font-lock-keywords中的progn表达式如何工作? [英] How does a progn form in font-lock-keywords work?
问题描述
以下代码将通过将一个progn表单传递给字体锁关键字,直观地将hello world替换为HW。
(font-lock-add-keywords
nil'((\\(hello world \\)
(0(progn(put-text-property(match-beginning 1) (匹配结束1)
'显示HW)
nil)))))
我查看了 Ch v font-lock-keywords
,看看这是否是字体锁定的记录功能。你好,世界元素似乎是这样的:
(MATCHER HIGHLIGHT ...)
这意味着(0 ...)
是HIGHLIGHT,文档说
HIGHLIGHT应该是MATCH-HIGHLIGHT或MATCH-ANCHORED。
和
MATCH-HIGHLIGHT应该是这样的形式:
(SUBEXP FACENAME [OVERRIDE [LAXMATCH]])
所以我猜是0是SUBEXP和(progn ...)
是FACENAME。但是如果(progn ..)
是一个有效的FACENAME,以下代码将会起作用但不起作用。
;; (MATCHER。FACENAME)
(font-lock-add-keywords
nil'((goodbye lenin
。(progn(put-text-property(match-begin 1) -end $)
$ b 这让我看到第一个代码的工作原理以及是否依赖于一个无证的功能。
更新:
旁注:没有字体锁定错误的更简单的视觉替换方式
(font-lock-add-keywords
nil'((my llama
(0(progn(put-text-property(match-beginning 0) (match-end 0)
'显示ML)
nil)))))
解决方案它有效 - 但是您的 MATCHER
不正确 - 匹配结果未被存储。这个例子不起作用:
(font-lock-add-keywords
nil'((再见lenin
(0(progn(put-text-property(match-beginning 1)(match-end 1)
'显示GL)
nil)))))
而这样做:
code>(font-lock-add-keywords
nil'((\\(goodbye lenin\\\)
。(progn(put-text-property -bginning 1)(match-end 1)
'显示GL)
nil))))
文档说: FACENAME
是一个表达式,其值是要使用的面部名称
而不是一张脸, FACENAME
可以评估一个属性列表
,格式为(face FACE PROP1 VAL1 PROP2 VAL2 ...)
在这种情况下,所有列出的文本属性将被设置而不是
只是 FACE
。
这里, FACENAME
表达式( progn
)的计算结果为 nil
,所以没有设置属性或面孔 - 由
put-text-property
导致的唯一效果。
Following code will visually replace "hello world" with "HW" by passing a progn form to font lock keywords.
(font-lock-add-keywords
nil '(("\\(hello world\\)"
(0 (progn (put-text-property (match-beginning 1) (match-end 1)
'display "HW")
nil)))))
I've look into C-h v font-lock-keywords
to see if this is a documented feature of font lock. The hello world element seemed to be of this form:
(MATCHER HIGHLIGHT ...)
which would mean that (0 ...)
is HIGHLIGHT and the doc says
HIGHLIGHT should be either MATCH-HIGHLIGHT or MATCH-ANCHORED.
and
MATCH-HIGHLIGHT should be of the form:
(SUBEXP FACENAME [OVERRIDE [LAXMATCH]])
So I guessed 0 was SUBEXP and (progn ...)
was FACENAME. But if (progn ..)
were a valid FACENAME, the following code would work but it doesn't work.
;; (MATCHER . FACENAME)
(font-lock-add-keywords
nil '(("goodbye lenin"
. (progn (put-text-property (match-beginning 1) (match-end 1)
'display "GL")
nil))))
That brings me to the question of how the first code works and whether it is relying on an undocumented feature.
Update:
Side note: simpler way of visual replacement without font lock errors
(font-lock-add-keywords
nil '(("my llama"
(0 (progn (put-text-property (match-beginning 0) (match-end 0)
'display "ML")
nil)))))
It does work - but your MATCHER
is not correct - the result of the match is not stored. This, for example does not work:
(font-lock-add-keywords
nil '(("goodbye lenin"
(0 (progn (put-text-property (match-beginning 1) (match-end 1)
'display "GL")
nil)))))
while this does:
(font-lock-add-keywords
nil '(("\\(goodbye lenin\\)"
. (progn (put-text-property (match-beginning 1) (match-end 1)
'display "GL")
nil))))
The documentation says: "FACENAME
is an expression whose value is the face name to use.
Instead of a face, FACENAME
can evaluate to a property list
of the form (face FACE PROP1 VAL1 PROP2 VAL2 ...)
in which case all the listed text-properties will be set rather than
just FACE
."
Here, the FACENAME
expression (progn
) evaluates to nil
, so no properties or faces are being set - the only effect that caused by put-text-property
.
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