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[原创]国赛babytree wp

发表于: 2022-6-5 16:55 7750

[原创]国赛babytree wp

wenling

2022-6-5 16:55

7750

题目给了一个txt文件，里面是swift的抽象语法树

文本很长而且是我不熟悉的swift语言，所以先了解一下swift的抽象语法树吧
swift开发环境搭建：https://www.fatbobman.com/posts/swift-in-linux/

例子：

使用如下命令将switf文件转换为ast文件

![图 2]

如图就是一个初始化语句的ast结构：

在题目给出的ast中，有类似的结构

所以这一块结构的意思就是：

再看一个例子：

![图 3]

if语句

赋值语句

其他的对应关系就不列出了，可以自己写代码对照

这段代码中，调用了print函数，打印的是result的值，result是Bool类型的数据，所以程序会输出true或者false

result变量就在call语句块的上方，可以分析出result是初始化的变量，用来初始化result变量的是一个call语句，调用的函数是check，参数分别是data和key

再往上可以找到key的定义

这里是data的定义，data是有一个subscript_expr语句块定义的，subscript_expr其实是在去数组的下标，这里取的是arguments[1]，也就是第二个命令行参数

在往上是一个if语句，操作符是 >=（extension.>=），操作数一个是argument.count()，一个是2,所以这一块的意思就是比较命令行参数是否大于等于2

![图 4]

在往上就是top_level_code_decl，顶层表达式了，如图所示，这个程序真是由一个func_decl和一个top_level_code_decl组成，我们已经分析完了下面的top_level_code_decl：

上方函数的大体结构为：参数，返回值和一个表达式

参数分别为encoded和keyValue，都是String类型

返回值为Bool类型

下方的语句块中又包含了3个定义变量的语句，1个for循环，1个返回语句

第一个定义变量的语句，变量名为b，类型是一个[UInt8]数组，这个数组是由ebcoded（decl=re.(file).check(::).encoded@re.swift）转换过来的

同上，接着定义一个变量k

接下来的语句块中定义了四个未初始化的变量r0, r1, r2, r3，类型是UInt8

可以看到(decl=Swift.(file).Comparable extension....),说明这是一个for-in循环

循环的范围是从0到b.count-4

![图 5]

紧跟着的是六条赋值语句
![图 6]

展开发现首尾的赋值语句格式相似,中间四条赋值语句格式相似,所以我们应该只需要仔细分析两种不同格式中的各一种
![图 7]

这是第一个赋值语句的结构,做的事情是用b数组的值填充r0到r3

![图 8]

第二个赋值语句,首先是一个取下标,取的是b[i+0]
![图 9]

![图 10]

接着是一个运算语句块
![图 11]

初步看出是用r2异或一个表达式
该表达式是另一个表达式 & 0xff得到
![图 13]

接着又是加运算
一个是k[0]
![图 15]

一个是r0 >> 4

综上,第二个赋值语句:

同理可以分析出接下来的几条赋值语句

for循环之后就是返回语句
![图 16]

返回语句由一条判断语句组成,操作符是==
![图 17]

第一个参数是b数组
![图 18]
第二个参数是一个给定的数组
[88, 35, 88, 225, 7, 201, 57, 94, 77, 56, 75, 168, 72, 218, 64, 91, 16, 101, 32, 207, 73, 130, 74, 128, 76, 201, 16, 248, 41, 205, 103, 84, 91, 99, 79, 202, 22, 131, 63, 255, 20, 16]

re.swift

解题脚本

swiftc -dump-ast hello.swift

(pattern_binding_decl range=[re.swift:18:5 - line:18:15]

            (pattern_named type='String' 'key')

            Original init:

            (string_literal_expr type='String' location=re.swift:18:15 range=[re.swift:18:15 - line:18:15] encoding=utf8 value="345y" builtin_initializer=Swift.(file).String extension.init(_builtinStringLiteral:utf8CodeUnitCount:isASCII:) initializer=**NULL**)

            Processed init:

            (string_literal_expr type='String' location=re.swift:18:15 range=[re.swift:18:15 - line:18:15] encoding=utf8 value="345y" builtin_initializer=Swift.(file).String extension.init(_builtinStringLiteral:utf8CodeUnitCount:isASCII:) initializer=**NULL**))
 
          (var_decl range=[re.swift:18:9 - line:18:9] "key" type='String' interface type='String' access=fileprivate let readImpl=stored immutable)

(pattern_binding_decl range=[re.swift:18:5 - line:18:15]

(pattern_named type='String' 'key')

Original init:

(string_literal_expr type='String' location=re.swift:18:15 range=[re.swift:18:15 - line:18:15] encoding=utf8 value="345y" builtin_initializer=Swift.(file).String extension.init(_builtinStringLiteral:utf8CodeUnitCount:isASCII:) initializer=**NULL**)

Processed init:

(var_decl range=[re.swift:18:9 - line:18:9] "key" type='String' interface type='String' access=fileprivate let readImpl=stored immutable)

(call_expr type='()' location=re.swift:20:5 range=[re.swift:20:5 - line:20:17] nothrow

            (declref_expr type='(Any..., String, String) -> ()' location=re.swift:20:5 range=[re.swift:20:5 - line:20:5] decl=Swift.(file).print(_:separator:terminator:) function_ref=single)

            (argument_list labels=_:separator:terminator:

              (argument

                (vararg_expansion_expr implicit type='Any...' location=re.swift:20:11 range=[re.swift:20:11 - line:20:11]

                  (array_expr implicit type='Any...' location=re.swift:20:11 range=[re.swift:20:11 - line:20:11] initializer=**NULL**

                    (erasure_expr implicit type='Any' location=re.swift:20:11 range=[re.swift:20:11 - line:20:11]

                      (declref_expr type='Bool' location=re.swift:20:11 range=[re.swift:20:11 - line:20:11] decl=re.(file).top-level code.result@re.swift:19:9 function_ref=unapplied)))))

              (argument label=separator

                (default_argument_expr implicit type='String' location=re.swift:20:10 range=[re.swift:20:10 - line:20:10] default_args_owner=Swift.(file).print(_:separator:terminator:) param=1))

              (argument label=terminator

                (default_argument_expr implicit type='String' location=re.swift:20:10 range=[re.swift:20:10 - line:20:10] default_args_owner=Swift.(file).print(_:separator:terminator:) param=2))

            )))))))

(call_expr type='()' location=re.swift:20:5 range=[re.swift:20:5 - line:20:17] nothrow

(declref_expr type='(Any..., String, String) -> ()' location=re.swift:20:5 range=[re.swift:20:5 - line:20:5] decl=Swift.(file).print(_:separator:terminator:) function_ref=single)

(argument_list labels=_:separator:terminator:

(argument

(vararg_expansion_expr implicit type='Any...' location=re.swift:20:11 range=[re.swift:20:11 - line:20:11]

(array_expr implicit type='Any...' location=re.swift:20:11 range=[re.swift:20:11 - line:20:11] initializer=**NULL**

(erasure_expr implicit type='Any' location=re.swift:20:11 range=[re.swift:20:11 - line:20:11]

(declref_expr type='Bool' location=re.swift:20:11 range=[re.swift:20:11 - line:20:11] decl=re.(file).top-level code.result@re.swift:19:9 function_ref=unapplied)))))

(argument label=separator

(default_argument_expr implicit type='String' location=re.swift:20:10 range=[re.swift:20:10 - line:20:10] default_args_owner=Swift.(file).print(_:separator:terminator:) param=1))

(argument label=terminator

(default_argument_expr implicit type='String' location=re.swift:20:10 range=[re.swift:20:10 - line:20:10] default_args_owner=Swift.(file).print(_:separator:terminator:) param=2))

)))))))

(pattern_binding_decl range=[re.swift:19:5 - line:19:33]

            (pattern_named type='Bool' 'result')

            Original init:

            (call_expr type='Bool' location=re.swift:19:18 range=[re.swift:19:18 - line:19:33] nothrow

              (declref_expr type='(String, String) -> Bool' location=re.swift:19:18 range=[re.swift:19:18 - line:19:18] decl=re.(file).check@re.swift:1:6 function_ref=single)

              (argument_list

                (argument

                  (declref_expr type='String' location=re.swift:19:24 range=[re.swift:19:24 - line:19:24] decl=re.(file).top-level code.data@re.swift:17:9 function_ref=unapplied))

                (argument

                  (declref_expr type='String' location=re.swift:19:30 range=[re.swift:19:30 - line:19:30] decl=re.(file).top-level code.key@re.swift:18:9 function_ref=unapplied))

              ))

            Processed init:

            (call_expr type='Bool' location=re.swift:19:18 range=[re.swift:19:18 - line:19:33] nothrow

              (declref_expr type='(String, String) -> Bool' location=re.swift:19:18 range=[re.swift:19:18 - line:19:18] decl=re.(file).check@re.swift:1:6 function_ref=single)

              (argument_list

                (argument

                  (declref_expr type='String' location=re.swift:19:24 range=[re.swift:19:24 - line:19:24] decl=re.(file).top-level code.data@re.swift:17:9 function_ref=unapplied))

                (argument

                  (declref_expr type='String' location=re.swift:19:30 range=[re.swift:19:30 - line:19:30] decl=re.(file).top-level code.key@re.swift:18:9 function_ref=unapplied))

              )))
 
          (var_decl range=[re.swift:19:9 - line:19:9] "result" type='Bool' interface type='Bool' access=fileprivate let readImpl=stored immutable)

(pattern_binding_decl range=[re.swift:19:5 - line:19:33]

(pattern_named type='Bool' 'result')

Original init:

(call_expr type='Bool' location=re.swift:19:18 range=[re.swift:19:18 - line:19:33] nothrow

(declref_expr type='(String, String) -> Bool' location=re.swift:19:18 range=[re.swift:19:18 - line:19:18] decl=re.(file).check@re.swift:1:6 function_ref=single)

(argument_list

(argument

(declref_expr type='String' location=re.swift:19:24 range=[re.swift:19:24 - line:19:24] decl=re.(file).top-level code.data@re.swift:17:9 function_ref=unapplied))

(argument

(declref_expr type='String' location=re.swift:19:30 range=[re.swift:19:30 - line:19:30] decl=re.(file).top-level code.key@re.swift:18:9 function_ref=unapplied))

))

Processed init:

(call_expr type='Bool' location=re.swift:19:18 range=[re.swift:19:18 - line:19:33] nothrow

(declref_expr type='(String, String) -> Bool' location=re.swift:19:18 range=[re.swift:19:18 - line:19:18] decl=re.(file).check@re.swift:1:6 function_ref=single)

(argument_list

(argument

(declref_expr type='String' location=re.swift:19:24 range=[re.swift:19:24 - line:19:24] decl=re.(file).top-level code.data@re.swift:17:9 function_ref=unapplied))

(argument

(declref_expr type='String' location=re.swift:19:30 range=[re.swift:19:30 - line:19:30] decl=re.(file).top-level code.key@re.swift:18:9 function_ref=unapplied))

)))

(var_decl range=[re.swift:19:9 - line:19:9] "result" type='Bool' interface type='Bool' access=fileprivate let readImpl=stored immutable)

(pattern_binding_decl range=[re.swift:18:5 - line:18:15]

            (pattern_named type='String' 'key')

            Original init:

            (string_literal_expr type='String' location=re.swift:18:15 range=[re.swift:18:15 - line:18:15] encoding=utf8 value="345y" builtin_initializer=Swift.(file).String extension.init(_builtinStringLiteral:utf8CodeUnitCount:isASCII:) initializer=**NULL**)

            Processed init:

            (string_literal_expr type='String' location=re.swift:18:15 range=[re.swift:18:15 - line:18:15] encoding=utf8 value="345y" builtin_initializer=Swift.(file).String extension.init(_builtinStringLiteral:utf8CodeUnitCount:isASCII:) initializer=**NULL**))
 
          (var_decl range=[re.swift:18:9 - line:18:9] "key" type='String' interface type='String' access=fileprivate let readImpl=stored immutable)

(pattern_binding_decl range=[re.swift:18:5 - line:18:15]

(pattern_named type='String' 'key')

Original init:

Processed init:

(var_decl range=[re.swift:18:9 - line:18:9] "key" type='String' interface type='String' access=fileprivate let readImpl=stored immutable)

(pattern_binding_decl range=[re.swift:17:5 - line:17:39]

            (pattern_named type='String' 'data')

            Original init:

            (subscript_expr type='<null>'

              (member_ref_expr type='@lvalue [String]' location=re.swift:17:28 range=[re.swift:17:16 - line:17:28] decl=Swift.(file).CommandLine.arguments

                (type_expr type='CommandLine.Type' location=re.swift:17:16 range=[re.swift:17:16 - line:17:16] typerepr='CommandLine'))

              (argument_list

                (argument

                  (integer_literal_expr type='Int' location=re.swift:17:38 range=[re.swift:17:38 - line:17:38] value=1 builtin_initializer=Swift.(file).Int.init(_builtinIntegerLiteral:) initializer=**NULL**))

              ))

            Processed init:

            (load_expr implicit type='String' location=re.swift:17:37 range=[re.swift:17:16 - line:17:39]

              (subscript_expr type='@lvalue String' location=re.swift:17:37 range=[re.swift:17:16 - line:17:39] decl=Swift.(file).Array extension.subscript(_:) [with (substitution_map generic_signature=<Element> (substitution Element -> String))]

                (inout_expr implicit type='inout Array<String>' location=re.swift:17:16 range=[re.swift:17:16 - line:17:28]

                  (member_ref_expr type='@lvalue [String]' location=re.swift:17:28 range=[re.swift:17:16 - line:17:28] decl=Swift.(file).CommandLine.arguments

                    (type_expr type='CommandLine.Type' location=re.swift:17:16 range=[re.swift:17:16 - line:17:16] typerepr='CommandLine')))

                (argument_list

                  (argument

                    (integer_literal_expr type='Int' location=re.swift:17:38 range=[re.swift:17:38 - line:17:38] value=1 builtin_initializer=Swift.(file).Int.init(_builtinIntegerLiteral:) initializer=**NULL**))

                ))))
 
          (var_decl range=[re.swift:17:9 - line:17:9] "data" type='String' interface type='String' access=fileprivate let readImpl=stored immutable)

(pattern_binding_decl range=[re.swift:17:5 - line:17:39]

(pattern_named type='String' 'data')

Original init:

(subscript_expr type='<null>'

(member_ref_expr type='@lvalue [String]' location=re.swift:17:28 range=[re.swift:17:16 - line:17:28] decl=Swift.(file).CommandLine.arguments

(type_expr type='CommandLine.Type' location=re.swift:17:16 range=[re.swift:17:16 - line:17:16] typerepr='CommandLine'))

(argument_list

(argument

(integer_literal_expr type='Int' location=re.swift:17:38 range=[re.swift:17:38 - line:17:38] value=1 builtin_initializer=Swift.(file).Int.init(_builtinIntegerLiteral:) initializer=**NULL**))

))

Processed init:

(load_expr implicit type='String' location=re.swift:17:37 range=[re.swift:17:16 - line:17:39]

(subscript_expr type='@lvalue String' location=re.swift:17:37 range=[re.swift:17:16 - line:17:39] decl=Swift.(file).Array extension.subscript(_:) [with (substitution_map generic_signature=<Element> (substitution Element -> String))]

(inout_expr implicit type='inout Array<String>' location=re.swift:17:16 range=[re.swift:17:16 - line:17:28]

(member_ref_expr type='@lvalue [String]' location=re.swift:17:28 range=[re.swift:17:16 - line:17:28] decl=Swift.(file).CommandLine.arguments

(type_expr type='CommandLine.Type' location=re.swift:17:16 range=[re.swift:17:16 - line:17:16] typerepr='CommandLine')))

(argument_list

(argument

))))

(var_decl range=[re.swift:17:9 - line:17:9] "data" type='String' interface type='String' access=fileprivate let readImpl=stored immutable)

(if_stmt range=[re.swift:16:1 - line:21:1]

        (binary_expr type='Bool' location=re.swift:16:32 range=[re.swift:16:4 - line:16:35] nothrow

          (dot_syntax_call_expr implicit type='(Int, Int) -> Bool' location=re.swift:16:32 range=[re.swift:16:32 - line:16:32] nothrow

            (declref_expr type='(Int.Type) -> (Int, Int) -> Bool' location=re.swift:16:32 range=[re.swift:16:32 - line:16:32] decl=Swift.(file).Int extension.>= function_ref=single)

            (argument_list implicit

              (argument

                (type_expr implicit type='Int.Type' location=re.swift:16:32 range=[re.swift:16:32 - line:16:32] typerepr='Int'))

            ))

          (argument_list implicit

            (argument

              (member_ref_expr type='Int' location=re.swift:16:26 range=[re.swift:16:4 - line:16:26] decl=Swift.(file).Array extension.count [with (substitution_map generic_signature=<Element> (substitution Element -> String))]

                (load_expr implicit type='[String]' location=re.swift:16:16 range=[re.swift:16:4 - line:16:16]

                  (member_ref_expr type='@lvalue [String]' location=re.swift:16:16 range=[re.swift:16:4 - line:16:16] decl=Swift.(file).CommandLine.arguments

                    (type_expr type='CommandLine.Type' location=re.swift:16:4 range=[re.swift:16:4 - line:16:4] typerepr='CommandLine')))))

            (argument

              (integer_literal_expr type='Int' location=re.swift:16:35 range=[re.swift:16:35 - line:16:35] value=2 builtin_initializer=Swift.(file).Int.init(_builtinIntegerLiteral:) initializer=**NULL**))

          ))

(if_stmt range=[re.swift:16:1 - line:21:1]

(binary_expr type='Bool' location=re.swift:16:32 range=[re.swift:16:4 - line:16:35] nothrow

(dot_syntax_call_expr implicit type='(Int, Int) -> Bool' location=re.swift:16:32 range=[re.swift:16:32 - line:16:32] nothrow

(declref_expr type='(Int.Type) -> (Int, Int) -> Bool' location=re.swift:16:32 range=[re.swift:16:32 - line:16:32] decl=Swift.(file).Int extension.>= function_ref=single)

(argument_list implicit

(argument

(type_expr implicit type='Int.Type' location=re.swift:16:32 range=[re.swift:16:32 - line:16:32] typerepr='Int'))

))

(argument_list implicit

(argument

(member_ref_expr type='Int' location=re.swift:16:26 range=[re.swift:16:4 - line:16:26] decl=Swift.(file).Array extension.count [with (substitution_map generic_signature=<Element> (substitution Element -> String))]

(load_expr implicit type='[String]' location=re.swift:16:16 range=[re.swift:16:4 - line:16:16]

(member_ref_expr type='@lvalue [String]' location=re.swift:16:16 range=[re.swift:16:4 - line:16:16] decl=Swift.(file).CommandLine.arguments

(type_expr type='CommandLine.Type' location=re.swift:16:4 range=[re.swift:16:4 - line:16:4] typerepr='CommandLine')))))

(argument

(integer_literal_expr type='Int' location=re.swift:16:35 range=[re.swift:16:35 - line:16:35] value=2 builtin_initializer=Swift.(file).Int.init(_builtinIntegerLiteral:) initializer=**NULL**))

))

(func_decl range=[re.swift:1:1 - line:14:1] "check(_:_:)" interface type='(String, String) -> Bool' access=internal

    (parameter_list range=[re.swift:1:11 - line:1:49]

      (parameter "encoded" type='String' interface type='String')

      (parameter "keyValue" type='String' interface type='String'))

    (result

      (type_ident

        (component id='Bool' bind=Swift.(file).Bool)))

    (brace_stmt range=[re.swift:1:59 - line:14:1]

(func_decl range=[re.swift:1:1 - line:14:1] "check(_:_:)" interface type='(String, String) -> Bool' access=internal

(parameter_list range=[re.swift:1:11 - line:1:49]

(parameter "encoded" type='String' interface type='String')

(parameter "keyValue" type='String' interface type='String'))

(result

(type_ident

(component id='Bool' bind=Swift.(file).Bool)))

(brace_stmt range=[re.swift:1:59 - line:14:1]

(parameter_list range=[re.swift:1:11 - line:1:49]

      (parameter "encoded" type='String' interface type='String')

      (parameter "keyValue" type='String' interface type='String'))

(parameter_list range=[re.swift:1:11 - line:1:49]

(parameter "encoded" type='String' interface type='String')

(parameter "keyValue" type='String' interface type='String'))

(result

      (type_ident

        (component id='Bool' bind=Swift.(file).Bool)))

(result

(type_ident

(component id='Bool' bind=Swift.(file).Bool)))

(brace_stmt range=[re.swift:1:59 - line:14:1]

      (pattern_binding_decl range=[re.swift:2:5 - line:2:33]

      (var_decl range=[re.swift:2:9 - line:2:9] "b" type='[UInt8]' interface type='[UInt8]' access=private readImpl=stored writeImpl=stored readWriteImpl=stored)

      (pattern_binding_decl range=[re.swift:3:5 - line:3:34]

      (var_decl range=[re.swift:3:9 - line:3:9] "k" type='[UInt8]' interface type='[UInt8]' access=private readImpl=stored writeImpl=stored readWriteImpl=stored)

      (pattern_binding_decl range=[re.swift:4:5 - line:4:25]

      (var_decl range=[re.swift:4:9 - line:4:9] "r0" type='UInt8' interface type='UInt8' access=private readImpl=stored writeImpl=stored readWriteImpl=stored)

      (var_decl range=[re.swift:4:13 - line:4:13] "r1" type='UInt8' interface type='UInt8' access=private readImpl=stored writeImpl=stored readWriteImpl=stored)

      (var_decl range=[re.swift:4:17 - line:4:17] "r2" type='UInt8' interface type='UInt8' access=private readImpl=stored writeImpl=stored readWriteImpl=stored)

      (var_decl range=[re.swift:4:21 - line:4:21] "r3" type='UInt8' interface type='UInt8' access=private readImpl=stored writeImpl=stored readWriteImpl=stored)

      (for_each_stmt range=[re.swift:5:5 - line:12:5]

      (return_stmt range=[re.swift:13:5 - line:13:198]

(brace_stmt range=[re.swift:1:59 - line:14:1]

(pattern_binding_decl range=[re.swift:2:5 - line:2:33]

(var_decl range=[re.swift:2:9 - line:2:9] "b" type='[UInt8]' interface type='[UInt8]' access=private readImpl=stored writeImpl=stored readWriteImpl=stored)

(pattern_binding_decl range=[re.swift:3:5 - line:3:34]

(var_decl range=[re.swift:3:9 - line:3:9] "k" type='[UInt8]' interface type='[UInt8]' access=private readImpl=stored writeImpl=stored readWriteImpl=stored)

(pattern_binding_decl range=[re.swift:4:5 - line:4:25]

(var_decl range=[re.swift:4:9 - line:4:9] "r0" type='UInt8' interface type='UInt8' access=private readImpl=stored writeImpl=stored readWriteImpl=stored)

(var_decl range=[re.swift:4:13 - line:4:13] "r1" type='UInt8' interface type='UInt8' access=private readImpl=stored writeImpl=stored readWriteImpl=stored)

(var_decl range=[re.swift:4:17 - line:4:17] "r2" type='UInt8' interface type='UInt8' access=private readImpl=stored writeImpl=stored readWriteImpl=stored)

(var_decl range=[re.swift:4:21 - line:4:21] "r3" type='UInt8' interface type='UInt8' access=private readImpl=stored writeImpl=stored readWriteImpl=stored)

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最后于 2024-1-26 13:51 被kanxue编辑，原因：

#Reverse

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