Pattern components
Pattern components
This library is abandoned. Please consider using a different library.
A pattern is composed from one or more segments delimited by separators.
Examples
| Pattern | Separator | Segments |
|---|---|---|
/a/b/c |
/ |
a, b, c |
a/b |
/ |
a, b |
a.b.c/d |
. |
a, b, c/d |
Segments
A segment can be one of the following:
- data
- placeholder
- combination of data and placeholders
When a segment contains only one optional placeholder and nothing more, then the separator symbol character also becomes optional, depending on the capture mode.
The pattern a//{p}/{p1?}/test-{p2}-for-{p3?}
has the following segments
a- data- empty data
{p}- placeholder{p1?}- optional placeholdertest-{p2}-for-{p3?}- combination of data and placeholders
Above, the separator symbol used was / (slash), use the
separator symbol option
to change it.
Data
Data inside a segment is automatically escaped, depending on the regex delimiter option.
Examples
| Delimiter | Data | Escaped |
|---|---|---|
~ |
a~b |
a\~b |
# |
a#b |
a\#b |
Placeholder
The placeholder is always delimited by the start symbol and the end symbol. To change the placeholder delimiters please use those options.
Any placeholder is composed from:
- name (optional)
- optional symbol (optional)
- inline regex (optional if a name is present, required otherwise)
If a placeholder doesn’t have a name, it is considered to be anonymous and must have an inline regex. An anonymous placeholder can also be marked as optional.
Examples
| Placeholders | Name | Optional | Regex |
|---|---|---|---|
{var} |
var |
No | default |
{opt?} |
opt |
Yes | default |
{num=\d+} |
num |
No | \d+ |
{num?=[a-z]{5,10}} |
num |
Yes | [a-z]{5,10} |
{=[abc]*} |
anonymous | No | [abc]* |
{?=[abc]+} |
anonymous | Yes | [abc]+ |
Placeholder name
The placeholder name must begin with a letter, and after the first letter can contain any number of letters, digits or underscores.
The name of the placeholder must be unique across the pattern.
Examples
| Pattern | Valid | Reason |
|---|---|---|
{abc} |
Yes | |
{A1B2c3} |
Yes | |
{a_1_B_2} |
Yes | |
{=\d} |
Yes | |
{?=[a-z]{2, 3}} |
Yes | |
{123A} |
No | Must start with a letter |
{_a_b} |
No | Must start with a letter |
{A-B} |
No | Contains - (minus sign) |
{?=} |
No | Must have inline regex |
{} |
No | Must have inline regex |
{=} |
No | Must have inline regex |
{a}/{b}/{a} |
No | Duplicate name a |
{a}/{b}/{A} |
Yes |
Optional placeholder
A placeholder can be marked as optional using the optional symbol right after the placeholder name.
If the placeholder is optional and is the only thing in the segment, it will also make the adjacent separator optional, depending on the capture mode.
Example
To make {var} optional, just add ? after the name, resulting
{var?}.
Inline regex
A placeholder can contain an inline regex using the assign symbol right after the placeholder name if the placeholder is not anonymous, or after the optional symbol if the placeholder is marked as optional.
If a named placeholder doesn’t have an inline regex, it uses the default regex expression.
Examples
To add an inline regex for {var}, add = and the regex, just after the name,
resulting {var=my-regex}.
To add an inline regex for {var?}, add = and the regex, just after the ?,
resulting {var?=my-regex}.
To add an anonymous placeholder with inline regex, use {=my-regex}
or {?=my-regex} if you want to mark this placeholder as optional.
