local expr_lexer = require 'expr-lexer' local function accept(lexer, token_type) if lexer.token.type == token_type then lexer:next() return true end return false end local function expect(lexer, token_type) if not accept(lexer, token_type) then lexer:local_error("expecting " .. token_type) end end local expr local function factor(lexer, actions) local token = lexer.token if token.type == 'ident' then local id = token.value lexer:next() if accept(lexer, '(') then local arg = expr(lexer, actions, 0) expect(lexer, ')') return actions.func_eval(id, arg) else return actions.ident(id) end elseif token.type == 'literal' then local x = token.value lexer:next() return actions.literal(x) elseif token.type == 'number' then local x = token.value lexer:next() return actions.number(x) elseif token.type == '(' then lexer:next() local a = expr(lexer, actions, 0) expect(lexer, ')') return a elseif token.type == 'operator' and token.symbol == '%' then lexer:next() if lexer.token.type ~= 'ident' then lexer:local_error("expecting identifier:") end local id = lexer.token.value lexer:next() return actions.enum(id) end lexer:local_error('unexpected symbol:') end local function ident_singleton(lexer, actions) local token = lexer.token if token.type == 'ident' then local id = token.value lexer:next() if accept(lexer, '(') then lexer:local_error('expecting simple identifier') end return actions.ident(id) else lexer:local_error('expecting simple identifier') end end local max_oper_prio = expr_lexer.max_oper_prio expr = function(lexer, actions, prio) if prio> max_oper_prio then return factor(lexer, actions) end local a local token = lexer.token if prio == 0 and token.type == 'operator' and token.symbol == '-' then local symbol = token.symbol lexer:next() local b = expr(lexer, actions, prio + 1) a = actions.prefix(symbol, b) else a = expr(lexer, actions, prio + 1) end token = lexer.token while token.type == 'operator' and token.priority>= prio do local symbol = token.symbol accept(lexer, 'operator') local b = expr(lexer, actions, prio + 1) a, token = actions.infix(symbol, a, b), lexer.token end return a end local function expr_list(lexer, actions) local a = expr(lexer, actions, 0) local els = actions.exprlist(a) while accept(lexer, ',') do local b = expr(lexer, actions, 0) els = actions.exprlist(b, els) end return els end local function ident_list(lexer, actions) local a = ident_singleton(lexer, actions) local els = actions.exprlist(a) while accept(lexer, ',') do local b = ident_singleton(lexer, actions) els = actions.exprlist(b, els) end return els end local function enums(lexer, actions) if accept(lexer, '|') then return ident_list(lexer, actions) end return {} end local function conditions(lexer, actions) if accept(lexer, ':') then return expr_list(lexer, actions) end return {} end local function schema(lexer, actions, accept_enums) local y = expr(lexer, actions, 0) expect(lexer, '~') local x = expr_list(lexer, actions) local enums = accept_enums and enums(lexer, actions) local conds = conditions(lexer, actions) expect(lexer, 'EOF') return actions.schema(x, y, conds, enums) end local function schema_multivar(lexer, actions) local y = expr_list(lexer, actions, 0) expect(lexer, '~') local x = expr_list(lexer, actions) local enums = enums(lexer, actions) local conds = conditions(lexer, actions) expect(lexer, 'EOF') return actions.schema(x, y, conds, enums) end local expr_parse = {} function expr_parse.schema(formula, actions, accept_enums) local l = expr_lexer.new(formula) return schema(l, actions, accept_enums) end function expr_parse.schema_multivar(formula, actions) local l = expr_lexer.new(formula) return schema_multivar(l, actions) end function expr_parse.expr(formula, actions) local l = expr_lexer.new(formula) return expr(l, actions, 0) end return expr_parse