The order of application of patterns and extensions in --langmap

When applying mappings for a name of given source file, Exuberant-ctags tests file name patterns AFTER file extensions (e-map-order). Universal-ctags does this differently; it tests file name patterns BEFORE file extensions (u-map-order).

This incompatible change is introduced to deal with the following situation:

Which parser should be used for parsing "build.xml"? The assumption of Universal-ctags is the user may want to use the "Ant" parser; the file name pattern it declares is more specific than the file extension that the "XML" parser declares. However, e-map-order chooses the "XML" parser.

So Universal-ctags uses the u-map-order even though it introduces an incompatibility.

--list-map-extensions=language and --list-map-patterns=language options are helpful to verify and the file extensions and the file name patterns of given language.

Remove --file-tags and --file-scope options

Even in Exuberant-ctags, "--file-tags" is not documented in its man page. Instead of specifying "--file-tags" or "--file-tags=yes", use "--extras=+f" or "--extras=+{inputFile}".

Instead of specifying "--file-tags=no", use "--extras=-f" or "--extras=-{inputFile}".

Universal-ctags introduces "F/fileScope" extra as the replacement for --file-scope option.

Instead of specifying "--file-tags" or "--file-tags=yes", use "--extras=+F" or "--extras=+{fileScope}".

Instead of specifying "--file-tags=no", use "--extras=-F" or "--extras=-{fileScope}".

Language and kind definitions

Language name defined with --langdef=name option

The characters you can use are more restricted than Exuberant-ctags. For more details, see the description of --langdef=name in ctags-optlib(7).

Obsoleting --<LANG>-kinds option

Some options have <LANG> as parameterized parts in their name like --foo-<LANG>=... or --<LANG>-foo=.... The most of all such options in Exuberant-ctags have the former form, --foo-<LANG>=.... The exception is --<LANG>-kinds.

Universal-ctags uses the former form for all <LANG> parameterized option. Use --kinds-<LANG> instead of --<LANG>-kinds in Universal-ctags. --<LANG>-kinds still works but it will be removed in the future.

The former form may be friendly to shell completion engines.

Disallowing to define a kind with file as name

The kind name "file" is reserved. Using it as part of kind spec in --regex-<LANG> option is now disallowed.

Disallowing to define a kind with F as letter

The kind letter "F" is reserved. Using it as part of a kind spec in --regex-<LANG> option is now disallowed.

Disallowing to use other than alphabetical character as kind letter

Exuberant-ctags accepts a character other than alphabetical character as kind letter in --regex-<LANG>=... option. Universal-ctags accepts only an alphabetical character.

Acceptable characters as parts of a kind name

Exuberant-ctags accepts any character as a part of a kind name defined with --regex-<LANG>=/regex/replacement/kind-spec/.

Universal-ctags accepts only an alphabetical character as the initial letter of a kind name. Universal-ctags accepts only an alphabetical character or numerical character as the rest letters.

An example:

--regex-Foo=/abstract +class +([a-z]+)/\1/a,abstract class/i

Universal-ctags rejects this because the kind name, "abstract class", includes a whitespace character.

This requirement is for making the output of Universal-ctags follow the tags file format.

A combination of a kind letter and a kind name

In Universal-ctags, the combination of a kind letter and a kind name must be unique in a language.

You cannot define more than one kind reusing a kind letter with different kind names. You cannot define more than one kind reusing a kind name with different kind letters.

An example:

--regex-Foo=/abstract +class +([a-z]+)/\1/a,abstractClass/i
--regex-Foo=/attribute +([a-z]+)/\1/a,attribute/i

Universal-ctags rejects this because the kind letter, "a", used twice for defining a kind "abstractClass" and "attribute".

Using numerical character in the name part of tag tagfield

The version 2 tags file format, the default output format of Exuberant-ctags, accepts only alphabetical characters in the name part of tag tagfield.

Universal-ctags introduces an exception to this specification; it may use numerical characters in addition to alphabetical characters as the letters other than initial letter of the name part.

The kinds "heading1", "heading2", and "heading3" in the HTML parser are the examples.

Truncating the pattern for long input lines

To prevent generating overly large tags files, a pattern field is truncated, by default, when its size exceeds 96 bytes. A different limit can be specified with --pattern-length-limit=N. Specifying 0 as N results no truncation as Exuberant-ctags does not.