Change std::stringstream& to std::ostream& in render_to() (#76)

* Change std::stringstream& to std::ostream& in render_to()

Fixes #75

* Expose render_to

* Update readme with example of render_to

Author: Timmmm

README.md

@@ -19,6 +19,11 @@ data["name"] = "world";
 inja::render("Hello {{ name }}!", data); // Returns "Hello world!"
 ```
 
+`inja::render()` returns a `std::string` but you can also output to a `std::ostream&`, for example:
+
+```c++
+inja::render_to(std::cout, "Hello {{ name }}!", data);
+```
 
 ## Integration
 

include/inja/environment.hpp

@@ -133,7 +133,7 @@ class Environment {
 		write(temp, data, filename_out);
 	}
 
-  std::stringstream& render_to(std::stringstream& os, const Template& tmpl, const json& data) {
+  std::ostream& render_to(std::ostream& os, const Template& tmpl, const json& data) {
     Renderer(m_impl->included_templates, m_impl->callbacks).render_to(os, tmpl, data);
     return os;
   }
@@ -164,12 +164,20 @@ class Environment {
 };
 
 /*!
-@brief render with default settings
+@brief render with default settings to a string
 */
 inline std::string render(std::string_view input, const json& data) {
   return Environment().render(input, data);
 }
 
+/*!
+@brief render with default settings to the given output stream
+*/
+inline void render_to(std::ostream& os, std::string_view input, const json& data) {
+  Environment env;
+  env.render_to(os, env.parse(input), data);
+}
+
 }
 
 #endif // PANTOR_INJA_ENVIRONMENT_HPP

include/inja/renderer.hpp

@@ -167,7 +167,7 @@ class Renderer {
     m_tmp_args.reserve(4);
   }
 
-  void render_to(std::stringstream& os, const Template& tmpl, const json& data) {
+  void render_to(std::ostream& os, const Template& tmpl, const json& data) {
     m_data = &data;
 
     for (size_t i = 0; i < tmpl.bytecodes.size(); ++i) {

single_include/inja/inja.hpp

@@ -1443,7 +1443,7 @@ class Renderer {
     m_tmp_args.reserve(4);
   }
 
-  void render_to(std::stringstream& os, const Template& tmpl, const json& data) {
+  void render_to(std::ostream& os, const Template& tmpl, const json& data) {
     m_data = &data;
 
     for (size_t i = 0; i < tmpl.bytecodes.size(); ++i) {
@@ -1957,7 +1957,7 @@ class Environment {
 		write(temp, data, filename_out);
 	}
 
-  std::stringstream& render_to(std::stringstream& os, const Template& tmpl, const json& data) {
+  std::ostream& render_to(std::ostream& os, const Template& tmpl, const json& data) {
     Renderer(m_impl->included_templates, m_impl->callbacks).render_to(os, tmpl, data);
     return os;
   }
@@ -1988,12 +1988,20 @@ class Environment {
 };
 
 /*!
-@brief render with default settings
+@brief render with default settings to a string
 */
 inline std::string render(std::string_view input, const json& data) {
   return Environment().render(input, data);
 }
 
+/*!
+@brief render with default settings to the given output stream
+*/
+inline void render_to(std::ostream& os, std::string_view input, const json& data) {
+  Environment env;
+  env.render_to(os, env.parse(input), data);
+}
+
 }
 
 #endif // PANTOR_INJA_ENVIRONMENT_HPP