EditorConfig Specification

Introduction

EditorConfig helps maintain consistent coding styles for multiple developers working on the same project across various editors and IDEs. The EditorConfig project consists of a file format for defining coding styles and a collection of text editor plugins that enable editors to read the file format and adhere to defined styles. EditorConfig files are easily readable and they work nicely with version control systems.

File Format

EditorConfig uses an INI file format. In an EditorConfig file (usually named .editorconfig), all beginning whitespace on each line is considered irrelevant. Each line must be one of the following:

  • Blank: contains only whitespace characters.
  • Comment: starts with a ; or a #.
    • Inserting a # or ; after non-whitespace characters in a line (i.e., inline) shall neither be parsed as a comment nor as part of the section name, pair (defined below) key or value in which it was inserted. This may change in the future; thus, is not recommended.
  • Section Header: starts with a [ and ends with a ].
    • May not use any non-whitespace characters outside of the surrounding brackets.
    • May contain any characters between the square brackets (e.g., [ and ] and even spaces and tabs are allowed).
    • Forward slashes (/) are used as path separators.
    • Backslashes (\\) are not allowed as path separators (even on Windows).
  • Key-Value Pair (or Pair): contains a key and a value, separated by an =.
    • Key: the part before the first = (trimmed of whitespace).
    • Value: The part after the first = (trimmed of whitespace).

Any line that is not one of the above is invalid.

EditorConfig files should be UTF-8 encoded, with LF or CRLF line separators.

Additionaly, EditorConfig defines the following terms:

  • Preamble: the lines that precedes the first section. The preamble is optional and may contain key-value pairs, comments and blank lines.
  • Section Name: the string between the beginning [ and the ending ].
  • Section: the lines starting from a Section Header until the beginning of the next Section Header or the end of the file.

Glob Expressions

Section names in EditorConfig files are filepath globs, similar to the format accepted by .gitignore. They support pattern matching through Unix shell-style wildcards. These filepath globs recognize the following as special characters for wildcard matching:

Special Characters Matching
* any string of characters, except path separators (/)
** any string of characters
? any single character
[seq] any single character in seq
[!seq] any single character not in seq
{s1,s2,s3} any of the strings given (separated by commas, can be nested)
{num1..num2} any integer numbers between num1 and num2, where num1 and num2 can be either positive or negative

The backslash character (\\) can be used to escape a character so it is not interpreted as a special character.

The maximum length of a section name is 4096 characters. All sections exceeding this limit are ignored.

File Processing

When a filename is given to EditorConfig a search is performed in the directory of the given file and all parent directories for an EditorConfig file (named “.editorconfig” by default). Non-existing directories are treated as if they exist and are empty. All found EditorConfig files are searched for sections with section names matching the given filename. The search shall stop if an EditorConfig file is found with the root key set to true in the preamble or when reaching the root filesystem directory.

Files are read top to bottom and the most recent rules found take precedence. If multiple EditorConfig files have matching sections, the rules from the closer EditorConfig file are read last, so pairs in closer files take precedence.

Supported Pairs

EditorConfig file sections contain key-value pairs separated by an equal sign (=). With the exception of the root key, all pairs MUST be located under a section to take effect. EditorConfig plugins shall ignore unrecognized keys and invalid/unsupported values for those keys.

Here is the list of all keys understood by EditorConfig and the supported values associated with them:

indent_style Set to tab or space to use hard tabs or soft tabs respectively. The values are case insensitive.
indent_size Set to a whole number defining the number of columns used for each indentation level and the width of soft tabs (when supported). If this equals tab, the indent_size shall be set to the tab size, which should be tab_width (if specified); else, the tab size set by the editor. The values are case insensitive.
tab_width Set to a whole number defining the number of columns used to represent a tab character. This defaults to the value of indent_size and should not usually need to be specified.
end_of_line Set to lf, cr, or crlf to control how line breaks are represented. The values are case insensitive.
charset Set to latin1, utf-8, utf-8-bom, utf-16be or utf-16le to control the character set. Use of utf-8-bom is discouraged.
trim_trailing_whitespace Set to true to remove all whitespace characters preceeding newline characters in the file and false to ensure it doesn’t.
insert_final_newline Set to true ensure file ends with a newline when saving and false to ensure it doesn’t.
root Must be specified in the preamble. Set to true to stop the .editorconfig file search on the current file. The value is case insensitive.

For any pair, a value of unset removes the effect of that pair, even if it has been set before. For example, add indent_size = unset to undefine the indent_size pair (and use editor defaults).

Pair keys are case insensitive. All keys are lowercased after parsing. The maximum length of a pair key is 50 characters and the maximum length of a pair value is 255 characters. Any key or value beyond these limits shall be ignored.

Suggestions for Plugin Developers

TODO. For now please read the Plugin Guidelines on GitHub wiki.