8257912: Convert enum iteration to use range-based for loops

[iklam]

Now that range-based for loops are allowed by the HotSpot Style Guide, I have converted the more verbose syntax:

for (vmIntrinsicsIterator it = vmIntrinsicsRange.begin(); it != vmIntrinsicsRange.end(); ++it) {
  vmIntrinsicID index = *it;
  nt[as_int(index)] = string;
}

to

  for (vmIntrinsicID index : EnumRange<vmIntrinsicID>{}) {
    nt[as_int(index)] = string;
  }

I also removed the "convenient" declarations such as vmIntrinsicsRange and vmIntrinsicsIterator -- these are useful only when writing a traditional for loop, and are probably confusing to everyone else. I've left examples in enumIterator.hpp in case anyone wants to write a traditional for loop.

I also added gtest cases for using range-based for loops with EnumRange<>.

---

Progress

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Issue

• JDK-8257912: Convert enum iteration to use range-based for loops

Reviewers

• Kim Barrett (@kimbarrett - Reviewer) ⚠️ Review applies to 26ad3f0
• Thomas Schatzl (@tschatzl - Reviewer) ⚠️ Review applies to 26ad3f0
• Gerard Ziemski (@gerard-ziemski - Committer) ⚠️ Review applies to 26ad3f0

Download

$ git fetch https://git.openjdk.java.net/jdk pull/1707/head:pull/1707
$ git checkout pull/1707

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[mlbridge]

Webrevs

• 01: Full - Incremental (ceaebee)
• 00: Full (26ad3f0)

[openjdk]

@iklam This change now passes all automated pre-integration checks.

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After integration, the commit message for the final commit will be:

8257912: Convert enum iteration to use range-based for loops

Reviewed-by: kbarrett, tschatzl, gziemski

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At the time when this comment was updated there had been 4 new commits pushed to the master branch:

• 164c55b: 8258056: jdk/javadoc/doclet/testHtmlTableTags/TestHtmlTableTags.java fails against jdk17
• 42264b2: 8257971: (fs) Remove unused code from WindowsPath.subpath(begin, end)
• 3342eca: 8258054: runtime/sealedClasses/GetPermittedSubclassesTest.java fails w/ jdk17
• f574056: 8256424: Move ciSymbol::symbol_name() to ciSymbols::symbol_name()

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[tschatzl]

Lgtm

[gerard-ziemski]

I like the change very much.

Did you consider leaving the convenience symbol "vmSymbolsIterator" as is and then using it in the loop, so instead of:

for (vmSymbolID index : EnumRange<vmSymbolID>{}) {

we would have:

for (vmSymbolID index : vmSymbolsIterator) {

which would be more concise (but less self-documenting I guess) and more similar to:

for (JVMFlagOrigin origin : range) {

[iklam]

I like the change very much.

Did you consider leaving the convenience symbol "vmSymbolsIterator" as is and then using it in the loop, so instead of:

for (vmSymbolID index : EnumRange<vmSymbolID>{}) {

we would have:

for (vmSymbolID index : vmSymbolsIterator) {

which would be more concise (but less self-documenting I guess) and more similar to:

for (JVMFlagOrigin origin : range) {

Hi Gerard, thanks for the review.

vmSymbolsIterator is the "cursor" type. I think you meant this:

for (vmSymbolID index : vmSymbolsRange{}) {...}

which is probably less readable, because you have to find out what vmSymbolsRange actually is.

I think the following pattern is easier to read. It will also make the iteration of different enum types more consistent. Iteration of any enum type E can be done the same way with EnumRange<E>. You don't need to invent a new ERange type.

for (MyEnumType e : EnumRange<MyEnumType>{}) {...}`

Note that the {} is required here because we need to construct an instance of EnumRange<MyEnumType> with its no-arg constructor. You can also use () but I think that would be less readable -- it's not clear whether you are calling a function or constructing an object. With {}, it's clear that we are making an initialization with the brace operator.

You can also initialize a non-default range with EnumRange<MyEnumType>{start, end}, etc.

[iklam]

/integrate

[openjdk]

@iklam Since your change was applied there have been 4 commits pushed to the master branch:

• 164c55b: 8258056: jdk/javadoc/doclet/testHtmlTableTags/TestHtmlTableTags.java fails against jdk17
• 42264b2: 8257971: (fs) Remove unused code from WindowsPath.subpath(begin, end)
• 3342eca: 8258054: runtime/sealedClasses/GetPermittedSubclassesTest.java fails w/ jdk17
• f574056: 8256424: Move ciSymbol::symbol_name() to ciSymbols::symbol_name()

Your commit was automatically rebased without conflicts.

Pushed as commit 80dac5a.

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