Amber is a Jade-Lang inspired C++ HTML template engine. Amber takes a simple but powerful input lang and generates C++ that produces HTML.
Talk is cheap, let us begin:
<{{
#include <boost/variant.hpp>
#include <unordered_map>
#include <string>
}}>
< html // this is a comment until the end of the line
< head
< title A web page &{{ params["title"] }}&>
>
< body
< h1.foo A web page made with Amber >
Some line &{{ params["firstline"] }}&
&{{ params["secondline"] }}& another line
< ul
& for(int i = 0; i < params["runs"]; ++i) {
< li Item &{{ i }}& >
& }
>
>
>
running
$ amber -i example.am -n example -o example.hpp
will create a file called "example.hpp" with the following content.
#pragma once
#include <ostream>
#include <boost/variant.hpp>
#include <unordered_map>
#include <string>
#include <sstream>
#include <iostream>
template<typename O, typename P>
void example(O& out, P& params) {
out<<"<!DOCTYPE html>\n";
out<<"<html>\n";
out<<"<head>\n";
out<<"<title>\n";
out<<"A web page ";
out<<( params["title"] );
out<<"</title>\n";
out<<"</head>\n";
out<<"<body>\n";
out<<"<h1 class=\"foo\">\n";
out<<"A web page made with Amber ";
out<<"</h1>\n";
out<<"Some line ";
out<<( params["firstline"] );
out<<( params["secondline"] );
out<<"another line";
out<<"<ul>\n";
for(int i = 0; i < boost::get<int>(params["runs"]); ++i) {
out<<"<li>\n";
out<<"Item ";
out<<( i );
out<<"</li>\n";
}
out<<"</ul>\n";
out<<"</body>\n";
out<<"</html>\n";
}
This file contains a single function called example. The functions takes two arguments. The first argument must be something that acts as an output stream. The second argument can be anything, but the name params suggest it to be parameters.
Removing the first line adding a main function:
int main(int argc, char *argv[]) {
std::unordered_map<std::string, boost::variant<std::string,int>> map;
map["title"] = "Amber is awesome";
map["firstline"] = "Some useful string";
map["secondline"] = "Another line";
map["runs"] = 2;
std::stringstream out;
example(out, map);
std::cout<<out.str()<<std::endl;
return 0;
}
and than compiling and running it should give you something like:
<!DOCTYPE html>
<html>
<head>
<title>
A web page Amber is awesome</title>
</head>
<body>
<h1 class="foo">
A web page made with Amber </h1>
Some line Some useful stringAnother lineanother line<ul>
<li>
Item 0</li>
<li>
Item 1</li>
</ul>
</body>
</html>
Dumping this into a file and opening it in a browser will give you a working webpage.
Not complete yet!
Tag := < TagStart (Tag|CodeBlock|CodeLine|Text)* >
TagStart := Identifier
| Identifier.classTag
| Identifier.classTag#idTag
| Identifier.classTag#idTag(node_attribute_list_ESCAPE_QUOTES)
| Identifier#idTag
| Identifier#idTag(node_attribute_list_ESCAPE_QUOTES)
| Identifier(node_attribute_list_ESCAPE_QUOTES)
CodeBlock := <{{ .* }}>
CodeLine := \n&.*\n
Text := Some text plus InlineCPP more text\n
InlineCPP := &{{ some expression }}&