Snippets only working when preceeded by space

Question

I have created my snippets in texmath.snippets as:

priority -50 

snippet \d "dot" Aw
\dot{$1}
endsnippet

snippet ^^ "superscript" A
^{$1}
endsnippet

snippet __ "subscript" A 
_{$1}
endsnippet

The problem is, ^^ and __ works only when preceeded by a space, like w options in Ultisnips. But, as you can see, there is no w, so this should not be in word limit.

But, still, in latex, $H__$ doesn't expands to $H_{}$, while $H __$ does properly.

What I am doing wrong here?

I am using Ultisnips as snippet engine. This texmath.snippets structure is following honza/snippets

Answer 1

You have to use the i option. This is in the help page:

   i   In-word expansion - By default a snippet is expanded only if the tab
       trigger is the first word on the line or is preceded by one or more
       whitespace characters. A snippet with this option is expanded
       regardless of the preceding character. In other words, the snippet can
       be triggered in the middle of a word.

So it should look like that in the end:

snippet ^^ "superscript" Ai
^{$1}
endsnippet

snippet __ "subscript" Ai
_{$1}
endsnippet