python class 定义迁移到 go struct

在 python 迁移到 go 的过程中，面对已经成型的对象类定义，迁移和修改类定义不同于逻辑代码，是很枯燥痛苦的过程。

通过以下脚本文件可以实现快速转换。

gen_struct.py

使用注意

• 如果字段名称中包含 dict 字符串，可能被替换修改，如果出现该问题，请根据实际业务情况修改 map_go_type 方法。
• msg tag 为我个人业务需求，可以直接删除或修改为其他tag。

import io

import regex

class_name_reg = regex.compile(r"class\s(?P<name>[a-zA-Z0-9]+)(\(BaseModel\))?:")
single_line_doc_reg = regex.compile(r'""".*"""')
field_reg = regex.compile(r"(?P<name>[a-z-A-Z0-9]+):\s*(?P<type>\S+)\s*=?\s*(?P<default>\S+)?\s*#?(?P<descript>.*)?")

with io.open("struct", "rb") as f:
    const_file = f.read().decode("utf-8")

lines = const_file.split("\n")

class_entry = ""
field_list = []
doc_entry = False


class FieldDeclaration:
    name: str
    type: str
    default: str
    descript: str

    def __init__(self, reg_group):
        self.name = reg_group['name']
        self.type = reg_group['type']
        self.default = reg_group['default']
        self.descript = reg_group['descript']


class ClassDeclaration:
    name: str
    fields: list[FieldDeclaration]

    def __init__(self, name, fields):
        self.name = name
        self.fields = fields


class_list = []


for line in lines:
    line = line.strip()
    if not class_entry and line.startswith("class"):
        class_entry = class_name_reg.match(line).groups()[0]
        continue
    if class_entry:
        if single_line_doc_reg.match(line):
            continue
        # multi lines doc
        if line == '"""':
            if doc_entry:
                doc_entry = False
            else:
                doc_entry = True
            continue
        if doc_entry:
            continue
        # emtpy line, class scope escape
        if not line:
            if class_entry:
                # class store
                class_list.append(ClassDeclaration(class_entry, field_list))
                class_entry = ""
                field_list = []
            continue
        # field
        field_list.append(FieldDeclaration(field_reg.match(line).groupdict()))


def upper_camel(s) -> str:
    return s[0].upper() + s[1:]


def map_go_type(s) -> str:
    s = s.replace("[str]", "[string]")
    s = s.replace("dict", "map[string]any")
    if s.startswith("Optional["):
        s = s[9:-1]
    if s.startswith("list["):
        s = f"[]{s[5:-1]}"
    if s == "str":
        s = "string"
    if s == "list":
        s = "[]any"
    return s


clz_sb = []


for clz in class_list:
    sb = [
        f"// {upper_camel(clz.name)} generated by gen_struct.py",
        f"type {upper_camel(clz.name)} struct{{",
        "\n".join([f'  {upper_camel(f.name)}\t{map_go_type(f.type)}\t`json:"{f.name}" msg:"{f.name}"`' for f in clz.fields]), "}",
    ]
    clz_sb.append("\n".join(sb))


with io.open("struct_out", "w") as f:
    f.write("\n\n".join(clz_sb))

使用

读取文件：struct

class User(BaseModel):
    """profile.user"""
    userId: int
    name: str
    rank: int

生成文件：struct_out

// User generated by gen_struct.py
type User struct{
  UserId	int	`json:"userId" msg:"userId"`
  Name	string	`json:"name" msg:"name"`
  Rank	int	`json:"rank" msg:"rank"`
}