从 c 代码获取人类可读的 AST
Clang 之前通过 -emit-asm 标志提供了此功能，该标志已被删除。那么问题就来了：目前有没有一种简单的方法来完成这个任务？
解决方案中有两个实例，一个是简单的，一个是具有挑战性的（C 的“最令人烦恼的解析”）。以下是来自 http://talkbinary.com/programming/c/fibonacci-in-c/ 的斐波那契程序示例：
int fib(int n) {
if ( n == 0 || n == 1 )
return n;
int fib1 = 0;
int fib2 = 1;
int fib = 0;
for ( int i = 2; i < n; i++ )
{
fib = fib1 + fib2;
fib1 = fib2;
fib2 = fib;
}
return fib;
}以此作为输入，DMS 软件重组工具包（带有完整的 C 11/17 解析器）生成此 AST：
(translation_unit
(function_definition
(function_head
(simple_type_specifier
('int' 'int')
)
(noptr_declarator
(IDENTIFIER 'fib')
('('
(parameter_declaration
(simple_type_specifier
('int' 'int')
)
(IDENTIFIER 'n')
)
)
(function_qualifiers)
)
)
(compound_statement
('{'
(statement_seq
(statement_seq
(statement_seq
(statement_seq
(selection_statement
('if'
('('
(logical_or_expression
(equality_expression
(IDENTIFIER 'n')
('==' 'int')
(INT_LITERAL '0')
)
('||' '||')
(equality_expression
(IDENTIFIER 'n')
('==' 'int')
(INT_LITERAL '1')
)
)
)
(jump_statement
('return'
(IDENTIFIER 'n')
(';' 'int')
)
)
)
)
(simple_declaration
(simple_type_specifier
('int' 'int')
)
(init_declarator
(IDENTIFIER 'fib1')
(initializer
('=' 'int')
(INT_LITERAL '0')
)
)
(';' 'int')
)
)
(simple_declaration
(simple_type_specifier
('int' 'int')
)
(init_declarator
(IDENTIFIER 'fib2')
(initializer
('=' 'int')
(INT_LITERAL '1')
)
)
(';' 'int')
)
)
(simple_declaration
(simple_type_specifier
('int' 'int')
)
(init_declarator
(IDENTIFIER 'fib')
(initializer
('=' 'int')
(INT_LITERAL '0')
)
)
(';' 'int')
)
)
(iteration_statement
('for'
('('
(simple_declaration
(simple_type_specifier
('int' 'int')
)
(init_declarator
(IDENTIFIER 'i')
(initializer
('=' 'int')
(INT_LITERAL '2')
)
)
(';' 'int')
)
(relational_expression
(IDENTIFIER 'i')
('<' '<')
(IDENTIFIER 'n')
)
(';' 'int')
(postfix_expression
(IDENTIFIER 'i')
('++' 'inc')
)
)
(compound_statement
('{'
(statement_seq
(statement_seq
(expression_statement
(assignment_expression
(IDENTIFIER 'fib')
('=' 'int')
(additive_expression
(IDENTIFIER 'fib1')
('+')
(IDENTIFIER 'fib2')
)
)
(';' 'int')
)
)
(expression_statement
(assignment_expression
(IDENTIFIER 'fib1')
('=' 'int')
(IDENTIFIER 'fib2')
)
(';' 'int')
)
)
(expression_statement
(assignment_expression
(IDENTIFIER 'fib2')
('=' 'int')
(IDENTIFIER 'fib')
)
(';' 'int')
)
)
)
)
)
(jump_statement
('return'
(IDENTIFIER 'fib')
(';' 'int')
)
)
)
)
)
)以上是如何从 C 代码中轻松获得人类可读的抽象语法树 (AST)？的详细内容。更多信息请关注PHP中文网其他相关文章！
