summaryrefslogtreecommitdiffstats
path: root/runtime/indent/rust.vim
blob: d30629b64e56c795f3d1118d3df2389e017f605d (plain)
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
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
" Vim indent file
" Language:         Rust
" Author:           Chris Morgan <me@chrismorgan.info>
" Last Change:      2017 Jun 13
" For bugs, patches and license go to https://github.com/rust-lang/rust.vim

" Only load this indent file when no other was loaded.
if exists("b:did_indent")
	finish
endif
let b:did_indent = 1

setlocal cindent
setlocal cinoptions=L0,(0,Ws,J1,j1
setlocal cinkeys=0{,0},!^F,o,O,0[,0]
" Don't think cinwords will actually do anything at all... never mind
setlocal cinwords=for,if,else,while,loop,impl,mod,unsafe,trait,struct,enum,fn,extern

" Some preliminary settings
setlocal nolisp		" Make sure lisp indenting doesn't supersede us
setlocal autoindent	" indentexpr isn't much help otherwise
" Also do indentkeys, otherwise # gets shoved to column 0 :-/
setlocal indentkeys=0{,0},!^F,o,O,0[,0]

setlocal indentexpr=GetRustIndent(v:lnum)

" Only define the function once.
if exists("*GetRustIndent")
	finish
endif

let s:save_cpo = &cpo
set cpo&vim

" Come here when loading the script the first time.

function! s:get_line_trimmed(lnum)
	" Get the line and remove a trailing comment.
	" Use syntax highlighting attributes when possible.
	" NOTE: this is not accurate; /* */ or a line continuation could trick it
	let line = getline(a:lnum)
	let line_len = strlen(line)
	if has('syntax_items')
		" If the last character in the line is a comment, do a binary search for
		" the start of the comment.  synID() is slow, a linear search would take
		" too long on a long line.
		if synIDattr(synID(a:lnum, line_len, 1), "name") =~ 'Comment\|Todo'
			let min = 1
			let max = line_len
			while min < max
				let col = (min + max) / 2
				if synIDattr(synID(a:lnum, col, 1), "name") =~ 'Comment\|Todo'
					let max = col
				else
					let min = col + 1
				endif
			endwhile
			let line = strpart(line, 0, min - 1)
		endif
		return substitute(line, "\s*$", "", "")
	else
		" Sorry, this is not complete, nor fully correct (e.g. string "//").
		" Such is life.
		return substitute(line, "\s*//.*$", "", "")
	endif
endfunction

function! s:is_string_comment(lnum, col)
	if has('syntax_items')
		for id in synstack(a:lnum, a:col)
			let synname = synIDattr(id, "name")
			if synname == "rustString" || synname =~ "^rustComment"
				return 1
			endif
		endfor
	else
		" without syntax, let's not even try
		return 0
	endif
endfunction

function GetRustIndent(lnum)

	" Starting assumption: cindent (called at the end) will do it right
	" normally. We just want to fix up a few cases.

	let line = getline(a:lnum)

	if has('syntax_items')
		let synname = synIDattr(synID(a:lnum, 1, 1), "name")
		if synname == "rustString"
			" If the start of the line is in a string, don't change the indent
			return -1
		elseif synname =~ '\(Comment\|Todo\)'
					\ && line !~ '^\s*/\*'  " not /* opening line
			if synname =~ "CommentML" " multi-line
				if line !~ '^\s*\*' && getline(a:lnum - 1) =~ '^\s*/\*'
					" This is (hopefully) the line after a /*, and it has no
					" leader, so the correct indentation is that of the
					" previous line.
					return GetRustIndent(a:lnum - 1)
				endif
			endif
			" If it's in a comment, let cindent take care of it now. This is
			" for cases like "/*" where the next line should start " * ", not
			" "* " as the code below would otherwise cause for module scope
			" Fun fact: "  /*\n*\n*/" takes two calls to get right!
			return cindent(a:lnum)
		endif
	endif

	" cindent gets second and subsequent match patterns/struct members wrong,
	" as it treats the comma as indicating an unfinished statement::
	"
	" match a {
	"     b => c,
	"         d => e,
	"         f => g,
	" };

	" Search backwards for the previous non-empty line.
	let prevlinenum = prevnonblank(a:lnum - 1)
	let prevline = s:get_line_trimmed(prevlinenum)
	while prevlinenum > 1 && prevline !~ '[^[:blank:]]'
		let prevlinenum = prevnonblank(prevlinenum - 1)
		let prevline = s:get_line_trimmed(prevlinenum)
	endwhile

	" Handle where clauses nicely: subsequent values should line up nicely.
	if prevline[len(prevline) - 1] == ","
				\ && prevline =~# '^\s*where\s'
		return indent(prevlinenum) + 6
	endif

	if prevline[len(prevline) - 1] == ","
				\ && s:get_line_trimmed(a:lnum) !~ '^\s*[\[\]{}]'
				\ && prevline !~ '^\s*fn\s'
				\ && prevline !~ '([^()]\+,$'
				\ && s:get_line_trimmed(a:lnum) !~ '^\s*\S\+\s*=>'
		" Oh ho! The previous line ended in a comma! I bet cindent will try to
		" take this too far... For now, let's normally use the previous line's
		" indent.

		" One case where this doesn't work out is where *this* line contains
		" square or curly brackets; then we normally *do* want to be indenting
		" further.
		"
		" Another case where we don't want to is one like a function
		" definition with arguments spread over multiple lines:
		"
		" fn foo(baz: Baz,
		"        baz: Baz) // <-- cindent gets this right by itself
		"
		" Another case is similar to the previous, except calling a function
		" instead of defining it, or any conditional expression that leaves
		" an open paren:
		"
		" foo(baz,
		"     baz);
		"
		" if baz && (foo ||
		"            bar) {
		"
		" Another case is when the current line is a new match arm.
		"
		" There are probably other cases where we don't want to do this as
		" well. Add them as needed.
		return indent(prevlinenum)
	endif

	if !has("patch-7.4.355")
		" cindent before 7.4.355 doesn't do the module scope well at all; e.g.::
		"
		" static FOO : &'static [bool] = [
		" true,
		"	 false,
		"	 false,
		"	 true,
		"	 ];
		"
		"	 uh oh, next statement is indented further!

		" Note that this does *not* apply the line continuation pattern properly;
		" that's too hard to do correctly for my liking at present, so I'll just
		" start with these two main cases (square brackets and not returning to
		" column zero)

		call cursor(a:lnum, 1)
		if searchpair('{\|(', '', '}\|)', 'nbW',
					\ 's:is_string_comment(line("."), col("."))') == 0
			if searchpair('\[', '', '\]', 'nbW',
						\ 's:is_string_comment(line("."), col("."))') == 0
				" Global scope, should be zero
				return 0
			else
				" At the module scope, inside square brackets only
				"if getline(a:lnum)[0] == ']' || search('\[', '', '\]', 'nW') == a:lnum
				if line =~ "^\\s*]"
					" It's the closing line, dedent it
					return 0
				else
					return shiftwidth()
				endif
			endif
		endif
	endif

	" Fall back on cindent, which does it mostly right
	return cindent(a:lnum)
endfunction

let &cpo = s:save_cpo
unlet s:save_cpo