Regex distinguish < in logical operations and parenthesis pairs

I am coding a plugin that automatically adds spaces around symbols, I use the search function to locate symbols that match the regular expression and then modify. But I can't write an expression to distinguish the < in

#include<stdio.h>
a<b
a<b>
a<v and c>d

it should be

#include<stdio.h>
a < b
a<b>
a < v and c > d

but it will be

#include < stdio.h>
a < b
a < b>
a < v and c > d

I would be very grateful if you could help me write this expression.

Thanks.

I used [^ <']<[^ <='] for search the <, but obviously this doesn't work.

Solution

If lookarounds are supported, you could use

(?<!\S)([^\s<>+])([<>])([^\s<>]+)(?!\S)

The pattern matches:

(?<!\S) Assert a whitespace boundary to the left
([^\s<>+]) Capture group 1, match 1+ non whitespace chars other than < >
([<>]) Capture group 2, capture either < or >
([^\s<>]+) Capture group 3, match 1+ non whitespace chars other than < >
(?!\S) Assert a whitespace boundary to the right

Regex demo

In the replacement use the 3 capture groups with a space between the group values.

$1 $2 $3

The output after the replacement:

#include<stdio.h>
a < b
a<b>
a < v and c > d

In vim using the very magic mode \v

:%s/\v\S@<!([^\s<>+])([<>])([^\s<>]+)\S@!/\1 \2 \3/g