inja/README.md

# Inja

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## Design

```c++
json data;
data["name"] = "world";

inja::render("Hello {{ name }}!", data); // "Hello World!"
```

## Integration

Inja is headers only. Just one dependency: json by nlohmann. 

```c++
#include "json.hpp"
#include "inja.hpp"

// For convenience
using namespace inja;
using json = nlohmann::json;
```
    

## Tutorial


### Template Rendering
```c++
json data;
data["name"] = "world";

render("Hello {{ name }}!", data); // "Hello World!"

// For more advanced usage, an environment is recommended
Environment env = Environment();

// Render a string with json data
std::string result = env.render("Hello {{ name }}!", data);

// Or directly read a template file
std::string result_template = env.render_temlate("template.txt", data);

// And read a json file for data
std::string result_template_2 = env.render_temlate_with_json_file("template.txt", "data.json");
```

The environment class can be configured.
```c++
// With default settings
Environment env_default = Environment();

// With global path to template files
Environment env_default = Environment("../path/templates/"); 
```

### Variables

Variables can be rendered with the `{{ ... }}` syntax.

```c++
json data;
data["name"] = "world";
data["guests"] = {"Jeff", "Pierre", "Tom"};
data["time"]["start"]["hour"] = 16;
data["time"]["end"]["hour"] = 21;

string template = """
    {{ guests/0 }}
    
    {{ time/start/hour }} to {{ time/end/hour }} or {{ 24 }}
""";
```

Valid Json -> Printed. Json Pointer.


### Statements

Statements can be written with the `(% ... %)` syntax. The most important statements are loops, conditions and file includes.All statements can be nested.

#### Loops

<table>
	<tbody>
		<tr>
      		<th>Template</th>
      		<th>Json</th>
      		<th>Result</th>
    	</tr>
		<tr>
			<td>
<pre lang="txt">
Guests:
(% for guest in guests %){{ index1 }}: {{ guest }}
(% endfor %)</pre>
			</td>
			<td>
<pre lang="json">
{
  "guests":  [
    "Jeff",
    "Pierre",
    "Tom"
  ]
}</pre>
			</td>
			<td>
<pre lang="txt">
Guests:
1. Jeff
2. Pierre
3. Tom
</pre>
			</td>
		</tr>
	</tbody>
</table>

In the loop, some special variables are available:
- `int index, index1`
- `bool is_first`
- `bool is_last`

#### Conditions

If, else if, else. Nested. conditions:
- `not`
- `==`, `>`, `<`, `>=`, `<=`, `!=`
- `in`

#### Includes

Include other files like `(% include "footer.html" %)`. Relative from file.

### Comments

Comments can be rendered with the `{# ... #}` syntax.

```c++
render("Hello{# Todo #}!", data); // "Hello!"
```

## Supported compilers

Currently, the following compilers are tested:

- GCC 4.9 - 7.1 (and possibly later)
- Clang 3.6 - 3.8 (and possibly later)


## License

The class is licensed under the [MIT License](https://raw.githubusercontent.com/pantor/inja/master/LICENSE).