-- Copyright 2006-2020 Mitchell. See LICENSE.
-- Shell 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('bash')

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

-- Keywords.
lex:add_rule('keyword', token(lexer.KEYWORD, word_match[[
  if then elif else fi case in esac while for do done continue local return
  select
  -- Operators.
  -a -b -c -d -e -f -g -h -k -p -r -s -t -u -w -x -O -G -L -S -N -nt -ot -ef -o
  -z -n -eq -ne -lt -le -gt -ge
]]))

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

-- Strings.
local sq_str = lexer.range("'", false, false)
local dq_str = lexer.range('"')
local ex_str = lexer.range('`')
local heredoc = '<<' * P(function(input, index)
  local _, e, _, delimiter = input:find(
    '^%-?(["\']?)([%a_][%w_]*)%1[\n\r\f;]+', index)
  if not delimiter then return end
  _, e = input:find('[\n\r\f]+' .. delimiter, e)
  return e and e + 1 or #input + 1
end)
lex:add_rule('string', token(lexer.STRING, sq_str + dq_str + ex_str + heredoc))

-- Comments.
lex:add_rule('comment', token(lexer.COMMENT, lexer.to_eol('#')))

-- Numbers.
lex:add_rule('number', token(lexer.NUMBER, lexer.number))

-- Variables.
lex:add_rule('variable', token(lexer.VARIABLE, '$' * (
  S('!#?*@$') + lexer.digit^1 + lexer.word +
    lexer.range('{', '}', true, false, true)
)))

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

-- Fold points.
lex:add_fold_point(lexer.KEYWORD, 'if', 'fi')
lex:add_fold_point(lexer.KEYWORD, 'case', 'esac')
lex:add_fold_point(lexer.KEYWORD, 'do', 'done')
lex:add_fold_point(lexer.OPERATOR, '{', '}')
lex:add_fold_point(lexer.COMMENT, lexer.fold_consecutive_lines('#'))

return lex
