Compression of cascading style sheet files

Patent metadata

Field	Value
Publication number	US-2016110324-A1
Application number	US-201514881066-A
Country	US
Kind code	A1
Filing date	Oct 12, 2015
Priority date	Oct 15, 2014
Publication date	Apr 21, 2016
Grant date	—

Abstract

One embodiment of the present invention provides a system for facilitating compression of a Cascading Style Sheet (CSS) file. During operation, the system stores the CSS file in a local storage device and identifies a merge parameter in the CSS file. The merge parameter can be one of: a repeated selector, a repeated property in a selector, and a same value of a property in different selectors. The system then determines whether a merge condition is satisfied for the merge parameter and merges the merge parameter in the CSS file to obtain a compressed merge parameter. The merge condition indicates whether merging of the merge parameter is consistent with original style in the CSS file.

First claim

What is claimed is:

1 . A computer-implemented method for facilitating compression of a Cascading Style Sheet (CSS) file, the method comprising:
identifying a merge parameter in the CSS file, wherein the merge parameter is one of: a repeated selector, a repeated property in a selector, and a same value of a property in different selectors; determining whether a merge condition is satisfied for the merge parameter, wherein the merge condition indicates whether merging of the merge parameter is consistent with original style in the CSS file; and merging the merge parameter in the CSS file to obtain a compressed merge parameter.

2 . The method of claim 1 , further comprising determining whether the compressed merge parameter is valid based on a length of the compressed merge parameter.

3 . The method of claim 1 , wherein determining whether a merge condition is satisfied comprises:
determining whether a first selector and a second selector are adjacent; and in response to the first and second selectors not being adjacent, determining whether a third selector between the first and second selectors includes a property included in the first and second selectors.

4 . The method of claim 3 , wherein determining whether a merge condition is satisfied further comprises determining whether the property has one or more of:
a same value in the first, second, and third selectors; different priorities in the first, second, and third selectors.

5 . The method of claim 1 , further comprising determining the merge condition to be satisfied in response to determining that:
a latter value of a property of the merge parameter overwrites a former value of the property and the latter value has a equal or higher priority; or a former value of the property overwrites a latter value of the property and the former value has a higher priority.

6 . The method of claim 1 , wherein merging the merge parameter comprises removing a second value of a property for a selector, wherein the second value appears before a first value, has a lower priority than the first value, or has a overwriting relationship with the first value.

7 . The method of claim 1 , further comprising:
representing selectors of the CSS file and corresponding properties in a table; and determining a common area in the table for a respective property.

8 . The method of claim 7 , further comprising:
identifying a current maximum common area in the table for a property; extracting the property as a common factor; merging the common factor across a respective selector comprising the property.

9 . The method of claim 1 , further comprising generating a compressed CSS file based on a plurality of compressed merge parameters.

10 . The method of claim 1 , further comprising preparing the CSS file for compression by organizing properties of all selectors in the CSS file in an alphabetic order.

11 . A non-transitory storage medium storing instructions, which when executed by a processor cause the processor to perform a method for facilitating dynamic load-based merging, the method comprising:
identifying a merge parameter in the CSS file, wherein the merge parameter is one of: a repeated selector, a repeated property in a selector, and a same value of a property in different selectors; determining whether a merge condition is satisfied for the merge parameter, wherein the merge condition indicates whether merging of the merge parameter is consistent with original style in the CSS file; and merging the merge parameter in the CSS file to obtain a compressed merge parameter.

12 . The non-transitory storage medium of claim 11 , wherein the method further comprises determining whether the compressed merge parameter is valid based on a length of the compressed merge parameter.

13 . The non-transitory storage medium of claim 11 , wherein
determining whether a merge condition is satisfied comprises:
determining whether a first selector and a second selector are adjacent; and
in response to the first and second selectors not being adjacent, determining whether a third selector between the first and second selectors includes a property included in the first and second selectors.

14 . The non-transitory storage medium of claim 13 , wherein
determining whether a merge condition is satisfied further comprises determining whether the property has one or more of:
a same value in the first, second, and third selectors;
different priorities in the first, second, and third selectors.

15 . The non-transitory storage medium of claim 11 , wherein the method further comprises determining the merge condition to be satisfied in response to determining that:
a latter value of a property of the merge parameter overwrites a former value of the property and the latter value has a equal or higher priority; or a former value of the property overwrites a latter value of the property and the former value has a higher priority.

16 . The non-transitory storage medium of claim 11 , wherein merging the merge parameter comprises removing a second value of a property for a selector, wherein the second value appears before a first value, has a lower priority than the first value, or has a overwriting relationship with the first value.

17 . The non-transitory storage medium of claim 11 , wherein the method further comprises:
representing selectors of the CSS file and corresponding properties in a table; and determining a common area in the table for a respective property.

18 . The non-transitory storage medium of claim 17 , wherein the method further comprises:
identifying a current maximum common area in the table for a property; extracting the property as a common factor; merging the common factor across a respective selector comprising the property.

19 . The non-transitory storage medium of claim 11 , wherein the method further comprises generating a compressed CSS file based on a plurality of compressed merge parameters.

20 . The non-transitory storage medium of claim 11 , wherein the method further comprises preparing the CSS file for compression by organizing properties of all selectors in the CSS file in an alphabetic order.

21 . A computing system for facilitating dynamic load-based merging, the computing system comprising:
a processor; a memory coupled to the processor and storing instructions, which when executed by the processor cause the processor to perform a method, the method comprising: identifying a merge parameter in the CSS file, wherein the merge parameter is one of: a repeated selector, a repeated property in a selector, or a same value of a property in different selectors; determining whether a merge condition is satisfied for the merge parameter, wherein the merge condition indicates whether merging of the merge parameter is consistent with original style in the CSS file; and merging the merge parameter in the CSS file to obtain a compressed merge parameter.

Assignees

• Alibaba Group Holding Ltd

Inventors

• Hao Lixin

Classifications

• G06F40/146

  Coding or compression of tree-structured data · CPC title

• H03M7/3068

  Precoding preceding compression, e.g. Burrows-Wheeler transformation · CPC title

• H03M7/707 Primary

  Structured documents, e.g. XML · CPC title

• H03M7/6011

  Encoder aspects · CPC title

• H03M7/30 Primary

  Compression (speech analysis-synthesis for redundancy reduction G10L19/00; for image communication H04N); Expansion; Suppression of unnecessary data, e.g. redundancy reduction · CPC title