A program convert simple C / C++ code to Visual Basic 6 code
Project description
c2vb
A Python program convert simple C / C++ code to Visual Basic 6 code
Warning: only support very little C / C++ grammar
特性
将 C / C++ 转成 AST 再转成 VB
- 实现基本语法
- 简单类型推断(区分
/
和\
) - 可打印带缩进 AST
- 可生成 Graphviz dot 语言 AST
使用方法
$ pip install c2vb
$ c2vb sample.c
$ c2vb sample.cpp
import c2vb
f = open('sample.c', 'r')
src = f.read()
lex = c2vb.Lexer(src) # 词法
parser = c2vb.Parser(lex.tokens) # 语法
c2vb.proc(parser.ast) # 类型推断
parser.ast.vb() == c2vb.run(file='sample.c') == c2vb.run(src='sample.c') # 返回 VB 代码
parser.ast.dot() # 返回以 dot 语言表示的 AST
str(parser.ast) # 返回字符串带缩进 AST
注意
- 不支持预处理命令(
#include
#define
...)- 可以试试
g++ -E file.cpp
来处理#define
- 可以试试
++
--
是被看作赋值的,不能在表达式中出现。- 不支持
struct
class
- 不支持数组初始化
- 也就是说
const
数组不行
- 也就是说
- 不能连赋值
a=b=c
- 高级语法一个都没有实现
- 注意删掉
cin/cout
因为没有实现运算符重载
- 注意删掉
for(s1;s2;s3;)
s1
必须为赋值或定义,s2
必须为数学表达式,s3
必须为赋值- 所有
for
都将被翻译为Do While ... Loop
- 不支持
do ... while()
- 语句只有 if/for/while/return/break/const/变量定义/函数调用
- 也就是说 表达式 加
;
当语句是不行的
- 也就是说 表达式 加
- 类型只有
int/float/double/bool/string
贡献
欢迎提 bug, issue, pull request
TODO:
- 表达式中含有
++
--
- 这件事比较麻烦因为这会把一个赋值变成两三个
- 连赋值
a=b=c
- 特殊
for
翻译成For
(遥遥无期) - C / C++ 中常用函数写入语法之中方便运行
- 数组初始化
支持的语法
statements --> statement | statements statement
statement --> if | while | for | const | declare | return | break
| "{" statements "}"
| call ";" | assigns ";"
program --> program ( const | declare | func )
expr --> 支持函数调用, 数组, `- ! ~ * / % + - < <= > >= == != & ^ | && ||`
| 字符串常量
type --> "int" | "float" | "double" | "string" | "void" | "bool"
identifier --> ID | identifier"["expr"]"
call --> identifier "(" ")"
| identifier "(" expr ( "," expr )* ")"
assign_opt --> "+=" | "-=" | "*=" | "/=" | "%="
| "&=" | "^=" | "|=" | "="
assign --> ( "++" | "--" ) identifier
| identifier ( "++" | "--" )
| identifier assign_opt expr
assigns --> assign ( "," assign )*
arg --> type identifier
func --> type identifier "(" ")" statement
| type identifier "(" arg ( "," arg )* ")" statement
const --> "const" declare
if --> "if" "(" expr ")" statement
| "if" "(" expr ")" statement "else" statement
for --> "for" "(" (declare | assigns ";" ) expr ";" assigns ")" statement
while --> "while" "(" expr ")" statement
return --> "return"
| "return" expr ";"
break --> "break" ";"
declare_item --> identifier
| identifier "=" expr
declare --> type declare_item ( "," declare_item )* ";"
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