-- Copyright 2006-2021 Mitchell. See LICENSE.
-- Verilog LPeg lexer.

local lexer = require('lexer')
local token, word_match = lexer.token, lexer.word_match
local P, S = lpeg.P, lpeg.S

local lex = lexer.new('verilog')

-- Whitespace.
lex:add_rule('whitespace', token(lexer.WHITESPACE, lexer.space^1))

-- Keywords.
lex:add_rule('keyword', token(lexer.KEYWORD, word_match[[
  always assign begin case casex casez default deassign disable else end endcase
  endfunction endgenerate endmodule endprimitive endspecify endtable endtask for
  force forever fork function generate if initial join macromodule module
  negedge posedge primitive repeat release specify table task wait while
  -- Compiler directives.
  `include `define `undef `ifdef `ifndef `else `endif `timescale `resetall
  `signed `unsigned `celldefine `endcelldefine `default_nettype
  `unconnected_drive `nounconnected_drive `protect `endprotect `protected
  `endprotected `remove_gatename `noremove_gatename `remove_netname
  `noremove_netname `expand_vectornets `noexpand_vectornets
  `autoexpand_vectornets
  -- Signal strengths.
  strong0 strong1 pull0 pull1 weak0 weak1 highz0 highz1 small medium large
]]))

-- Function.
lex:add_rule('function', token(lexer.FUNCTION, word_match[[
  $stop $finish $time $stime $realtime $settrace $cleartrace $showscopes
  $showvars $monitoron $monitoroff $random $printtimescale $timeformat $display
  -- Built-in primitives.
  and nand or nor xor xnor buf bufif0 bufif1 not notif0 notif1 nmos pmos cmos
  rnmos rpmos rcmos tran tranif0 tranif1 rtran rtranif0 rtranif1 pullup pulldown
]]))

-- Types.
lex:add_rule('type', token(lexer.TYPE, word_match[[
  integer reg time realtime defparam parameter event wire wand wor tri triand
  trior tri0 tri1 trireg vectored scalared input output inout supply0 supply1
]]))

-- Identifiers.
lex:add_rule('identifier', token(lexer.IDENTIFIER, lexer.word))

-- Strings.
lex:add_rule('string', token(lexer.STRING, lexer.range('"')))

-- Comments.
local line_comment = lexer.to_eol('//')
local block_comment = lexer.range('/*', '*/')
lex:add_rule('comment', token(lexer.COMMENT, line_comment + block_comment))

-- Numbers.
local bin_suffix = S('bB') * S('01_xXzZ')^1
local oct_suffix = S('oO') * S('01234567_xXzZ')^1
local dec_suffix = S('dD') * S('0123456789_xXzZ')^1
local hex_suffix = S('hH') * S('0123456789abcdefABCDEF_xXzZ')^1
lex:add_rule('number', token(lexer.NUMBER, (lexer.digit + '_')^1 + "'" *
  (bin_suffix + oct_suffix + dec_suffix + hex_suffix)))

-- Operators.
lex:add_rule('operator', token(lexer.OPERATOR, S('=~+-/*<>%&|^~,:;()[]{}')))

-- Fold points.
lex:add_fold_point(lexer.KEYWORD, 'case', 'endcase')
lex:add_fold_point(lexer.KEYWORD, 'casex', 'endcase')
lex:add_fold_point(lexer.KEYWORD, 'casez', 'endcase')
lex:add_fold_point(lexer.KEYWORD, 'function', 'endfunction')
lex:add_fold_point(lexer.KEYWORD, 'fork', 'join')
lex:add_fold_point(lexer.KEYWORD, 'table', 'endtable')
lex:add_fold_point(lexer.KEYWORD, 'task', 'endtask')
lex:add_fold_point(lexer.KEYWORD, 'generate', 'endgenerate')
lex:add_fold_point(lexer.KEYWORD, 'specify', 'endspecify')
lex:add_fold_point(lexer.KEYWORD, 'primitive', 'endprimitive')
lex:add_fold_point(lexer.KEYWORD, 'module', 'endmodule')
lex:add_fold_point(lexer.KEYWORD, 'begin', 'end')
lex:add_fold_point(lexer.OPERATOR, '(', ')')
lex:add_fold_point(lexer.OPERATOR, '{', '}')
lex:add_fold_point(lexer.COMMENT, '/*', '*/')
lex:add_fold_point(lexer.COMMENT, lexer.fold_consecutive_lines('//'))

return lex
