云风的 BLOG

我们来看一个从群星中随便摘录的例子（有点长，但挺有代表性）：

country_event = {
    id = primitive.16
    hide_window = yes

    trigger = {
        is_country_type = primitive
        has_country_flag = early_space_age
        #NOT = { has_country_flag = recently_advanced }
        OR = {
            AND = {
                exists = from
                from = {
                    OR = {
                        is_country_type = default
                        is_country_type = awakened_fallen_empire
                    }
                }
            }
            years_passed > 25
        }
    }

    mean_time_to_happen = {
        years = 100

        modifier = {
            factor = 0.6
            has_country_flag = acquired_tech
        }
    }

    immediate = {
        remove_country_flag = early_space_age
        set_country_flag = primitives_can_into_space
        set_country_type = default
        change_country_flag = random
        if = {
            limit = { is_species_class = MAM }
            set_graphical_culture = mammalian_01
        }
        if = {
            limit = { is_species_class = REP }
            set_graphical_culture = reptilian_01
        }
        if = {
            limit = { is_species_class = AVI }
            set_graphical_culture = avian_01
        }
        if = {
            limit = { is_species_class = ART }
            set_graphical_culture = arthropoid_01
        }
        if = {
            limit = { is_species_class = MOL }
            set_graphical_culture = molluscoid_01
        }
        if = {
            limit = { is_species_class = FUN }
            set_graphical_culture = fungoid_01
        }
        change_government = {
            authority = random
            civics = random
        }
        set_name = random
        if = {
            limit = {
                home_planet = {
                    has_observation_outpost = yes
                }
            }
            home_planet = {
                observation_outpost_owner = {
                    country_event = { id = primitive.17 }
                }
            }
        }
        add_minerals = 1000 # enough for a spaceport and then some
        add_energy = 500
        add_influence = 300
        capital_scope = {
            every_tile = {
                limit = {
                    has_blocker = yes
                    NOR = {
                        has_blocker = tb_decrepit_dwellings
                        has_blocker = tb_failing_infrastructure
                    }
                }
                remove_blocker = yes
            }
            while = {
                limit = { 
                    num_pops < 8
                    any_tile = {
                        has_grown_pop = no
                        has_growing_pop = no
                        has_blocker = no
                    }
                }
                random_tile = {
                    limit = {
                        has_grown_pop = no
                        has_growing_pop = no
                        has_blocker = no
                    }
                    create_pop = {
                        species = owner
                    }
                }
            }
            random_tile = {
                limit = {
                    has_grown_pop = yes
                    OR = {
                        has_building = "building_primitive_farm"
                        has_building = "building_primitive_factory"
                        has_building = no
                    }
                }
                clear_deposits = yes
                add_deposit = d_mineral_food_deposit
                set_building = "building_capital_2"
            }
            random_tile = {
                limit = {
                    has_grown_pop = yes
                    OR = {
                        has_building = "building_primitive_farm"
                        has_building = "building_primitive_factory"
                        has_building = no
                    }
                }
                clear_deposits = yes
                add_deposit = d_mineral_deposit
                set_building = "building_mining_network_1"
            }
            random_tile = {
                limit = {
                    has_grown_pop = yes
                    OR = {
                        has_building = "building_primitive_farm"
                        has_building = "building_primitive_factory"
                        has_building = no
                    }
                }
                clear_deposits = yes
                add_deposit = d_mineral_deposit
                set_building = "building_mining_network_1"
            }
            random_tile = {
                limit = {
                    has_grown_pop = yes
                    OR = {
                        has_building = "building_primitive_farm"
                        has_building = "building_primitive_factory"
                        has_building = no
                    }
                }
                clear_deposits = yes
                add_deposit = d_farmland_deposit
                set_building = "building_hydroponics_farm_1"
            }
            random_tile = {
                limit = {
                    has_grown_pop = yes
                    OR = {
                        has_building = "building_primitive_farm"
                        has_building = "building_primitive_factory"
                        has_building = no
                    }
                }
                clear_deposits = yes
                add_deposit = d_farmland_deposit
                set_building = "building_hydroponics_farm_1"
            }
            random_tile = {
                limit = {
                    has_grown_pop = yes
                    OR = {
                        has_building = "building_primitive_farm"
                        has_building = "building_primitive_factory"
                        has_building = no
                    }
                }
                clear_deposits = yes
                add_deposit = d_energy_deposit
                set_building = "building_power_plant_1"
            }
            random_tile = {
                limit = {
                    has_grown_pop = yes
                    OR = {
                        has_building = "building_primitive_farm"
                        has_building = "building_primitive_factory"
                        has_building = no
                    }
                }
                clear_deposits = yes
                add_deposit = d_energy_deposit
                set_building = "building_power_plant_1"
            }
            random_tile = {
                limit = {
                    has_grown_pop = yes
                    OR = {
                        has_building = "building_primitive_farm"
                        has_building = "building_primitive_factory"
                        has_building = no
                    }
                }
                clear_deposits = yes
                add_deposit = d_energy_deposit
                set_building = "building_power_plant_1"
            }
            remove_all_armies = yes
            create_army = {
                name = random
                owner = PREV
                species = owner_main_species
                type = "defense_army"
            }
            create_army = {
                name = random
                owner = PREV
                species = owner_main_species
                type = "defense_army"
            }
            create_army = {
                name = random
                owner = PREV
                species = owner_main_species
                type = "defense_army"
            }
            create_army = {
                name = random
                owner = PREV
                species = owner_main_species
                type = "defense_army"
            }
        }
        random_owned_ship = {
            limit = { is_ship_size = primitive_space_station }
            fleet = { destroy_fleet = THIS }
        }
    }
}

起初，我很疑惑在这个格式中，为啥赋值和相等都用的 = ，这不是容易引起歧义么？但是你从 lisp 的角度来看就简单了。等于号只是为了便于策划书写和阅读的一个变形。所谓 id = primitive.16 你可以理解为 ( id, primitive.16 ) 而 iscountrytype = default 一样可以理解为 ( iscountrytype , default ) 。 而

create_army = {
                name = random
                owner = PREV
                species = owner_main_species
                type = "defense_army"
            }

本质上是 ( create_army , ( ( name, random ) , (owner, PREV), (species, owner_main_species), (type, "defense_army") ) )。

基础数据结构只要能表达出来，怎么理解这些 list 是更上层的工作，这就和我们在 csv 中去模拟树结构是一样的道理。只不过 years_passed > 25 这样的东西，被翻译成 ( years_passed, > , 25 ) 有三个元素。上层解析的时候，如果确定它是一个逻辑表达式，就很容易在 2 个元素的 list 中间插入一个 = 补全。

这种结构很容易描述一些控制结构，比如上面例子中的 if 。我还在其它数据中发现了 repeat while 等控制结构，这些都是上层的工作，和底层数据模型无关。但不得不说，lisp 模式比 csv 模式更容易做此类控制结构。

把这种数据结构翻译成 lua 也很容易：只需要用 lua table 的 array 来保存即可。但为了使用方便，可以加一个代理结构。如果上层业务想把一个 list 解析成字典，就在 cache 中临时生成一个 hash 表加快查询即可。我们甚至可以把它直接存在 C 内存中，只在 lua 中暴露出遍历以及高层的访问方法。所谓高层的访问方法指，可以直接读取 if repeat 等控制结构，或是把带 AND OR 这样的复合 list 直接翻译成一个条件表达式。

8 月 8 日补充：

我实现了一个简单的 lua parser : https://github.com/cloudwu/pdxparser 。