[英]Rebol/Red parse: how to copy between 2 marks
I want to be able to parse between 2 marks in parse rule. 我希望能够在解析规则中解析2个标记之间。 For a contrieved example:
举一个人为的例子:
src: {a b c d e f}
rule: [
to "b" mark1: thru "e" mark2:
to mark1 copy text to mark2
]
This doesn't work, text contains "[" instead of what I'd like to get: 这不起作用,文本包含“ [”,而不是我想要的内容:
b c d e
You're trying to implement a "DO desire" of copying using PARSE. 您正在尝试实现使用PARSE复制的“ DO愿望”。 PARSE's COPY is looking for patterns, not treating the series as positions.
PARSE的COPY正在寻找模式,而不是将系列视为头寸。
You can escape into DO in mid-parse via a PAREN!, it will run if the parse rule reaches that point. 您可以通过PAREN!在解析过程中转入DO,如果解析规则到达该点,它将运行。
src: {a b c d e f}
rule: [
to "b" mark1: thru "e" mark2:
(text: copy/part mark1 mark2)
to end ;-- not strictly necessary, but makes PARSE return true
]
parse src rule
That will give you text as bcde
那会给你文本为
bcde
Note that you can't have it both ways, either with COPY or with TO. 请注意,使用COPY或TO不能同时使用这两种方法。
TO <series!>
meant "look for b", not "jump to the position of b". TO <series!>
意思是“寻找b”,而不是“跳到b的位置”。 So when you say to mark1
you're invoking another match. 因此,当您说到
to mark1
您正在调用另一个匹配项。 If you want to set the parse position to the specific position recorded in mark1, use :mark1
in the parse rule. 如果要将解析位置设置为
:mark1
中记录的特定位置 ,请在解析规则中使用:mark1
。
two alternative solutions/rules working in Red Red中的两个替代解决方案/规则
rule: [
to "b" copy text thru "e" to end
]
and 和
rule: [ to "b" collect [keep thru "e"] to end]
text: first parse src rule
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