/*
 * [The "BSD license"]
 *  Copyright (c) 2012-2015 Terence Parr
 *  Copyright (c) 2012-2015 Sam Harwell
 *  Copyright (c) 2015 Gerald Rosenberg
 *  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 grammar for ANTLR v4 implemented using v4 syntax
 *
 *	Modified 2015.06.16 gbr
 *	-- update for compatibility with Antlr v4.5
 */

// ======================================================
// Lexer specification
// ======================================================

lexer grammar ANTLRv4Lexer;

options { superClass = LexerAdaptor; }
import LexBasic;

// Standard set of fragments
tokens { TOKEN_REF , RULE_REF , LEXER_CHAR_SET }
channels { OFF_CHANNEL , COMMENT }

// -------------------------
// Comments
DOC_COMMENT
   : DocComment -> channel (COMMENT)
   ;

BLOCK_COMMENT
   : BlockComment -> channel (COMMENT)
   ;

LINE_COMMENT
   : LineComment -> channel (COMMENT)
   ;

// -------------------------
// Integer

INT
   : DecimalNumeral
   ;

// -------------------------
// Literal string
//
// ANTLR makes no distinction between a single character literal and a
// multi-character string. All literals are single quote delimited and
// may contain unicode escape sequences of the form \uxxxx, where x
// is a valid hexadecimal number (per Unicode standard).
STRING_LITERAL
   : SQuoteLiteral
   ;

UNTERMINATED_STRING_LITERAL
   : USQuoteLiteral
   ;

// -------------------------
// Arguments
//
// Certain argument lists, such as those specifying call parameters
// to a rule invocation, or input parameters to a rule specification
// are contained within square brackets.
BEGIN_ARGUMENT
   : LBrack
   { this.handleBeginArgument(); }
   ;

// -------------------------
// Target Language Actions
BEGIN_ACTION
   : LBrace -> pushMode (TargetLanguageAction)
   ;

// -------------------------
// Keywords
//
// 'options', 'tokens', and 'channels' are considered keywords
// but only when followed by '{', and considered as a single token.
// Otherwise, the symbols are tokenized as RULE_REF and allowed as
// an identifier in a labeledElement.
OPTIONS      : 'options'  WSNLCHARS* '{'  ;
TOKENS       : 'tokens'   WSNLCHARS* '{'  ;
CHANNELS     : 'channels' WSNLCHARS* '{'  ;

fragment WSNLCHARS : ' ' | '\t' | '\f' | '\n' | '\r' ;

IMPORT
   : 'import'
   ;

FRAGMENT
   : 'fragment'
   ;

LEXER
   : 'lexer'
   ;

PARSER
   : 'parser'
   ;

GRAMMAR
   : 'grammar'
   ;

PROTECTED
   : 'protected'
   ;

PUBLIC
   : 'public'
   ;

PRIVATE
   : 'private'
   ;

RETURNS
   : 'returns'
   ;

LOCALS
   : 'locals'
   ;

THROWS
   : 'throws'
   ;

CATCH
   : 'catch'
   ;

FINALLY
   : 'finally'
   ;

MODE
   : 'mode'
   ;
   // -------------------------
   // Punctuation

COLON
   : Colon
   ;

COLONCOLON
   : DColon
   ;

COMMA
   : Comma
   ;

SEMI
   : Semi
   ;

LPAREN
   : LParen
   ;

RPAREN
   : RParen
   ;

LBRACE
   : LBrace
   ;

RBRACE
   : RBrace
   ;

RARROW
   : RArrow
   ;

LT
   : Lt
   ;

GT
   : Gt
   ;

ASSIGN
   : Equal
   ;

QUESTION
   : Question
   ;

STAR
   : Star
   ;

PLUS_ASSIGN
   : PlusAssign
   ;

PLUS
   : Plus
   ;

OR
   : Pipe
   ;

DOLLAR
   : Dollar
   ;

RANGE
   : Range
   ;

DOT
   : Dot
   ;

AT
   : At
   ;

POUND
   : Pound
   ;

NOT
   : Tilde
   ;
   // -------------------------
   // Identifiers - allows unicode rule/token names

ID
   : Id
   ;
   // -------------------------
   // Whitespace

WS
   : Ws+ -> channel (OFF_CHANNEL)
   ;

// -------------------------
// Illegal Characters
//
// This is an illegal character trap which is always the last rule in the
// lexer specification. It matches a single character of any value and being
// the last rule in the file will match when no other rule knows what to do
// about the character. It is reported as an error but is not passed on to the
// parser. This means that the parser to deal with the gramamr file anyway
// but we will not try to analyse or code generate from a file with lexical
// errors.

// Comment this rule out to allow the error to be propagated to the parser
ERRCHAR
   : . -> channel (HIDDEN)
   ;

// ======================================================
// Lexer modes
// -------------------------
// Arguments
mode Argument;
// E.g., [int x, List<String> a[]]
NESTED_ARGUMENT
   : LBrack -> type (ARGUMENT_CONTENT) , pushMode (Argument)
   ;

ARGUMENT_ESCAPE
   : EscAny -> type (ARGUMENT_CONTENT)
   ;

ARGUMENT_STRING_LITERAL
   : DQuoteLiteral -> type (ARGUMENT_CONTENT)
   ;

ARGUMENT_CHAR_LITERAL
   : SQuoteLiteral -> type (ARGUMENT_CONTENT)
   ;

END_ARGUMENT
   : RBrack
   { this.handleEndArgument(); }
   ;

// added this to return non-EOF token type here. EOF does something weird
UNTERMINATED_ARGUMENT
   : EOF -> popMode
   ;

ARGUMENT_CONTENT
   : .
   ;

// TODO: This grammar and the one used in the Intellij Antlr4 plugin differ
// for "actions". This needs to be resolved at some point.
// The Intellij Antlr4 grammar is here:
// https://github.com/antlr/intellij-plugin-v4/blob/1f36fde17f7fa63cb18d7eeb9cb213815ac658fb/src/main/antlr/org/antlr/intellij/plugin/parser/ANTLRv4Lexer.g4#L587

// -------------------------
// Target Language Actions
//
// Many language targets use {} as block delimiters and so we
// must recursively match {} delimited blocks to balance the
// braces. Additionally, we must make some assumptions about
// literal string representation in the target language. We assume
// that they are delimited by ' or " and so consume these
// in their own alts so as not to inadvertantly match {}.
mode TargetLanguageAction;
NESTED_ACTION
   : LBrace -> type (ACTION_CONTENT) , pushMode (TargetLanguageAction)
   ;

ACTION_ESCAPE
   : EscAny -> type (ACTION_CONTENT)
   ;

ACTION_STRING_LITERAL
   : DQuoteLiteral -> type (ACTION_CONTENT)
   ;

ACTION_CHAR_LITERAL
   : SQuoteLiteral -> type (ACTION_CONTENT)
   ;

ACTION_DOC_COMMENT
   : DocComment -> type (ACTION_CONTENT)
   ;

ACTION_BLOCK_COMMENT
   : BlockComment -> type (ACTION_CONTENT)
   ;

ACTION_LINE_COMMENT
   : LineComment -> type (ACTION_CONTENT)
   ;

END_ACTION
   : RBrace
   { this.handleEndAction(); }
   ;

UNTERMINATED_ACTION
   : EOF -> popMode
   ;

ACTION_CONTENT
   : .
   ;

// -------------------------
mode LexerCharSet;
LEXER_CHAR_SET_BODY
   : (~ [\]\\] | EscAny)+ -> more
   ;

LEXER_CHAR_SET
   : RBrack -> popMode
   ;

UNTERMINATED_CHAR_SET
   : EOF -> popMode
   ;

// ------------------------------------------------------------------------------
// Grammar specific Keywords, Punctuation, etc.
fragment Id
   : NameStartChar NameChar*
   ;