-- Copyright 2020 Florian Fischer. See LICENSE.
-- Meson file LPeg lexer.

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

local M = {_NAME = 'meson'}

-- Whitespace.
local ws = token(l.WHITESPACE, l.space^1)

-- Comments.
local comment = token(l.COMMENT, '#' * l.nonnewline_esc^0)

-- Strings.
local str = l.delimited_range("'", true)
local multiline_str = "'''" * (l.any - "'''")^0 * P("'''")^-1
local string = token(l.STRING, multiline_str + str)

-- Numbers.
local dec = R('19')^1 * R('09')^0
local bin = '0b' * S('01')^1
local oct = '0o' * R('07')^1
local integer = S('+-')^-1 * (bin + l.hex_num + oct + dec)
local number = token(l.NUMBER, integer)

-- Keywords.
local keyword = token(l.KEYWORD, word_match{
  'and', 'or', 'not',
  'if', 'elif', 'else', 'endif',
  'foreach', 'break', 'continue', 'endforeach',
})

-- Methods.
-- https://mesonbuild.com/Reference-manual.html#builtin-objects
-- https://mesonbuild.com/Reference-manual.html#returned-objects
local method_names = word_match{
  -- array --
  'contains', 'get', 'length',
  -- boolean --
  'to_int', 'to_string',
  -- dictionary --
  'has_key', 'get', 'keys',
  -- disabler --
  'found',
  -- integer --
  'is_even', 'is_odd',
  -- string --
  'contains', 'endswith', 'format', 'join', 'split', 'startswith', 'substring',
  'strip', 'to_int', 'to_lower', 'to_upper', 'underscorify', 'version_compare',
  -- meson object --
  'add_dist_script', 'add_install_script', 'add_postconf_script', 'backend',
  'build_root', 'source_root', 'project_build_root', 'project_source_root',
  'current_build_dir', 'current_source_dir', 'get_compiler',
  'get_cross_property', 'get_external_property', 'can_run_host_binaries',
  'has_exe_wrapper', 'install_dependency_manifest', 'is_cross_build',
  'is_subproject', 'is_unity', 'override_find_program', 'override_dependency',
  'project_version', 'project_license', 'project_name', 'version',
  -- *_machine object --
  'cpu_family', 'cpu', 'system', 'endian',
  -- compiler object --
  'alignment', 'cmd_array', 'compiles', 'compute_int', 'find_library',
  'first_supported_argument', 'first_supported_link_argument', 'get_define',
  'get_id', 'get_argument_syntax', 'get_linker_id', 'get_supported_arguments',
  'get_supported_link_arguments', 'has_argument', 'has_link_argument',
  'has_function', 'check_header', 'has_header', 'has_header_symbol',
  'has_member', 'has_members', 'has_multi_arguments',
  'has_multi_link_arguments', 'has_type', 'links', 'run',
  'symbols_have_underscore_prefix', 'sizeof', 'version',
  'has_function_attribute', 'get_supported_function_attributes',
  -- build target object --
  'extract_all_objects', 'extract_objects', 'full_path', 'private_dir_include',
  'name',
  -- configuration data object --
  'get', 'get_unquoted', 'has', 'keys', 'merge_from', 'set', 'set10',
  'set_quoted',
  -- custom target object --
  'full_path', 'to_list',
  -- dependency object --
  'found', 'name', 'get_pkgconfig_variable', 'get_configtool_variable',
  'type_name', 'version', 'include_type', 'as_system', 'as_link_whole',
  'partial_dependency', 'found',
  -- external program object --
  'found', 'path', 'full_path',
  -- environment object --
  'append', 'prepend', 'set',
  -- external library object --
  'found', 'type_name', 'partial_dependency', 'enabled', 'disabled', 'auto',
  -- generator object --
  'process',
  -- subproject object --
  'found', 'get_variable',
  -- run result object --
  'compiled', 'returncode', 'stderr', 'stdout',
}
-- A method call must be followed by an opening parenthesis.
local method = token('method', method_names * #P(l.space^0 * S('(')))

-- Function.
-- https://mesonbuild.com/Reference-manual.html#functions
local func_names =  word_match{
  'add_global_arguments', 'add_global_link_arguments', 'add_languages',
  'add_project_arguments', 'add_project_link_arguments', 'add_test_setup',
  'alias_targ', 'assert', 'benchmark', 'both_libraries', 'build_target',
  'configuration_data', 'configure_file', 'custom_target', 'declare_dependency',
  'dependency', 'disabler', 'error', 'environment', 'executable',
  'find_library', 'find_program', 'files', 'generator', 'get_option',
  'get_variable', 'import', 'include_directories', 'install_data',
  'install_headers', 'install_man', 'install_subdir', 'is_disabler',
  'is_variable', 'jar', 'join_paths', 'library', 'message', 'warning',
  'summary', 'project', 'run_command', 'run_targ', 'set_variable',
  'shared_library', 'shared_module', 'static_library', 'subdir', 'subdir_done',
  'subproject', 'test', 'vcs_tag',
}
-- A function call must be followed by an opening parenthesis.
-- The matching of function calls instead of just their names is needed to not
-- falsely highlight function names which can also be keyword arguments.
-- For example 'include_directories' can be a function call itself or a keyword
-- argument of an 'executable' or 'library' function call.
local func = token(l.FUNCTION, func_names * #P(l.space^0 * S('(')))

-- Builtin objects.
-- https://mesonbuild.com/Reference-manual.html#builtin-objects
local object = token('object', word_match{
  'meson', 'build_machine', 'host_machine', 'target_machine',
})

-- Constants.
local constant = token(l.CONSTANT, word_match{
  'false', 'true',
})

-- Identifiers.
local identifier = token(l.IDENTIFIER, l.word)

-- Operators.
local operator = token(l.OPERATOR, S('()[]{}-=+/%:.,?<>'))

M._rules = {
  {'whitespace', ws},
  {'keyword', keyword},
  {'method', method},
  {'function', func},
  {'object', object},
  {'constant', constant},
  {'identifier', identifier},
  {'comment', comment},
  {'string', string},
  {'number', number},
  {'operator', operator},
}

M._tokenstyles = {
  method = l.STYLE_FUNCTION,
  object = l.STYLE_TYPE,
}

M._FOLDBYINDENTATION = true

return M