ctags-json-output

JSON based ctags output

Version:1.0
Manual group:Universal Ctags
Manual section:5

SYNOPSIS

ctags --output-format=json …

DESCRIPTION

Universal Ctags supports JSON (strictly speaking JSON Lines) output format if the ctags executable is built with libjansson. JSON output goes to standard output by default.

FORMAT

Each JSON line represents a tag.

$ ctags --extras=+p --output-format=json --fields=-s input.py
{"_type": "ptag", "name": "JSON_OUTPUT_VERSION", "path": "1.0", "pattern": "in development"}
{"_type": "ptag", "name": "TAG_FILE_SORTED", "path": "1", "pattern": "0=unsorted, 1=sorted, 2=foldcase"}
...
{"_type": "tag", "name": "Klass", "path": "/tmp/input.py", "pattern": "/^class Klass:$/", "language": "Python", "kind": "class"}
{"_type": "tag", "name": "method", "path": "/tmp/input.py", "pattern": "/^    def method(self):$/", "language": "Python", "kind": "member", "scope": "Klass", "scopeKind": "class"}
...

A key not starting with _ is mapped to a field of ctags. “--output-format=json --list-fields” options list the fields.

A key starting with _ represents meta information of the JSON line. Currently only _type key is used. If the value for the key is tag, the JSON line represents a regular tag. If the value is ptag, the line represents a pseudo-tag.

The output format can be changed in the future. JSON_OUTPUT_VERSION pseudo-tag provides a change client-tools to handle the changes. Current version is “1.0”. A client-tool can extract the version with path key from the pseudo-tag.

The JSON output format is newly designed and has no limitation found in the default tags file format.

  • The values for kind key are represented in long-name flags. No one-letter is here.
  • Scope names and scope kinds have distinguished keys: scope and scopeKind. They are combined in the default tags file format.

DATA TYPE USED IN A FIELD

Values for the most of all keys are represented in JSON string type. However, some of them are represented in string, integer, and/or boolean type.

“--output-format=json --list-fields” options show What kind of data type used in a field of JSON.

$ ctags --output-format=json --list-fields
#LETTER NAME           ENABLED LANGUAGE         JSTYPE FIXED DESCRIPTION
F       input          yes     NONE             s--    no    input file
...
P       pattern        yes     NONE             s-b    no    pattern
...
f       file           yes     NONE             --b    no    File-restricted scoping
...
e       end            no      NONE             -i-    no    end lines of various items
...

JSTYPE column shows the data types.

‘s’
string
‘i’
integer
‘b’
boolean (true or false)

For an example, the value for pattern field of ctags takes a string or a boolean value.

VERSIONS

Change since “0.0”

  • New key kindName for TAG_ROLE_DESCRIPTION pseudo tag

    kindName is added to store the name of the kind in TAG_ROLE_DESCRIPTION pseudo tags.

    In 0.0, a “TAG_ROLE_DESCRIPTION” pseudo tag was printed like:

    {"_type": "ptag", "name": "TAG_ROLE_DESCRIPTION",
                  "parserName": "LANG!KIND", }

    In 1.0, it is printed like:

    {"_type": "ptag", "name": "TAG_ROLE_DESCRIPTION",
                  "parserName": "LANG",
                  "kindName": "KIND",  }