From 5d96bf908db82c97ca751a01c6a7637337ca360a Mon Sep 17 00:00:00 2001
From: Milo Turner <iitalics@gmail.com>
Date: Thu, 13 Feb 2020 12:53:03 -0500
Subject: [PATCH] [back] backend stub

less stubby
---
 src/backend.h     | 17 +++++++++++++++++
 src/backend/sdl.c | 21 +++++++++++++++++++++
 src/ctxt.h        |  6 ++++++
 src/ctxt/ctxt.c   | 29 +++++++++++++++++++++++++++--
 src/util/region.h |  8 ++++++++
 5 files changed, 79 insertions(+), 2 deletions(-)
 create mode 100644 src/backend.h
 create mode 100644 src/backend/sdl.c

diff --git a/src/backend.h b/src/backend.h
new file mode 100644
index 0000000..b4a0927
--- /dev/null
+++ b/src/backend.h
@@ -0,0 +1,17 @@
+#pragma once
+
+#include <stddef.h>
+#include <stdint.h>
+
+struct rgn;
+
+struct ax_backend;
+struct ax_font_h;
+
+extern const char* ax__backend_impl_name;
+
+struct ax_backend* ax__backend_new(
+    struct rgn* init_rgn);
+
+const char* ax__backend_get_error(
+    struct ax_backend* bac);
diff --git a/src/backend/sdl.c b/src/backend/sdl.c
new file mode 100644
index 0000000..9085424
--- /dev/null
+++ b/src/backend/sdl.c
@@ -0,0 +1,21 @@
+#include "../backend.h"
+#include "../util/region.h"
+
+struct ax_backend {
+};
+
+const char* ax__backend_impl_name = "SDL";
+
+struct ax_backend* ax__backend_new(
+    struct rgn* init_rgn)
+{
+    struct ax_backend* bac = ralloc_typed(init_rgn, struct ax_backend, 1);
+    return bac;
+}
+
+const char* ax__backend_get_error(
+    struct ax_backend* bac)
+{
+    (void) bac;
+    return NULL;
+}
diff --git a/src/ctxt.h b/src/ctxt.h
index 30b6e42..c12dd0e 100644
--- a/src/ctxt.h
+++ b/src/ctxt.h
@@ -6,6 +6,7 @@
 
 struct ax_theme;
 struct ax_theme_builder;
+struct ax_backend;
 
 struct ax_ctxt {
     struct rgn* init_rgn;
@@ -18,6 +19,9 @@ struct ax_ctxt {
     struct rgn err_rgn;
     const char* err;
 
+    // backend
+    struct ax_backend* bac;
+
     // theme
     struct rgn thmb_rgn;
     struct ax_theme_builder* thmb;
@@ -39,3 +43,5 @@ static inline void ax__set_error(struct ax_ctxt* ax, const char* text)
 {
     strcpy(ax__make_error_buf(ax, strlen(text) + 1), text);
 }
+
+struct ax_backend* ax__backend(struct ax_ctxt* ax);
diff --git a/src/ctxt/ctxt.c b/src/ctxt/ctxt.c
index 6bf393c..810305d 100644
--- a/src/ctxt/ctxt.c
+++ b/src/ctxt/ctxt.c
@@ -1,6 +1,7 @@
+#include "../ax.h"
+#include "../backend.h"
 #include "../ctxt.h"
 #include "../util.h"
-#include "../ax.h"
 #include "theme.h"
 
 /* -----------------------------------------------------------------------------
@@ -47,6 +48,8 @@ void ax__ctxt_init(struct ax_ctxt* ax, struct rgn* init_rgn)
     rgn_init(&ax->thmb_rgn, THEME_BUILDER_DESIRED_REGION_SIZE);
     ax->thmb = NULL;
     ax->sel_theme = NULL;
+
+    ax->bac = NULL;
 }
 
 void ax__ctxt_cleanup(struct ax_ctxt* ax)
@@ -55,6 +58,20 @@ void ax__ctxt_cleanup(struct ax_ctxt* ax)
     rgn_cleanup(&ax->err_rgn);
 }
 
+struct ax_backend* ax__backend(struct ax_ctxt* ax)
+{
+    if (ax->bac == NULL) {
+        struct rgn msg_rgn;
+        rgn_init(&msg_rgn, SMALL);
+        ax_log(ax, rsprintf(&msg_rgn, "initializing `%s' backend",
+                            ax__backend_impl_name));
+        rgn_cleanup(&msg_rgn);
+
+        ax->bac = ax__backend_new(ax->init_rgn);
+    }
+    return ax->bac;
+}
+
 /* -----------------------------------------------------------------------------
  * API functions :: logging
  * -------------------------------------------------------------------------- */
@@ -89,8 +106,16 @@ void ax_begin_theme(struct ax_ctxt* ax)
 void ax_end_theme(struct ax_ctxt* ax, struct ax_theme** out_thm)
 {
     ASSERT(ax->thmb != NULL, "`ax_end_theme' called while not building a theme");
-    ax__theme_builder_finish(ax->thmb, ax->init_rgn, out_thm);
+
+    struct ax_theme* thm;
+    ax__theme_builder_finish(ax->thmb, ax->init_rgn, &thm);
     rgn_clear(&ax->thmb_rgn);
+
+    (void) ax__backend(ax); // TODO: tell backend to load this theme
+
+    if (out_thm != NULL) {
+        *out_thm = thm;
+    }
 }
 
 void ax_set_theme_color(
diff --git a/src/util/region.h b/src/util/region.h
index 0b589b2..381c08c 100644
--- a/src/util/region.h
+++ b/src/util/region.h
@@ -66,3 +66,11 @@ static inline char* rstrdup(struct rgn* rgn, const char* str)
 
 #define rmemdup_typed(_rgn, T, _p, _n)          \
     ((T*) rmemdup(_rgn, _p, sizeof(T) * (_n)))
+
+#define rsprintf(_rgn, ...) ({                              \
+            size_t sprintf__len =                           \
+                snprintf(NULL, 0, __VA_ARGS__);             \
+            char* sprintf__msg =                            \
+                ralloc_typed(_rgn, char, sprintf__len + 1); \
+            sprintf(sprintf__msg, __VA_ARGS__);             \
+            sprintf__msg; })