https://github.com/dflydev/dflydev-placeholder-resolver
Provides a mechanism to resolve placeholders from an arbitrary data source.
https://github.com/dflydev/dflydev-placeholder-resolver
Last synced: about 1 year ago
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Provides a mechanism to resolve placeholders from an arbitrary data source.
- Host: GitHub
- URL: https://github.com/dflydev/dflydev-placeholder-resolver
- Owner: dflydev
- License: mit
- Created: 2012-04-01T06:36:47.000Z (about 14 years ago)
- Default Branch: master
- Last Pushed: 2022-01-25T02:43:47.000Z (over 4 years ago)
- Last Synced: 2025-03-28T17:09:48.311Z (about 1 year ago)
- Language: PHP
- Homepage:
- Size: 26.4 KB
- Stars: 141
- Watchers: 2
- Forks: 5
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# Placeholder Resolver
Given a data source representing key => value pairs, resolve placeholders
like `${foo.bar}` to the value associated with the `foo.bar` key in
the data source.
Placeholder Resolver is intended to be used at a relatively low level.
For example, a configuration library could use Placeholder Resolver
behind the scenes to allow for configuration values to reference
other configuration values.
## Example
```yml
conn.driver: mysql
conn.db_name: example
conn.hostname: 127.0.0.1
conn.username: root
conn.password: pa$$word
```
Given the appropriate `DataSourceInterface` implementation to provide
the above data as a set of key => value pairs, the Placeholder Resolver
would resolve the value of `$dsnPattern` to `mysql:dbname=example;host=127.0.0.1`.
```php
$dsnPattern = '${conn.driver}:dbname=${conn.db_name};host=${conn.hostname}';
$dsn = $placeholderResolver->resolveValue($dsnPattern);
// mysql:dbname=example;host=127.0.0.1
```
## Requirements
* PHP 5.3+
## Usage
```php
use Dflydev\PlaceholderResolver\RegexPlaceholderResolver;
// YourDataSource implements Dflydev\PlaceholderResolver\DataSource\DataSourceInterface
$dataSource = new YourDataSource;
// Create the placeholder resolver
$placeholderResolver = new RegexPlaceholderResolver($dataSource);
// Start resolving placeholders
$value = $placeholderResolver->resolvePlaceholder('${foo}');
```
The `RegexPlaceholderResolver` constructor accepts two additional arguments,
a placeholder prefix and a placeholder suffix. The default placeholder
prefix is `${` and the default placeholder suffix is `}`.
To handle placeholders that look like `` instead of `${foo.bar}`,
one would instantiate the class like this:
```php
$placeholderResolver = new RegexPlaceholderResolver($dataSource, '<', '>');
```
Placeholders can recursively resolve placeholders. For example, given a
data source with the following:
```php
array(
'foo' => 'FOO',
'bar' => 'BAR',
'FOO.BAR' => 'BAZ!',
);
```
The placeholder `${${foo}.${bar}}` would internally be resolved to
`${FOO.BAR}` before being further resolved to `BAZ!`.
Resolved placeholders are cached using the `CacheInterface`. The default
`Cache` implementation is used unless it is explicitly set on the
Placeholder Resolver.
```php
// YourCache implements Dflydev\PlaceholderResolver\Cache\CacheInterface
$cache = new YourCache;
$placeholderResolver->setCache($cache);
```
## License
This library is licensed under the New BSD License - see the LICENSE file
for details.
## Community
If you have questions or want to help out, join us in the
[#dflydev](irc://irc.freenode.net/#dflydev) channel on irc.freenode.net.
## Not Invented Here
Much of the ideas behind this library came from Spring's Property
Placeholder Configurer implementation.