[bicep console] Use visitor pattern to handle multi-line inputs

[levimatheri]

Description

Use visitor pattern to handle more multi-line input scenarios, including standalone expressions (previously this only worked for VariableDeclarationSyntax).

Example Usage

Recording.2025-10-07.213924.mp4

Checklist

• I have read and adhere to the contribution guide.

Microsoft Reviewers: Open in CodeFlow

[github-actions]

Test this change out locally with the following install scripts (Action run 18390422032)

VSCode

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-vsix.sh) --run-id 18390422032

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-vsix.ps1) } -RunId 18390422032"

Azure CLI

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-cli.sh) --run-id 18390422032

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-cli.ps1) } -RunId 18390422032"

[github-actions]

Dotnet Test Results

    96 files   -     48      96 suites   - 48   42m 16s ⏱️ - 38m 13s
12 426 tests +     3  12 426 ✅ +     4  0 💤 ±0  0 ❌  - 1 
28 597 runs   - 14 244  28 597 ✅  - 14 243  0 💤 ±0  0 ❌  - 1 

Results for commit 991a3f9. ± Comparison against base commit 6bb5d5f.

This pull request removes 1919 and adds 668 tests. Note that renamed tests count towards both.

		nestedProp1: 1
		nestedProp2: 2
		prop1: true
		prop2: false
	1
	2
	\$'")
	prop1: true
	prop2: false
…

Bicep.Cli.UnitTests.Helpers.Repl.StructuralCompletenessHelperTests ‑ IsStructurallyComplete_CompleteExpressions_ReturnsExpectedResult ("'''
Hello
World
'''",True)
Bicep.Cli.UnitTests.Helpers.Repl.StructuralCompletenessHelperTests ‑ IsStructurallyComplete_CompleteExpressions_ReturnsExpectedResult ("'''
Hello
World",False)
Bicep.Cli.UnitTests.Helpers.Repl.StructuralCompletenessHelperTests ‑ IsStructurallyComplete_CompleteExpressions_ReturnsExpectedResult ("'hello'",True)
Bicep.Cli.UnitTests.Helpers.Repl.StructuralCompletenessHelperTests ‑ IsStructurallyComplete_CompleteExpressions_ReturnsExpectedResult ("(length(",False)
Bicep.Cli.UnitTests.Helpers.Repl.StructuralCompletenessHelperTests ‑ IsStructurallyComplete_CompleteExpressions_ReturnsExpectedResult ("42",True)
Bicep.Cli.UnitTests.Helpers.Repl.StructuralCompletenessHelperTests ‑ IsStructurallyComplete_CompleteExpressions_ReturnsExpectedResult ("[",False)
Bicep.Cli.UnitTests.Helpers.Repl.StructuralCompletenessHelperTests ‑ IsStructurallyComplete_CompleteExpressions_ReturnsExpectedResult ("filter(map([1,2],
x => x + 1),
y => y % 2 == 0",False)
Bicep.Cli.UnitTests.Helpers.Repl.StructuralCompletenessHelperTests ‑ IsStructurallyComplete_CompleteExpressions_ReturnsExpectedResult ("filter(map([1,2],",False)
Bicep.Cli.UnitTests.Helpers.Repl.StructuralCompletenessHelperTests ‑ IsStructurallyComplete_CompleteExpressions_ReturnsExpectedResult ("items([1, 2, 3])",True)
Bicep.Cli.UnitTests.Helpers.Repl.StructuralCompletenessHelperTests ‑ IsStructurallyComplete_CompleteExpressions_ReturnsExpectedResult ("items({",False)
…

♻️ This comment has been updated with latest results.

[anthony-c-martin]

One possible complexity with the visitor pattern is that you can get "stuck" inside a piece of deeply nested syntax - e.g. something like:

{
  foo: {
    bar: [
      'abc'
    abc: 'def'
  }
}

Here I accidentally missed a ], and so my expression is not structurally complete. It's not very clear to me that I need to type a ], and so it could feel like I'm "stuck" - e.g. I can't exit the statement whatever I press.

Is that something to consider here, or do you have a mitigation for this already?

[levimatheri]

handled via #18320