[英]Getting ECL symbol name as string in C++
I'm working on embedding Embeddable Common Lisp into a library and I've been writing utility functions to convert ECL's cl_object
to various C/C++ types - eg to convert a cl_object
representing a string to a std::string. 我正在将Embeddable Common Lisp嵌入到库中,并且我一直在编写实用程序函数以将ECL的
cl_object
转换为各种C / C ++类型-例如,将表示字符串的cl_object
转换为std :: string。
My question is this - why am I failing to retrieve a string containing the name of a symbol in ECL? 我的问题是-为什么我无法在ECL中检索包含符号名称的字符串?
I'm having trouble getting the following function ecl_symbol_to_string
to work, which should take an ECL symbol and return a std::string with it's name: 我在使以下函数
ecl_symbol_to_string
正常工作时遇到麻烦,该函数应使用ECL符号并返回名称为std :: string的名称:
string ecl_symbol_to_string(cl_object sym) {
return ecl_string_to_string(sym->symbol.name);
}
string ecl_string_to_string(cl_object echar) {
string res("");
int j = echar->string.dim; //get dimension
ecl_character* selv = echar->string.self; //get pointer
//do simple pointer addition
for(int i=0;i<j;i++){
res += (*(selv+i));
}
return res;
};
Note that ecl_string_to_string
works for lisp strings. 请注意,
ecl_string_to_string
适用于ecl_string_to_string
字符串。
A simple unit test illustrates the failure: 一个简单的单元测试说明了失败:
TEST_CASE( "ecl_symbol_to_string returns a string for symbol",
"[ecl_string_to_string]" ) {
LispRuntime *rt = new LispRuntime("()");
std::string eval_script;
cl_object eval_result;
std::string subject_result;
eval_script = "'mysymbol";
eval_result = rt->evaluate(eval_script);
REQUIRE( ECL_SYMBOLP(eval_result) );
subject_result = ecl_symbol_to_string(eval_result);
REQUIRE ( ECL_STRINGP(cl_symbol_name(eval_result)) );
std::cout << subject_result.c_str() << std::endl;
REQUIRE( subject_result.compare("mysymbol") == 0 );
delete rt;
}
This test case prints out MM
for the call to cout. 该测试用例打印出
MM
,以调用cout。 I have also tried comparing to "MYSYMBOL", which fails, and "M" which passes. 我还尝试过比较失败的“ MYSYMBOL”和通过的“ M”。
LispRuntime::eval_script simply converts and evaluates the form: LispRuntime :: eval_script只需转换并评估以下形式:
cl_object LispRuntime::evaluate(std::string &code) {
cl_object form = c_string_to_object(code.c_str());
cl_object result = cl_eval(form);
return result;
}
I compiled ECL version 16.1.3 locally with the C++ option enabled, with debugging symbols and with all other settings default. 我在本地启用了C ++选项,调试符号和所有其他默认设置的情况下编译了ECL 16.1.3版。 Any assistance is greatly appreciated.
非常感谢您的协助。
I believe this is a unicode/non-unicode mix-up: ECL defines two string types in object.h . 我相信这是Unicode /非Unicode的混合体:ECL在object.h中定义了两种字符串类型。 One is
ecl_base_string
, where the member self
ultimately typedefs to an unsigned char*
and the other is ecl_string
where the member self
usually (depending on compile time arguments, I think) typedefs to a int*
. 一个是
ecl_base_string
,其中成员self
最终将typedef定义为一个unsigned char*
,另一个是ecl_string
,其中成员self
通常将ecl_string
定义为一个int*
(取决于编译时参数)。 You're accessing it as an ecl_string
. 您正在作为
ecl_string
访问它。
If you trace through the workings of ecl_make_symbol
you find it ends up calling the function make_constant_base_string
which returns a base string. 如果跟踪
ecl_make_symbol
的工作原理,您会发现它最终调用了函数make_constant_base_string
,该函数返回一个基本字符串。 Thus your ecl_string_to_string
accesses it through the wrong type. 因此,您的
ecl_string_to_string
通过错误的类型进行访问。
I suspect the easiest solution is to build a type-check/conversion into ecl_string_to_string
: 我怀疑最简单的解决方案是将类型检查/转换构建为
ecl_string_to_string
:
string ecl_string_to_string(cl_object echar) {
switch (ecl_t_of(echar)) {
#ifdef ECL_UNICODE
case t_string:
if (!ecl_fits_in_base_string(echar)) {
echar = cl_copy_seq(echar);
} else {
echar = si_copy_to_simple_base_string(echar);
}
break;
#endif
case t_base_string:
// OK
break;
default:
// PRINT SOME ERROR
return string(); // or raise an exception
}
string res("");
int j = echar->base_string.dim; //get dimension
ecl_base_char* selv = echar->base_string.self; //get pointer
//do simple pointer addition
for(int i=0;i<j;i++){
res += (*(selv+i));
}
return res;
};
The extra code I've added was heavily copied from the ECL function cl_make_symbol
. 我添加的额外代码是从ECL函数
cl_make_symbol
大量复制的。 I decided to convert to ecl_base_string
rather than ecl_string
since the C++ string won't accept unicode characters anyway. 我决定转换为
ecl_base_string
而不是ecl_string
因为C ++字符串无论如何都不接受unicode字符。 You could probably do it the other way round if you had good reason to. 如果您有充分的理由,则可以采取另一种方法。
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