英文:
how to check if a string is valid json in c using jq
问题
基本上，我想在C语言中创建一个名为bool json_is_valid(char* input)的函数。由于我在处理JSON的其他部分时使用了jq，我希望也能在这里使用它，但是我无法找到一个合适的方法来实现它。除此之外，我尝试了以下方法：
bool json_is_valid(char* input){
jq_state* state = jq_init();
jv compiled = jq_compile_args(state, ""."", NULL);
return !(jv_is_valid(compiled));
}
然而，这仍然不起作用。如何修复这个问题？
英文:
basically I want to have a function bool json_is_valid(char* input) in c. As I use jq for the rest of my json stuff, I want to use it for this as well, however I am unable to find a proper way of doing it. Among other things I've tried the following:
bool json_is_valid(char* input){
jq_state* state = jq_init();
jv compiled = jq_compile_args(state, ".", NULL);
return !(jv_is_valid(compiled));
}
However, this still doesn't work. How could this be fixed?
答案1
得分: 1
根据我了解，jv_parse 可用于验证 JSON 字符串。
它在 src/jv.h 中声明如下：
jv jv_parse(const char* string);
将此函数的结果传递给 jv_is_valid 看起来可以完成任务。jv_is_valid 在 src/jv.h 中定义如下：
static int jv_is_valid(jv x) {
return jv_get_kind(x) != JV_KIND_INVALID;
}
一个简单的示例：
#include <jq.h>
#include <stdio.h>
#include <string.h>
int json_is_valid(const char *json)
{
jv ele = jv_parse(json);
int valid = jv_is_valid(ele);
jv_free(ele);
return valid;
}
int main(void)
{
while (1) {
char buf[512];
if (!fgets(buf, sizeof buf, stdin))
break;
buf[strcspn(buf, "\n")] = '\0';
printf("<<%s>> Valid? %s.\n", buf, json_is_valid(buf) ? "Yes" : "No");
}
}
{}
<<{}>> Valid? Yes.
[]
<<[]>> Valid? Yes.
[{}]
<<[{}]>> Valid? Yes.
[][]
<<[][]>> Valid? No.
"foo"
<<"foo">> Valid? Yes.
"foo":"bar"
<<"foo":"bar">> Valid? No.
51
<<51>> Valid? Yes.
{42: []}
<<{42: []}>> Valid? No.
{"42":[1, 2, 3]}
<<{"42":[1, 2, 3]}>> Valid? Yes.
'qux'
<<'qux'>> Valid? No.
jq_compile (jq_compile_args) 的问题在于它似乎解析了手册中描述的 jq 过滤语言。
可能有一种更正确的方法，但是缺乏适当的 C API 文档使得研究变得不方便。
英文:
As far as I can tell, jv_parse can be used to validate strings of JSON.
Its declared in src/jv.h as:
jv jv_parse(const char* string);
Passing the result of this function to jv_is_valid appears to get the job done. jv_is_valid is defined in src/jv.h as:
static int jv_is_valid(jv x) {
return jv_get_kind(x) != JV_KIND_INVALID;
}
A cursory example:
#include <jq.h>
#include <stdio.h>
#include <string.h>
int json_is_valid(const char *json)
{
jv ele = jv_parse(json);
int valid = jv_is_valid(ele);
jv_free(ele);
return valid;
}
int main(void)
{
while (1) {
char buf[512];
if (!fgets(buf, sizeof buf, stdin))
break;
buf[strcspn(buf, "\n")] = '\0';
printf("<<%s>> Valid? %s.\n", buf, json_is_valid(buf) ? "Yes" : "No");
}
}
{}
<<{}>> Valid? Yes.
[]
<<[]>> Valid? Yes.
[{}]
<<[{}]>> Valid? Yes.
[][]
<<[][]>> Valid? No.
"foo"
<<"foo">> Valid? Yes.
"foo":"bar"
<<"foo":"bar">> Valid? No.
51
<<51>> Valid? Yes.
{42: []}
<<{42: []}>> Valid? No.
{"42":[1, 2, 3]}
<<{"42":[1, 2, 3]}>> Valid? Yes.
'qux'
<<'qux'>> Valid? No.
The problem with jq_compile (jq_compile_args) is that it would seem to parse the jq filtering language described in the manual.
There might be a more correct method, but the lack of a proper C API documentation makes this an unwieldy problem to research.
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