Add initial support for block statements

We needed to add `end` versions of the block identifiers or else the
lexer would identify them as generic tokens.

.gitignore

@@ -8,3 +8,6 @@ dist/
 htmlcov/
 .tox/
 docs/_build/
+
+.antlr/
+*.input.txt

grammar/JinjaGrammar.g4

@@ -0,0 +1,99 @@
+parser grammar JinjaGrammar;
+
+options {
+    tokenVocab=JinjaLexer;
+}
+
+start : expressions;
+
+expression
+    : inline_statement
+    | block_statement
+    ;
+
+expressions     : expression*;
+
+list_literal            : LSQB SP? list_literal_values? SP? RSQB;
+list_literal_values
+    :
+    (list_literal_value SP? COMMA SP?)*
+    list_literal_value
+    ;
+list_literal_value
+    : STRING_LITERAL
+    | variable_name
+    ;
+
+variable_name : IDENTIFIER;
+
+statement_block
+    :
+    STATEMENT_ID_BLOCK SP IDENTIFIER
+    ;
+
+statement_include_template
+    : STRING_LITERAL
+    | list_literal
+    | variable_name
+    ;
+
+statement_include_context
+    : STATEMENT_INCLUDE_WITH_CONTEXT
+    | STATEMENT_INCLUDE_WITHOUT_CONTEXT
+    ;
+
+statement_include
+    : STATEMENT_ID_INCLUDE
+        (SP statement_include_template)
+        (SP STATEMENT_INCLUDE_IGNORE_MISSING)?
+        (SP statement_include_context)?
+    ;
+
+statement_import_file
+    : STRING_LITERAL
+    | variable_name
+    ;
+
+statement_import_variable
+    : variable_name (SP STATEMENT_ID_IMPORT_AS SP variable_name)?
+    ;
+
+statement_import_variable_list
+    : (statement_import_variable SP? COMMA SP?)* statement_import_variable
+    ;
+
+statement_import
+    : STATEMENT_ID_IMPORT SP statement_import_file SP STATEMENT_ID_IMPORT_AS SP variable_name (SP statement_include_context)?
+    | STATEMENT_ID_FROM SP statement_import_file SP STATEMENT_ID_IMPORT SP statement_import_variable_list (SP statement_include_context)?
+    ;
+
+block_end_statement_id
+    : STATEMENT_END_ID_BLOCK
+    | STATEMENT_END_ID_SET
+    ;
+
+// block_statement_with_parameters
+//     : block_statement_id
+//     | block_statement_id
+//     ;
+
+block_statement_without_parameters
+    : statement_block
+    ;
+
+block_statement_start_content
+    : block_statement_without_parameters
+    // | block_statement_with_parameters
+    ;
+
+inline_statement_content
+    : statement_include
+    | statement_import
+    ;
+
+inline_statement            : STATEMENT_OPEN inline_statement_content STATEMENT_CLOSE;
+
+block_statement_start       : STATEMENT_OPEN block_statement_start_content STATEMENT_CLOSE;
+block_statement_end         : STATEMENT_OPEN block_end_statement_id STATEMENT_CLOSE;
+
+block_statement             : block_statement_start expressions block_statement_end;

grammar/JinjaLexer.g4

@@ -0,0 +1,100 @@
+lexer grammar JinjaLexer;
+
+TRUE_LOWER      : 'true';
+TRUE_PY         : 'True';
+TRUE
+    : TRUE_LOWER
+    | TRUE_PY
+    ;
+
+FALSE_LOWER     : 'false';
+FALSE_PY        : 'False';
+FALSE
+    : FALSE_LOWER
+    | FALSE_PY
+    ;
+
+BOOLEAN
+    : TRUE
+    | FALSE
+    ;
+
+NONE_LOWER      : 'none';
+NONE_PY         : 'None';
+NONE
+    : NONE_LOWER
+    | NONE_PY
+    ;
+
+LPAR            : '(';
+LSQB            : '[';
+LBRACE          : '{';
+RPAR            : ')';
+RSQB            : ']';
+RBRACE          : '}';
+DOT             : '.';
+COLON           : ':';
+COMMA           : ',';
+SEMI            : ';';
+PLUS            : '+';
+MINUS           : '-';
+STAR            : '*';
+SLASH           : '/';
+VBAR            : '|';
+AMPER           : '&';
+LESS            : '<';
+GREATER         : '>';
+EQUAL           : '=';
+PERCENT         : '%';
+EQEQUAL         : '==';
+NOTEQUAL        : '!=';
+LESSEQUAL       : '<=';
+GREATEREQUAL    : '>=';
+TILDE           : '~';
+CIRCUMFLEX      : '^';
+LEFTSHIFT       : '<<';
+RIGHTSHIFT      : '>>';
+DOUBLESTAR      : '**';
+DOUBLESLASH     : '//';
+AT              : '@';
+RARROW          : '->';
+ELLIPSIS        : '...';
+EXCLAMATION     : '!';
+
+STATEMENT_OPEN      : '{%' SP?;
+STATEMENT_CLOSE     : SP? '%}';
+
+EXPRESSION_OPEN     : '{{';
+EXPRESSION_CLOSE    : '}}';
+
+COMMENT_OPEN        : '{#';
+COMMENT_CLOSE       : '#}';
+
+STRING_LITERAL                           : STRING_LITERAL_SINGLE_QUOTE | STRING_LITERAL_DOUBLE_QUOTE;
+fragment STRING_LITERAL_SINGLE_QUOTE     : '\'' (~[\\\r\n'])* '\'';
+fragment STRING_LITERAL_DOUBLE_QUOTE     : '"' (~[\\\r\n"])* '"';
+
+SP              : [ \t\f]+;
+
+// Statement identifiers for built-in statements
+
+STATEMENT_ID_BLOCK      : 'block';
+STATEMENT_END_ID_BLOCK  : 'endblock';
+STATEMENT_ID_FROM       : 'from';
+STATEMENT_ID_IMPORT     : 'import';
+STATEMENT_ID_INCLUDE    : 'include';
+STATEMENT_ID_RAW        : 'raw';
+STATEMENT_ID_SET        : 'set';
+STATEMENT_END_ID_SET    : 'endset';
+
+STATEMENT_ID_IMPORT_AS  : 'as';
+
+STATEMENT_INCLUDE_IGNORE_MISSING    : 'ignore missing';
+STATEMENT_INCLUDE_WITH_CONTEXT      : 'with context';
+STATEMENT_INCLUDE_WITHOUT_CONTEXT   : 'without context';
+
+END_STATEMENT_ID_PREFIX    : 'end';
+
+IDENTIFIER                       : IDENTIFIER_START IDENTIFIER_CONTINUE*;
+fragment IDENTIFIER_START        : [a-zA-Z_];
+fragment IDENTIFIER_CONTINUE     : [a-zA-Z0-0_];