Added keywords grammar

src/SUMMARY.md

@@ -8,6 +8,7 @@
 
 - [Lexical structure](lexical-structure.md)
     - [Input format](input-format.md)
+    - [Keywords](keywords.md)
     - [Identifiers](identifiers.md)
     - [Comments](comments.md)
     - [Whitespace](whitespace.md)

src/keywords.md

@@ -0,0 +1,84 @@
+# Keywords
+
+Rust divides keywords in three categories:
+  - [strict](#strict-keywords)
+  - [weak](#weak-keywords)
+  - [reserved](#reserved-keywords)
+
+## Strict keywords
+
+These keywords can only be used in their correct contexts. For example, it is
+not allowed to declare a variable with name `struct`.
+
+> **<sup>Lexer:<sup>**  
+> KW_AS             : `as`  
+> KW_BOX            : `box`  
+> KW_BREAK          : `break`  
+> KW_CONST          : `const`  
+> KW_CONTINUE       : `continue`  
+> KW_CRATE          : `crate`  
+> KW_ELSE           : `else`  
+> KW_ENUM           : `enum`  
+> KW_EXTERN         : `extern`  
+> KW_FALSE          : `false`  
+> KW_FN             : `fn`  
+> KW_FOR            : `for`  
+> KW_IF             : `if`  
+> KW_IMPL           : `impl`  
+> KW_IN             : `in`  
+> KW_LET            : `let`  
+> KW_LOOP           : `loop`  
+> KW_MATCH          : `match`  
+> KW_MOD            : `mod`  
+> KW_MOVE           : `move`  
+> KW_MUT            : `mut`  
+> KW_PUB            : `pub`  
+> KW_REF            : `ref`  
+> KW_RETURN         : `return`  
+> KW_SELFVALUE      : `self`  
+> KW_SELFTYPE       : `Self`  
+> KW_STATIC         : `static`  
+> KW_STRUCT         : `struct`  
+> KW_SUPER          : `super`  
+> KW_TRAIT          : `trait`  
+> KW_TRUE           : `true`  
+> KW_TYPE           : `type`  
+> KW_UNSAFE         : `unsafe`  
+> KW_USE            : `use`  
+> KW_WHERE          : `wher`  
+> KW_WHILE          : `while`  
+
+## Weak keywords
+
+These keywords have special meaning only in certain contexts. For example,
+it is possible to declare a variable or method with the name `union`.
+
+> **<sup>Lexer</sup>**  
+> KW_CATCH          : `catch`  
+> KW_DEFAULT        : `default`  
+> KW_UNION          : `union`  
+> KW_STATICLIFETIME : `'static`  
+
+## Reserved keywords
+
+These keywords aren't used yet, but they are reserved for future use.
+The reasoning behind this is to make current programs forward compatible with
+future versions of rust by forbiding them to use these keywords.
+
+> **<sup>Lexer</sup>**  
+> KW_ABSTRACT       : `abstract`  
+> KW_ALIGNOF        : `alignof`  
+> KW_BECOME         : `become`  
+> KW_DO             : `do`  
+> KW_FINAL          : `final`  
+> KW_MACRO          : `macro`  
+> KW_OFFSETOF       : `offsetof`  
+> KW_OVERRIDE       : `override`  
+> KW_PRIV           : `priv`  
+> KW_PROC           : `proc`  
+> KW_PURE           : `pure`  
+> KW_SIZEOF         : `sizeof`  
+> KW_TYPEOF         : `typeof`  
+> KW_UNSIZED        : `unsized`  
+> KW_VIRTUAL        : `virtual`  
+> KW_YIELD          : `yield`