Rule Syntax

Whistle modifies requests and responses through concise rule configurations, with each rule following the same basic syntax structure.

Syntax Structure

pattern operation [lineProps...] [filters...]

Each rule consists of the following four components:

Component	Required	Description
pattern	Yes	Expression for matching request URLs. Detailed documentation: pattern
operation	Yes	Operation command, formatted as protocol://value. Detailed documentation: operation
lineProps	No	Additional configurations that apply only to the current rule. Detailed documentation: lineProps
filters	No	Filter conditions for precise control over when the rule takes effect. Detailed documentation: filters

Advanced Rule Configuration

1. Combined Configuration

A single rule can contain multiple operation commands, enabling complex functional combinations.

Syntax:

pattern operation1 operation2 ... [includeFilter://pattern1 ... excludeFilter://patternN ...]

Example:

www.example.com/* file:///static-files cache://3600 resCors://*

Explanation:

• Multiple operation commands are executed in order.
• Supports combining any number of operation commands.
• Filter conditions apply to the entire rule.

2. Position Swapping

When operation and the first pattern are not both in URL or domain format, their positions can be swapped.

Syntax:

operation pattern1 pattern2 ... [includeFilter://pattern1 ... excludeFilter://patternN ...]

Example:

# Standard writing
www.example.com proxy://127.0.0.1:8080

# Position-swapped writing
proxy://127.0.0.1:8080 www.example.com api.example.com

Limitations: operation and the first pattern cannot simultaneously be in the following formats:

• https://test.com/path
• //test.com/path
• test.com/path
• test.com

Applicable Scenarios:

• More concise when applying the same operation to multiple domains.
• Batch configuration of proxy, redirect, and other rules.

3. Multi-line Configuration

Use code blocks to achieve multi-line configurations, improving readability of complex rules.

Syntax:

line`
operation
pattern1
pattern2
...
[includeFilter://pattern1
...
excludeFilter://patternN 
...]
`

Example:

line`
proxy://127.0.0.1:8080
www.example.com
api.example.com
static.example.com
includeFilter://m:GET
excludeFilter:///admin/
`

Features:

• Whistle automatically replaces line breaks within the code block with spaces.
• Maintains clean code formatting for easy reading and maintenance.
• Suitable for scenarios involving multiple matching patterns and complex filter conditions.

Equivalent Conversion: The above multi-line configuration is equivalent to:

proxy://127.0.0.1:8080 www.example.com api.example.com static.example.com includeFilter://m:GET excludeFilter:///admin/

Notes

1. Rule Priority

• Rules are executed in top-to-bottom order.
• Later rules may override the effects of earlier rules.
• Use lineProps://important to increase the priority of important rules.

2. Debugging Tips

1. Step-by-step verification: Start with simple rules and gradually add complex conditions.
2. Log viewing: Use the Overview panel in the Whistle Network interface to check rule matching.
3. Browser debugging: Use browser developer tools to inspect actual effects.
4. Temporary disabling: Use # to comment out rules temporarily for testing.