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Merged
merged 12 commits into from
Dec 16, 2024
Merged

In bidi default strategy, make steps consistent with each other #969

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6e8513a
In bidi default strategy, make steps consistent with each other
catamorphism Dec 6, 2024
39e9056
Don't replace entire formatted output
catamorphism Dec 6, 2024
c69013d
Reformulate the default bidi strategy as a function
catamorphism Dec 9, 2024
386fa2f
Rewrite imperatively
catamorphism Dec 11, 2024
019a29f
Add last line (emit output)
catamorphism Dec 11, 2024
f42453c
Fix formatting
catamorphism Dec 11, 2024
4c918ac
Fix formatting harder
catamorphism Dec 11, 2024
7c5bf61
Fix formatting again
catamorphism Dec 11, 2024
53aa0fb
Remove erroneously-added file
catamorphism Dec 11, 2024
daa95ad
Update spec/formatting.md
catamorphism Dec 11, 2024
0b2f7a3
Fix indentation
catamorphism Dec 11, 2024
e9afb9d
Apply suggestions from Eemeli
catamorphism Dec 13, 2024
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25 changes: 13 additions & 12 deletions spec/formatting.md
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Original file line number Diff line number Diff line change
Expand Up @@ -928,7 +928,8 @@ Implementations MAY provide other _bidirectional isolation strategies_.

Implementations MAY supply a _bidirectional isolation strategy_ that performs no processing.

The _Default Bidi Strategy_ is defined as follows:
The _Default Bidi Strategy_ is defined as a function `B` from expressions
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@aphillips aphillips Dec 10, 2024

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Linkify expressions.

This is weird? Where does B come from? Why is it a "function"? The text above this talks about "bidirectional isolation strategies". I think this needs to be different.

Perhaps:

The Default Bidi Strategy is defined as follows:

  1. Let out be an empty string to contain the formatted output of the message
  2. Let msgdir...
  3. For each expression exp in the pattern:
    1. If exp is a plain literal (text), append exp to out.
    2. If exp is an placeholder, let fmt be the formatted string representation of
      the resolved value of exp.
    3. Let dir be the directionality of fmt...
      // etc.
    4. Append fmt to out.
  4. Emit out as the formatted output of the message.

Note that we don't have a name for the non-placeholder bits of text in a pattern. I call them expressions here, but they aren't really expressions.

It would be even better if the section on formatting just above here defined how to make the string output. The "bidi strategy" then could be reference in that set of instructions ("apply the appropriate bidirectional isolation strategy to the contents of expression")

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@catamorphism catamorphism Dec 11, 2024

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I rewrote this imperatively instead of as a function. I also did a rewrite to call the components of a pattern a "part", and distinguish between text parts and placeholder parts.

to formatted strings, as follows.

1. Let `msgdir` be the directionality of the whole message,
one of « `'LTR'`, `'RTL'`, `'unknown'` ».
Expand All @@ -942,19 +943,19 @@ The _Default Bidi Strategy_ is defined as follows:
True if the `u:dir` _option_ of the _resolved value_ of `exp` has a value other than `'inherit'`,
or False otherwise.
1. If `dir` is `'LTR'`:
1. If `msgdir` is `'LTR'` in the formatted output
1. If `msgdir` is `'LTR'`
and `isolate` is False,
let `fmt` be itself
1. Else, in the formatted output,
prefix `fmt` with U+2066 LEFT-TO-RIGHT ISOLATE
and postfix it with U+2069 POP DIRECTIONAL ISOLATE.
`B(exp)` is `fmt`.
1. Else, `B(exp)` is
`fmt` prefixed with U+2066 LEFT-TO-RIGHT ISOLATE
and postfixed with U+2069 POP DIRECTIONAL ISOLATE.
1. Else, if `dir` is `'RTL'`:
1. In the formatted output,
prefix `fmt` with U+2067 RIGHT-TO-LEFT ISOLATE
and postfix it with U+2069 POP DIRECTIONAL ISOLATE.
1. `B(exp)` is
`fmt` prefixed with U+2067 RIGHT-TO-LEFT ISOLATE
and postfixed with U+2069 POP DIRECTIONAL ISOLATE.
1. Else:
1. In the formatted output,
prefix `fmt` with U+2068 FIRST STRONG ISOLATE
and postfix it with U+2069 POP DIRECTIONAL ISOLATE.
1. `B(exp)` is
`fmt` prefixed with U+2068 FIRST STRONG ISOLATE
and postfixed with U+2069 POP DIRECTIONAL ISOLATE.