一種新的語言

Question

的語法我有這個語法對此我無法理解爲如何使一個解析器它：

module = properties fields methods module#3 'end' 

properties = list#0 (property add#2)* 
property = 'class' 'name' class# ';' 

fields = list#0 (field add#2)* 
field = type list#0 id add#2 [';'/','] ! (',' id add#2)* ';' field#2 

methods = list#0 (method add#2)* 
method = (type id/nothing#0 id) ! '(' args ')' follow method#4 
args = list#0 (arg add#2 (',' arg add#2)*)? 
arg = type id ! arg#2/nothing#0 id ! arg#2 

statements = list#0 (statement add#2)* 
statement = do/jump/compound/simple 
follow = block/jump/compound/simple 
jump = break/continue/return 
compound = if/while 
simple = local/assign 

do = 'do' '{' statements '}' do#1 
block = '{' statements '}' block#1 

break = 'break' ';' break#0 
continue = 'continue' ';' continue#0 
return = 'return' (exp/nothing#0) ';' return#1 

if = 'if' '(' exp ')' follow ('else' follow/nothing#0) if#3 
while = 'while' '(' exp ')' follow while#2 

local = type id ! init? local#2 ';' 
init = 'assign' exp assign#2/'.' id dot#2 '(' exps ')' call#2 
assign = id 'assign' ! exp assign#2 ';' 

exp = id ('(' exps ')' call#2/'.' id dot#2 '(' exps ')' call#2)? 
exps = list#0 (exp add#2 (',' exp add#2)*)? 
type = 'name' type# 
id = 'name' id# 

'.' = 'DOT' 

任何人都可以，請讓我理解這個語法。 感謝

Answer 1

此：

module = properties fields methods module#3 'end' 

意味着：

a module consists of properties, followed by fields, followed by methods, followed by the word "end" 

所以爲了解析模塊編譯器應該：

parse properties 
parse fields 
parse methods 
match the word "end" 

該項目以 「＃」是它應該創建的語法節點的類型，該數字表示之前解析res的數量應該將ults傳遞給它。

在Python語言的代碼可能是這個樣子：

def parse_module(): 
    properties = parse_properties() 
    fields = parse_fields() 
    methods = parse_methods() 
    module = make_module(properties, fields, methods) 
    match("end") 
    return module 

A 「/」 分隔的替代品， 「（......）*」 表示任何數量的重複，和 「？」表示可選項目。