-- Copyright 2006-2023 Mitchell. See LICENSE.
-- Go LPeg lexer.

local lexer = lexer
local P, S = lpeg.P, lpeg.S

local lex = lexer.new(...)

-- Keywords.
lex:add_rule('keyword', lex:tag(lexer.KEYWORD, lex:word_match(lexer.KEYWORD)))

-- Constants.
lex:add_rule('constant', lex:tag(lexer.CONSTANT_BUILTIN, lex:word_match(lexer.CONSTANT_BUILTIN)))

-- Types.
lex:add_rule('type', lex:tag(lexer.TYPE, lex:word_match(lexer.TYPE)))

-- Functions.
local builtin_func = -lpeg.B('.') *
  lex:tag(lexer.FUNCTION_BUILTIN, lex:word_match(lexer.FUNCTION_BUILTIN))
local func = lex:tag(lexer.FUNCTION, lexer.word)
local method = lpeg.B('.') * lex:tag(lexer.FUNCTION_METHOD, lexer.word)
lex:add_rule('function', (builtin_func + method + func) * #(lexer.space^0 * '('))

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

-- Strings.
local sq_str = lexer.range("'", true)
local dq_str = lexer.range('"', true)
local raw_str = lexer.range('`', false, false)
lex:add_rule('string', lex:tag(lexer.STRING, sq_str + dq_str + raw_str))

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

-- Numbers.
lex:add_rule('number', lex:tag(lexer.NUMBER, lexer.number * P('i')^-1))

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

-- Fold points.
lex:add_fold_point(lexer.OPERATOR, '{', '}')
lex:add_fold_point(lexer.COMMENT, '/*', '*/')

-- Word lists.
lex:set_word_list(lexer.KEYWORD, {
  'break', 'case', 'chan', 'const', 'continue', 'default', 'defer', 'else', 'fallthrough', 'for',
  'func', 'go', 'goto', 'if', 'import', 'interface', 'map', 'package', 'range', 'return', 'select',
  'struct', 'switch', 'type', 'var'
})

lex:set_word_list(lexer.CONSTANT_BUILTIN, 'true false iota nil')

lex:set_word_list(lexer.TYPE, {
  'any', 'bool', 'byte', 'comparable', 'complex64', 'complex128', 'error', 'float32', 'float64',
  'int', 'int8', 'int16', 'int32', 'int64', 'rune', 'string', 'uint', 'uint8', 'uint16', 'uint32',
  'uint64', 'uintptr'
})

lex:set_word_list(lexer.FUNCTION_BUILTIN, {
  'append', 'cap', 'close', 'complex', 'copy', 'delete', 'imag', 'len', 'make', 'new', 'panic',
  'print', 'println', 'real', 'recover'
})

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

return lex
