TOML: structured DottedKey AST and path-lookup utilities

[knutwannheden]

Motivation

A dotted TOML key like physical.color was previously flattened into a single Toml.Identifier whose name was the joined string of all child tokens. That representation cannot distinguish site."google.com" (two segments, the second containing a literal dot) from site.google.com (three bare segments) — both became the string site.google.com.

The same logical key in TOML can be written in many equivalent ways:

[a.b.c]
x = 1

[a]
[a.b]
[a.b.c]
x = 1

a.b.c.x = 1

[a.b]
c.x = 1

Recipes wanting to find or modify a value at a logical key path each ended up doing ad-hoc traversal that handled only some of these forms.

Examples

A new Toml.DottedKey AST node carries an ordered list of segments:

Toml.KeyValue kv = ...;  // physical.color = "orange"
TomlKey key = kv.getKey();
key.getPath();  // ["physical", "color"]

Quoted segments containing literal dots stay one segment:

// site."google.com" = true
Toml.KeyValue kv = ...;
kv.getKey().getPath();  // ["site", "google.com"]   — length 2

// site.google.com = false
Toml.KeyValue other = ...;
other.getKey().getPath();  // ["site", "google", "com"]   — length 3

A new TomlPaths static utility resolves a logical path to a KeyValue (or Table) regardless of authoring form:

Toml.Document doc = ...;  // any of the four equivalent forms above
Toml.KeyValue found = TomlPaths.findKeyValue(doc, List.of("a", "b", "c", "x"));
// non-null in every case; null when no such key exists

Summary

• Adds Toml.DottedKey implements TomlKey with List<TomlRightPadded<Toml.Identifier>> segments. Each segment preserves its own prefix/source for round-tripping; right-padding holds the whitespace before the next dot. Dots are emitted by the printer between segments and not stored.
• Widens Toml.Table.name from TomlRightPadded<Toml.Identifier> to TomlRightPadded<TomlKey> so headers can carry either shape.
• Adds TomlKey#getPath() returning the canonical unquoted segment list (length 1 for Identifier, N for DottedKey), and TomlKey#getName() returning the dot-joined form. The latter matches existing Identifier.getName() semantics so consumers comparing names as strings keep working unchanged.
• New org.openrewrite.toml.TomlPaths static utility with findKeyValue and findTable.
• TomlVisitor.visitTable now visits the table name (previously the name was silently skipped, breaking visitor-based transformations targeting headers).
• SemanticallyEqual.keyEquals and TomlPathMatcher.buildPath simplified to use getPath().
• PythonDependencyParser.indexTables adjusted so dotted-header tables (e.g. [tool.uv]) keep being indexed under their joined name.

Builds on the simple-key strip-quotes work landed in #7521.

Test plan

• TomlParserTest.dottedKeys extended with structural assertions distinguishing site."google.com" (2 segments) from site.google.com (3 segments).
• TomlParserTest.extraWhitespaceTable extended with structural assertion that [a.b.c] and [ j . "ʞ" . 'l' ] produce 3-segment DottedKey.
• New TomlPathsTest covering each equivalent authoring form resolving to the same path, quoted-segment-with-dot semantics, missing-path returns null, and array tables not searched.
• All existing :rewrite-toml:test tests pass (round-trip preservation for every fixture).
• :rewrite-python:test passes for all TOML-touching tests.