Refactor AST and Parser into modular subdirectories

- Split ast.h into granular headers in v0/ast/
- Split parser.c into modular implementation files in v0/parser/
- Move and rename parser tests to v0/parser/test_*.c
- Update build system (include.mk) with modular sub-makefiles
- Maintain v0/ast.h and v0/parser.h as umbrella headers

v0/parser/module.c

@@ -0,0 +1,125 @@
+#include "internal.h"
+#include "../log.h"
+#include <stdlib.h>
+#include <string.h>
+
+bool parse_module_declaration(Parser* p, Module* module) {
+    if (!parser_expect(p, TOKEN_MODULE, "expected keyword 'module'")) {
+        return false;
+    }
+
+    if (!parser_require(p, TOKEN_IDENTIFIER, "expected module identifier")) {
+        return false;
+    }
+    module->name = parser_to_text(p);
+
+    return parser_expect(p, TOKEN_SEMICOLON, "expected ';' after module name");
+}
+
+Module* parser_parse(TokenStream* ts) {
+    Parser* p = malloc(sizeof(Parser));
+    p->ts = ts;
+    parser_next_token(p);
+
+    Module* module = malloc(sizeof(Module));
+    memset(module, 0, sizeof(Module));
+    if (!parse_module_declaration(p, module)) {
+        goto fail;
+    }
+
+    while (!parser_peek(p, TOKEN_EOF)) {
+        bool is_public = false;
+        bool is_static = false;
+        bool is_const = false;
+        bool terminal = false;
+        
+        while (!terminal) {
+            if (parser_accept(p, TOKEN_IMPORT)) {
+                if (is_static) {
+                    log_on_line(&p->token.location, "import declarations cannot be static or const");
+                    goto fail;
+                }
+                if (is_const) {
+                    log_on_line(&p->token.location, "import declarations cannot be static or const");
+                    goto fail;
+                }
+                if (!parse_import_declaration(p, module, is_public)) {
+                    goto fail;
+                }
+                terminal = true;
+            } else if (parser_accept(p, TOKEN_ALIAS)) {
+                if (is_static) {
+                    log_on_line(&p->token.location, "alias declarations cannot be static or const");
+                    goto fail;
+                }
+                if (is_const) {
+                    log_on_line(&p->token.location, "alias declarations cannot be static or const");
+                    goto fail;
+                }
+                if (!parse_alias_declaration(p, module, is_public)) {
+                    goto fail;
+                }
+                terminal = true;
+            } else if (parser_accept(p, TOKEN_PUBLIC)) {
+                is_public = true;
+            } else if (parser_accept(p, TOKEN_STATIC)) {
+                is_static = true;
+            } else if (parser_accept(p, TOKEN_CONST)) {
+                is_const = true;
+            } else if (parser_accept(p, TOKEN_VAR) || parser_accept_primitive(p)) {
+                if (!parse_variable_declaration(p, module, is_public, is_static, is_const)) {
+                    goto fail;
+                }
+                terminal = true;
+            } else {
+                log_on_line(&p->token.location, "unexpected token");
+                goto fail;
+            }
+        }
+    }
+
+    free(p);
+    return module;
+fail:
+    free(p);
+    parser_free(module);
+    return NULL;
+}
+
+void parser_free(Module* module) {
+	if (module == NULL) {
+        return;
+    }
+
+    if (module->imports != NULL) {
+        for(size_t i = 0; i < module->import_count; i++) {
+            free(module->imports[i].module_name);
+        }
+        free(module->imports);
+    }
+    
+    if (module->aliases != NULL) {
+        for(size_t i = 0; i < module->alias_count; i++) {
+            free((void*)module->aliases[i].name);
+            free_type_expression(&module->aliases[i].value);
+        }
+        free(module->aliases);
+    }
+
+    if (module->variables != NULL) {
+        for(size_t i = 0; i < module->variable_count; i++) {
+            free(module->variables[i].name);
+            free_type_expression(&module->variables[i].type);
+            if (module->variables[i].initializer) {
+                if (module->variables[i].initializer->tag == EXPRESSION_STRING) {
+                    free((void*)module->variables[i].initializer->string);
+                }
+                free(module->variables[i].initializer);
+            }
+        }
+        free(module->variables);
+    }
+
+    free(module->name);
+    free(module);
+}