiler.h b/src/compiler.h
index fe36ecf..023a039 100644
--- a/src/compiler.h
+++ b/src/compiler.h
@@ -23,6 +23,7 @@ do { \
     array_insert(current_context, buf, n_chars); \
 } while(false);
 
+static Environment *current_env = NULL;
 
 // TODO: Separate c/h files
 // TODO: Create a "driver.c" file with the (display) function for external
@@ -51,7 +52,7 @@ do { \
 void compile_object(Object *obj);
 void compile_fixnum(Object *obj);
 void compile_proc_call(Object *obj);
-void compile(Root *roots);
+void compile(Program program);
 
 char *
 generate_label(char *prefix) {
@@ -505,6 +506,25 @@ compile_lambda(Object *obj) {
     context_printf("    ;; <-- compile_lambda\n");
 }
 
+void
+compile_def(Object *obj) {
+    context_printf("    ;; --> compile_def\n");
+    compile_object(obj->var_expr);
+    ssize_t idx = find_local_index(current_env->locals, obj->var_name);
+    context_printf("    pop     rax\n");
+    context_printf("    mov     [rbp + %ld], rax\n", 8 * (idx + 1));
+    context_printf("    ;; <-- compile_def\n");
+}
+
+void
+compile_symbol(Object *obj) {
+    context_printf("    ;; --> compile_symbol\n");
+    ssize_t idx = find_local_index(current_env->locals, obj);
+    context_printf("    mov     rax, [rbp + %ld]\n", 8 * (idx + 1));
+    context_printf("    push    rax\n");
+    context_printf("    ;; <-- compile_symbol\n");
+}
+
 void
 compile_object(Object *obj) {
     switch (obj->type) {
@@ -516,6 +536,8 @@ compile_object(Object *obj) {
         case OBJ_TYPE_STRING: { compile_string(obj); } break;
         case OBJ_TYPE_IF: { compile_if(obj); } break;
         case OBJ_TYPE_LAMBDA: { compile_lambda(obj); } break;
+        case OBJ_TYPE_DEF: { compile_def(obj); } break;
+        case OBJ_TYPE_SYMBOL: { compile_symbol(obj); } break;
         default: break;
     }
 }
@@ -555,16 +577,17 @@ emit_data_section(void) {
 }
 
 void
-compile(Root *roots) {
+compile(Program program) {
     // Prepare compilation variables.
     array_init(constants, 0);
     array_init(labels, 0);
     array_init(procedures, 0);
     array_init(current_context, 0);
+    current_env = program.env;
 
     // Compile program.
-    for (size_t i = 0; i < array_size(roots); i++) {
-        Object *root = roots[i];
+    for (size_t i = 0; i < array_size(program.roots); i++) {
+        Object *root = program.roots[i];
         compile_object(root);
     }
 
@@ -604,7 +627,15 @@ compile(Root *roots) {
     printf("alignb  8\n");
     printf("global _start\n");
     printf("_start:\n");
+
+    // Initialize heap pointer.
     printf("    mov     r15, bdl_heap\n");
+
+    // Initialize main locals.
+    printf("    sub     rsp, %zu\n", 8 * array_size(program.env->locals));
+    printf("    mov     rbp, rsp\n");
+
+    // Keep the bottom stack value set as NIL_VAL for a default return value.
     printf("    push    NIL_VAL\n");
     for (size_t i = 0; i < array_size(current_context); i++) {
         putchar(current_context[i]);
diff --git a/src/main.c b/src/main.c
index 8962519..d006d2d 100644
--- a/src/main.c
+++ b/src/main.c
@@ -45,7 +45,7 @@ process_source(const StringView *source, const char *file_name) {
     // TODO: Optimization.
 
     // Compilation.
-    compile(program.roots);
+    compile(program);
 
     // Free resources.
     free_objects();
diff --git a/src/parser.c b/src/parser.c
index 100916b..2bf95d4 100644
--- a/src/parser.c
+++ b/src/parser.c
@@ -569,6 +569,7 @@ parse(Token *tokens, Errors *errors) {
 
     // Prepare global environment of builtin functions.
     Environment *global_env = env_alloc(NULL);
+    Environment *env = env_alloc(global_env);
     size_t n_builtins = sizeof(builtins) / sizeof(char*);
     for (size_t i = 0; i < n_builtins; i++) {
         // Prepare builtin symbol.
@@ -600,7 +601,7 @@ parse(Token *tokens, Errors *errors) {
             }
         }
         array_push(final_roots, root);
-        semantic_analysis(global_env, root, errors);
+        semantic_analysis(env, root, errors);
         if (errors->n != 0) {
             array_free(final_roots);
             return (Program){0};
@@ -614,7 +615,7 @@ parse(Token *tokens, Errors *errors) {
     // TODO: Type check basic expressions (e.g. arithmetic/numeric comparisons).
     // We can't be sure when we have functions unless the return type is known.
 
-    return (Program){roots, global_env};
+    return (Program){roots, env};
 }
 
 Environment *
-- 
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