regex101: PCRE (Legacy) Match Workspace

Group em_all(?<em_all> (?: (?<!\\|\*) # Check it was not escaped with a \ (?<em_type>\*) # Emphasis type: * (?<em_text> (?: (?:\*{2}|\_{2}) | [^[:blank:]\h\*\_] ) .*? ) (?<=\S) # making sure preceding stuff was a non-space \g{em_type} # Balanced closing tag (?!\*) # Should not be followed by * ) | (?: (?<!\\|\_) # Check it was not escaped with a \ (?<em_type>\_) # Emphasis type: _ (?<em_text> (?: (?:\*{2}|\_{2}) | [^[:blank:]\h\*\_] ) .*? ) (?<=\S) # making sure preceding stuff was a non-space \g{em_type} # Balanced closing tag (?!\_) # Should not be followed by _ ) )

1st Alternative (?: (?<!\\|\*) # Check it was not escaped with a \ (?<em_type>\*) # Emphasis type: * (?<em_text> (?: (?:\*{2}|\_{2}) | [^[:blank:]\h\*\_] ) .*? ) (?<=\S) # making sure preceding stuff was a non-space \g{em_type} # Balanced closing tag (?!\*) # Should not be followed by * )

Non-Capturing Group(?: (?<!\\|\*) # Check it was not escaped with a \ (?<em_type>\*) # Emphasis type: * (?<em_text> (?: (?:\*{2}|\_{2}) | [^[:blank:]\h\*\_] ) .*? ) (?<=\S) # making sure preceding stuff was a non-space \g{em_type} # Balanced closing tag (?!\*) # Should not be followed by * )

Negative Lookbehind(?<!\\|\*)

1st Alternative\\

\\the literal \ (92₁₀ / 134₈ / 5C₁₆)

2nd Alternative\*

\*the literal * (42₁₀ / 52₈ / 2A₁₆)

Comment: Check it was not escaped with a \

Group em_type(?<em_type>\*)

\*the literal * (42₁₀ / 52₈ / 2A₁₆)

Comment: Emphasis type: *

Group em_text(?<em_text> (?: (?:\*{2}|\_{2}) | [^[:blank:]\h\*\_] ) .*? )

Non-Capturing Group(?: (?:\*{2}|\_{2}) | [^[:blank:]\h\*\_] )

1st Alternative (?:\*{2}|\_{2})

Non-Capturing Group(?:\*{2}|\_{2})

1st Alternative\*{2}

\*{2}the literal * (42₁₀ / 52₈ / 2A₁₆) , repeated exactly 2 times

2nd Alternative\_{2}

\_{2}the literal _ (95₁₀ / 137₈ / 5F₁₆) , repeated exactly 2 times

2nd Alternative [^[:blank:]\h\*\_]

Negated Character Class[^[:blank:]\h\*\_]

[:blank:]a whitespace character, excluding line breaks [ \t]

\hany horizontal whitespace character

\*the literal * (42₁₀ / 52₈ / 2A₁₆)

\_the literal _ (95₁₀ / 137₈ / 5F₁₆)

.*?any character (except for line terminators), repeated any number of times

Positive Lookbehind(?<=\S)

\Sany non-whitespace character

Comment: making sure preceding stuff was a non-space

\g{em_type}the text saved by group em_type

Comment: Balanced closing tag

Negative Lookahead(?!\*)

\*the literal * (42₁₀ / 52₈ / 2A₁₆)

Comment: Should not be followed by *

2nd Alternative (?: (?<!\\|\_) # Check it was not escaped with a \ (?<em_type>\_) # Emphasis type: _ (?<em_text> (?: (?:\*{2}|\_{2}) | [^[:blank:]\h\*\_] ) .*? ) (?<=\S) # making sure preceding stuff was a non-space \g{em_type} # Balanced closing tag (?!\_) # Should not be followed by _ )

Non-Capturing Group(?: (?<!\\|\_) # Check it was not escaped with a \ (?<em_type>\_) # Emphasis type: _ (?<em_text> (?: (?:\*{2}|\_{2}) | [^[:blank:]\h\*\_] ) .*? ) (?<=\S) # making sure preceding stuff was a non-space \g{em_type} # Balanced closing tag (?!\_) # Should not be followed by _ )

Negative Lookbehind(?<!\\|\_)

1st Alternative\\

\\the literal \ (92₁₀ / 134₈ / 5C₁₆)

2nd Alternative\_

\_the literal _ (95₁₀ / 137₈ / 5F₁₆)

Comment: Check it was not escaped with a \

Group em_type(?<em_type>\_)

\_the literal _ (95₁₀ / 137₈ / 5F₁₆)

Comment: Emphasis type: _

Group em_text(?<em_text> (?: (?:\*{2}|\_{2}) | [^[:blank:]\h\*\_] ) .*? )

Non-Capturing Group(?: (?:\*{2}|\_{2}) | [^[:blank:]\h\*\_] )

1st Alternative (?:\*{2}|\_{2})

2nd Alternative [^[:blank:]\h\*\_]

.*?any character (except for line terminators), repeated any number of times

Positive Lookbehind(?<=\S)

Comment: making sure preceding stuff was a non-space

\g{em_type}the text saved by group em_type

Comment: Balanced closing tag

Negative Lookahead(?!\_)

Comment: Should not be followed by _

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

x modifier: extended. Ignores unescaped whitespace and comments outside character classes

J modifier: Allow duplicate subpattern names

25 tokens

Regular Expression

(?<em_all>
    (?:
        (?<!\\|\*)              # Check it was not escaped with a \
        (?<em_type>\*)          # Emphasis type: *
        (?<em_text>
            (?:
                (?:\*{2}|\_{2})
                |
                [^[:blank:]\h\*\_]
            )
            .*?
        )
        (?<=\S)                 # making sure preceding stuff was a non-space
        \g{em_type}             # Balanced closing tag
        (?!\*)                  # Should not be followed by *
    )
    |
    (?:
        (?<!\\|\_)              # Check it was not escaped with a \
        (?<em_type>\_)          # Emphasis type: _
        (?<em_text>
            (?:
                (?:\*{2}|\_{2})
                |
                [^[:blank:]\h\*\_]
            )
            .*?
        )
        (?<=\S)                 # making sure preceding stuff was a non-space
        \g{em_type}             # Balanced closing tag
        (?!\_)                  # Should not be followed by _
    )
)

New

*test __test__*

*test  **test*  test**

***This is strong and em.***