Negate multiple words

Question

Test String:

${$var1} bla ${$var2} bla ${$var2}
\${$var2} bla \\\${$var2} bla $var1
\\${$var1} bla \\${$var2} bla \${$var2}
\\\{$var2} bla \\${$var2} bla \${$var2}
$var1 bla \$var1 bla \\$var1 bla \\\$var1
\$var1 bla \\$var1 bla \\\$var1
\\$var1 bla \\\$var1 bla \$var1 bla
\\\$var1 bla \\$var1 bla \\\$var1

Selection I'm looking for:

I'm looking for a regex to select only ${$varN}, \\${$varN}, $varN, \\$varN without selecting \${$varN}, \\\${$varN}, \$varN, \\\$varN

Regex I've tried: (\$\{\$\w*\})|(\$\w*) but it selects all ${$varN} and $varN

Answer 1

You can use this regex with a negative lookbehind:

(?<!\\|{)(?:\\\\)*\$(?:{\$)?\w*}?

RegEx Demo

RegEx Description:

• (?<!\\|{) - Negative lookahead to assert we don't have backslash or { as previous character
• (?:\\\\)* - match 0 or more pairs of backslashes
• \$ - Match a literal $
• (?:{\$)? - Match optional { followed by $
• \w+ - Match 1 or more words
• }?- Match optional closing }

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Update: If you want more precise matching (one that disallows ${$var3) then use this advanced PCRE regex that uses if-else-then construct:

(?<!\\|{)(?:\\\\)*\$({\$)?\w+(?(1)})

RegEx Demo2