regex101: PasCamelCase

Pro

1st Alternative^([A-Z](([A-Z]{1,2}[a-z0-9]+)+([A-Z]{1,3}[a-z0-9]+)*[A-Z]{0,3}|([a-z0-9]+[A-Z]{0,3})*|[A-Z]{1,2}))$

^start of line

Group 1([A-Z](([A-Z]{1,2}[a-z0-9]+)+([A-Z]{1,3}[a-z0-9]+)*[A-Z]{0,3}|([a-z0-9]+[A-Z]{0,3})*|[A-Z]{1,2}))

Character Class[A-Z]

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

Group 2(([A-Z]{1,2}[a-z0-9]+)+([A-Z]{1,3}[a-z0-9]+)*[A-Z]{0,3}|([a-z0-9]+[A-Z]{0,3})*|[A-Z]{1,2})

1st Alternative([A-Z]{1,2}[a-z0-9]+)+([A-Z]{1,3}[a-z0-9]+)*[A-Z]{0,3}

Group 3([A-Z]{1,2}[a-z0-9]+)+

+repeats the group contents below at least once:

Character Class[A-Z]{1,2}

{1,2}matches between 1 and 2 characters from the set below:

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

Character Class[a-z0-9]+

+matches at least one character from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

0-9one character from 0 (48₁₀) to 9 (57₁₀)

Group 4([A-Z]{1,3}[a-z0-9]+)*

*repeats the group contents below any number of times:

Character Class[A-Z]{1,3}

{1,3}matches between 1 and 3 characters from the set below:

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

Character Class[a-z0-9]+

+matches at least one character from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

0-9one character from 0 (48₁₀) to 9 (57₁₀)

Character Class[A-Z]{0,3}

{0,3}matches between 0 and 3 characters from the set below:

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

2nd Alternative([a-z0-9]+[A-Z]{0,3})*

Group 5([a-z0-9]+[A-Z]{0,3})*

*repeats the group contents below any number of times:

Character Class[a-z0-9]+

+matches at least one character from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

0-9one character from 0 (48₁₀) to 9 (57₁₀)

Character Class[A-Z]{0,3}

{0,3}matches between 0 and 3 characters from the set below:

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

3rd Alternative[A-Z]{1,2}

Character Class[A-Z]{1,2}

{1,2}matches between 1 and 2 characters from the set below:

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

$end of line

2nd Alternative^([a-z][a-z0-9]*(([A-Z]{1,3}[a-z0-9]+)*[A-Z]{0,3}|([a-z0-9]+[A-Z]{1,3})*|[A-Z]{1,3}))$

^start of line

Group 6([a-z][a-z0-9]*(([A-Z]{1,3}[a-z0-9]+)*[A-Z]{0,3}|([a-z0-9]+[A-Z]{1,3})*|[A-Z]{1,3}))

Character Class[a-z]

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

Character Class[a-z0-9]*

*matches any number of characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

0-9one character from 0 (48₁₀) to 9 (57₁₀)

Group 7(([A-Z]{1,3}[a-z0-9]+)*[A-Z]{0,3}|([a-z0-9]+[A-Z]{1,3})*|[A-Z]{1,3})

1st Alternative([A-Z]{1,3}[a-z0-9]+)*[A-Z]{0,3}

Group 8([A-Z]{1,3}[a-z0-9]+)*

*repeats the group contents below any number of times:

Character Class[A-Z]{1,3}

Character Class[a-z0-9]+

Character Class[A-Z]{0,3}

2nd Alternative([a-z0-9]+[A-Z]{1,3})*

3rd Alternative[A-Z]{1,3}

$end of line

Global pattern flags

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

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

25 tokens

Regular Expression

^([A-Z](([A-Z]{1,2}[a-z0-9]+)+([A-Z]{1,3}[a-z0-9]+)*[A-Z]{0,3}|([a-z0-9]+[A-Z]{0,3})*|[A-Z]{1,2}))$|^([a-z][a-z0-9]*(([A-Z]{1,3}[a-z0-9]+)*[A-Z]{0,3}|([a-z0-9]+[A-Z]{1,3})*|[A-Z]{1,3}))$

Unit Tests

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