1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
|
;; treecrumbs.el --- Fast, tree-sitter based breadcrumbs -*- lexical-binding: t; -*-
;;
;; Copyright (C) Free Software Foundation, Inc.
;; SPDX-License-Identifier: GPL-3.0-or-later
;;
;; Author: Vincent Ambo <tazjin@tvl.su>
;; Created: 2024-03-08
;; Version: 1.0
;; Keywords: convenience
;; Package-Requires: ((emacs "29.1"))
;; URL: https://code.tvl.fyi/tree/tools/emacs-pkgs/treecrumbs
;;
;; This file is not (yet) part of GNU Emacs.
;;; Commentary:
;; This package provides a tree-sitter based implementation of "breadcrumbs",
;; that is indicators displaying where in the semantic structure of a document
;; the point is currently located.
;;
;; Imagine a large YAML-document where the names of the parent keys are far out
;; of view: Treecrumbs can quickly display the hierarchy of keys (e.g. `foo < []
;; < baz') and help figure out where point is.
;;
;; Treecrumbs only works if a tree-sitter parser for the target language is
;; available in the buffer, and the language is supported in the
;; `treecrumbs-languages'. Adding a new language is not difficult, and patches
;; for this are welcome.
;;
;; To active treecrumbs, enable `treecrumbs-mode'. This buffer-local minor mode
;; adds the crumbs to the buffer's `header-line-format'. Alternatively, users
;; can also use the `treecrumbs-line-segment' either in their own header-line,
;; tab-line or mode-line configuration.
;;; Code:
(require 'seq)
(require 'treesit)
(defvar treecrumbs-languages nil
"Describes the tree-sitter language grammars supported by
treecrumbs, and how the breadcrumbs for their node types are
generated.
Alist of symbols representing tree-sitter languages (e.g. `yaml')
to another alist (the \"node type list\") describing how
different node types should be displayed in the crumbs.
See `define-treecrumbs-language' for more details on how to add a
language.")
(defmacro define-treecrumbs-language (lang &rest clauses)
"Defines a new language for use in treecrumbs. LANG should be a
symbol representing the language as understood by treesit (e.g.
`yaml').
Each of CLAUSES is a cons cell mapping the name of a tree
node (in string format) to one of either:
1. a static string, which will become the breadcrumb verbatim
2. a tree-sitter query (in S-expression syntax) which must capture
exactly one argument named `@key' that will become the
breadcrumb (e.g. the name of a function, the key in a map, ...)
Treecrumbs will only consider node types that are mentioned in
CLAUSES. All other nodes are ignored when constructing the
crumbs.
The defined languages are stored in `treecrumbs-languages'."
(declare (indent 1))
(let ((compiled
(seq-map (lambda (clause)
(if (stringp (cdr clause))
`(cons ,(car clause) ,(cdr clause))
`(cons ,(car clause)
(treesit-query-compile ',lang ',(cdr clause)))))
clauses)))
`(setf (alist-get ',lang treecrumbs-languages nil nil #'equal) (list ,@compiled))))
(define-treecrumbs-language yaml
;; In YAML documents, crumbs are generated from the keys of maps, and from
;; elements of arrays. "block"-nodes are standard YAML syntax, "flow"-nodes
;; are inline JSON-ish syntax.
("block_mapping_pair" . ((block_mapping_pair key: (_) @key)))
("block_sequence" . "[]")
;; TODO: Why can this query not match on to (flow_pair)?
("flow_pair" . ((_) key: (_) @key))
("flow_sequence" . "[]"))
(define-treecrumbs-language json
;; In JSON documents, crumbs are generated from key names and array fields.
("pair" . ((pair key: (string (string_content) @key))))
("array" . "[]"))
(define-treecrumbs-language cpp
;; In C++ files, crumbs are generated from namespaces and
;; identifier declarations.
("namespace_definition" . ([(namespace_definition
name: (namespace_identifier) @key)
(namespace_definition
"namespace" @key
!name)]))
("function_definition" . ((function_definition
declarator:
(function_declarator
declarator: (_) @key))))
("class_specifier" . ((class_specifier
name: (type_identifier) @key)))
("struct_specifier" . ((struct_specifier
name: (type_identifier) @key)))
("field_declaration" . ((field_declaration
declarator: (_) @key)))
("init_declarator" . ((init_declarator
declarator: (_) @key))))
(defvar-local treecrumbs--current-crumbs nil
"Current crumbs to display in the header line. Only updated when
the node under point changes.")
(defun treecrumbs--crumbs-for (node)
"Construct the crumbs for the given NODE, if its language is
supported in `treecrumbs-languages'. This functions return value
is undefined, it directly updates the buffer-local
`treecrumbs--current-crumbs'."
(let ((lang (cdr (assoc (treesit-node-language node) treecrumbs-languages))))
(unless lang
(user-error "No supported treecrumbs language at point!"))
(setq-local treecrumbs--current-crumbs "")
(treesit-parent-while
node
(lambda (parent)
(when-let ((query (cdr (assoc (treesit-node-type parent) lang))))
(setq-local treecrumbs--current-crumbs
(concat treecrumbs--current-crumbs
(if (string-empty-p treecrumbs--current-crumbs) ""
" < ")
(if (stringp query)
query
(substring-no-properties
(treesit-node-text (cdar (treesit-query-capture parent query))))))))
t))))
(defvar-local treecrumbs--last-node nil
"Caches the node that was last seen at point.")
(defun treecrumbs-at-point ()
"Returns the treecrumbs at point as a string, if point is on a
node in a language supported in `treecrumbs-languages'.
The last known crumbs in a given buffer are cached, and only if
the node under point changes are they updated."
(let ((node (treesit-node-at (point))))
(when (or (not treecrumbs--current-crumbs)
(not (equal treecrumbs--last-node node)))
(setq-local treecrumbs--last-node node)
(treecrumbs--crumbs-for node)))
treecrumbs--current-crumbs)
(defvar treecrumbs-line-segment
'(:eval (treecrumbs-at-point))
"Treecrumbs segment for use in the header-line or mode-line.")
;;;###autoload
(define-minor-mode treecrumbs-mode
"Display header line hints about current position in structure."
:init-value nil
:lighter " Crumbs"
(if treecrumbs-mode
(if (treesit-parser-list)
(push treecrumbs-line-segment header-line-format)
(user-error "Treecrumbs mode works only in tree-sitter based buffers!"))
(setq header-line-format
(delq treecrumbs-line-segment header-line-format))))
(provide 'treecrumbs)
;;; treecrumbs.el ends here
|
