pantor · pantor · May 25, 2021 · May 20, 2021 · May 20, 2021 · May 20, 2021
diff --git a/LICENSE b/LICENSE
@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2018 lbersch
+Copyright (c) 2018-2021 lbersch
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

diff --git a/README.md b/README.md
@@ -254,25 +254,6 @@ render("{{ isArray(guests) }}", data); // "true"
 // Implemented type checks: isArray, isBoolean, isFloat, isInteger, isNumber, isObject, isString,
 ```
 
-### Whitespace Control
-
-In the default configuration, no whitespace is removed while rendering the file. To support a more readable template style, you can configure the environment to control whitespaces before and after a statement automatically. While enabling `set_trim_blocks` removes the first newline after a statement, `set_lstrip_blocks` strips tabs and spaces from the beginning of a line to the start of a block.
-
-```.cpp
-Environment env;
-env.set_trim_blocks(true);
-env.set_lstrip_blocks(true);
-```
-
-With both `trim_blocks` and `lstrip_blocks` enabled, you can put statements on their own lines. Furthermore, you can also strip whitespaces for both statements and expressions by hand. If you add a minus sign (`-`) to the start or end, the whitespaces before or after that block will be removed:
-
-```.cpp
-render("Hello       {{- name -}}     !", data); // "Hello Inja!"
-render("{% if neighbour in guests -%}   I was there{% endif -%}   !", data); // Renders without any whitespaces
-```
-
-Stripping behind a statement or expression also removes any newlines.
-
 ### Callbacks
 
 You can create your own and more complex functions with callbacks. These are implemented with `std::function`, so you can for example use C++ lambdas. Inja `Arguments` are a vector of json pointers.
@@ -316,6 +297,61 @@ env.add_void_callback("log", 1, [greet](Arguments args) {
 env.render("{{ log(neighbour) }}", data); // Prints nothing to result, only to cout...
 ```
 
+### Template Inheritance
+
+Template inheritance allows you to build a base *skeleton* template that contains all the common elements and defines blocks that child templates can override. Lets show an example: The base template
+```.html
+<!DOCTYPE html>
+<html>
+<head>
+  {% block head %}
+  <link rel="stylesheet" href="style.css" />
+  <title>{% block title %}{% endblock %} - My Webpage</title>
+  {% endblock %}
+</head>
+<body>
+  <div id="content">{% block content %}{% endblock %}</div>
+</body>
+</html>
+```
+contains three `blocks` that child templates can fill in. The child template
+```.html
+{% extends "base.html" %}
+{% block title %}Index{% endblock %}
+{% block head %}
+  {{ super() }}
+  <style type="text/css">
+    .important { color: #336699; }
+  </style>
+{% endblock %}
+{% block content %}
+  <h1>Index</h1>
+  <p class="important">
+    Welcome to my blog!
+  </p>
+{% endblock %}
+```
+calls a parent template with the `extends` keyword; it should be the first element in the template. It is possible to render the contents of the parent block by calling `super()`. In the case of multiple levels of `{% extends %}`, super references may be called with an argument (e.g. `super(2)`) to skip levels in the inheritance tree.
+
+### Whitespace Control
+
+In the default configuration, no whitespace is removed while rendering the file. To support a more readable template style, you can configure the environment to control whitespaces before and after a statement automatically. While enabling `set_trim_blocks` removes the first newline after a statement, `set_lstrip_blocks` strips tabs and spaces from the beginning of a line to the start of a block.
+
+```.cpp
+Environment env;
+env.set_trim_blocks(true);
+env.set_lstrip_blocks(true);
+```
+
+With both `trim_blocks` and `lstrip_blocks` enabled, you can put statements on their own lines. Furthermore, you can also strip whitespaces for both statements and expressions by hand. If you add a minus sign (`-`) to the start or end, the whitespaces before or after that block will be removed:
+
+```.cpp
+render("Hello       {{- name -}}     !", data); // "Hello Inja!"
+render("{% if neighbour in guests -%}   I was there{% endif -%}   !", data); // Renders without any whitespaces
+```
+
+Stripping behind a statement or expression also removes any newlines.
+
 ### Comments
 
 Comments can be written with the `{# ... #}` syntax.

diff --git a/include/inja/config.hpp b/include/inja/config.hpp
@@ -1,4 +1,4 @@
-// Copyright (c) 2019 Pantor. All rights reserved.
+// Copyright (c) 2021 Pantor. All rights reserved.
 
 #ifndef INCLUDE_INJA_CONFIG_HPP_
 #define INCLUDE_INJA_CONFIG_HPP_

diff --git a/include/inja/environment.hpp b/include/inja/environment.hpp
@@ -1,4 +1,4 @@
-// Copyright (c) 2019 Pantor. All rights reserved.
+// Copyright (c) 2021 Pantor. All rights reserved.
 
 #ifndef INCLUDE_INJA_ENVIRONMENT_HPP_
 #define INCLUDE_INJA_ENVIRONMENT_HPP_

diff --git a/include/inja/exceptions.hpp b/include/inja/exceptions.hpp
@@ -1,4 +1,4 @@
-// Copyright (c) 2020 Pantor. All rights reserved.
+// Copyright (c) 2021 Pantor. All rights reserved.
 
 #ifndef INCLUDE_INJA_EXCEPTIONS_HPP_
 #define INCLUDE_INJA_EXCEPTIONS_HPP_

diff --git a/include/inja/function_storage.hpp b/include/inja/function_storage.hpp
@@ -1,4 +1,4 @@
-// Copyright (c) 2020 Pantor. All rights reserved.
+// Copyright (c) 2021 Pantor. All rights reserved.
 
 #ifndef INCLUDE_INJA_FUNCTION_STORAGE_HPP_
 #define INCLUDE_INJA_FUNCTION_STORAGE_HPP_
@@ -64,6 +64,7 @@ class FunctionStorage {
     Round,
     Sort,
     Upper,
+    Super,
     Callback,
     ParenLeft,
     ParenRight,
@@ -106,6 +107,8 @@ class FunctionStorage {
     {std::make_pair("round", 2), FunctionData { Operation::Round }},
     {std::make_pair("sort", 1), FunctionData { Operation::Sort }},
     {std::make_pair("upper", 1), FunctionData { Operation::Upper }},
+    {std::make_pair("super", 0), FunctionData { Operation::Super }},
+    {std::make_pair("super", 1), FunctionData { Operation::Super }},
   };
 
 public:

diff --git a/include/inja/inja.hpp b/include/inja/inja.hpp
@@ -1,4 +1,4 @@
-// Copyright (c) 2020 Pantor. All rights reserved.
+// Copyright (c) 2021 Pantor. All rights reserved.
 
 #ifndef INCLUDE_INJA_INJA_HPP_
 #define INCLUDE_INJA_INJA_HPP_

diff --git a/include/inja/lexer.hpp b/include/inja/lexer.hpp
@@ -51,7 +51,7 @@ class Lexer {
     if (tok_start >= m_in.size()) {
       return make_token(Token::Kind::Eof);
     }
-    char ch = m_in[tok_start];
+    const char ch = m_in[tok_start];
     if (ch == ' ' || ch == '\t' || ch == '\r') {
       tok_start += 1;
       goto again;
@@ -61,15 +61,15 @@ class Lexer {
     if (!close_trim.empty() && inja::string_view::starts_with(m_in.substr(tok_start), close_trim)) {
       state = State::Text;
       pos = tok_start + close_trim.size();
-      Token tok = make_token(closeKind);
+      const Token tok = make_token(closeKind);
       skip_whitespaces_and_newlines();
       return tok;
     }
 
     if (inja::string_view::starts_with(m_in.substr(tok_start), close)) {
       state = State::Text;
       pos = tok_start + close.size();
-      Token tok = make_token(closeKind);
+      const Token tok = make_token(closeKind);
       if (trim) {
         skip_whitespaces_and_first_newline();
       }
@@ -88,7 +88,7 @@ class Lexer {
       return scan_id();
     }
 
-    MinusState current_minus_state = minus_state;
+    const MinusState current_minus_state = minus_state;
     if (minus_state == MinusState::Operator) {
       minus_state = MinusState::Number;
     }
@@ -183,7 +183,7 @@ class Lexer {
       if (pos >= m_in.size()) {
         break;
       }
-      char ch = m_in[pos];
+      const char ch = m_in[pos];
       if (!std::isalnum(ch) && ch != '.' && ch != '/' && ch != '_' && ch != '-') {
         break;
       }
@@ -197,7 +197,7 @@ class Lexer {
       if (pos >= m_in.size()) {
         break;
       }
-      char ch = m_in[pos];
+      const char ch = m_in[pos];
       // be very permissive in lexer (we'll catch errors when conversion happens)
       if (!std::isdigit(ch) && ch != '.' && ch != 'e' && ch != 'E' && ch != '+' && ch != '-') {
         break;
@@ -213,7 +213,7 @@ class Lexer {
       if (pos >= m_in.size()) {
         break;
       }
-      char ch = m_in[pos++];
+      const char ch = m_in[pos++];
       if (ch == '\\') {
         escape = true;
       } else if (!escape && ch == m_in[tok_start]) {
@@ -302,7 +302,7 @@ class Lexer {
     default:
     case State::Text: {
       // fast-scan to first open character
-      size_t open_start = m_in.substr(pos).find_first_of(config.open_chars);
+      const size_t open_start = m_in.substr(pos).find_first_of(config.open_chars);
       if (open_start == nonstd::string_view::npos) {
         // didn't find open, return remaining text as text token
         pos = m_in.size();

diff --git a/include/inja/node.hpp b/include/inja/node.hpp
@@ -1,4 +1,4 @@
-// Copyright (c) 2020 Pantor. All rights reserved.
+// Copyright (c) 2021 Pantor. All rights reserved.
 
 #ifndef INCLUDE_INJA_NODE_HPP_
 #define INCLUDE_INJA_NODE_HPP_
@@ -28,6 +28,8 @@ class ForArrayStatementNode;
 class ForObjectStatementNode;
 class IfStatementNode;
 class IncludeStatementNode;
+class ExtendsStatementNode;
+class BlockStatementNode;
 class SetStatementNode;
 
 
@@ -46,6 +48,8 @@ class NodeVisitor {
   virtual void visit(const ForObjectStatementNode& node) = 0;
   virtual void visit(const IfStatementNode& node) = 0;
   virtual void visit(const IncludeStatementNode& node) = 0;
+  virtual void visit(const ExtendsStatementNode& node) = 0;
+  virtual void visit(const BlockStatementNode& node) = 0;
   virtual void visit(const SetStatementNode& node) = 0;
 };
 
@@ -329,6 +333,30 @@ class IncludeStatementNode : public StatementNode {
   };
 };
 
+class ExtendsStatementNode : public StatementNode {
+public:
+  const std::string file;
+
+  explicit ExtendsStatementNode(const std::string& file, size_t pos) : StatementNode(pos), file(file) { }
+
+  void accept(NodeVisitor& v) const {
+    v.visit(*this);
+  };
+};
+
+class BlockStatementNode : public StatementNode {
+public:
+  const std::string name;
+  BlockNode block;
+  BlockNode *const parent;
+
+  explicit BlockStatementNode(BlockNode *const parent, const std::string& name, size_t pos) : StatementNode(pos), parent(parent), name(name) { }
+
+  void accept(NodeVisitor& v) const {
+    v.visit(*this);
+  };
+};
+
 class SetStatementNode : public StatementNode {
 public:
   const std::string key;

diff --git a/include/inja/parser.hpp b/include/inja/parser.hpp
@@ -1,4 +1,4 @@
-// Copyright (c) 2020 Pantor. All rights reserved.
+// Copyright (c) 2021 Pantor. All rights reserved.
 
 #ifndef INCLUDE_INJA_PARSER_HPP_
 #define INCLUDE_INJA_PARSER_HPP_
@@ -50,6 +50,7 @@ class Parser {
   std::stack<std::shared_ptr<FunctionNode>> operator_stack;
   std::stack<IfStatementNode*> if_statement_stack;
   std::stack<ForStatementNode*> for_statement_stack;
+  std::stack<BlockStatementNode*> block_statement_stack;
 
   inline void throw_parser_error(const std::string &message) {
     INJA_THROW(ParserError(message, lexer.current_position()));
@@ -87,6 +88,22 @@ class Parser {
     arguments.emplace_back(function);
   }
 
+  void add_to_template_storage(nonstd::string_view path, std::string& template_name) {
+    if (config.search_included_templates_in_files && template_storage.find(template_name) == template_storage.end()) {
+      // Build the relative path
+      template_name = static_cast<std::string>(path) + template_name;
+      if (template_name.compare(0, 2, "./") == 0) {
+        template_name.erase(0, 2);
+      }
+
+      if (template_storage.find(template_name) == template_storage.end()) {
+        auto include_template = Template(load_file(template_name));
+        template_storage.emplace(template_name, include_template);
+        parse_into_template(template_storage[template_name], template_name);
+      }
+    }
+  }
+
   bool parse_expression(Template &tmpl, Token::Kind closing) {
     while (tok.kind != closing && tok.kind != Token::Kind::Eof) {
       // Literals
@@ -387,6 +404,37 @@ class Parser {
       current_block = if_statement_data->parent;
       if_statement_stack.pop();
 
+    } else if (tok.text == static_cast<decltype(tok.text)>("block")) {
+      get_next_token();
+
+      if (tok.kind != Token::Kind::Id) {
+        throw_parser_error("expected block name, got '" + tok.describe() + "'");
+      }
+
+      const std::string block_name = static_cast<std::string>(tok.text);
+
+      auto block_statement_node = std::make_shared<BlockStatementNode>(current_block, block_name, tok.text.data() - tmpl.content.c_str());
+      current_block->nodes.emplace_back(block_statement_node);
+      block_statement_stack.emplace(block_statement_node.get());
+      current_block = &block_statement_node->block;
+      auto success = tmpl.block_storage.emplace(block_name, block_statement_node);
+      if (!success.second) {
+        throw_parser_error("block with the name '" + block_name + "' does already exist");
+      }
+
+      get_next_token();
+
+    } else if (tok.text == static_cast<decltype(tok.text)>("endblock")) {
+      if (block_statement_stack.empty()) {
+        throw_parser_error("endblock without matching block");
+      }
+
+      auto &block_statement_data = block_statement_stack.top();
+      get_next_token();
+
+      current_block = block_statement_data->parent;
+      block_statement_stack.pop();
+
     } else if (tok.text == static_cast<decltype(tok.text)>("for")) {
       get_next_token();
 
@@ -450,21 +498,23 @@ class Parser {
       }
 
       std::string template_name = json::parse(tok.text).get_ref<const std::string &>();
-      if (config.search_included_templates_in_files && template_storage.find(template_name) == template_storage.end()) {
-        // Build the relative path
-        template_name = static_cast<std::string>(path) + template_name;
-        if (template_name.compare(0, 2, "./") == 0) {
-          template_name.erase(0, 2);
-        }
+      add_to_template_storage(path, template_name);
 
-        if (template_storage.find(template_name) == template_storage.end()) {
-          auto include_template = Template(load_file(template_name));
-          template_storage.emplace(template_name, include_template);
-          parse_into_template(template_storage[template_name], template_name);
-        }
+      current_block->nodes.emplace_back(std::make_shared<IncludeStatementNode>(template_name, tok.text.data() - tmpl.content.c_str()));
+
+      get_next_token();
+
+    } else if (tok.text == static_cast<decltype(tok.text)>("extends")) {
+      get_next_token();
+
+      if (tok.kind != Token::Kind::String) {
+        throw_parser_error("expected string, got '" + tok.describe() + "'");
       }
 
-      current_block->nodes.emplace_back(std::make_shared<IncludeStatementNode>(template_name, tok.text.data() - tmpl.content.c_str()));
+      std::string template_name = json::parse(tok.text).get_ref<const std::string &>();
+      add_to_template_storage(path, template_name);
+
+      current_block->nodes.emplace_back(std::make_shared<ExtendsStatementNode>(template_name, tok.text.data() - tmpl.content.c_str()));
 
       get_next_token();