(WIP) implement preprocessor for GLSL

common/gl_shader_preproc.hh

@@ -0,0 +1,62 @@
+#pragma once
+
+#include <fstream>
+#include <memory>
+#include <sstream>
+#include <string_view>
+
+#include "nf7.hh"
+
+
+namespace nf7::gl {
+
+inline nf7::Future<std::monostate> ExecPreprocessShader(
+    const std::shared_ptr<nf7::Context>& ctx,
+    const std::shared_ptr<std::ostream>& ost,
+    const std::shared_ptr<std::istream>& ist) noexcept;
+
+inline void PreprocessShader(
+    nf7::Future<std::monostate>::Promise& pro,
+    const std::shared_ptr<nf7::Context>&  ctx,
+    const std::shared_ptr<std::ostream>&  ost,
+    const std::shared_ptr<std::istream>&  ist) noexcept
+try {
+  std::string line;
+  while (std::getline(*ist, line)) {
+    if (line.starts_with('#')) {
+      std::string_view tok {line.begin() + 1, line.end()};
+      while (!tok.empty() && !std::isalpha(tok.front())) {
+        tok.remove_prefix(1);
+      }
+      if (tok.starts_with("include ")) {
+        tok.remove_prefix(sizeof("include")-1);
+
+        auto begin = std::find(tok.begin(), tok.end(), '"');
+        auto end   = std::find(begin,       tok.end(), '"');
+
+        auto f = std::make_shared<std::ifstream>(std::string {begin, end}, std::ios::binary);
+        ExecPreprocessShader(ctx, ost, f).ThenIf([=](auto&) mutable {
+          ExecPreprocessShader(ctx, ost, ist).Chain(pro);
+        });
+        return;
+      }
+    }
+    *ost << line;
+  }
+  pro.Return({});
+} catch (...) {
+  pro.Throw<nf7::Exception>("failed to preprocess GLSL");
+}
+
+inline nf7::Future<std::monostate> ExecPreprocessShader(
+    const std::shared_ptr<nf7::Context>& ctx,
+    const std::shared_ptr<std::ostream>& ost,
+    const std::shared_ptr<std::istream>& ist) noexcept {
+  nf7::Future<std::monostate>::Promise pro {ctx};
+  ctx->env().ExecAsync(ctx, [=]() mutable {
+    PreprocessShader(pro, ctx, ost, ist);
+  });
+  return pro.future();
+}
+
+}  // namespace nf7::gl

file/gl_obj.cc

@@ -35,6 +35,7 @@
 #include "common/gl_enum.hh"
 #include "common/gl_fence.hh"
 #include "common/gl_obj.hh"
+#include "common/gl_shader_preproc.hh"
 #include "common/gui_config.hh"
 #include "common/life.hh"
 #include "common/logger_ref.hh"
@@ -667,8 +668,21 @@ struct Shader {
   }
 
   nf7::Future<std::shared_ptr<Product>> Create(const CreateParam& p) noexcept {
-    // TODO: preprocessing GLSL source
-    return Product::Create(p.ctx, type_, src_);
+    nf7::Future<std::shared_ptr<Product>>::Promise pro {p.ctx};
+
+    // TODO test
+
+    auto ost = std::make_shared<std::ostringstream>(src_);
+    auto ist = std::make_shared<std::istringstream>();
+    gl::ExecPreprocessShader(p.ctx, ost, ist).
+        Then([p, ist, pro, type = type_](auto) mutable {
+          try {
+            Product::Create(p.ctx, type, ist->str()).Chain(pro);
+          } catch (nf7::Exception&) {
+            pro.Throw(std::current_exception());
+          }
+        });
+    return pro.future();
   }
 
   bool Handle(const HandleParam<Product>&) {