replace template variables in shaders

src/gpufont/shader_catalog.cpp

@@ -20,10 +20,10 @@ class UpdateList {
     std::unordered_map <std::string, std::chrono::steady_clock::time_point> updates;
 
     public:
-        void requestUpdate(const std::string & name){
+        void requestUpdate(const std::string & name, bool immediately){
             using namespace std::chrono_literals;
             std::lock_guard <std::mutex> guard(mutex);
-            updates[name] = std::chrono::steady_clock::now() + 50ms;
+            updates[name] = std::chrono::steady_clock::now() + (immediately ? 0ms : 50ms);
         }
 
         std::vector <std::string> collectDueUpdates(){
@@ -46,17 +46,39 @@ class ShaderCatalog::Impl {
     private:
         std::string dir;
         std::unordered_map <std::string, std::shared_ptr <Entry> > entries;
+        std::map <std::string, std::string> replacements;
+        std::mutex replacementMutex;
 
         UpdateList list;
 
     public:
+        void setReplacement(const std::string & a, const std::string & b){
+            std::lock_guard <std::mutex> guard(replacementMutex);
+            replacements[a] = b;
+        }
+        const map <std::string, std::string> & getReplacements(){
+            std::lock_guard <std::mutex> guard(replacementMutex);
+            return replacements;
+        }
         Impl(const std::string & dir) : dir(dir){
         }
-        void requestUpdate(const std::string & name){
-            list.requestUpdate(name);
+        void requestUpdate(const std::string & name, bool immediately){
+            list.requestUpdate(name, immediately);
         }
 
     private:
+
+        void replaceAll(std::string & str, const std::string & from, const std::string & to){
+            if(from.empty()){
+                return;
+            }
+            size_t start_pos = 0;
+            while((start_pos = str.find(from, start_pos)) != std::string::npos){
+                str.replace(start_pos, from.length(), to);
+                start_pos += to.length(); // In case 'to' contains 'from', like replacing 'x' with 'yx'
+            }
+        }
+
         std::string readFile(const std::string & filename, std::string & error){
             std::ifstream stream(filename, std::ios::binary);
             if(!stream){
@@ -70,11 +92,24 @@ class ShaderCatalog::Impl {
 
             std::string result = std::string(size, 0);
             stream.read(&result[0], size);
+
             if(!stream){
                 error = "failed to read: " + filename;
                 return "";
             }
 
+            {
+                //std::cout << "read shader from " << filename << " : " << result << std::endl;
+                const auto & r = getReplacements();
+                for(const auto & pair : r){
+                    replaceAll(result, pair.first, pair.second);
+                    //cout << "replace " << pair.first << " with " << pair.second << endl;
+                }
+
+                //std::cout << "after replacement " << filename << " : " << result << std::endl;
+
+            }
+
             return result;
         }
 
@@ -164,6 +199,7 @@ class ShaderCatalog::Impl {
             for(const std::string & name : updates){
                 auto it = entries.find(name);
                 if(it == entries.end()){
+                    //cout << "this should have do update but don't in " << __LINE__ << endl;
                     continue;
                 }
 
@@ -186,6 +222,18 @@ ShaderCatalog::ShaderCatalog(const std::string & dir) : impl(std::make_unique <I
 ShaderCatalog::~ShaderCatalog(){
 }
 
+void ShaderCatalog::setReplacement(const std::string & a, const std::string & b){
+    impl->setReplacement(a, b);
+}
+const std::string & ShaderCatalog::getReplacement(const std::string & a){
+    auto & replacements = impl->getReplacements();
+    if(replacements.count(a) > 0){
+        return replacements.at(a);
+    }else{
+        return dummy;
+    }
+}
+
 std::shared_ptr <ShaderCatalog::Entry> ShaderCatalog::get(const std::string & name){
     return impl->get(name);
 }
@@ -194,7 +242,7 @@ void ShaderCatalog::update(){
     impl->update();
 }
 
-void ShaderCatalog::requestUpdate(const std::string & name){
-    impl->requestUpdate(name);
+void ShaderCatalog::requestUpdate(const std::string & name, bool immediately){
+    impl->requestUpdate(name, immediately);
 }
 }

src/gpufont/shader_catalog.hpp

@@ -24,12 +24,15 @@ class ShaderCatalog {
         ShaderCatalog(const std::string & dir);
         ~ShaderCatalog();
 
+        void setReplacement(const std::string & a, const std::string & b);
+        const std::string & getReplacement(const std::string & a);
         std::shared_ptr <Entry> get(const std::string & name);
         void update();
-        void requestUpdate(const std::string & name);
+        void requestUpdate(const std::string & name, bool immediately = false);
 
     private:
         class Impl;
         std::unique_ptr <Impl> impl;
+        const std::string dummy = "";
 };
 }