-- Copyright 2006-2023 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 * -lexer.xdigit
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, '/*', '*/')

lexer.property['scintillua.comment'] = '//'

return lex
