/*
 [The "BSD licence"]
 Copyright (c) 2017 Sasa Coh, Michał Błotniak
 Copyright (c) 2019 Ivan Kochurkin, kvanttt@gmail.com, Positive Technologies
 Copyright (c) 2019 Dmitry Rassadin, flipparassa@gmail.com, Positive Technologies
 All rights reserved.

 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions
 are met:
 1. Redistributions of source code must retain the above copyright
    notice, this list of conditions and the following disclaimer.
 2. Redistributions in binary form must reproduce the above copyright
    notice, this list of conditions and the following disclaimer in the
    documentation and/or other materials provided with the distribution.
 3. The name of the author may not be used to endorse or promote products
    derived from this software without specific prior written permission.

 THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

/*
 * A Go grammar for ANTLR 4 derived from the Go Language Specification
 * https://golang.org/ref/spec
 */

lexer grammar GoLexer;

// Keywords

BREAK                  : 'break';
DEFAULT                : 'default';
FUNC                   : 'func';
INTERFACE              : 'interface';
SELECT                 : 'select';
CASE                   : 'case';
DEFER                  : 'defer';
GO                     : 'go';
MAP                    : 'map';
STRUCT                 : 'struct';
CHAN                   : 'chan';
ELSE                   : 'else';
GOTO                   : 'goto';
PACKAGE                : 'package';
SWITCH                 : 'switch';
CONST                  : 'const';
FALLTHROUGH            : 'fallthrough';
IF                     : 'if';
RANGE                  : 'range';
TYPE                   : 'type';
CONTINUE               : 'continue';
FOR                    : 'for';
IMPORT                 : 'import';
RETURN                 : 'return';
VAR                    : 'var';

NIL_LIT                : 'nil';

IDENTIFIER             : LETTER (LETTER | UNICODE_DIGIT)*;

// Punctuation

L_PAREN                : '(';
R_PAREN                : ')';
L_CURLY                : '{';
R_CURLY                : '}';
L_BRACKET              : '[';
R_BRACKET              : ']';
ASSIGN                 : '=';
COMMA                  : ',';
SEMI                   : ';';
COLON                  : ':';
DOT                    : '.';
PLUS_PLUS              : '++';
MINUS_MINUS            : '--';
DECLARE_ASSIGN         : ':=';
ELLIPSIS               : '...';

// Logical

LOGICAL_OR             : '||';
LOGICAL_AND            : '&&';

// Relation operators

EQUALS                 : '==';
NOT_EQUALS             : '!=';
LESS                   : '<';
LESS_OR_EQUALS         : '<=';
GREATER                : '>';
GREATER_OR_EQUALS      : '>=';

// Arithmetic operators

OR                     : '|';
DIV                    : '/';
MOD                    : '%';
LSHIFT                 : '<<';
RSHIFT                 : '>>';
BIT_CLEAR              : '&^';

// Unary operators

EXCLAMATION            : '!';

// Mixed operators

PLUS                   : '+';
MINUS                  : '-';
CARET                  : '^';
STAR                   : '*';
AMPERSAND              : '&';
RECEIVE                : '<-';

// Number literals

DECIMAL_LIT            : [1-9] [0-9]*;
OCTAL_LIT              : '0' OCTAL_DIGIT*;
HEX_LIT                : '0' [xX] HEX_DIGIT+;

FLOAT_LIT              : DECIMALS ('.' DECIMALS? EXPONENT? | EXPONENT)
                       | '.' DECIMALS EXPONENT?
                       ;

IMAGINARY_LIT          : (DECIMALS | FLOAT_LIT) 'i';

// Rune literals

RUNE_LIT               : '\'' (~[\n\\] | ESCAPED_VALUE) '\'';

// String literals

RAW_STRING_LIT         : '`' ~'`'*                      '`';
INTERPRETED_STRING_LIT : '"' (~["\\] | ESCAPED_VALUE)*  '"';

// Hidden tokens

WS                     : [ \t]+             -> channel(HIDDEN);
COMMENT                : '/*' .*? '*/'      -> channel(HIDDEN);
TERMINATOR             : [\r\n]+            -> channel(HIDDEN);
LINE_COMMENT           : '//' ~[\r\n]*      -> channel(HIDDEN);

// Fragments

fragment ESCAPED_VALUE
    : '\\' ('u' HEX_DIGIT HEX_DIGIT HEX_DIGIT HEX_DIGIT
           | 'U' HEX_DIGIT HEX_DIGIT HEX_DIGIT HEX_DIGIT HEX_DIGIT HEX_DIGIT HEX_DIGIT HEX_DIGIT
           | [abfnrtv\\'"]
           | OCTAL_DIGIT OCTAL_DIGIT OCTAL_DIGIT
           | 'x' HEX_DIGIT HEX_DIGIT)
    ;

fragment DECIMALS
    : [0-9]+
    ;

fragment OCTAL_DIGIT
    : [0-7]
    ;

fragment HEX_DIGIT
    : [0-9a-fA-F]
    ;

fragment EXPONENT
    : [eE] [+-]? DECIMALS
    ;

fragment LETTER
    : UNICODE_LETTER
    | '_'
    ;

fragment UNICODE_DIGIT
    : [\u0030-\u0039]
    | [\u0660-\u0669]
    | [\u06F0-\u06F9]
    | [\u0966-\u096F]
    | [\u09E6-\u09EF]
    | [\u0A66-\u0A6F]
    | [\u0AE6-\u0AEF]
    | [\u0B66-\u0B6F]
    | [\u0BE7-\u0BEF]
    | [\u0C66-\u0C6F]
    | [\u0CE6-\u0CEF]
    | [\u0D66-\u0D6F]
    | [\u0E50-\u0E59]
    | [\u0ED0-\u0ED9]
    | [\u0F20-\u0F29]
    | [\u1040-\u1049]
    | [\u1369-\u1371]
    | [\u17E0-\u17E9]
    | [\u1810-\u1819]
    | [\uFF10-\uFF19]
    ;

fragment UNICODE_LETTER
    : [\u0041-\u005A]
    | [\u0061-\u007A]
    | [\u00AA]
    | [\u00B5]
    | [\u00BA]
    | [\u00C0-\u00D6]
    | [\u00D8-\u00F6]
    | [\u00F8-\u021F]
    | [\u0222-\u0233]
    | [\u0250-\u02AD]
    | [\u02B0-\u02B8]
    | [\u02BB-\u02C1]
    | [\u02D0-\u02D1]
    | [\u02E0-\u02E4]
    | [\u02EE]
    | [\u037A]
    | [\u0386]
    | [\u0388-\u038A]
    | [\u038C]
    | [\u038E-\u03A1]
    | [\u03A3-\u03CE]
    | [\u03D0-\u03D7]
    | [\u03DA-\u03F3]
    | [\u0400-\u0481]
    | [\u048C-\u04C4]
    | [\u04C7-\u04C8]
    | [\u04CB-\u04CC]
    | [\u04D0-\u04F5]
    | [\u04F8-\u04F9]
    | [\u0531-\u0556]
    | [\u0559]
    | [\u0561-\u0587]
    | [\u05D0-\u05EA]
    | [\u05F0-\u05F2]
    | [\u0621-\u063A]
    | [\u0640-\u064A]
    | [\u0671-\u06D3]
    | [\u06D5]
    | [\u06E5-\u06E6]
    | [\u06FA-\u06FC]
    | [\u0710]
    | [\u0712-\u072C]
    | [\u0780-\u07A5]
    | [\u0905-\u0939]
    | [\u093D]
    | [\u0950]
    | [\u0958-\u0961]
    | [\u0985-\u098C]
    | [\u098F-\u0990]
    | [\u0993-\u09A8]
    | [\u09AA-\u09B0]
    | [\u09B2]
    | [\u09B6-\u09B9]
    | [\u09DC-\u09DD]
    | [\u09DF-\u09E1]
    | [\u09F0-\u09F1]
    | [\u0A05-\u0A0A]
    | [\u0A0F-\u0A10]
    | [\u0A13-\u0A28]
    | [\u0A2A-\u0A30]
    | [\u0A32-\u0A33]
    | [\u0A35-\u0A36]
    | [\u0A38-\u0A39]
    | [\u0A59-\u0A5C]
    | [\u0A5E]
    | [\u0A72-\u0A74]
    | [\u0A85-\u0A8B]
    | [\u0A8D]
    | [\u0A8F-\u0A91]
    | [\u0A93-\u0AA8]
    | [\u0AAA-\u0AB0]
    | [\u0AB2-\u0AB3]
    | [\u0AB5-\u0AB9]
    | [\u0ABD]
    | [\u0AD0]
    | [\u0AE0]
    | [\u0B05-\u0B0C]
    | [\u0B0F-\u0B10]
    | [\u0B13-\u0B28]
    | [\u0B2A-\u0B30]
    | [\u0B32-\u0B33]
    | [\u0B36-\u0B39]
    | [\u0B3D]
    | [\u0B5C-\u0B5D]
    | [\u0B5F-\u0B61]
    | [\u0B85-\u0B8A]
    | [\u0B8E-\u0B90]
    | [\u0B92-\u0B95]
    | [\u0B99-\u0B9A]
    | [\u0B9C]
    | [\u0B9E-\u0B9F]
    | [\u0BA3-\u0BA4]
    | [\u0BA8-\u0BAA]
    | [\u0BAE-\u0BB5]
    | [\u0BB7-\u0BB9]
    | [\u0C05-\u0C0C]
    | [\u0C0E-\u0C10]
    | [\u0C12-\u0C28]
    | [\u0C2A-\u0C33]
    | [\u0C35-\u0C39]
    | [\u0C60-\u0C61]
    | [\u0C85-\u0C8C]
    | [\u0C8E-\u0C90]
    | [\u0C92-\u0CA8]
    | [\u0CAA-\u0CB3]
    | [\u0CB5-\u0CB9]
    | [\u0CDE]
    | [\u0CE0-\u0CE1]
    | [\u0D05-\u0D0C]
    | [\u0D0E-\u0D10]
    | [\u0D12-\u0D28]
    | [\u0D2A-\u0D39]
    | [\u0D60-\u0D61]
    | [\u0D85-\u0D96]
    | [\u0D9A-\u0DB1]
    | [\u0DB3-\u0DBB]
    | [\u0DBD]
    | [\u0DC0-\u0DC6]
    | [\u0E01-\u0E30]
    | [\u0E32-\u0E33]
    | [\u0E40-\u0E46]
    | [\u0E81-\u0E82]
    | [\u0E84]
    | [\u0E87-\u0E88]
    | [\u0E8A]
    | [\u0E8D]
    | [\u0E94-\u0E97]
    | [\u0E99-\u0E9F]
    | [\u0EA1-\u0EA3]
    | [\u0EA5]
    | [\u0EA7]
    | [\u0EAA-\u0EAB]
    | [\u0EAD-\u0EB0]
    | [\u0EB2-\u0EB3]
    | [\u0EBD-\u0EC4]
    | [\u0EC6]
    | [\u0EDC-\u0EDD]
    | [\u0F00]
    | [\u0F40-\u0F6A]
    | [\u0F88-\u0F8B]
    | [\u1000-\u1021]
    | [\u1023-\u1027]
    | [\u1029-\u102A]
    | [\u1050-\u1055]
    | [\u10A0-\u10C5]
    | [\u10D0-\u10F6]
    | [\u1100-\u1159]
    | [\u115F-\u11A2]
    | [\u11A8-\u11F9]
    | [\u1200-\u1206]
    | [\u1208-\u1246]
    | [\u1248]
    | [\u124A-\u124D]
    | [\u1250-\u1256]
    | [\u1258]
    | [\u125A-\u125D]
    | [\u1260-\u1286]
    | [\u1288]
    | [\u128A-\u128D]
    | [\u1290-\u12AE]
    | [\u12B0]
    | [\u12B2-\u12B5]
    | [\u12B8-\u12BE]
    | [\u12C0]
    | [\u12C2-\u12C5]
    | [\u12C8-\u12CE]
    | [\u12D0-\u12D6]
    | [\u12D8-\u12EE]
    | [\u12F0-\u130E]
    | [\u1310]
    | [\u1312-\u1315]
    | [\u1318-\u131E]
    | [\u1320-\u1346]
    | [\u1348-\u135A]
    | [\u13A0-\u13B0]
    | [\u13B1-\u13F4]
    | [\u1401-\u1676]
    | [\u1681-\u169A]
    | [\u16A0-\u16EA]
    | [\u1780-\u17B3]
    | [\u1820-\u1877]
    | [\u1880-\u18A8]
    | [\u1E00-\u1E9B]
    | [\u1EA0-\u1EE0]
    | [\u1EE1-\u1EF9]
    | [\u1F00-\u1F15]
    | [\u1F18-\u1F1D]
    | [\u1F20-\u1F39]
    | [\u1F3A-\u1F45]
    | [\u1F48-\u1F4D]
    | [\u1F50-\u1F57]
    | [\u1F59]
    | [\u1F5B]
    | [\u1F5D]
    | [\u1F5F-\u1F7D]
    | [\u1F80-\u1FB4]
    | [\u1FB6-\u1FBC]
    | [\u1FBE]
    | [\u1FC2-\u1FC4]
    | [\u1FC6-\u1FCC]
    | [\u1FD0-\u1FD3]
    | [\u1FD6-\u1FDB]
    | [\u1FE0-\u1FEC]
    | [\u1FF2-\u1FF4]
    | [\u1FF6-\u1FFC]
    | [\u207F]
    | [\u2102]
    | [\u2107]
    | [\u210A-\u2113]
    | [\u2115]
    | [\u2119-\u211D]
    | [\u2124]
    | [\u2126]
    | [\u2128]
    | [\u212A-\u212D]
    | [\u212F-\u2131]
    | [\u2133-\u2139]
    | [\u2160-\u2183]
    | [\u3005-\u3007]
    | [\u3021-\u3029]
    | [\u3031-\u3035]
    | [\u3038-\u303A]
    | [\u3041-\u3094]
    | [\u309D-\u309E]
    | [\u30A1-\u30FA]
    | [\u30FC-\u30FE]
    | [\u3105-\u312C]
    | [\u3131-\u318E]
    | [\u31A0-\u31B7]
    | [\u3400]
    | [\u4DB5]
    | [\u4E00]
    | [\u9FA5]
    | [\uA000-\uA48C]
    | [\uAC00]
    | [\uD7A3]
    | [\uF900-\uFA2D]
    | [\uFB00-\uFB06]
    | [\uFB13-\uFB17]
    | [\uFB1D]
    | [\uFB1F-\uFB28]
    | [\uFB2A-\uFB36]
    | [\uFB38-\uFB3C]
    | [\uFB3E]
    | [\uFB40-\uFB41]
    | [\uFB43-\uFB44]
    | [\uFB46-\uFBB1]
    | [\uFBD3-\uFD3D]
    | [\uFD50-\uFD8F]
    | [\uFD92-\uFDC7]
    | [\uFDF0-\uFDFB]
    | [\uFE70-\uFE72]
    | [\uFE74]
    | [\uFE76-\uFEFC]
    | [\uFF21-\uFF3A]
    | [\uFF41-\uFF5A]
    | [\uFF66-\uFFBE]
    | [\uFFC2-\uFFC7]
    | [\uFFCA-\uFFCF]
    | [\uFFD2-\uFFD7]
    | [\uFFDA-\uFFDC]
    ;
