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Recent synopsis changes move from literal code blocks to [RST line blocks]. This does not translate well to HTML: it's not rendered in monospace, so aligment is lost. Additionally, we don't get syntax highlighting in HTML, which adds differences to our code samples which are highlighted. We hard-wrap synopsis lines (like code blocks). To align continuation lines in manpages we need [backslashes in weird places]. Combined with the **, *, and `` markup, it's a bit hard to get the alignment right. Fix these by moving synopsis sources back to code blocks and compute HTML syntax highlighting and manpage markup with a custom Sphinx extension. The new Pygments lexer can tokenize a synopsis and assign the various highlighting roles, which closely matches fish's syntax highlighing: - command/keyword (dark blue) - parameter (light blue) - operator like and/or/not/&&/|| (cyan) - grammar metacharacter (black) For manpage output, we don't project the fish syntax highlighting but follow the markup convention in GNU's man(1): bold text type exactly as shown. italic text replace with appropriate argument. To make it easy to separate these two automatically, formalize that (italic) placeholders must be uppercase; while all lowercase text is interpreted literally (so rendered bold). This makes manpages more consistent, see string-join(1) and and(1). Implementation notes: Since we want manpage formatting but Sphinx's Pygments highlighing plugin does not support manpage output, add our custom "synopsis" directive. This directive parses differently when manpage output is specified. This means that the HTML and manpage build processes must not share a cache, because the parsed doctrees are cached. Work around this by using separate cache locations for build targets "sphinx-docs" (which creates HTML) and "sphinx-manpages". A better solution would be to only override Sphinx's ManualPageBuilder but that would take a bit more code (ideally we could override ManualPageWriter but Sphinx 4.3.2 doesn't really support that). --- Alternative solution: stick with line blocks but use roles like :command: or :option: (or custom ones). While this would make it possible to produce HTML that is consistent with code blocks (by adding a bit of CSS), the source would look uglier and is harder to maintain. (Let's say we want to add custom formatting to the [|] metacharacters in HTML. This is much easier with the proposed patch.) --- [RST line blocks]: https://docutils.sourceforge.io/docs/ref/rst/restructuredtext.html#line-blocks [backslashes in weird places]: https://github.com/fish-shell/fish-shell/pull/8626#discussion_r782837750
49 lines
1.5 KiB
ReStructuredText
49 lines
1.5 KiB
ReStructuredText
.. _cmd-for:
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for - perform a set of commands multiple times
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==============================================
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Synopsis
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--------
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.. synopsis::
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for VARNAME in [VALUES ...]; COMMANDS ...; end
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Description
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-----------
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**for** is a loop construct. It will perform the commands specified by *COMMANDS* multiple times. On each iteration, the local variable specified by *VARNAME* is assigned a new value from *VALUES*. If *VALUES* is empty, *COMMANDS* will not be executed at all. The *VARNAME* is visible when the loop terminates and will contain the last value assigned to it. If *VARNAME* does not already exist it will be set in the local scope. For our purposes if the **for** block is inside a function there must be a local variable with the same name. If the **for** block is not nested inside a function then global and universal variables of the same name will be used if they exist.
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Much like :ref:`set <cmd-set>`, **for** does not modify $status, but the evaluation of its subordinate commands can.
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Example
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-------
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::
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for i in foo bar baz; echo $i; end
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# would output:
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foo
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bar
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baz
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Notes
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-----
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The ``VARNAME`` was local to the for block in releases prior to 3.0.0. This means that if you did something like this:
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::
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for var in a b c
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if break_from_loop
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break
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end
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end
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echo $var
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The last value assigned to ``var`` when the loop terminated would not be available outside the loop. What ``echo $var`` would write depended on what it was set to before the loop was run. Likely nothing.
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